Jen Smith

Crowd at ASCO 2015

©ASCO/Rodney White

CHICAGO—A 3-drug combination is safe and highly active in certain patients with relapsed B-cell malignancies, according to a speaker at the 2015 ASCO Annual Meeting.

The combination consists of the anti-CD20 monoclonal antibody ublituximab, the PI3Kδ inhibitor TGR-1202, and the BTK inhibitor ibrutinib.

In a small, phase 1 study, the triplet produced an overall response rate of 62%. It was particularly active in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and those with mantle cell lymphoma (MCL).

The most common adverse events were infusion reactions, gastrointestinal events, rash, and fatigue. Grade 3 neutropenia and leukopenia occurred in 1 patient each.

Nathan Fowler, MD, of MD Anderson Cancer Center in Houston, Texas, presented these results at the meeting as abstract 8501.*

The trial enrolled 16 patients with CLL/SLL or non-Hodgkin lymphoma (NHL). Four had CLL, 1 had SLL, and 1 had Richter’s transformation. Four patients had follicular lymphoma (FL), 3 had diffuse large B-cell lymphoma (DLBCL), 2 had mantle cell lymphoma (MCL), and 1 had marginal zone lymphoma (MZL).

The patients’ median age was 63, and their median number of prior treatment regimens was 4 (range, 1-5). Fifty percent of patients (n=8) were refractory to prior therapy.

Treatment consisted of 900 mg of ublituximab, ibrutinib at either 420 mg (CLL/SLL) or 560 mg (NHL), and TGR-1202 at 3 different doses: 400 mg, 600 mg, or 800 mg. Ibrutinib and TGR-1202 were given once-daily beginning on day 1 of each cycle. Ublituximab was given on days 1, 8, and 15 of cycles 1 and 2, then on day 1 of cycles 4, 6, 9, and 12.

Safety and efficacy

Sixteen patients were evaluable for safety and 13 for efficacy. One of the patients was removed from the efficacy analysis at the discretion of the investigators, and it was too early to evaluate the other 2 patients.

The median time on study was 4 months (range, 1-9 months). The 5 CLL/SLL patients received TGR-1202 at 400 mg. One of these patients had a dose-limiting toxicity—reactivation of varicella zoster.

Of the NHL patients, 3 received TGR-1202 at 400 mg, 4 received 600 mg, and 4 received 800 mg. There were no dose-limiting toxicities in any of these patients.

Adverse events that were considered possibly related to treatment included infusion reactions (25%), diarrhea (19%), nausea (19%), fatigue (19%), rash (19%), anemia (13%), neutropenia (13%), leukopenia (13%), and insomnia (13%). Grade 3 events included neutropenia and leukopenia (6% each), and there were no grade 4 events.

“The majority of patients have demonstrated a response to the therapy,” Dr Fowler said. “All of the patients that have responded continue on treatment, and the longest [treatment duration] is about 10 months.”

The only complete response occurred in a patient with MCL. Partial responses occurred in all 3 CLL patients, 2 FL patients, the SLL patient, the MZL patient, and 1 MCL patient. One patient with FL, 2 with DLBCL, and 1 with Richter’s transformation did not respond to treatment.

In closing, Dr Fowler said this treatment was well-tolerated and showed significant early activity in this heavily pretreated patient population. Dose-escalation with TGR-1202 continues at 800 mg, and phase 2 studies of the triplet are planned.

*Information in the abstract differs from that presented at the meeting.

Crowd at ASCO 2015

©ASCO/Rodney White

CHICAGO—A 3-drug combination is safe and highly active in certain patients with relapsed B-cell malignancies, according to a speaker at the 2015 ASCO Annual Meeting.

The combination consists of the anti-CD20 monoclonal antibody ublituximab, the PI3Kδ inhibitor TGR-1202, and the BTK inhibitor ibrutinib.

In a small, phase 1 study, the triplet produced an overall response rate of 62%. It was particularly active in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and those with mantle cell lymphoma (MCL).

The most common adverse events were infusion reactions, gastrointestinal events, rash, and fatigue. Grade 3 neutropenia and leukopenia occurred in 1 patient each.

Nathan Fowler, MD, of MD Anderson Cancer Center in Houston, Texas, presented these results at the meeting as abstract 8501.*

The trial enrolled 16 patients with CLL/SLL or non-Hodgkin lymphoma (NHL). Four had CLL, 1 had SLL, and 1 had Richter’s transformation. Four patients had follicular lymphoma (FL), 3 had diffuse large B-cell lymphoma (DLBCL), 2 had mantle cell lymphoma (MCL), and 1 had marginal zone lymphoma (MZL).

The patients’ median age was 63, and their median number of prior treatment regimens was 4 (range, 1-5). Fifty percent of patients (n=8) were refractory to prior therapy.

Treatment consisted of 900 mg of ublituximab, ibrutinib at either 420 mg (CLL/SLL) or 560 mg (NHL), and TGR-1202 at 3 different doses: 400 mg, 600 mg, or 800 mg. Ibrutinib and TGR-1202 were given once-daily beginning on day 1 of each cycle. Ublituximab was given on days 1, 8, and 15 of cycles 1 and 2, then on day 1 of cycles 4, 6, 9, and 12.

Safety and efficacy

Sixteen patients were evaluable for safety and 13 for efficacy. One of the patients was removed from the efficacy analysis at the discretion of the investigators, and it was too early to evaluate the other 2 patients.

The median time on study was 4 months (range, 1-9 months). The 5 CLL/SLL patients received TGR-1202 at 400 mg. One of these patients had a dose-limiting toxicity—reactivation of varicella zoster.

Of the NHL patients, 3 received TGR-1202 at 400 mg, 4 received 600 mg, and 4 received 800 mg. There were no dose-limiting toxicities in any of these patients.

Adverse events that were considered possibly related to treatment included infusion reactions (25%), diarrhea (19%), nausea (19%), fatigue (19%), rash (19%), anemia (13%), neutropenia (13%), leukopenia (13%), and insomnia (13%). Grade 3 events included neutropenia and leukopenia (6% each), and there were no grade 4 events.

“The majority of patients have demonstrated a response to the therapy,” Dr Fowler said. “All of the patients that have responded continue on treatment, and the longest [treatment duration] is about 10 months.”

The only complete response occurred in a patient with MCL. Partial responses occurred in all 3 CLL patients, 2 FL patients, the SLL patient, the MZL patient, and 1 MCL patient. One patient with FL, 2 with DLBCL, and 1 with Richter’s transformation did not respond to treatment.

In closing, Dr Fowler said this treatment was well-tolerated and showed significant early activity in this heavily pretreated patient population. Dose-escalation with TGR-1202 continues at 800 mg, and phase 2 studies of the triplet are planned.

*Information in the abstract differs from that presented at the meeting.

Crowd at ASCO 2015

©ASCO/Rodney White

CHICAGO—A 3-drug combination is safe and highly active in certain patients with relapsed B-cell malignancies, according to a speaker at the 2015 ASCO Annual Meeting.

The combination consists of the anti-CD20 monoclonal antibody ublituximab, the PI3Kδ inhibitor TGR-1202, and the BTK inhibitor ibrutinib.

In a small, phase 1 study, the triplet produced an overall response rate of 62%. It was particularly active in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and those with mantle cell lymphoma (MCL).

The most common adverse events were infusion reactions, gastrointestinal events, rash, and fatigue. Grade 3 neutropenia and leukopenia occurred in 1 patient each.

Nathan Fowler, MD, of MD Anderson Cancer Center in Houston, Texas, presented these results at the meeting as abstract 8501.*

The trial enrolled 16 patients with CLL/SLL or non-Hodgkin lymphoma (NHL). Four had CLL, 1 had SLL, and 1 had Richter’s transformation. Four patients had follicular lymphoma (FL), 3 had diffuse large B-cell lymphoma (DLBCL), 2 had mantle cell lymphoma (MCL), and 1 had marginal zone lymphoma (MZL).

The patients’ median age was 63, and their median number of prior treatment regimens was 4 (range, 1-5). Fifty percent of patients (n=8) were refractory to prior therapy.

Treatment consisted of 900 mg of ublituximab, ibrutinib at either 420 mg (CLL/SLL) or 560 mg (NHL), and TGR-1202 at 3 different doses: 400 mg, 600 mg, or 800 mg. Ibrutinib and TGR-1202 were given once-daily beginning on day 1 of each cycle. Ublituximab was given on days 1, 8, and 15 of cycles 1 and 2, then on day 1 of cycles 4, 6, 9, and 12.

Safety and efficacy

Sixteen patients were evaluable for safety and 13 for efficacy. One of the patients was removed from the efficacy analysis at the discretion of the investigators, and it was too early to evaluate the other 2 patients.

The median time on study was 4 months (range, 1-9 months). The 5 CLL/SLL patients received TGR-1202 at 400 mg. One of these patients had a dose-limiting toxicity—reactivation of varicella zoster.

Of the NHL patients, 3 received TGR-1202 at 400 mg, 4 received 600 mg, and 4 received 800 mg. There were no dose-limiting toxicities in any of these patients.

Adverse events that were considered possibly related to treatment included infusion reactions (25%), diarrhea (19%), nausea (19%), fatigue (19%), rash (19%), anemia (13%), neutropenia (13%), leukopenia (13%), and insomnia (13%). Grade 3 events included neutropenia and leukopenia (6% each), and there were no grade 4 events.

“The majority of patients have demonstrated a response to the therapy,” Dr Fowler said. “All of the patients that have responded continue on treatment, and the longest [treatment duration] is about 10 months.”

The only complete response occurred in a patient with MCL. Partial responses occurred in all 3 CLL patients, 2 FL patients, the SLL patient, the MZL patient, and 1 MCL patient. One patient with FL, 2 with DLBCL, and 1 with Richter’s transformation did not respond to treatment.

In closing, Dr Fowler said this treatment was well-tolerated and showed significant early activity in this heavily pretreated patient population. Dose-escalation with TGR-1202 continues at 800 mg, and phase 2 studies of the triplet are planned.

*Information in the abstract differs from that presented at the meeting.

Crowd at ASCO 2015

© ASCO/Rodney White

CHICAGO—Researchers say they have identified 3 leukemia stem cell (LSC) phenotypes that are correlated with cytogenetic/molecular abnormalities and prognosis in acute myeloid leukemia (AML).

The investigators believe this knowledge could aid risk stratification of AML patients, particularly those without identifiable cytogenetic or molecular risk factors.

The findings may also pave the way for scientists to identify novel therapeutic targets on LSCs and monitor LSCs in response to therapy.

Jonathan Michael Gerber, MD, of Levine Cancer Institute in Charlotte, North Carolina, presented the findings at the 2015 ASCO Annual Meeting (abstract 7000*).

Via previous research, Dr Gerber and his colleagues identified 3 different LSC phenotypes in AML:

• LSCs that are CD34-negative
• LSCs that are CD34-positive, CD38-negative, and have intermediate levels of aldehyde dehydrogenase (ALDH^int)
• LSCs that are CD34-positive, CD38-negative, and have high levels of ALDH (ALDH^high).

With the current study, the researchers wanted to determine if these phenotypes correlate with cytogenetic/molecular features and treatment outcomes.

So they analyzed diagnostic samples from 98 patients with newly diagnosed AML who had normal or unfavorable cytogenetics. The patients were enrolled on a phase 2 trial comparing FLAM and 7+3 (Zeidner et al, haematologica 2015).

Dr Gerber and his colleagues identified 22 patients with CD34^- LSCs, 43 with ALDH^int LSCs, and 33 with ALDH^high LSCs.

Risk factors

“We found that leukemia stem cell phenotype indeed correlated quite strongly with cytogenetic and molecular risk factors,” Dr Gerber said.

NPM1 mutations were more common in patients with CD34^- LSCs (64%) than those with ALDH^int LSCs (14%) or ALDH^high LSCs (6%, P<0.001). NPM1 mutations were the sole abnormality in 50% of patients with CD34^- LSCs.

Poor-risk cytogenetics and/or FLT3-ITD mutations were more common in patients with ALDH^high LSCs (85%) than those with ALDH^int LCSs (35%) or CD34^- LSCs (18%, P<0.001).

Nine percent of patients in the CD34^- LSC group fell into the European Leukemia Network poor-risk category, compared to 73% of patients in the ALDH^high LSC group.

Only 2 patients had 11q23, and both had CD34^- LSCs. Fifty-five percent of patients with ALDH^high LSCs had prior myelodysplastic syndromes or myeloproliferative neoplasms.

Prognosis

“We found that leukemia stem cell phenotype correlated strongly with outcomes as well,” Dr Gerber said. “It turned out that CD34^- patients fared more favorably overall.”

Patients with CD34^- LSCs had the highest complete response rate (86%), followed by those with ALDH^int LSCs (67%) and ALDH^high LSCs (45%, P<0.01).

Patients in the CD34^- group also had a higher rate of event-free survival at 2 years (46%) than patients in the ALDH^int group (26%) or the ALDH^high group (0%). The median event-free survival was 13 months, 11.3 months, and 2.2 months, respectively (P<0.01).

The rate of overall survival at 2 years was best for the CD34^- group (76%), followed by the ALDH^int group (38%) and the ALDH^high group (34%). The median overall survival was not reached, 18.7 months, and 9.4 months, respectively (P=0.02).

Dr Gerber also noted that ALDH^high patients fared much better if they underwent hematopoietic stem cell transplant.

“There is 0% leukemia-free survival at the 2-year mark for the ALDH^high patients who were not transplanted,” he said. “Those that were transplanted fared about the same as everyone else in the series. So it was very striking that there were no chemotherapy survivors in that group.”

In closing, Dr Gerber said this research suggests the 3 LSC phenotypes are mutually exclusive and correlate with cytogenetic and molecular risk factors as well as outcomes in patients with AML.

“This [discovery] may allow for rapid risk stratification in this explosive disease, facilitate enrollment onto induction protocols . . . , and allow us to divert those ALDH^high, very high-risk patients earlier to novel therapies and/or transplant, given that they’re not really helped much by conventional chemotherapy.”

*Information in the abstract differs from that presented at the meeting.

Crowd at ASCO 2015

© ASCO/Rodney White

CHICAGO—Researchers say they have identified 3 leukemia stem cell (LSC) phenotypes that are correlated with cytogenetic/molecular abnormalities and prognosis in acute myeloid leukemia (AML).

The investigators believe this knowledge could aid risk stratification of AML patients, particularly those without identifiable cytogenetic or molecular risk factors.

The findings may also pave the way for scientists to identify novel therapeutic targets on LSCs and monitor LSCs in response to therapy.

Jonathan Michael Gerber, MD, of Levine Cancer Institute in Charlotte, North Carolina, presented the findings at the 2015 ASCO Annual Meeting (abstract 7000*).

Via previous research, Dr Gerber and his colleagues identified 3 different LSC phenotypes in AML:

• LSCs that are CD34-negative
• LSCs that are CD34-positive, CD38-negative, and have intermediate levels of aldehyde dehydrogenase (ALDH^int)
• LSCs that are CD34-positive, CD38-negative, and have high levels of ALDH (ALDH^high).

With the current study, the researchers wanted to determine if these phenotypes correlate with cytogenetic/molecular features and treatment outcomes.

So they analyzed diagnostic samples from 98 patients with newly diagnosed AML who had normal or unfavorable cytogenetics. The patients were enrolled on a phase 2 trial comparing FLAM and 7+3 (Zeidner et al, haematologica 2015).

Dr Gerber and his colleagues identified 22 patients with CD34^- LSCs, 43 with ALDH^int LSCs, and 33 with ALDH^high LSCs.

Risk factors

“We found that leukemia stem cell phenotype indeed correlated quite strongly with cytogenetic and molecular risk factors,” Dr Gerber said.

NPM1 mutations were more common in patients with CD34^- LSCs (64%) than those with ALDH^int LSCs (14%) or ALDH^high LSCs (6%, P<0.001). NPM1 mutations were the sole abnormality in 50% of patients with CD34^- LSCs.

Poor-risk cytogenetics and/or FLT3-ITD mutations were more common in patients with ALDH^high LSCs (85%) than those with ALDH^int LCSs (35%) or CD34^- LSCs (18%, P<0.001).

Nine percent of patients in the CD34^- LSC group fell into the European Leukemia Network poor-risk category, compared to 73% of patients in the ALDH^high LSC group.

Only 2 patients had 11q23, and both had CD34^- LSCs. Fifty-five percent of patients with ALDH^high LSCs had prior myelodysplastic syndromes or myeloproliferative neoplasms.

Prognosis

“We found that leukemia stem cell phenotype correlated strongly with outcomes as well,” Dr Gerber said. “It turned out that CD34^- patients fared more favorably overall.”

Patients with CD34^- LSCs had the highest complete response rate (86%), followed by those with ALDH^int LSCs (67%) and ALDH^high LSCs (45%, P<0.01).

Patients in the CD34^- group also had a higher rate of event-free survival at 2 years (46%) than patients in the ALDH^int group (26%) or the ALDH^high group (0%). The median event-free survival was 13 months, 11.3 months, and 2.2 months, respectively (P<0.01).

The rate of overall survival at 2 years was best for the CD34^- group (76%), followed by the ALDH^int group (38%) and the ALDH^high group (34%). The median overall survival was not reached, 18.7 months, and 9.4 months, respectively (P=0.02).

Dr Gerber also noted that ALDH^high patients fared much better if they underwent hematopoietic stem cell transplant.

“There is 0% leukemia-free survival at the 2-year mark for the ALDH^high patients who were not transplanted,” he said. “Those that were transplanted fared about the same as everyone else in the series. So it was very striking that there were no chemotherapy survivors in that group.”

In closing, Dr Gerber said this research suggests the 3 LSC phenotypes are mutually exclusive and correlate with cytogenetic and molecular risk factors as well as outcomes in patients with AML.

“This [discovery] may allow for rapid risk stratification in this explosive disease, facilitate enrollment onto induction protocols . . . , and allow us to divert those ALDH^high, very high-risk patients earlier to novel therapies and/or transplant, given that they’re not really helped much by conventional chemotherapy.”

*Information in the abstract differs from that presented at the meeting.

Crowd at ASCO 2015

© ASCO/Rodney White

CHICAGO—Researchers say they have identified 3 leukemia stem cell (LSC) phenotypes that are correlated with cytogenetic/molecular abnormalities and prognosis in acute myeloid leukemia (AML).

The investigators believe this knowledge could aid risk stratification of AML patients, particularly those without identifiable cytogenetic or molecular risk factors.

The findings may also pave the way for scientists to identify novel therapeutic targets on LSCs and monitor LSCs in response to therapy.

Jonathan Michael Gerber, MD, of Levine Cancer Institute in Charlotte, North Carolina, presented the findings at the 2015 ASCO Annual Meeting (abstract 7000*).

Via previous research, Dr Gerber and his colleagues identified 3 different LSC phenotypes in AML:

• LSCs that are CD34-negative
• LSCs that are CD34-positive, CD38-negative, and have intermediate levels of aldehyde dehydrogenase (ALDH^int)
• LSCs that are CD34-positive, CD38-negative, and have high levels of ALDH (ALDH^high).

With the current study, the researchers wanted to determine if these phenotypes correlate with cytogenetic/molecular features and treatment outcomes.

So they analyzed diagnostic samples from 98 patients with newly diagnosed AML who had normal or unfavorable cytogenetics. The patients were enrolled on a phase 2 trial comparing FLAM and 7+3 (Zeidner et al, haematologica 2015).

Dr Gerber and his colleagues identified 22 patients with CD34^- LSCs, 43 with ALDH^int LSCs, and 33 with ALDH^high LSCs.

Risk factors

“We found that leukemia stem cell phenotype indeed correlated quite strongly with cytogenetic and molecular risk factors,” Dr Gerber said.

NPM1 mutations were more common in patients with CD34^- LSCs (64%) than those with ALDH^int LSCs (14%) or ALDH^high LSCs (6%, P<0.001). NPM1 mutations were the sole abnormality in 50% of patients with CD34^- LSCs.

Poor-risk cytogenetics and/or FLT3-ITD mutations were more common in patients with ALDH^high LSCs (85%) than those with ALDH^int LCSs (35%) or CD34^- LSCs (18%, P<0.001).

Nine percent of patients in the CD34^- LSC group fell into the European Leukemia Network poor-risk category, compared to 73% of patients in the ALDH^high LSC group.

Only 2 patients had 11q23, and both had CD34^- LSCs. Fifty-five percent of patients with ALDH^high LSCs had prior myelodysplastic syndromes or myeloproliferative neoplasms.

Prognosis

“We found that leukemia stem cell phenotype correlated strongly with outcomes as well,” Dr Gerber said. “It turned out that CD34^- patients fared more favorably overall.”

Patients with CD34^- LSCs had the highest complete response rate (86%), followed by those with ALDH^int LSCs (67%) and ALDH^high LSCs (45%, P<0.01).

Patients in the CD34^- group also had a higher rate of event-free survival at 2 years (46%) than patients in the ALDH^int group (26%) or the ALDH^high group (0%). The median event-free survival was 13 months, 11.3 months, and 2.2 months, respectively (P<0.01).

The rate of overall survival at 2 years was best for the CD34^- group (76%), followed by the ALDH^int group (38%) and the ALDH^high group (34%). The median overall survival was not reached, 18.7 months, and 9.4 months, respectively (P=0.02).

Dr Gerber also noted that ALDH^high patients fared much better if they underwent hematopoietic stem cell transplant.

“There is 0% leukemia-free survival at the 2-year mark for the ALDH^high patients who were not transplanted,” he said. “Those that were transplanted fared about the same as everyone else in the series. So it was very striking that there were no chemotherapy survivors in that group.”

In closing, Dr Gerber said this research suggests the 3 LSC phenotypes are mutually exclusive and correlate with cytogenetic and molecular risk factors as well as outcomes in patients with AML.

“This [discovery] may allow for rapid risk stratification in this explosive disease, facilitate enrollment onto induction protocols . . . , and allow us to divert those ALDH^high, very high-risk patients earlier to novel therapies and/or transplant, given that they’re not really helped much by conventional chemotherapy.”

*Information in the abstract differs from that presented at the meeting.

CLL cells

PHILADELPHIA—A DNA-dependent protein kinase (DNA-PK) inhibitor can sensitize chronic lymphocytic leukemia (CLL) cells to chemotherapy, according to

preclinical research.

The inhibitor, NDD0004, sensitized CLL cells—even those from patients with high-risk cytogenetics—to treatment with mitoxantrone.

However, not all CLL samples were sensitive to treatment, so researchers are now trying to determine which patients might derive benefit from DNA-PK inhibitors.

Gesa Junge, a PhD student at Newcastle University in the UK, and her colleagues conducted this research and presented the results at the AACR Annual Meeting 2015 (abstract 3624*). The work was supported by AstraZeneca.

The researchers’ goal was to validate that DNA-PK inhibition is a valid approach to chemosensitization in CLL. So the team tested NU7441—a compound that inhibits DNA-PK and PI3 kinase—and NDD0004—a more selective DNA-PK inhibitor.

The team isolated CLL cells from patients’ peripheral blood, cultured the cells, and treated them with mitoxantrone and/or 1μM of NDD0004 or 1μM of NU7441.

Junge and her colleagues found that NDD0004 sensitized cells to mitoxantrone more effectively than NU7441. Sensitization was 202-fold higher with NDD004 plus mitoxantrone than with mitoxantrone alone and 69-fold higher with NU7441 plus mitoxantrone than with mitoxantrone alone (P=0.02).

However, sensitization varied between CLL samples, and the researchers have yet to determine why. Their experiments showed that variability was not a result of DNA-PK levels.

Still, the team found that CLL cells from patients with poor prognostic markers were sensitive to DNA-PK inhibition.

Sensitization with NU7441 plus mitoxantrone was 69-fold higher than mitoxantrone alone in CLL samples with del(13q), 25-fold higher in samples with del(11q), 12-fold higher in samples with TP53 mutation, and 16-fold higher in samples with ATM dysfunction.

Sensitization with NDD0004 plus mitoxantrone was 201-fold higher than mitoxantrone alone in CLL samples with del(13q), 314-fold higher in samples with del(11q), 27-fold higher in samples with TP53 mutation, and 18-fold higher in samples with ATM dysfunction.

To confirm that sensitization was a result of DNA-PK inhibition, Junge and her colleagues tested NDD0004 in an isogenic pair of DNA-PK-deficient and DNA-PK-proficient HCT116 cells. They found that HCT116 cells lacking DNA-PK were not sensitive to NDD0004, but cells with DNA-PK were sensitive.

The researchers also investigated the mechanism of NDD0004. Their results suggest the drug works by inhibiting the repair of DNA double-strand breaks.

“What we think is happening is that we are inducing DNA damage with mitoxantrone, and that gets repaired by 24 hours,” Junge said. “But if the DNA-PK inhibitor is there, the damage persists, and that seems to translate quite nicely into an apoptosis response.”

To further this research, Junge and her colleagues are hoping to identify biomarkers that can help them determine which CLL patients are likely to respond to DNA-PK inhibitors.

*Information in the abstract differs from that presented at the meeting.

CLL cells

PHILADELPHIA—A DNA-dependent protein kinase (DNA-PK) inhibitor can sensitize chronic lymphocytic leukemia (CLL) cells to chemotherapy, according to

preclinical research.

The inhibitor, NDD0004, sensitized CLL cells—even those from patients with high-risk cytogenetics—to treatment with mitoxantrone.

However, not all CLL samples were sensitive to treatment, so researchers are now trying to determine which patients might derive benefit from DNA-PK inhibitors.

Gesa Junge, a PhD student at Newcastle University in the UK, and her colleagues conducted this research and presented the results at the AACR Annual Meeting 2015 (abstract 3624*). The work was supported by AstraZeneca.

The researchers’ goal was to validate that DNA-PK inhibition is a valid approach to chemosensitization in CLL. So the team tested NU7441—a compound that inhibits DNA-PK and PI3 kinase—and NDD0004—a more selective DNA-PK inhibitor.

The team isolated CLL cells from patients’ peripheral blood, cultured the cells, and treated them with mitoxantrone and/or 1μM of NDD0004 or 1μM of NU7441.

Junge and her colleagues found that NDD0004 sensitized cells to mitoxantrone more effectively than NU7441. Sensitization was 202-fold higher with NDD004 plus mitoxantrone than with mitoxantrone alone and 69-fold higher with NU7441 plus mitoxantrone than with mitoxantrone alone (P=0.02).

However, sensitization varied between CLL samples, and the researchers have yet to determine why. Their experiments showed that variability was not a result of DNA-PK levels.

Still, the team found that CLL cells from patients with poor prognostic markers were sensitive to DNA-PK inhibition.

Sensitization with NU7441 plus mitoxantrone was 69-fold higher than mitoxantrone alone in CLL samples with del(13q), 25-fold higher in samples with del(11q), 12-fold higher in samples with TP53 mutation, and 16-fold higher in samples with ATM dysfunction.

Sensitization with NDD0004 plus mitoxantrone was 201-fold higher than mitoxantrone alone in CLL samples with del(13q), 314-fold higher in samples with del(11q), 27-fold higher in samples with TP53 mutation, and 18-fold higher in samples with ATM dysfunction.

To confirm that sensitization was a result of DNA-PK inhibition, Junge and her colleagues tested NDD0004 in an isogenic pair of DNA-PK-deficient and DNA-PK-proficient HCT116 cells. They found that HCT116 cells lacking DNA-PK were not sensitive to NDD0004, but cells with DNA-PK were sensitive.

The researchers also investigated the mechanism of NDD0004. Their results suggest the drug works by inhibiting the repair of DNA double-strand breaks.

“What we think is happening is that we are inducing DNA damage with mitoxantrone, and that gets repaired by 24 hours,” Junge said. “But if the DNA-PK inhibitor is there, the damage persists, and that seems to translate quite nicely into an apoptosis response.”

To further this research, Junge and her colleagues are hoping to identify biomarkers that can help them determine which CLL patients are likely to respond to DNA-PK inhibitors.

*Information in the abstract differs from that presented at the meeting.

CLL cells

PHILADELPHIA—A DNA-dependent protein kinase (DNA-PK) inhibitor can sensitize chronic lymphocytic leukemia (CLL) cells to chemotherapy, according to

preclinical research.

The inhibitor, NDD0004, sensitized CLL cells—even those from patients with high-risk cytogenetics—to treatment with mitoxantrone.

However, not all CLL samples were sensitive to treatment, so researchers are now trying to determine which patients might derive benefit from DNA-PK inhibitors.

Gesa Junge, a PhD student at Newcastle University in the UK, and her colleagues conducted this research and presented the results at the AACR Annual Meeting 2015 (abstract 3624*). The work was supported by AstraZeneca.

The researchers’ goal was to validate that DNA-PK inhibition is a valid approach to chemosensitization in CLL. So the team tested NU7441—a compound that inhibits DNA-PK and PI3 kinase—and NDD0004—a more selective DNA-PK inhibitor.

The team isolated CLL cells from patients’ peripheral blood, cultured the cells, and treated them with mitoxantrone and/or 1μM of NDD0004 or 1μM of NU7441.

Junge and her colleagues found that NDD0004 sensitized cells to mitoxantrone more effectively than NU7441. Sensitization was 202-fold higher with NDD004 plus mitoxantrone than with mitoxantrone alone and 69-fold higher with NU7441 plus mitoxantrone than with mitoxantrone alone (P=0.02).

However, sensitization varied between CLL samples, and the researchers have yet to determine why. Their experiments showed that variability was not a result of DNA-PK levels.

Still, the team found that CLL cells from patients with poor prognostic markers were sensitive to DNA-PK inhibition.

Sensitization with NU7441 plus mitoxantrone was 69-fold higher than mitoxantrone alone in CLL samples with del(13q), 25-fold higher in samples with del(11q), 12-fold higher in samples with TP53 mutation, and 16-fold higher in samples with ATM dysfunction.

Sensitization with NDD0004 plus mitoxantrone was 201-fold higher than mitoxantrone alone in CLL samples with del(13q), 314-fold higher in samples with del(11q), 27-fold higher in samples with TP53 mutation, and 18-fold higher in samples with ATM dysfunction.

To confirm that sensitization was a result of DNA-PK inhibition, Junge and her colleagues tested NDD0004 in an isogenic pair of DNA-PK-deficient and DNA-PK-proficient HCT116 cells. They found that HCT116 cells lacking DNA-PK were not sensitive to NDD0004, but cells with DNA-PK were sensitive.

The researchers also investigated the mechanism of NDD0004. Their results suggest the drug works by inhibiting the repair of DNA double-strand breaks.

“What we think is happening is that we are inducing DNA damage with mitoxantrone, and that gets repaired by 24 hours,” Junge said. “But if the DNA-PK inhibitor is there, the damage persists, and that seems to translate quite nicely into an apoptosis response.”

To further this research, Junge and her colleagues are hoping to identify biomarkers that can help them determine which CLL patients are likely to respond to DNA-PK inhibitors.

*Information in the abstract differs from that presented at the meeting.

PHILADELPHIA—The tumor microenvironment may play a key role in treatment with CUDC-427, according to researchers.

Their experiments showed that certain diffuse large B-cell lymphoma (DLBCL) cell lines were sensitive to CUDC-427, and others were not.

However, co-culturing with stromal cells or TNF family ligands made resistant cell lines sensitive to CUDC-427.

And mice bearing cells that resisted CUDC-427 in vitro responded very well to treatment, experiencing complete tumor regression.

Ze Tian, PhD, and her colleagues from Curis, Inc. (the company developing CUDC-427) presented these findings at the AACR Annual Meeting 2015 (abstract 5502).

CUDC-427 is an inhibitor of apoptosis (IAP) antagonist that is in early stage clinical testing in patients with solid tumors and lymphomas.

For the current research, Dr Tian and her colleagues first evaluated the effects of CUDC-427 against a range of hematologic malignancies in vitro. They tested the drug in activated B-cell-like (ABC) DLBCL, germinal center B-cell-like (GCB) DLBCL, other non-Hodgkin lymphomas, Hodgkin lymphoma, multiple myeloma, and various leukemia cell lines.

DLBCL cells (both ABC and GCB) proved the most sensitive to treatment, and CUDC-427 induced apoptosis in these cells. However, certain DLBCL cell lines, such as Karpas 422, were not sensitive to treatment.

The researchers found they could remedy that in two ways. The presence of stromal cells in culture sensitized resistant DLBCL cells to treatment, as did TNF family ligands (TNFα or TRAIL). In previous research, TNF family ligands were shown to synergize with IAP antagonists.

The investigators then analyzed CUDC-427’s mechanism of action. In the sensitive WSU-DLCL2 cell line, the drug worked by activating caspases 3, 8, and 9 by inhibiting cIAP1 and XIAP, as well as activating the non-canonical NF-ĸB pathway and inducing TNFα.

In the resistant Karpas 422 cell line, there was no caspase activity following CUDC-427 treatment. However, when the researchers co-cultured the cell line with stromal cells, they saw caspase activity.

“Because of this finding, we think that the microenvironment may play a role in CUDC-427 treatment,” Dr Tian said.

So the investigators went on to test CUDC-427 in mouse models. The drug inhibited tumor growth by 94% in the WSU-DLCL2 xenograft model. But CUDC-427 induced complete tumor regression in the Karpas 422 xenograft model.

To further investigate the interaction between the tumor microenvironment and CUDC-427, the researchers tested the drug in the A20 B-cell lymphoma mouse syngeneic model.

They found that CUDC-427 induced tumor stasis in this fast-growing lymphoma. They believe this may be due, in part, to the high levels of TRAIL in this model.

Dr Tian and her colleagues said the interaction between CUDC-427 and TNF family ligands or stromal cells warrants further analysis. And this research supports additional investigation to improve outcomes in patients with DLBCL.

PHILADELPHIA—The tumor microenvironment may play a key role in treatment with CUDC-427, according to researchers.

Their experiments showed that certain diffuse large B-cell lymphoma (DLBCL) cell lines were sensitive to CUDC-427, and others were not.

However, co-culturing with stromal cells or TNF family ligands made resistant cell lines sensitive to CUDC-427.

And mice bearing cells that resisted CUDC-427 in vitro responded very well to treatment, experiencing complete tumor regression.

Ze Tian, PhD, and her colleagues from Curis, Inc. (the company developing CUDC-427) presented these findings at the AACR Annual Meeting 2015 (abstract 5502).

CUDC-427 is an inhibitor of apoptosis (IAP) antagonist that is in early stage clinical testing in patients with solid tumors and lymphomas.

For the current research, Dr Tian and her colleagues first evaluated the effects of CUDC-427 against a range of hematologic malignancies in vitro. They tested the drug in activated B-cell-like (ABC) DLBCL, germinal center B-cell-like (GCB) DLBCL, other non-Hodgkin lymphomas, Hodgkin lymphoma, multiple myeloma, and various leukemia cell lines.

DLBCL cells (both ABC and GCB) proved the most sensitive to treatment, and CUDC-427 induced apoptosis in these cells. However, certain DLBCL cell lines, such as Karpas 422, were not sensitive to treatment.

The researchers found they could remedy that in two ways. The presence of stromal cells in culture sensitized resistant DLBCL cells to treatment, as did TNF family ligands (TNFα or TRAIL). In previous research, TNF family ligands were shown to synergize with IAP antagonists.

The investigators then analyzed CUDC-427’s mechanism of action. In the sensitive WSU-DLCL2 cell line, the drug worked by activating caspases 3, 8, and 9 by inhibiting cIAP1 and XIAP, as well as activating the non-canonical NF-ĸB pathway and inducing TNFα.

In the resistant Karpas 422 cell line, there was no caspase activity following CUDC-427 treatment. However, when the researchers co-cultured the cell line with stromal cells, they saw caspase activity.

“Because of this finding, we think that the microenvironment may play a role in CUDC-427 treatment,” Dr Tian said.

So the investigators went on to test CUDC-427 in mouse models. The drug inhibited tumor growth by 94% in the WSU-DLCL2 xenograft model. But CUDC-427 induced complete tumor regression in the Karpas 422 xenograft model.

To further investigate the interaction between the tumor microenvironment and CUDC-427, the researchers tested the drug in the A20 B-cell lymphoma mouse syngeneic model.

They found that CUDC-427 induced tumor stasis in this fast-growing lymphoma. They believe this may be due, in part, to the high levels of TRAIL in this model.

Dr Tian and her colleagues said the interaction between CUDC-427 and TNF family ligands or stromal cells warrants further analysis. And this research supports additional investigation to improve outcomes in patients with DLBCL.

PHILADELPHIA—The tumor microenvironment may play a key role in treatment with CUDC-427, according to researchers.

Their experiments showed that certain diffuse large B-cell lymphoma (DLBCL) cell lines were sensitive to CUDC-427, and others were not.

However, co-culturing with stromal cells or TNF family ligands made resistant cell lines sensitive to CUDC-427.

And mice bearing cells that resisted CUDC-427 in vitro responded very well to treatment, experiencing complete tumor regression.

Ze Tian, PhD, and her colleagues from Curis, Inc. (the company developing CUDC-427) presented these findings at the AACR Annual Meeting 2015 (abstract 5502).

CUDC-427 is an inhibitor of apoptosis (IAP) antagonist that is in early stage clinical testing in patients with solid tumors and lymphomas.

For the current research, Dr Tian and her colleagues first evaluated the effects of CUDC-427 against a range of hematologic malignancies in vitro. They tested the drug in activated B-cell-like (ABC) DLBCL, germinal center B-cell-like (GCB) DLBCL, other non-Hodgkin lymphomas, Hodgkin lymphoma, multiple myeloma, and various leukemia cell lines.

DLBCL cells (both ABC and GCB) proved the most sensitive to treatment, and CUDC-427 induced apoptosis in these cells. However, certain DLBCL cell lines, such as Karpas 422, were not sensitive to treatment.

The researchers found they could remedy that in two ways. The presence of stromal cells in culture sensitized resistant DLBCL cells to treatment, as did TNF family ligands (TNFα or TRAIL). In previous research, TNF family ligands were shown to synergize with IAP antagonists.

The investigators then analyzed CUDC-427’s mechanism of action. In the sensitive WSU-DLCL2 cell line, the drug worked by activating caspases 3, 8, and 9 by inhibiting cIAP1 and XIAP, as well as activating the non-canonical NF-ĸB pathway and inducing TNFα.

In the resistant Karpas 422 cell line, there was no caspase activity following CUDC-427 treatment. However, when the researchers co-cultured the cell line with stromal cells, they saw caspase activity.

“Because of this finding, we think that the microenvironment may play a role in CUDC-427 treatment,” Dr Tian said.

So the investigators went on to test CUDC-427 in mouse models. The drug inhibited tumor growth by 94% in the WSU-DLCL2 xenograft model. But CUDC-427 induced complete tumor regression in the Karpas 422 xenograft model.

To further investigate the interaction between the tumor microenvironment and CUDC-427, the researchers tested the drug in the A20 B-cell lymphoma mouse syngeneic model.

They found that CUDC-427 induced tumor stasis in this fast-growing lymphoma. They believe this may be due, in part, to the high levels of TRAIL in this model.

Dr Tian and her colleagues said the interaction between CUDC-427 and TNF family ligands or stromal cells warrants further analysis. And this research supports additional investigation to improve outcomes in patients with DLBCL.

PHILADELPHIA—Results of preclinical research suggest the BCL-2 inhibitor ABT-199 (venetoclax) may be effective in certain pediatric patients with acute lymphoblastic leukemia (ALL).

In xenograft models of various ALL subtypes, ABT-199 produced an objective response rate below 30%.

However, additional analyses unearthed information that could potentially help us identify which ALL patients might respond to the drug.

Santi Suryani, PhD, of the Children’s Cancer Institute in Sydney, New South Wales, Australia, and her colleagues presented this research at the AACR Annual Meeting 2015 (abstract 3276*). The work was supported by AbbVie, one of the companies developing ABT-199.

Dr Suryani and her colleagues decided to investigate ABT-199 in pediatric ALL after observing mixed results with the BCL-2/BCL-W/BCL-XL inhibitor ABT-263 (navitoclax).

ABT-263 delayed ALL progression in nearly all of the xenograft models the team tested and produced a 61% response rate. However, the drug also induced BCL-XL-mediated thrombocytopenia.

As ABT-199 doesn’t target BCL-XL, the researchers thought the drug might produce similar responses as ABT-263 without inducing thrombocytopenia.

“When ABT-199 came into the picture, we were very excited,” Dr Suryani said. “We thought, ‘This is a wonder drug. This will cure pediatric ALL.’”

To test this hypothesis, the team compared ABT-199 (100 mg/kg x 21 days) and vehicle control in 19 pediatric ALL patient-derived xenografts, including infant mixed-lineage leukemia (MLL) ALL (n=4), B-cell precursor (BCP) ALL (n=5), BCP-ALL categorized as Ph-like (n=4), T-cell ALL (n=4), and early T-cell precursor (ETP) ALL (n=2).

ABT-199 significantly delayed progression in 12 xenografts (63%) for periods ranging from 0.4 days to 28 days. And the drug produced objective responses in 5 xenografts (26%).

Responses occurred in MLL-ALL, BCP-ALL, and Ph-like BCP ALL, but not T-cell ALL or ETP-ALL. Complete responses were seen in MLL-ALL (n=1) and BCP-ALL (n=2), and partial responses occurred in MLL-ALL (n=1) and Ph-like BCP-ALL (n=1).

As the response rate with ABT-263 was more than double that of ABT-199 (61% vs 26%), the researchers found the results with ABT-199 “a little bit disappointing,” according to Dr Suryani.

“But we thought, ‘That’s okay. That already tells us the science behind it—that pediatric ALL is probably more BCL-XL-dependent, rather than BCL-2-dependent,’” she said. “We wondered if there was any way we could come up with a predictive biomarker so we could select patients who will benefit from this treatment.”

With that in mind, the researchers evaluated the link between protein expression and response. They looked at BCL-2 and BCL-XL, as well as a range of other proteins, including BCL-W, MCL1, BAK1, and BAX, among others.

And they found that high BCL-XL and low BCL-2 expression were significantly associated with ABT-199 resistance.

The researchers are still investigating ways to guide treatment with ABT-199 in ALL. They are also hoping to improve responses by administering the drug in combination with other agents.

*Information in the abstract differs from that presented at the meeting.

PHILADELPHIA—Results of preclinical research suggest the BCL-2 inhibitor ABT-199 (venetoclax) may be effective in certain pediatric patients with acute lymphoblastic leukemia (ALL).

In xenograft models of various ALL subtypes, ABT-199 produced an objective response rate below 30%.

However, additional analyses unearthed information that could potentially help us identify which ALL patients might respond to the drug.

Santi Suryani, PhD, of the Children’s Cancer Institute in Sydney, New South Wales, Australia, and her colleagues presented this research at the AACR Annual Meeting 2015 (abstract 3276*). The work was supported by AbbVie, one of the companies developing ABT-199.

Dr Suryani and her colleagues decided to investigate ABT-199 in pediatric ALL after observing mixed results with the BCL-2/BCL-W/BCL-XL inhibitor ABT-263 (navitoclax).

ABT-263 delayed ALL progression in nearly all of the xenograft models the team tested and produced a 61% response rate. However, the drug also induced BCL-XL-mediated thrombocytopenia.

As ABT-199 doesn’t target BCL-XL, the researchers thought the drug might produce similar responses as ABT-263 without inducing thrombocytopenia.

“When ABT-199 came into the picture, we were very excited,” Dr Suryani said. “We thought, ‘This is a wonder drug. This will cure pediatric ALL.’”

To test this hypothesis, the team compared ABT-199 (100 mg/kg x 21 days) and vehicle control in 19 pediatric ALL patient-derived xenografts, including infant mixed-lineage leukemia (MLL) ALL (n=4), B-cell precursor (BCP) ALL (n=5), BCP-ALL categorized as Ph-like (n=4), T-cell ALL (n=4), and early T-cell precursor (ETP) ALL (n=2).

ABT-199 significantly delayed progression in 12 xenografts (63%) for periods ranging from 0.4 days to 28 days. And the drug produced objective responses in 5 xenografts (26%).

Responses occurred in MLL-ALL, BCP-ALL, and Ph-like BCP ALL, but not T-cell ALL or ETP-ALL. Complete responses were seen in MLL-ALL (n=1) and BCP-ALL (n=2), and partial responses occurred in MLL-ALL (n=1) and Ph-like BCP-ALL (n=1).

As the response rate with ABT-263 was more than double that of ABT-199 (61% vs 26%), the researchers found the results with ABT-199 “a little bit disappointing,” according to Dr Suryani.

“But we thought, ‘That’s okay. That already tells us the science behind it—that pediatric ALL is probably more BCL-XL-dependent, rather than BCL-2-dependent,’” she said. “We wondered if there was any way we could come up with a predictive biomarker so we could select patients who will benefit from this treatment.”

With that in mind, the researchers evaluated the link between protein expression and response. They looked at BCL-2 and BCL-XL, as well as a range of other proteins, including BCL-W, MCL1, BAK1, and BAX, among others.

And they found that high BCL-XL and low BCL-2 expression were significantly associated with ABT-199 resistance.

The researchers are still investigating ways to guide treatment with ABT-199 in ALL. They are also hoping to improve responses by administering the drug in combination with other agents.

*Information in the abstract differs from that presented at the meeting.

PHILADELPHIA—Results of preclinical research suggest the BCL-2 inhibitor ABT-199 (venetoclax) may be effective in certain pediatric patients with acute lymphoblastic leukemia (ALL).

In xenograft models of various ALL subtypes, ABT-199 produced an objective response rate below 30%.

However, additional analyses unearthed information that could potentially help us identify which ALL patients might respond to the drug.

Santi Suryani, PhD, of the Children’s Cancer Institute in Sydney, New South Wales, Australia, and her colleagues presented this research at the AACR Annual Meeting 2015 (abstract 3276*). The work was supported by AbbVie, one of the companies developing ABT-199.

Dr Suryani and her colleagues decided to investigate ABT-199 in pediatric ALL after observing mixed results with the BCL-2/BCL-W/BCL-XL inhibitor ABT-263 (navitoclax).

ABT-263 delayed ALL progression in nearly all of the xenograft models the team tested and produced a 61% response rate. However, the drug also induced BCL-XL-mediated thrombocytopenia.

As ABT-199 doesn’t target BCL-XL, the researchers thought the drug might produce similar responses as ABT-263 without inducing thrombocytopenia.

“When ABT-199 came into the picture, we were very excited,” Dr Suryani said. “We thought, ‘This is a wonder drug. This will cure pediatric ALL.’”

To test this hypothesis, the team compared ABT-199 (100 mg/kg x 21 days) and vehicle control in 19 pediatric ALL patient-derived xenografts, including infant mixed-lineage leukemia (MLL) ALL (n=4), B-cell precursor (BCP) ALL (n=5), BCP-ALL categorized as Ph-like (n=4), T-cell ALL (n=4), and early T-cell precursor (ETP) ALL (n=2).

ABT-199 significantly delayed progression in 12 xenografts (63%) for periods ranging from 0.4 days to 28 days. And the drug produced objective responses in 5 xenografts (26%).

Responses occurred in MLL-ALL, BCP-ALL, and Ph-like BCP ALL, but not T-cell ALL or ETP-ALL. Complete responses were seen in MLL-ALL (n=1) and BCP-ALL (n=2), and partial responses occurred in MLL-ALL (n=1) and Ph-like BCP-ALL (n=1).

As the response rate with ABT-263 was more than double that of ABT-199 (61% vs 26%), the researchers found the results with ABT-199 “a little bit disappointing,” according to Dr Suryani.

“But we thought, ‘That’s okay. That already tells us the science behind it—that pediatric ALL is probably more BCL-XL-dependent, rather than BCL-2-dependent,’” she said. “We wondered if there was any way we could come up with a predictive biomarker so we could select patients who will benefit from this treatment.”

With that in mind, the researchers evaluated the link between protein expression and response. They looked at BCL-2 and BCL-XL, as well as a range of other proteins, including BCL-W, MCL1, BAK1, and BAX, among others.

And they found that high BCL-XL and low BCL-2 expression were significantly associated with ABT-199 resistance.

The researchers are still investigating ways to guide treatment with ABT-199 in ALL. They are also hoping to improve responses by administering the drug in combination with other agents.

*Information in the abstract differs from that presented at the meeting.

AML cells in the bone marrow

PHILADELPHIA—Preclinical research suggests a novel agent has preferential activity in acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations.

The agent, VNLG-152, proved more cytotoxic in AML cell lines and patient samples with FLT3-ITD than in samples and cell lines with wild-type FLT3.

Exactly how and why this occurs remains somewhat of a mystery, however.

Sheetal Karne, MD, of the University of Maryland School of Medicine in Baltimore, and her colleagues detailed this mystery in a poster presentation at the AACR Annual Meeting 2015 (abstract 5408*).

Dr Karne noted that VNLG-152 targets translation by promoting the degradation of MAPK-interacting kinases (Mnks).

“[VNLG-152] has been previously published as functioning in Mnk degradation, which has been shown in triple-negative breast cancer and prostate cancer—in vivo and in vitro,” she said. “Our hypothesis was that, since [the drug] worked via decreasing translation, it would function in leukemia cells and, specifically, in leukemic cells with ITD mutations.”

So the investigators tested VNLG-152 in samples from AML patients, as well as both murine and human cell lines. They found that VNLG-152 was more cytotoxic in the presence of FLT3-ITD mutations, as evidenced by low micromolar IC₅₀ concentrations.

The IC₅₀ concentration was 3.4 μM in Ba/F3-ITD cells and 5.8 μM in Ba/F3-WT cells, which are murine cells transfected with human FLT3-ITD and wild-type FLT3, respectively. Similarly, the IC₅₀ concentration was 1.8 μM in 32D-ITD cells and 18.2 μM in 32D-WT cells.

In the human FLT3-ITD AML cell lines MV4-11 and MOLM-14, IC₅₀ concentrations were 2.3 μM and 4.2 μM, respectively. But concentrations were greater than 10 µM in the wild-type FLT3 human cell lines HL60 and U937.

In patient samples, the IC₅₀ concentration was 1.0 μM in FLT3-ITD AML and 7.5 μM in AML with wild-type FLT3.

In additional tests with murine cell lines, the investigators found that VNLG-152 inhibits the growth of Ba/F3-ITD and Ba/F3-WT cells. But the drug induces apoptosis in these cell lines only when given in high concentrations.

Looking into the mechanism of VNLG-152, the investigators found that the drug decreased Mnk-1 expression in Ba/F3-ITD and Ba/F3-WT cell lines.

“We saw that VNLG-152 worked via degradation of Mnk, but it was the same in both wild-type and ITD, so we’re still looking for an explanation as to what caused this difference,” Dr Karne said.

She and her colleagues believe the Mnk degradation inhibits the phosphorylation of eukaryotic translation initiation factor 4E (eIF4E), a downstream target of FLT3-ITD. But they are still investigating that possibility.

The team is also hoping to test VNLG-152 in combination with other drugs, such as FLT3 inhibitors or chemotherapeutic agents.

*Information in the abstract differs from that presented at the meeting.

AML cells in the bone marrow

PHILADELPHIA—Preclinical research suggests a novel agent has preferential activity in acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations.

The agent, VNLG-152, proved more cytotoxic in AML cell lines and patient samples with FLT3-ITD than in samples and cell lines with wild-type FLT3.

Exactly how and why this occurs remains somewhat of a mystery, however.

Sheetal Karne, MD, of the University of Maryland School of Medicine in Baltimore, and her colleagues detailed this mystery in a poster presentation at the AACR Annual Meeting 2015 (abstract 5408*).

Dr Karne noted that VNLG-152 targets translation by promoting the degradation of MAPK-interacting kinases (Mnks).

“[VNLG-152] has been previously published as functioning in Mnk degradation, which has been shown in triple-negative breast cancer and prostate cancer—in vivo and in vitro,” she said. “Our hypothesis was that, since [the drug] worked via decreasing translation, it would function in leukemia cells and, specifically, in leukemic cells with ITD mutations.”

So the investigators tested VNLG-152 in samples from AML patients, as well as both murine and human cell lines. They found that VNLG-152 was more cytotoxic in the presence of FLT3-ITD mutations, as evidenced by low micromolar IC₅₀ concentrations.

The IC₅₀ concentration was 3.4 μM in Ba/F3-ITD cells and 5.8 μM in Ba/F3-WT cells, which are murine cells transfected with human FLT3-ITD and wild-type FLT3, respectively. Similarly, the IC₅₀ concentration was 1.8 μM in 32D-ITD cells and 18.2 μM in 32D-WT cells.

In the human FLT3-ITD AML cell lines MV4-11 and MOLM-14, IC₅₀ concentrations were 2.3 μM and 4.2 μM, respectively. But concentrations were greater than 10 µM in the wild-type FLT3 human cell lines HL60 and U937.

In patient samples, the IC₅₀ concentration was 1.0 μM in FLT3-ITD AML and 7.5 μM in AML with wild-type FLT3.

In additional tests with murine cell lines, the investigators found that VNLG-152 inhibits the growth of Ba/F3-ITD and Ba/F3-WT cells. But the drug induces apoptosis in these cell lines only when given in high concentrations.

Looking into the mechanism of VNLG-152, the investigators found that the drug decreased Mnk-1 expression in Ba/F3-ITD and Ba/F3-WT cell lines.

“We saw that VNLG-152 worked via degradation of Mnk, but it was the same in both wild-type and ITD, so we’re still looking for an explanation as to what caused this difference,” Dr Karne said.

She and her colleagues believe the Mnk degradation inhibits the phosphorylation of eukaryotic translation initiation factor 4E (eIF4E), a downstream target of FLT3-ITD. But they are still investigating that possibility.

The team is also hoping to test VNLG-152 in combination with other drugs, such as FLT3 inhibitors or chemotherapeutic agents.

*Information in the abstract differs from that presented at the meeting.

AML cells in the bone marrow

PHILADELPHIA—Preclinical research suggests a novel agent has preferential activity in acute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations.

The agent, VNLG-152, proved more cytotoxic in AML cell lines and patient samples with FLT3-ITD than in samples and cell lines with wild-type FLT3.

Exactly how and why this occurs remains somewhat of a mystery, however.

Sheetal Karne, MD, of the University of Maryland School of Medicine in Baltimore, and her colleagues detailed this mystery in a poster presentation at the AACR Annual Meeting 2015 (abstract 5408*).

Dr Karne noted that VNLG-152 targets translation by promoting the degradation of MAPK-interacting kinases (Mnks).

“[VNLG-152] has been previously published as functioning in Mnk degradation, which has been shown in triple-negative breast cancer and prostate cancer—in vivo and in vitro,” she said. “Our hypothesis was that, since [the drug] worked via decreasing translation, it would function in leukemia cells and, specifically, in leukemic cells with ITD mutations.”

So the investigators tested VNLG-152 in samples from AML patients, as well as both murine and human cell lines. They found that VNLG-152 was more cytotoxic in the presence of FLT3-ITD mutations, as evidenced by low micromolar IC₅₀ concentrations.

The IC₅₀ concentration was 3.4 μM in Ba/F3-ITD cells and 5.8 μM in Ba/F3-WT cells, which are murine cells transfected with human FLT3-ITD and wild-type FLT3, respectively. Similarly, the IC₅₀ concentration was 1.8 μM in 32D-ITD cells and 18.2 μM in 32D-WT cells.

In the human FLT3-ITD AML cell lines MV4-11 and MOLM-14, IC₅₀ concentrations were 2.3 μM and 4.2 μM, respectively. But concentrations were greater than 10 µM in the wild-type FLT3 human cell lines HL60 and U937.

In patient samples, the IC₅₀ concentration was 1.0 μM in FLT3-ITD AML and 7.5 μM in AML with wild-type FLT3.

In additional tests with murine cell lines, the investigators found that VNLG-152 inhibits the growth of Ba/F3-ITD and Ba/F3-WT cells. But the drug induces apoptosis in these cell lines only when given in high concentrations.

Looking into the mechanism of VNLG-152, the investigators found that the drug decreased Mnk-1 expression in Ba/F3-ITD and Ba/F3-WT cell lines.

“We saw that VNLG-152 worked via degradation of Mnk, but it was the same in both wild-type and ITD, so we’re still looking for an explanation as to what caused this difference,” Dr Karne said.

She and her colleagues believe the Mnk degradation inhibits the phosphorylation of eukaryotic translation initiation factor 4E (eIF4E), a downstream target of FLT3-ITD. But they are still investigating that possibility.

The team is also hoping to test VNLG-152 in combination with other drugs, such as FLT3 inhibitors or chemotherapeutic agents.

*Information in the abstract differs from that presented at the meeting.

A macrophage stretching its

pseudopodia to engulf particles

PHILADELPHIA—New research suggests the prognostic value of tumor-associated macrophages (TAMs) is disease-specific as well as treatment-specific.

Investigators set out to determine if TAMs have a negative prognostic impact in diffuse large B-cell lymphoma (DLBCL), as previous studies produced conflicting results.

The team found that higher TAM levels are associated with worse survival in DLBCL, but only in patients who do not receive rituximab. The drug can overcome the poor prognosis TAMs confer in DLBCL.

Eri Matsuki, MD, PhD, of Memorial Sloan-Kettering Cancer Center in New York, New York, and her colleagues presented these findings in a poster at the AACR Annual Meeting 2015 (abstract 2371*).

To ascertain the role of TAMs in DLBCL, the investigators analyzed specimens from 103 DLBCL patients, 61 of whom received rituximab, 33 who did not, and 9 whose rituximab status was unknown. The team first looked at the expression of CD163 as a marker of TAMs.

“CD163 is more specific to M2-type macrophages, which have pro-tumor effects, compared to a more pan-macrophage marker which is widely used—CD68,” Dr Matsuki noted.

She and her colleagues found that a high level of CD163-positive cells (more than 150) was significantly associated with advanced-stage disease (P=0.016), non-GCB DLBCL (P=0.0071), and higher expression of c-Myc (P=0.0022).

“Our interpretation of that at this point is that, the more aggressive the tumor, the more likely that it would induce macrophages into the tissue,” Dr Matsuki said.

The investigators then assessed the impact of rituximab use. Among patients who didn’t receive rituximab, having a high level of CD163-positive cells (more than 150) was associated with inferior overall survival (OS, P=0.022). However, if patients did receive rituximab, there was no significant difference in OS.

Dr Matsuki said this supports previous studies showing that the prognostic effect of TAMs diminishes with rituximab use, as well as the in vitro finding that M2 macrophages exhibit increased phagocytosis of rituximab-opsonized tumor cells.

“So overall, what we’re seeing is that . . . the negative influence of TAMs can be overcome with rituximab use,” she summarized.

Dr Matsuki and her colleagues also looked at the patients’ lymphocyte-to-monocyte-ratio (LMR) because TAMs partly arise from peripheral blood monocytes.

The team found that having an LMR higher than 2.77 was significantly associated with superior OS (P=0.03) in patients who did not receive rituximab. And there was a trend toward improved OS with a higher LMR in patients who did receive the drug (P=0.07).

The investigators believe the differences they observed in the prognostic value of CD163 and LMR could be explained by the fact that TAMs are derived from both circulating monocytes and resident macrophages.

Dr Matsuki said this research has improved her group’s understanding of DLBCL, but they are still working to identify additional biomarkers associated with prognosis in this disease.

*Information in the abstract differs from that presented at the meeting.

A macrophage stretching its

pseudopodia to engulf particles

PHILADELPHIA—New research suggests the prognostic value of tumor-associated macrophages (TAMs) is disease-specific as well as treatment-specific.

Investigators set out to determine if TAMs have a negative prognostic impact in diffuse large B-cell lymphoma (DLBCL), as previous studies produced conflicting results.

The team found that higher TAM levels are associated with worse survival in DLBCL, but only in patients who do not receive rituximab. The drug can overcome the poor prognosis TAMs confer in DLBCL.

Eri Matsuki, MD, PhD, of Memorial Sloan-Kettering Cancer Center in New York, New York, and her colleagues presented these findings in a poster at the AACR Annual Meeting 2015 (abstract 2371*).

To ascertain the role of TAMs in DLBCL, the investigators analyzed specimens from 103 DLBCL patients, 61 of whom received rituximab, 33 who did not, and 9 whose rituximab status was unknown. The team first looked at the expression of CD163 as a marker of TAMs.

“CD163 is more specific to M2-type macrophages, which have pro-tumor effects, compared to a more pan-macrophage marker which is widely used—CD68,” Dr Matsuki noted.

She and her colleagues found that a high level of CD163-positive cells (more than 150) was significantly associated with advanced-stage disease (P=0.016), non-GCB DLBCL (P=0.0071), and higher expression of c-Myc (P=0.0022).

“Our interpretation of that at this point is that, the more aggressive the tumor, the more likely that it would induce macrophages into the tissue,” Dr Matsuki said.

The investigators then assessed the impact of rituximab use. Among patients who didn’t receive rituximab, having a high level of CD163-positive cells (more than 150) was associated with inferior overall survival (OS, P=0.022). However, if patients did receive rituximab, there was no significant difference in OS.

Dr Matsuki said this supports previous studies showing that the prognostic effect of TAMs diminishes with rituximab use, as well as the in vitro finding that M2 macrophages exhibit increased phagocytosis of rituximab-opsonized tumor cells.

“So overall, what we’re seeing is that . . . the negative influence of TAMs can be overcome with rituximab use,” she summarized.

Dr Matsuki and her colleagues also looked at the patients’ lymphocyte-to-monocyte-ratio (LMR) because TAMs partly arise from peripheral blood monocytes.

The team found that having an LMR higher than 2.77 was significantly associated with superior OS (P=0.03) in patients who did not receive rituximab. And there was a trend toward improved OS with a higher LMR in patients who did receive the drug (P=0.07).

The investigators believe the differences they observed in the prognostic value of CD163 and LMR could be explained by the fact that TAMs are derived from both circulating monocytes and resident macrophages.

Dr Matsuki said this research has improved her group’s understanding of DLBCL, but they are still working to identify additional biomarkers associated with prognosis in this disease.

*Information in the abstract differs from that presented at the meeting.

A macrophage stretching its

pseudopodia to engulf particles

PHILADELPHIA—New research suggests the prognostic value of tumor-associated macrophages (TAMs) is disease-specific as well as treatment-specific.

Investigators set out to determine if TAMs have a negative prognostic impact in diffuse large B-cell lymphoma (DLBCL), as previous studies produced conflicting results.

The team found that higher TAM levels are associated with worse survival in DLBCL, but only in patients who do not receive rituximab. The drug can overcome the poor prognosis TAMs confer in DLBCL.

Eri Matsuki, MD, PhD, of Memorial Sloan-Kettering Cancer Center in New York, New York, and her colleagues presented these findings in a poster at the AACR Annual Meeting 2015 (abstract 2371*).

To ascertain the role of TAMs in DLBCL, the investigators analyzed specimens from 103 DLBCL patients, 61 of whom received rituximab, 33 who did not, and 9 whose rituximab status was unknown. The team first looked at the expression of CD163 as a marker of TAMs.

“CD163 is more specific to M2-type macrophages, which have pro-tumor effects, compared to a more pan-macrophage marker which is widely used—CD68,” Dr Matsuki noted.

She and her colleagues found that a high level of CD163-positive cells (more than 150) was significantly associated with advanced-stage disease (P=0.016), non-GCB DLBCL (P=0.0071), and higher expression of c-Myc (P=0.0022).

“Our interpretation of that at this point is that, the more aggressive the tumor, the more likely that it would induce macrophages into the tissue,” Dr Matsuki said.

The investigators then assessed the impact of rituximab use. Among patients who didn’t receive rituximab, having a high level of CD163-positive cells (more than 150) was associated with inferior overall survival (OS, P=0.022). However, if patients did receive rituximab, there was no significant difference in OS.

Dr Matsuki said this supports previous studies showing that the prognostic effect of TAMs diminishes with rituximab use, as well as the in vitro finding that M2 macrophages exhibit increased phagocytosis of rituximab-opsonized tumor cells.

“So overall, what we’re seeing is that . . . the negative influence of TAMs can be overcome with rituximab use,” she summarized.

Dr Matsuki and her colleagues also looked at the patients’ lymphocyte-to-monocyte-ratio (LMR) because TAMs partly arise from peripheral blood monocytes.

The team found that having an LMR higher than 2.77 was significantly associated with superior OS (P=0.03) in patients who did not receive rituximab. And there was a trend toward improved OS with a higher LMR in patients who did receive the drug (P=0.07).

The investigators believe the differences they observed in the prognostic value of CD163 and LMR could be explained by the fact that TAMs are derived from both circulating monocytes and resident macrophages.

Dr Matsuki said this research has improved her group’s understanding of DLBCL, but they are still working to identify additional biomarkers associated with prognosis in this disease.

*Information in the abstract differs from that presented at the meeting.

 

 

AACR Annual Meeting 2015

 

PHILADELPHIA—A retrospective study has revealed factors that appear to influence a person’s susceptibility to Waldenström’s macroglobulinemia (WM)/lymphoplasmacytic lymphoma (LPL) and other malignancies.

Study investigators looked at patients diagnosed with WM or LPL over a 20-year period and found about a 50% excess of second primary cancers in this population.

The patients had a significantly increased risk of multiple hematologic and solid tumor malignancies, and a few of these malignancies had shared susceptibility factors with WM/LPL.

The investigators believe that identifying these factors may prove useful for determining genetic susceptibility to WM/LPL.

Mary L. McMaster, MD, of the National Cancer Institute in Bethesda, Maryland, and her colleagues presented these findings at the AACR Annual Meeting 2015 (abstract 3709).

The team used data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SSER) database to evaluate the risk of subsequent primary cancer in 3825 patients diagnosed with WM (n=2163) or LPL (n=1662) from 1992 to 2011. The patients’ median age was 70, most of them were male (n=2221), and most were white (n=3153).

Dr McMaster said she and her colleagues looked at both WM and LPL in this study because SEER does not include information about immunoglobulin subtype, which makes it difficult to identify all WM cases with absolute certainty.

“[D]epending on what information a pathologist has when they review a bone marrow biopsy, for example, they may or may not know whether there’s IgM present,” Dr McMaster said. “So you may have a diagnosis of LPL and not have the information required to make the diagnosis of WM. For that reason, we combined both entities for this study.”

Dr McMaster and her colleagues calculated the observed-to-expected standardized incidence ratios (SIRs) for invasive cancers. After adjusting for multiple comparisons, the team found that survivors of WM/LPL had a significantly increased risk of developing a second primary malignancy (SIR=1.49).

This increased risk was seen for males and females and persisted throughout follow-up. The risk was higher for patients younger than 65 years of age (SIR=1.95).

Hematologic malignancies

WM/LPL survivors had a significantly increased risk of several hematologic malignancies. The SIR was 4.09 for all hematologic malignancies, 4.29 for lymphomas, and 3.16 for leukemias.

Dr McMaster pointed out that several lymphoma subtypes can have lymphoplasmacytic differentiation, the most common being marginal zone lymphoma. And this could potentially result in misclassification.

“So we actually ran the study with and without marginal zone lymphoma and saw no difference in the results,” she said. “So we don’t think misclassification accounts for the majority of what we’re seeing.”

The investigators found that WM/LPL survivors had the highest risk of developing Burkitt lymphoma (SIR=13.45), followed by Hodgkin lymphoma (SIR=9.80), T-cell non-Hodgkin lymphoma (SIR=6.62), mantle cell lymphoma (SIR=5.37), diffuse large B-cell lymphoma (DLBCL, SIR=4.76), multiple myeloma (SIR=4.40), any non-Hodgkin lymphoma (SIR=4.08), and acute myeloid leukemia (AML, SIR=3.27).

“Waldenström’s is known to transform, on occasion, to DLBCL,” Dr McMaster said. “So that may well account for the excess of DLBCL that we see in this population.”

She also noted that, prior to the early 2000s, WM was typically treated with alkylating agents. And alkylating agents have been linked to an increased risk of AML.

In this population, the risk of AML peaked 5 to 10 years after WM/LPL diagnosis and was only present in patients treated prior to 2002. This suggests the AML observed in this study was likely treatment-related.

Dr McMaster and her colleagues also found that WM/LPL survivors did not have a significantly increased risk of developing acute lymphocytic leukemia (SIR=0), hairy cell leukemia (SIR=0), chronic lymphocytic leukemia/small lymphocytic lymphoma (SIR=0.97), or follicular lymphoma (SIR=2.25).

Solid tumors

WM/LPL survivors did have a significantly increased risk of certain solid tumor malignancies. The overall SIR for solid tumors was 1.21.

The risk was significant for non-epithelial skin cancers (SIR=5.15), thyroid cancers (SIR=3.13), melanoma (SIR=1.72), and cancers of the lung and bronchus (SIR=1.44) or respiratory system (SIR=1.42).

“Melanoma has an immunological basis, as does Waldenström’s, so we think there may be some shared etiology there,” Dr McMaster said.

She also noted that a strong risk factor for thyroid cancer, particularly papillary thyroid cancer, is a history of autoimmune thyroid disease.

“Autoimmune disease of any sort is a risk factor for Waldenström’s macroglobulinemia,” she said. “So again, we think there might be a basis for shared susceptibility there.”

Dr McMaster said this research suggests that multiple primary cancers may occur in a single individual because of shared genetic susceptibility, shared environmental exposures, treatment effects, or chance. She believes future research will show that both genetic and environmental factors contribute to WM.

Investigators are currently conducting whole-exome sequencing studies and genome-wide association studies in patients with familial and spontaneous WM, with the hopes of identifying genes that contribute to WM susceptibility.

 

 

AACR Annual Meeting 2015

 

PHILADELPHIA—A retrospective study has revealed factors that appear to influence a person’s susceptibility to Waldenström’s macroglobulinemia (WM)/lymphoplasmacytic lymphoma (LPL) and other malignancies.

Study investigators looked at patients diagnosed with WM or LPL over a 20-year period and found about a 50% excess of second primary cancers in this population.

The patients had a significantly increased risk of multiple hematologic and solid tumor malignancies, and a few of these malignancies had shared susceptibility factors with WM/LPL.

The investigators believe that identifying these factors may prove useful for determining genetic susceptibility to WM/LPL.

Mary L. McMaster, MD, of the National Cancer Institute in Bethesda, Maryland, and her colleagues presented these findings at the AACR Annual Meeting 2015 (abstract 3709).

The team used data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SSER) database to evaluate the risk of subsequent primary cancer in 3825 patients diagnosed with WM (n=2163) or LPL (n=1662) from 1992 to 2011. The patients’ median age was 70, most of them were male (n=2221), and most were white (n=3153).

Dr McMaster said she and her colleagues looked at both WM and LPL in this study because SEER does not include information about immunoglobulin subtype, which makes it difficult to identify all WM cases with absolute certainty.

“[D]epending on what information a pathologist has when they review a bone marrow biopsy, for example, they may or may not know whether there’s IgM present,” Dr McMaster said. “So you may have a diagnosis of LPL and not have the information required to make the diagnosis of WM. For that reason, we combined both entities for this study.”

Dr McMaster and her colleagues calculated the observed-to-expected standardized incidence ratios (SIRs) for invasive cancers. After adjusting for multiple comparisons, the team found that survivors of WM/LPL had a significantly increased risk of developing a second primary malignancy (SIR=1.49).

This increased risk was seen for males and females and persisted throughout follow-up. The risk was higher for patients younger than 65 years of age (SIR=1.95).

Hematologic malignancies

WM/LPL survivors had a significantly increased risk of several hematologic malignancies. The SIR was 4.09 for all hematologic malignancies, 4.29 for lymphomas, and 3.16 for leukemias.

Dr McMaster pointed out that several lymphoma subtypes can have lymphoplasmacytic differentiation, the most common being marginal zone lymphoma. And this could potentially result in misclassification.

“So we actually ran the study with and without marginal zone lymphoma and saw no difference in the results,” she said. “So we don’t think misclassification accounts for the majority of what we’re seeing.”

The investigators found that WM/LPL survivors had the highest risk of developing Burkitt lymphoma (SIR=13.45), followed by Hodgkin lymphoma (SIR=9.80), T-cell non-Hodgkin lymphoma (SIR=6.62), mantle cell lymphoma (SIR=5.37), diffuse large B-cell lymphoma (DLBCL, SIR=4.76), multiple myeloma (SIR=4.40), any non-Hodgkin lymphoma (SIR=4.08), and acute myeloid leukemia (AML, SIR=3.27).

“Waldenström’s is known to transform, on occasion, to DLBCL,” Dr McMaster said. “So that may well account for the excess of DLBCL that we see in this population.”

She also noted that, prior to the early 2000s, WM was typically treated with alkylating agents. And alkylating agents have been linked to an increased risk of AML.

In this population, the risk of AML peaked 5 to 10 years after WM/LPL diagnosis and was only present in patients treated prior to 2002. This suggests the AML observed in this study was likely treatment-related.

Dr McMaster and her colleagues also found that WM/LPL survivors did not have a significantly increased risk of developing acute lymphocytic leukemia (SIR=0), hairy cell leukemia (SIR=0), chronic lymphocytic leukemia/small lymphocytic lymphoma (SIR=0.97), or follicular lymphoma (SIR=2.25).

Solid tumors

WM/LPL survivors did have a significantly increased risk of certain solid tumor malignancies. The overall SIR for solid tumors was 1.21.

The risk was significant for non-epithelial skin cancers (SIR=5.15), thyroid cancers (SIR=3.13), melanoma (SIR=1.72), and cancers of the lung and bronchus (SIR=1.44) or respiratory system (SIR=1.42).

“Melanoma has an immunological basis, as does Waldenström’s, so we think there may be some shared etiology there,” Dr McMaster said.

She also noted that a strong risk factor for thyroid cancer, particularly papillary thyroid cancer, is a history of autoimmune thyroid disease.

“Autoimmune disease of any sort is a risk factor for Waldenström’s macroglobulinemia,” she said. “So again, we think there might be a basis for shared susceptibility there.”

Dr McMaster said this research suggests that multiple primary cancers may occur in a single individual because of shared genetic susceptibility, shared environmental exposures, treatment effects, or chance. She believes future research will show that both genetic and environmental factors contribute to WM.

Investigators are currently conducting whole-exome sequencing studies and genome-wide association studies in patients with familial and spontaneous WM, with the hopes of identifying genes that contribute to WM susceptibility.

 

 

AACR Annual Meeting 2015

 

PHILADELPHIA—A retrospective study has revealed factors that appear to influence a person’s susceptibility to Waldenström’s macroglobulinemia (WM)/lymphoplasmacytic lymphoma (LPL) and other malignancies.

Study investigators looked at patients diagnosed with WM or LPL over a 20-year period and found about a 50% excess of second primary cancers in this population.

The patients had a significantly increased risk of multiple hematologic and solid tumor malignancies, and a few of these malignancies had shared susceptibility factors with WM/LPL.

The investigators believe that identifying these factors may prove useful for determining genetic susceptibility to WM/LPL.

Mary L. McMaster, MD, of the National Cancer Institute in Bethesda, Maryland, and her colleagues presented these findings at the AACR Annual Meeting 2015 (abstract 3709).

The team used data from the National Cancer Institute’s Surveillance, Epidemiology and End Results (SSER) database to evaluate the risk of subsequent primary cancer in 3825 patients diagnosed with WM (n=2163) or LPL (n=1662) from 1992 to 2011. The patients’ median age was 70, most of them were male (n=2221), and most were white (n=3153).

Dr McMaster said she and her colleagues looked at both WM and LPL in this study because SEER does not include information about immunoglobulin subtype, which makes it difficult to identify all WM cases with absolute certainty.

“[D]epending on what information a pathologist has when they review a bone marrow biopsy, for example, they may or may not know whether there’s IgM present,” Dr McMaster said. “So you may have a diagnosis of LPL and not have the information required to make the diagnosis of WM. For that reason, we combined both entities for this study.”

Dr McMaster and her colleagues calculated the observed-to-expected standardized incidence ratios (SIRs) for invasive cancers. After adjusting for multiple comparisons, the team found that survivors of WM/LPL had a significantly increased risk of developing a second primary malignancy (SIR=1.49).

This increased risk was seen for males and females and persisted throughout follow-up. The risk was higher for patients younger than 65 years of age (SIR=1.95).

Hematologic malignancies

WM/LPL survivors had a significantly increased risk of several hematologic malignancies. The SIR was 4.09 for all hematologic malignancies, 4.29 for lymphomas, and 3.16 for leukemias.

Dr McMaster pointed out that several lymphoma subtypes can have lymphoplasmacytic differentiation, the most common being marginal zone lymphoma. And this could potentially result in misclassification.

“So we actually ran the study with and without marginal zone lymphoma and saw no difference in the results,” she said. “So we don’t think misclassification accounts for the majority of what we’re seeing.”

The investigators found that WM/LPL survivors had the highest risk of developing Burkitt lymphoma (SIR=13.45), followed by Hodgkin lymphoma (SIR=9.80), T-cell non-Hodgkin lymphoma (SIR=6.62), mantle cell lymphoma (SIR=5.37), diffuse large B-cell lymphoma (DLBCL, SIR=4.76), multiple myeloma (SIR=4.40), any non-Hodgkin lymphoma (SIR=4.08), and acute myeloid leukemia (AML, SIR=3.27).

“Waldenström’s is known to transform, on occasion, to DLBCL,” Dr McMaster said. “So that may well account for the excess of DLBCL that we see in this population.”

She also noted that, prior to the early 2000s, WM was typically treated with alkylating agents. And alkylating agents have been linked to an increased risk of AML.

In this population, the risk of AML peaked 5 to 10 years after WM/LPL diagnosis and was only present in patients treated prior to 2002. This suggests the AML observed in this study was likely treatment-related.

Dr McMaster and her colleagues also found that WM/LPL survivors did not have a significantly increased risk of developing acute lymphocytic leukemia (SIR=0), hairy cell leukemia (SIR=0), chronic lymphocytic leukemia/small lymphocytic lymphoma (SIR=0.97), or follicular lymphoma (SIR=2.25).

Solid tumors

WM/LPL survivors did have a significantly increased risk of certain solid tumor malignancies. The overall SIR for solid tumors was 1.21.

The risk was significant for non-epithelial skin cancers (SIR=5.15), thyroid cancers (SIR=3.13), melanoma (SIR=1.72), and cancers of the lung and bronchus (SIR=1.44) or respiratory system (SIR=1.42).

“Melanoma has an immunological basis, as does Waldenström’s, so we think there may be some shared etiology there,” Dr McMaster said.

She also noted that a strong risk factor for thyroid cancer, particularly papillary thyroid cancer, is a history of autoimmune thyroid disease.

“Autoimmune disease of any sort is a risk factor for Waldenström’s macroglobulinemia,” she said. “So again, we think there might be a basis for shared susceptibility there.”

Dr McMaster said this research suggests that multiple primary cancers may occur in a single individual because of shared genetic susceptibility, shared environmental exposures, treatment effects, or chance. She believes future research will show that both genetic and environmental factors contribute to WM.

Investigators are currently conducting whole-exome sequencing studies and genome-wide association studies in patients with familial and spontaneous WM, with the hopes of identifying genes that contribute to WM susceptibility.

AACR Annual Meeting 2015

PHILADELPHIA—Two multikinase inhibitors (MKIs) can treat chronic myeloid leukemia (CML) that is resistant to other inhibitors, according to preclinical research.

A series of in vitro experiments showed that the MKIs, sorafenib and axitinib, can overcome treatment resistance mediated by hyperactivation of the Src kinase Lyn, overexpression of the docking protein Gab2, and the presence of the Bcr-Abl T315I mutation.

Sebastian Halbach, of the University of Freiburg in Germany, and his colleagues presented these findings in a poster at the AACR Annual Meeting 2015 (abstract 2708).

Mechanisms of resistance

Halbach noted that CML is driven by the hyperactive fusion kinase Bcr-Abl, which builds up its own signaling network with various proteins, such as Gab2 and Lyn.

Resistance to tyrosine kinase inhibitors (TKIs) and MKIs can be caused by mutations in the Bcr-Abl oncogene, such as T315I, or by aberrant activity of components of the Bcr-Abl signaling network.

“We have previously shown in our lab that overexpression of the docking protein Gab2 . . . confers resistance against imatinib and dasatinib,” Halbach said. “And another mechanism of resistance is hyperactivation of the Src kinase Lyn.”

For the current study, Halbach and his colleagues investigated the role of Lyn by introducing imatinib, dasatinib, or DMSO to K562 cells (blast-phase CML), Lyn-transformed K562 cells, and Lyn-Y508F-transformed K562 cells.

They also compared imatinib and DMSO in Ba/F3 cells (a murine pro-B cell line), Lyn-transformed Ba/F3 cells, and Lyn-Y508F-transformed Ba/F3 cells.

The results of these experiments showed that hyperactive Lyn confers resistance to imatinib but not dasatinib.

“That’s not that surprising because dasatinib is a multikinase inhibitor which targets Src kinases,” Halbach noted. “Therefore, the hyperactivity of Lyn is directly targeted.”

Identifying new drugs

Having established that TKI and MKI resistance in CML can be mediated by Lyn and Gab2, as well as T315I, Halbach and his colleagues wanted to find drugs that would overcome this problem. They screened a panel of inhibitors and identified sorafenib and axitinib.

The researchers first evaluated the effects of sorafenib and axitinib against the T315I mutation. They tested the 2 MKIs—as well as imatinib, dasatinib, nilotinib, ponatinib, and DMSO—in the KBM5 cell line (blast-phase CML) and the KBM5-T315I cell line (imatinib-resistant CML).

Sorafenib and axitinib killed KBM5-T315I cells more effectively than any of the other inhibitors. The 2 MKIs also decreased the metabolic activity of T315I-positive cells more effectively than imatinib, dasatinib, or nilotinib, but not ponatinib, which produced similar results.

Next, Halbach and his colleagues tested sorafenib, axitinib, and the aforementioned inhibitors in K562 cells overexpressing Gab2. Overexpression of Gab2 conferred resistance to imatinib, dasatinib, nilotinib, and ponatinib, but not sorafenib and axitinib.

Both sorafenib and axitinib decreased the metabolic activity of Gab2-overexpressing cells more effectively than any of the other inhibitors.

Lastly, the researchers tested all of the inhibitors in Lyn-transformed K562 cells, Lyn-Y508F-transformed K562 cells, and K562 cells. They found that sorafenib and axitinib both overcame Lyn-Y508F-mediated resistance.

Sorafenib and axitinib killed K562 cells and Lyn-transformed K562 cells more effectively than any of the other inhibitors. The 2 MKIs also killed Lyn-Y508F-transformed K562 cells more effectively than imatinib and nilotinib, but not ponatinib or dasatinib.

Sorafenib decreased the metabolic activity of Lyn-Y508F-transformed K562 cells more effectively than all of the other inhibitors. But axitinib only proved more effective than imatinib in this regard.

Halbach said he hopes sorafenib and axitinib can one day serve as alternatives to ponatinib for CML patients, especially those with T315I mutations or high Gab2 levels.

For now, his team’s next step is to further analyze the influence of axitinib and sorafenib on the Bcr-Abl—Gab2 signaling complex.

AACR Annual Meeting 2015

PHILADELPHIA—Two multikinase inhibitors (MKIs) can treat chronic myeloid leukemia (CML) that is resistant to other inhibitors, according to preclinical research.

A series of in vitro experiments showed that the MKIs, sorafenib and axitinib, can overcome treatment resistance mediated by hyperactivation of the Src kinase Lyn, overexpression of the docking protein Gab2, and the presence of the Bcr-Abl T315I mutation.

Sebastian Halbach, of the University of Freiburg in Germany, and his colleagues presented these findings in a poster at the AACR Annual Meeting 2015 (abstract 2708).

Mechanisms of resistance

Halbach noted that CML is driven by the hyperactive fusion kinase Bcr-Abl, which builds up its own signaling network with various proteins, such as Gab2 and Lyn.

Resistance to tyrosine kinase inhibitors (TKIs) and MKIs can be caused by mutations in the Bcr-Abl oncogene, such as T315I, or by aberrant activity of components of the Bcr-Abl signaling network.

“We have previously shown in our lab that overexpression of the docking protein Gab2 . . . confers resistance against imatinib and dasatinib,” Halbach said. “And another mechanism of resistance is hyperactivation of the Src kinase Lyn.”

For the current study, Halbach and his colleagues investigated the role of Lyn by introducing imatinib, dasatinib, or DMSO to K562 cells (blast-phase CML), Lyn-transformed K562 cells, and Lyn-Y508F-transformed K562 cells.

They also compared imatinib and DMSO in Ba/F3 cells (a murine pro-B cell line), Lyn-transformed Ba/F3 cells, and Lyn-Y508F-transformed Ba/F3 cells.

The results of these experiments showed that hyperactive Lyn confers resistance to imatinib but not dasatinib.

“That’s not that surprising because dasatinib is a multikinase inhibitor which targets Src kinases,” Halbach noted. “Therefore, the hyperactivity of Lyn is directly targeted.”

Identifying new drugs

Having established that TKI and MKI resistance in CML can be mediated by Lyn and Gab2, as well as T315I, Halbach and his colleagues wanted to find drugs that would overcome this problem. They screened a panel of inhibitors and identified sorafenib and axitinib.

The researchers first evaluated the effects of sorafenib and axitinib against the T315I mutation. They tested the 2 MKIs—as well as imatinib, dasatinib, nilotinib, ponatinib, and DMSO—in the KBM5 cell line (blast-phase CML) and the KBM5-T315I cell line (imatinib-resistant CML).

Sorafenib and axitinib killed KBM5-T315I cells more effectively than any of the other inhibitors. The 2 MKIs also decreased the metabolic activity of T315I-positive cells more effectively than imatinib, dasatinib, or nilotinib, but not ponatinib, which produced similar results.

Next, Halbach and his colleagues tested sorafenib, axitinib, and the aforementioned inhibitors in K562 cells overexpressing Gab2. Overexpression of Gab2 conferred resistance to imatinib, dasatinib, nilotinib, and ponatinib, but not sorafenib and axitinib.

Both sorafenib and axitinib decreased the metabolic activity of Gab2-overexpressing cells more effectively than any of the other inhibitors.

Lastly, the researchers tested all of the inhibitors in Lyn-transformed K562 cells, Lyn-Y508F-transformed K562 cells, and K562 cells. They found that sorafenib and axitinib both overcame Lyn-Y508F-mediated resistance.

Sorafenib and axitinib killed K562 cells and Lyn-transformed K562 cells more effectively than any of the other inhibitors. The 2 MKIs also killed Lyn-Y508F-transformed K562 cells more effectively than imatinib and nilotinib, but not ponatinib or dasatinib.

Sorafenib decreased the metabolic activity of Lyn-Y508F-transformed K562 cells more effectively than all of the other inhibitors. But axitinib only proved more effective than imatinib in this regard.

Halbach said he hopes sorafenib and axitinib can one day serve as alternatives to ponatinib for CML patients, especially those with T315I mutations or high Gab2 levels.

For now, his team’s next step is to further analyze the influence of axitinib and sorafenib on the Bcr-Abl—Gab2 signaling complex.

AACR Annual Meeting 2015

PHILADELPHIA—Two multikinase inhibitors (MKIs) can treat chronic myeloid leukemia (CML) that is resistant to other inhibitors, according to preclinical research.

A series of in vitro experiments showed that the MKIs, sorafenib and axitinib, can overcome treatment resistance mediated by hyperactivation of the Src kinase Lyn, overexpression of the docking protein Gab2, and the presence of the Bcr-Abl T315I mutation.

Sebastian Halbach, of the University of Freiburg in Germany, and his colleagues presented these findings in a poster at the AACR Annual Meeting 2015 (abstract 2708).

Mechanisms of resistance

Halbach noted that CML is driven by the hyperactive fusion kinase Bcr-Abl, which builds up its own signaling network with various proteins, such as Gab2 and Lyn.

Resistance to tyrosine kinase inhibitors (TKIs) and MKIs can be caused by mutations in the Bcr-Abl oncogene, such as T315I, or by aberrant activity of components of the Bcr-Abl signaling network.

“We have previously shown in our lab that overexpression of the docking protein Gab2 . . . confers resistance against imatinib and dasatinib,” Halbach said. “And another mechanism of resistance is hyperactivation of the Src kinase Lyn.”

For the current study, Halbach and his colleagues investigated the role of Lyn by introducing imatinib, dasatinib, or DMSO to K562 cells (blast-phase CML), Lyn-transformed K562 cells, and Lyn-Y508F-transformed K562 cells.

They also compared imatinib and DMSO in Ba/F3 cells (a murine pro-B cell line), Lyn-transformed Ba/F3 cells, and Lyn-Y508F-transformed Ba/F3 cells.

The results of these experiments showed that hyperactive Lyn confers resistance to imatinib but not dasatinib.

“That’s not that surprising because dasatinib is a multikinase inhibitor which targets Src kinases,” Halbach noted. “Therefore, the hyperactivity of Lyn is directly targeted.”

Identifying new drugs

Having established that TKI and MKI resistance in CML can be mediated by Lyn and Gab2, as well as T315I, Halbach and his colleagues wanted to find drugs that would overcome this problem. They screened a panel of inhibitors and identified sorafenib and axitinib.

The researchers first evaluated the effects of sorafenib and axitinib against the T315I mutation. They tested the 2 MKIs—as well as imatinib, dasatinib, nilotinib, ponatinib, and DMSO—in the KBM5 cell line (blast-phase CML) and the KBM5-T315I cell line (imatinib-resistant CML).

Sorafenib and axitinib killed KBM5-T315I cells more effectively than any of the other inhibitors. The 2 MKIs also decreased the metabolic activity of T315I-positive cells more effectively than imatinib, dasatinib, or nilotinib, but not ponatinib, which produced similar results.

Next, Halbach and his colleagues tested sorafenib, axitinib, and the aforementioned inhibitors in K562 cells overexpressing Gab2. Overexpression of Gab2 conferred resistance to imatinib, dasatinib, nilotinib, and ponatinib, but not sorafenib and axitinib.

Both sorafenib and axitinib decreased the metabolic activity of Gab2-overexpressing cells more effectively than any of the other inhibitors.

Lastly, the researchers tested all of the inhibitors in Lyn-transformed K562 cells, Lyn-Y508F-transformed K562 cells, and K562 cells. They found that sorafenib and axitinib both overcame Lyn-Y508F-mediated resistance.

Sorafenib and axitinib killed K562 cells and Lyn-transformed K562 cells more effectively than any of the other inhibitors. The 2 MKIs also killed Lyn-Y508F-transformed K562 cells more effectively than imatinib and nilotinib, but not ponatinib or dasatinib.

Sorafenib decreased the metabolic activity of Lyn-Y508F-transformed K562 cells more effectively than all of the other inhibitors. But axitinib only proved more effective than imatinib in this regard.

Halbach said he hopes sorafenib and axitinib can one day serve as alternatives to ponatinib for CML patients, especially those with T315I mutations or high Gab2 levels.

For now, his team’s next step is to further analyze the influence of axitinib and sorafenib on the Bcr-Abl—Gab2 signaling complex.

Inside the Pennsylvania

Convention Center, site of the

AACR Annual Meeting 2015

PHILADELPHIA—When current treatment approaches failed to save a young patient with non-Hodgkin lymphoma (NHL), a researcher from The Children’s Hospital of Philadelphia was driven to investigate new therapeutic options.

The investigation led the researcher, Mala Talekar, MBBS, to ONC201 (formerly TIC10), a small molecule that induces apoptosis by increasing surface expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

Preclinical experiments showed that ONC201 is active against NHL as a single agent, and it synergizes with chemotherapeutic drugs that are already used to treat NHL.

Dr Talekar and her colleagues described these experiments in a poster presented at the AACR Annual Meeting 2015 (abstract 5387). Some of the investigators involved in this research are employed by Oncoceutics, Inc., the company developing ONC201.

A researcher’s inspiration

“When I was doing my fellowship training, I had a teenage boy who had a rare form of non-Hodgkin’s lymphoma,” Dr Talekar explained. “He did not survive, despite receiving multiple treatments that are available for pediatric non-Hodgkin’s lymphoma.”

The boy’s death inspired Dr Talekar to seek new and better approaches to treat NHL. A search of the medical literature unearthed several articles detailing a TRAIL-based approach to treating lymphoma. So she decided to further investigate the effects of TRAIL in NHL.

“I first tried TRAIL in one lymphoma cell line,” she said. “And even though it did kill the cancer cells, it did not really give a satisfactory response.”

So Dr Talekar turned to the TRAIL agonist antibodies lexatumumab and mapatumumab, introducing each of them to human lymphoma cells. Although the antibodies caused more cell death than TRAIL itself, the response was still not satisfactory, she said.

“Fortunately for me, while I was working in the lab, one of the postdocs, Joshua Allen, discovered a new molecule called TRAIL-inducing compound 10, or TIC10,” Dr Talekar said. “So I tried TIC10—it is now called ONC201—and it gave a beautiful dose-response curve, causing complete cell death of the lymphoma cells.”

Dr Talekar was “very inspired” by this result and decided to test ONC201 in 8 different NHL cell lines—4 Burkitt lymphoma (Daudi, Raji, Ramos, and BJAB), 1 anaplastic large-cell lymphoma (Karpas299), and 3 mantle cell lymphoma (UPN2, Granta, and NCEB) cell lines.

“I found a beautiful dose-response curve,” Dr Talekar said, “suggesting that this molecule works in micromolar concentrations across all of the lymphoma cell lines.”

Elucidating the mechanism

Dr Talekar then set out to determine exactly how ONC201 causes cell death in NHL. Flow cytometry revealed that, as the dose of ONC201 increases, cell death increases, as does sub-G1 DNA content. This suggests the drug is causing cell death by apoptosis.

Next, Dr Talekar introduced ONC201 to NHL cell lines along with a pan-caspase inhibitor. She found the inhibitor blocked ONC201-induced apoptosis, which suggests ONC201 works via the caspase-mediated apoptotic pathway.

“The initial mechanism of action proposed for ONC201 was dual inactivation of two kinases, Akt and ERK,” Dr Talekar noted. “The dual inactivation causes dephosphorylation of Foxo3a. This causes its translocation to the nucleus and downstream upregulation of TRAIL, and, therefore, increased surface TRAIL expression. And we know increases in surface TRAIL cause cell death by apoptosis.”

With this in mind, Dr Talekar looked for increases in surface TRIAL after she incubated lymphoma cells with ONC201. She observed a dose-dependent increase in surface TRAIL and a linear correlation between the increase in TRAIL and apoptosis.

Then, she introduced ONC201 and a TRAIL-sequestering antibody, RIK-2, to lymphoma cells. RIK-2 inhibited apoptosis, which suggests ONC201 works as an anti-apoptotic agent via the TRAIL pathway.

Further testing

As a final step, Dr Talekar tested ONC201 in combination with chemotherapy drugs that are already used to treat pediatric NHL. She observed at least an additive effect, and sometimes a synergistic effect, between the drugs. The best responses occurred when she combined ONC201 with cytarabine, bortezomib, or doxorubicin.

Now, Dr Talekar is working on testing ONC201 in combination with cytarabine in a xenograft model of Burkitt lymphoma.

She noted that other in vivo research has suggested ONC201 has a “very benign safety profile.” In another poster presented at AACR 2015 (abstract 4479), researchers reported results indicating that ONC201 is safe.

“They have tested it in mice and dogs and found that, at 10-fold the therapeutic dose, you don’t see much toxicity at all,” Dr Talekar said.

ONC201 is also being tested in a phase 1 study of adults with advanced solid tumors. Phase 1 studies of the drug in relapsed or refractory NHL and relapsed or refractory acute leukemias and high-risk myelodysplastic syndromes are not yet recruiting patients.

Inside the Pennsylvania

Convention Center, site of the

AACR Annual Meeting 2015

PHILADELPHIA—When current treatment approaches failed to save a young patient with non-Hodgkin lymphoma (NHL), a researcher from The Children’s Hospital of Philadelphia was driven to investigate new therapeutic options.

The investigation led the researcher, Mala Talekar, MBBS, to ONC201 (formerly TIC10), a small molecule that induces apoptosis by increasing surface expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

Preclinical experiments showed that ONC201 is active against NHL as a single agent, and it synergizes with chemotherapeutic drugs that are already used to treat NHL.

Dr Talekar and her colleagues described these experiments in a poster presented at the AACR Annual Meeting 2015 (abstract 5387). Some of the investigators involved in this research are employed by Oncoceutics, Inc., the company developing ONC201.

A researcher’s inspiration

“When I was doing my fellowship training, I had a teenage boy who had a rare form of non-Hodgkin’s lymphoma,” Dr Talekar explained. “He did not survive, despite receiving multiple treatments that are available for pediatric non-Hodgkin’s lymphoma.”

The boy’s death inspired Dr Talekar to seek new and better approaches to treat NHL. A search of the medical literature unearthed several articles detailing a TRAIL-based approach to treating lymphoma. So she decided to further investigate the effects of TRAIL in NHL.

“I first tried TRAIL in one lymphoma cell line,” she said. “And even though it did kill the cancer cells, it did not really give a satisfactory response.”

So Dr Talekar turned to the TRAIL agonist antibodies lexatumumab and mapatumumab, introducing each of them to human lymphoma cells. Although the antibodies caused more cell death than TRAIL itself, the response was still not satisfactory, she said.

“Fortunately for me, while I was working in the lab, one of the postdocs, Joshua Allen, discovered a new molecule called TRAIL-inducing compound 10, or TIC10,” Dr Talekar said. “So I tried TIC10—it is now called ONC201—and it gave a beautiful dose-response curve, causing complete cell death of the lymphoma cells.”

Dr Talekar was “very inspired” by this result and decided to test ONC201 in 8 different NHL cell lines—4 Burkitt lymphoma (Daudi, Raji, Ramos, and BJAB), 1 anaplastic large-cell lymphoma (Karpas299), and 3 mantle cell lymphoma (UPN2, Granta, and NCEB) cell lines.

“I found a beautiful dose-response curve,” Dr Talekar said, “suggesting that this molecule works in micromolar concentrations across all of the lymphoma cell lines.”

Elucidating the mechanism

Dr Talekar then set out to determine exactly how ONC201 causes cell death in NHL. Flow cytometry revealed that, as the dose of ONC201 increases, cell death increases, as does sub-G1 DNA content. This suggests the drug is causing cell death by apoptosis.

Next, Dr Talekar introduced ONC201 to NHL cell lines along with a pan-caspase inhibitor. She found the inhibitor blocked ONC201-induced apoptosis, which suggests ONC201 works via the caspase-mediated apoptotic pathway.

“The initial mechanism of action proposed for ONC201 was dual inactivation of two kinases, Akt and ERK,” Dr Talekar noted. “The dual inactivation causes dephosphorylation of Foxo3a. This causes its translocation to the nucleus and downstream upregulation of TRAIL, and, therefore, increased surface TRAIL expression. And we know increases in surface TRAIL cause cell death by apoptosis.”

With this in mind, Dr Talekar looked for increases in surface TRIAL after she incubated lymphoma cells with ONC201. She observed a dose-dependent increase in surface TRAIL and a linear correlation between the increase in TRAIL and apoptosis.

Then, she introduced ONC201 and a TRAIL-sequestering antibody, RIK-2, to lymphoma cells. RIK-2 inhibited apoptosis, which suggests ONC201 works as an anti-apoptotic agent via the TRAIL pathway.

Further testing

As a final step, Dr Talekar tested ONC201 in combination with chemotherapy drugs that are already used to treat pediatric NHL. She observed at least an additive effect, and sometimes a synergistic effect, between the drugs. The best responses occurred when she combined ONC201 with cytarabine, bortezomib, or doxorubicin.

Now, Dr Talekar is working on testing ONC201 in combination with cytarabine in a xenograft model of Burkitt lymphoma.

She noted that other in vivo research has suggested ONC201 has a “very benign safety profile.” In another poster presented at AACR 2015 (abstract 4479), researchers reported results indicating that ONC201 is safe.

“They have tested it in mice and dogs and found that, at 10-fold the therapeutic dose, you don’t see much toxicity at all,” Dr Talekar said.

ONC201 is also being tested in a phase 1 study of adults with advanced solid tumors. Phase 1 studies of the drug in relapsed or refractory NHL and relapsed or refractory acute leukemias and high-risk myelodysplastic syndromes are not yet recruiting patients.

Inside the Pennsylvania

Convention Center, site of the

AACR Annual Meeting 2015

PHILADELPHIA—When current treatment approaches failed to save a young patient with non-Hodgkin lymphoma (NHL), a researcher from The Children’s Hospital of Philadelphia was driven to investigate new therapeutic options.

The investigation led the researcher, Mala Talekar, MBBS, to ONC201 (formerly TIC10), a small molecule that induces apoptosis by increasing surface expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

Preclinical experiments showed that ONC201 is active against NHL as a single agent, and it synergizes with chemotherapeutic drugs that are already used to treat NHL.

Dr Talekar and her colleagues described these experiments in a poster presented at the AACR Annual Meeting 2015 (abstract 5387). Some of the investigators involved in this research are employed by Oncoceutics, Inc., the company developing ONC201.

A researcher’s inspiration

“When I was doing my fellowship training, I had a teenage boy who had a rare form of non-Hodgkin’s lymphoma,” Dr Talekar explained. “He did not survive, despite receiving multiple treatments that are available for pediatric non-Hodgkin’s lymphoma.”

The boy’s death inspired Dr Talekar to seek new and better approaches to treat NHL. A search of the medical literature unearthed several articles detailing a TRAIL-based approach to treating lymphoma. So she decided to further investigate the effects of TRAIL in NHL.

“I first tried TRAIL in one lymphoma cell line,” she said. “And even though it did kill the cancer cells, it did not really give a satisfactory response.”

So Dr Talekar turned to the TRAIL agonist antibodies lexatumumab and mapatumumab, introducing each of them to human lymphoma cells. Although the antibodies caused more cell death than TRAIL itself, the response was still not satisfactory, she said.

“Fortunately for me, while I was working in the lab, one of the postdocs, Joshua Allen, discovered a new molecule called TRAIL-inducing compound 10, or TIC10,” Dr Talekar said. “So I tried TIC10—it is now called ONC201—and it gave a beautiful dose-response curve, causing complete cell death of the lymphoma cells.”

Dr Talekar was “very inspired” by this result and decided to test ONC201 in 8 different NHL cell lines—4 Burkitt lymphoma (Daudi, Raji, Ramos, and BJAB), 1 anaplastic large-cell lymphoma (Karpas299), and 3 mantle cell lymphoma (UPN2, Granta, and NCEB) cell lines.

“I found a beautiful dose-response curve,” Dr Talekar said, “suggesting that this molecule works in micromolar concentrations across all of the lymphoma cell lines.”

Elucidating the mechanism

Dr Talekar then set out to determine exactly how ONC201 causes cell death in NHL. Flow cytometry revealed that, as the dose of ONC201 increases, cell death increases, as does sub-G1 DNA content. This suggests the drug is causing cell death by apoptosis.

Next, Dr Talekar introduced ONC201 to NHL cell lines along with a pan-caspase inhibitor. She found the inhibitor blocked ONC201-induced apoptosis, which suggests ONC201 works via the caspase-mediated apoptotic pathway.

“The initial mechanism of action proposed for ONC201 was dual inactivation of two kinases, Akt and ERK,” Dr Talekar noted. “The dual inactivation causes dephosphorylation of Foxo3a. This causes its translocation to the nucleus and downstream upregulation of TRAIL, and, therefore, increased surface TRAIL expression. And we know increases in surface TRAIL cause cell death by apoptosis.”

With this in mind, Dr Talekar looked for increases in surface TRIAL after she incubated lymphoma cells with ONC201. She observed a dose-dependent increase in surface TRAIL and a linear correlation between the increase in TRAIL and apoptosis.

Then, she introduced ONC201 and a TRAIL-sequestering antibody, RIK-2, to lymphoma cells. RIK-2 inhibited apoptosis, which suggests ONC201 works as an anti-apoptotic agent via the TRAIL pathway.

Further testing

As a final step, Dr Talekar tested ONC201 in combination with chemotherapy drugs that are already used to treat pediatric NHL. She observed at least an additive effect, and sometimes a synergistic effect, between the drugs. The best responses occurred when she combined ONC201 with cytarabine, bortezomib, or doxorubicin.

Now, Dr Talekar is working on testing ONC201 in combination with cytarabine in a xenograft model of Burkitt lymphoma.

She noted that other in vivo research has suggested ONC201 has a “very benign safety profile.” In another poster presented at AACR 2015 (abstract 4479), researchers reported results indicating that ONC201 is safe.

“They have tested it in mice and dogs and found that, at 10-fold the therapeutic dose, you don’t see much toxicity at all,” Dr Talekar said.

ONC201 is also being tested in a phase 1 study of adults with advanced solid tumors. Phase 1 studies of the drug in relapsed or refractory NHL and relapsed or refractory acute leukemias and high-risk myelodysplastic syndromes are not yet recruiting patients.