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The investigational anti-body drug conjugate (ADC) resistant to endocrine therapy, data from the phase 3 TROPION-Breast01 trial showed.
At a median follow-up of 10.8 months, the median progression-free survival (PFS) was 6.9 months for patients randomly assigned to receive Dato-DXd, compared with 4.9 months for the investigator’s choice of chemotherapy with either eribulin mesylate, vinorelbine, capecitabine, or gemcitabine. This difference translated into a 37% reduction in risk of disease progression with the ADC, reported Aditya Bardia, MD, MPH, director of the breast cancer research program at the Mass General Cancer Center in Boston.
Patients who received Dato-DXd had less than half the number of grade 3 or greater toxicities and fewer dose reductions or interruptions than patients who received chemotherapy, he noted in an oral abstract session at the 2023 European Society for Medical Oncology Congress.
“Overall, results support Dato-DXd as a potential new therapeutic option for patients with metastatic hormone receptor–positive breast cancer,” he said.
Different ADC, same target
Dr. Bardia noted that there is an unmet need for effective therapies for patients with metastatic HR+/HER2– breast cancer who experience disease progression after endocrine therapy and at least one line of systemic therapy.
Although chemotherapy is widely used in this population, it’s associated with low response rates, poor prognosis, and significant toxicities, including hematologic and neurologic adverse events (AEs).
Dato-DXd is composed of a monoclonal antibody targeting TROP2, a transmembrane glycoprotein overexpressed in cancer cells, linked to the topoisomerase 1 inhibitor deruxtecan as the toxic payload.
Dr. Bardia explained that Dato-DXd has four properties that distinguish it from other TROP2-directed ADCs: an optimized drug to antibody ratio of 4, a stable linker-payload, tumor-selective cleavable linker, both of which reduce off-target toxicities, and a bystander antitumor effect that can target TROP2-expressing cells in the tumor microenvironment.
In the phase I TROPION-PanTumor01 trial, Dato-DXd had promising anti-tumor activity and a manageable safety profile in patients with metastatic HR+/HER2– breast cancer, paving the way for the TROPION-Breast01 study reported here.
Efficacy results
In the Breast01 trial, 732 patients with inoperable or metastatic HR+/HER2– breast cancer previously treated with 1 or 2 lines of chemotherapy that had progressed on endocrine therapy were stratified by number of prior chemotherapy lines, geographic region, and prior CDK4/6 inhibitor status, and then randomized to either Dato-DXd 6 mg/kg intravenously on day 1 of each 3-week cycle (365 patients) or to investigator’s choice of chemotherapy (367 patients). According to the protocol, chemotherapy could be eribulin mesylate, vinorelbine, or gemcitabine delivered via IV on days 1 and 8 every 3 weeks, or oral capecitabine on days 1 through 14 of every 3-week cycle.
At the time of data cutoff, 93 patients assigned to the ADC and 39 assigned to chemotherapy were still on treatment.
As noted before, median PFS by blinded independent central review, one of two primary endpoints, was 6.9 months with Dato-DXd, compared with 4.9 months with chemotherapy, translating into a hazard ratio for progression of 0.63 (P < .0001).
The benefit was seen across nearly all subgroups except among patients who had not previously received a CDK4/6 inhibitor, and patients who had received a prior anthracycline but not a taxane.
Objective response rates (ORR) were 36.4% with Dato-DXd (99.5% partial and .5% complete response), compared with 22.9% with chemotherapy (all partial responses; P values not reported).
Overall survival data, the other primary endpoint, were not mature at a median OS follow-up of 9.7 months, and will be reported at a later date.
Safety results
“In terms of safety, the rate of grade 3 or higher treatment-related AEs in the Dato-DXd arm was less as compared to investigator choice of chemotherapy. This is a bit different from most of the studies; in general we see that the rate of adverse events is higher in the intervention arm as compared to the control arm,” Dr. Bardia commented.
Rates of dose reductions and dose interruptions due to treatment-related AEs were also lower with the ADC.
There were no patient deaths associated with Dato-DXd. One patient assigned to chemotherapy died from a complication associated with febrile neutropenia.
Most treatment-related AEs occurring in 15% of patients and AEs of special interest were of grade 1 and manageable.
The most common toxicities seen with the ADC were oral mucositis and dry eye. The most common side effects with chemotherapy were neutropenia and anemia, “the usual side effects you would expect with chemotherapy,” Dr. Bardia said, pointing out that the rate of grade 3 neutropenia was 31% with standard chemotherapy, compared with 1% with Dato-DXd.
Good, but we can do better
ESMO invited discussant Sarat Chandarlapaty, MD, PhD, a breast oncologist at Memorial Sloan Kettering Cancer Center in New York, commented that while the trial data showed superior efficacy and safety with Dato-DXd, compared with standard chemotherapy, it’s still unclear how it and other ADCs on the market and in the research pipeline may be used in therapy for this patient population.
“Would I rather prescribe Dato-DXd or more chemo after 1 to 2 lines of chemo in unselected HR-positive, HER2-negative breast cancer? The answer is Dato-DXd, but it leaves several unanswered questions for us,” he said.
“First, we have two ADCs approved in HR-positive breast cancer: another TROP2 ADC sacituzumab [govitecan] and a HER2 ADC trastuzumab deruxtecan. Would I rather give Dato over one of these? I don’t have an answer,” he added.
In addition, it’s unknown whether these drugs, which have the same topoisomerase-targeted payload, could be given in sequence, and there are as yet no clear answers as to whether patients might do better with Dato-DXd or with a PIK3ca inhibitor.
“I would say that the elephant in the room is really another question, and that is, ‘Is Dato-DXd in this context delivering on the promise of an ADC?’ ” Dr. Chandarlapaty said.
“I think translational research is urgently needed if we’re ultimately to deliver on the promise of these agents in the clinic,” he concluded.
The TROPION-Breast01 study is sponsored AstraZeneca, which is collaborating with Daiichi-Sankyo on global development and commercialization of Dato-DXd. Dr. Bardia disclosed advisory board activities and institutional research funding from AstraZeneca and Daiichi-Sankyo and others. Dr. Chandarlapaty disclosed research funding from both companies, and advisory board activities for AstraZeneca and others.
The investigational anti-body drug conjugate (ADC) resistant to endocrine therapy, data from the phase 3 TROPION-Breast01 trial showed.
At a median follow-up of 10.8 months, the median progression-free survival (PFS) was 6.9 months for patients randomly assigned to receive Dato-DXd, compared with 4.9 months for the investigator’s choice of chemotherapy with either eribulin mesylate, vinorelbine, capecitabine, or gemcitabine. This difference translated into a 37% reduction in risk of disease progression with the ADC, reported Aditya Bardia, MD, MPH, director of the breast cancer research program at the Mass General Cancer Center in Boston.
Patients who received Dato-DXd had less than half the number of grade 3 or greater toxicities and fewer dose reductions or interruptions than patients who received chemotherapy, he noted in an oral abstract session at the 2023 European Society for Medical Oncology Congress.
“Overall, results support Dato-DXd as a potential new therapeutic option for patients with metastatic hormone receptor–positive breast cancer,” he said.
Different ADC, same target
Dr. Bardia noted that there is an unmet need for effective therapies for patients with metastatic HR+/HER2– breast cancer who experience disease progression after endocrine therapy and at least one line of systemic therapy.
Although chemotherapy is widely used in this population, it’s associated with low response rates, poor prognosis, and significant toxicities, including hematologic and neurologic adverse events (AEs).
Dato-DXd is composed of a monoclonal antibody targeting TROP2, a transmembrane glycoprotein overexpressed in cancer cells, linked to the topoisomerase 1 inhibitor deruxtecan as the toxic payload.
Dr. Bardia explained that Dato-DXd has four properties that distinguish it from other TROP2-directed ADCs: an optimized drug to antibody ratio of 4, a stable linker-payload, tumor-selective cleavable linker, both of which reduce off-target toxicities, and a bystander antitumor effect that can target TROP2-expressing cells in the tumor microenvironment.
In the phase I TROPION-PanTumor01 trial, Dato-DXd had promising anti-tumor activity and a manageable safety profile in patients with metastatic HR+/HER2– breast cancer, paving the way for the TROPION-Breast01 study reported here.
Efficacy results
In the Breast01 trial, 732 patients with inoperable or metastatic HR+/HER2– breast cancer previously treated with 1 or 2 lines of chemotherapy that had progressed on endocrine therapy were stratified by number of prior chemotherapy lines, geographic region, and prior CDK4/6 inhibitor status, and then randomized to either Dato-DXd 6 mg/kg intravenously on day 1 of each 3-week cycle (365 patients) or to investigator’s choice of chemotherapy (367 patients). According to the protocol, chemotherapy could be eribulin mesylate, vinorelbine, or gemcitabine delivered via IV on days 1 and 8 every 3 weeks, or oral capecitabine on days 1 through 14 of every 3-week cycle.
At the time of data cutoff, 93 patients assigned to the ADC and 39 assigned to chemotherapy were still on treatment.
As noted before, median PFS by blinded independent central review, one of two primary endpoints, was 6.9 months with Dato-DXd, compared with 4.9 months with chemotherapy, translating into a hazard ratio for progression of 0.63 (P < .0001).
The benefit was seen across nearly all subgroups except among patients who had not previously received a CDK4/6 inhibitor, and patients who had received a prior anthracycline but not a taxane.
Objective response rates (ORR) were 36.4% with Dato-DXd (99.5% partial and .5% complete response), compared with 22.9% with chemotherapy (all partial responses; P values not reported).
Overall survival data, the other primary endpoint, were not mature at a median OS follow-up of 9.7 months, and will be reported at a later date.
Safety results
“In terms of safety, the rate of grade 3 or higher treatment-related AEs in the Dato-DXd arm was less as compared to investigator choice of chemotherapy. This is a bit different from most of the studies; in general we see that the rate of adverse events is higher in the intervention arm as compared to the control arm,” Dr. Bardia commented.
Rates of dose reductions and dose interruptions due to treatment-related AEs were also lower with the ADC.
There were no patient deaths associated with Dato-DXd. One patient assigned to chemotherapy died from a complication associated with febrile neutropenia.
Most treatment-related AEs occurring in 15% of patients and AEs of special interest were of grade 1 and manageable.
The most common toxicities seen with the ADC were oral mucositis and dry eye. The most common side effects with chemotherapy were neutropenia and anemia, “the usual side effects you would expect with chemotherapy,” Dr. Bardia said, pointing out that the rate of grade 3 neutropenia was 31% with standard chemotherapy, compared with 1% with Dato-DXd.
Good, but we can do better
ESMO invited discussant Sarat Chandarlapaty, MD, PhD, a breast oncologist at Memorial Sloan Kettering Cancer Center in New York, commented that while the trial data showed superior efficacy and safety with Dato-DXd, compared with standard chemotherapy, it’s still unclear how it and other ADCs on the market and in the research pipeline may be used in therapy for this patient population.
“Would I rather prescribe Dato-DXd or more chemo after 1 to 2 lines of chemo in unselected HR-positive, HER2-negative breast cancer? The answer is Dato-DXd, but it leaves several unanswered questions for us,” he said.
“First, we have two ADCs approved in HR-positive breast cancer: another TROP2 ADC sacituzumab [govitecan] and a HER2 ADC trastuzumab deruxtecan. Would I rather give Dato over one of these? I don’t have an answer,” he added.
In addition, it’s unknown whether these drugs, which have the same topoisomerase-targeted payload, could be given in sequence, and there are as yet no clear answers as to whether patients might do better with Dato-DXd or with a PIK3ca inhibitor.
“I would say that the elephant in the room is really another question, and that is, ‘Is Dato-DXd in this context delivering on the promise of an ADC?’ ” Dr. Chandarlapaty said.
“I think translational research is urgently needed if we’re ultimately to deliver on the promise of these agents in the clinic,” he concluded.
The TROPION-Breast01 study is sponsored AstraZeneca, which is collaborating with Daiichi-Sankyo on global development and commercialization of Dato-DXd. Dr. Bardia disclosed advisory board activities and institutional research funding from AstraZeneca and Daiichi-Sankyo and others. Dr. Chandarlapaty disclosed research funding from both companies, and advisory board activities for AstraZeneca and others.
The investigational anti-body drug conjugate (ADC) resistant to endocrine therapy, data from the phase 3 TROPION-Breast01 trial showed.
At a median follow-up of 10.8 months, the median progression-free survival (PFS) was 6.9 months for patients randomly assigned to receive Dato-DXd, compared with 4.9 months for the investigator’s choice of chemotherapy with either eribulin mesylate, vinorelbine, capecitabine, or gemcitabine. This difference translated into a 37% reduction in risk of disease progression with the ADC, reported Aditya Bardia, MD, MPH, director of the breast cancer research program at the Mass General Cancer Center in Boston.
Patients who received Dato-DXd had less than half the number of grade 3 or greater toxicities and fewer dose reductions or interruptions than patients who received chemotherapy, he noted in an oral abstract session at the 2023 European Society for Medical Oncology Congress.
“Overall, results support Dato-DXd as a potential new therapeutic option for patients with metastatic hormone receptor–positive breast cancer,” he said.
Different ADC, same target
Dr. Bardia noted that there is an unmet need for effective therapies for patients with metastatic HR+/HER2– breast cancer who experience disease progression after endocrine therapy and at least one line of systemic therapy.
Although chemotherapy is widely used in this population, it’s associated with low response rates, poor prognosis, and significant toxicities, including hematologic and neurologic adverse events (AEs).
Dato-DXd is composed of a monoclonal antibody targeting TROP2, a transmembrane glycoprotein overexpressed in cancer cells, linked to the topoisomerase 1 inhibitor deruxtecan as the toxic payload.
Dr. Bardia explained that Dato-DXd has four properties that distinguish it from other TROP2-directed ADCs: an optimized drug to antibody ratio of 4, a stable linker-payload, tumor-selective cleavable linker, both of which reduce off-target toxicities, and a bystander antitumor effect that can target TROP2-expressing cells in the tumor microenvironment.
In the phase I TROPION-PanTumor01 trial, Dato-DXd had promising anti-tumor activity and a manageable safety profile in patients with metastatic HR+/HER2– breast cancer, paving the way for the TROPION-Breast01 study reported here.
Efficacy results
In the Breast01 trial, 732 patients with inoperable or metastatic HR+/HER2– breast cancer previously treated with 1 or 2 lines of chemotherapy that had progressed on endocrine therapy were stratified by number of prior chemotherapy lines, geographic region, and prior CDK4/6 inhibitor status, and then randomized to either Dato-DXd 6 mg/kg intravenously on day 1 of each 3-week cycle (365 patients) or to investigator’s choice of chemotherapy (367 patients). According to the protocol, chemotherapy could be eribulin mesylate, vinorelbine, or gemcitabine delivered via IV on days 1 and 8 every 3 weeks, or oral capecitabine on days 1 through 14 of every 3-week cycle.
At the time of data cutoff, 93 patients assigned to the ADC and 39 assigned to chemotherapy were still on treatment.
As noted before, median PFS by blinded independent central review, one of two primary endpoints, was 6.9 months with Dato-DXd, compared with 4.9 months with chemotherapy, translating into a hazard ratio for progression of 0.63 (P < .0001).
The benefit was seen across nearly all subgroups except among patients who had not previously received a CDK4/6 inhibitor, and patients who had received a prior anthracycline but not a taxane.
Objective response rates (ORR) were 36.4% with Dato-DXd (99.5% partial and .5% complete response), compared with 22.9% with chemotherapy (all partial responses; P values not reported).
Overall survival data, the other primary endpoint, were not mature at a median OS follow-up of 9.7 months, and will be reported at a later date.
Safety results
“In terms of safety, the rate of grade 3 or higher treatment-related AEs in the Dato-DXd arm was less as compared to investigator choice of chemotherapy. This is a bit different from most of the studies; in general we see that the rate of adverse events is higher in the intervention arm as compared to the control arm,” Dr. Bardia commented.
Rates of dose reductions and dose interruptions due to treatment-related AEs were also lower with the ADC.
There were no patient deaths associated with Dato-DXd. One patient assigned to chemotherapy died from a complication associated with febrile neutropenia.
Most treatment-related AEs occurring in 15% of patients and AEs of special interest were of grade 1 and manageable.
The most common toxicities seen with the ADC were oral mucositis and dry eye. The most common side effects with chemotherapy were neutropenia and anemia, “the usual side effects you would expect with chemotherapy,” Dr. Bardia said, pointing out that the rate of grade 3 neutropenia was 31% with standard chemotherapy, compared with 1% with Dato-DXd.
Good, but we can do better
ESMO invited discussant Sarat Chandarlapaty, MD, PhD, a breast oncologist at Memorial Sloan Kettering Cancer Center in New York, commented that while the trial data showed superior efficacy and safety with Dato-DXd, compared with standard chemotherapy, it’s still unclear how it and other ADCs on the market and in the research pipeline may be used in therapy for this patient population.
“Would I rather prescribe Dato-DXd or more chemo after 1 to 2 lines of chemo in unselected HR-positive, HER2-negative breast cancer? The answer is Dato-DXd, but it leaves several unanswered questions for us,” he said.
“First, we have two ADCs approved in HR-positive breast cancer: another TROP2 ADC sacituzumab [govitecan] and a HER2 ADC trastuzumab deruxtecan. Would I rather give Dato over one of these? I don’t have an answer,” he added.
In addition, it’s unknown whether these drugs, which have the same topoisomerase-targeted payload, could be given in sequence, and there are as yet no clear answers as to whether patients might do better with Dato-DXd or with a PIK3ca inhibitor.
“I would say that the elephant in the room is really another question, and that is, ‘Is Dato-DXd in this context delivering on the promise of an ADC?’ ” Dr. Chandarlapaty said.
“I think translational research is urgently needed if we’re ultimately to deliver on the promise of these agents in the clinic,” he concluded.
The TROPION-Breast01 study is sponsored AstraZeneca, which is collaborating with Daiichi-Sankyo on global development and commercialization of Dato-DXd. Dr. Bardia disclosed advisory board activities and institutional research funding from AstraZeneca and Daiichi-Sankyo and others. Dr. Chandarlapaty disclosed research funding from both companies, and advisory board activities for AstraZeneca and others.
FROM ESMO CONGRESS 2023