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The U.S. Food and Drug Administration (FDA) recently granted Breakthrough Therapy Designation for inavolisib in combination with palbociclib and fulvestrant based on initial results of the study presented at a December 2023 meeting. The phase 3 results showed the inavolisib-based regimen more than doubled progression-free survival (PFS) compared with the two other drugs alone as first-line treatment, researchers reported.
The expanded analysis of the trial, which was presented at the annual meeting of the American Society of Clinical Oncology, looked at additional endpoints, including PFS2 (defined as time from randomization to end of next-line treatment), time to first chemotherapy, key adverse events (AEs) and patient-reported outcomes (PROs).
“Triple combination of inavolisib, a novel PI3K inhibitor, with palbociclib and fulvestrant, resulted in significant and clinically meaningful improvement in PFS (15.0 vs 7.3 months, hazard ratio [HR] 0.43, P less than .0001),” lead investigator Dejan Juric, MD, reported at the meeting, referring to the initial results.
In additional endpoints, the inavolisib-based triplet also “sustained benefit beyond disease progression, delay in chemotherapy initiation, a manageable safety profile, prolonged time to deterioration in pain severity, and maintained quality of life, supporting the overall conclusion that this triple combination is a promising new treatment option for patients with PIK3CA-mutated HR-positive, HER2-negative metastatic breast cancer,” said the oncologist, of Massachusetts General Hospital Cancer Center and assistant professor at Harvard Medical School in Boston.
Methods and Results
The trial enrolled 325 patients whose disease had progressed during or within 12 months of adjuvant endocrine therapy (ET) with an aromatase inhibitor or tamoxifen and who had not received prior systemic therapy for recurrent LA/mBC. Patients were enrolled from December 2019 to September 2023 and randomized to either the triplet combination of inavolisib with palbociclib and fulvestrant (n = 161) or the doublet therapy of placebo with palbociclib and fulvestrant (n = 164) until discontinuation due to progressive disease or toxicity.
At the analysis cutoff date at the end of September, 57.8% of patients in the experimental triple therapy arm and 70.1% in the doublet arm had discontinued treatment. In addition, “7.5% versus 11.6% of patients died without subsequent therapy,” said Dr. Juric, and 40.4% of those in the triplet arm, and 50% in the doublet arm received subsequent therapy.
In the expanded analysis, at a median follow-up of 21.3 months, the triplet combination was associated with a PFS2 benefit of 8.9 months over the doublet – meaning patients had 24 months versus 15.1 months from randomization to end of next-line treatment (HR = 0.54). There was a similar benefit in time to first chemotherapy.
Hyperglycemia, diarrhea, rash, and mucosal effects are a known toxicity of PI3K inhibition and were experienced more frequently in the inavolisib arm compared with the placebo arm: (59% vs 9%; 48% vs 16%; 25% vs 17%; and 51% vs 27% respectively). However, “in the vast majority of patients these AEs were experienced in a grade 1 or grade 2 level,” and had resolved by the cutoff date, said Dr. Juric.
There was a 6.2% rate of inavolisib discontinuation due to AEs, but most AEs could be managed with “common approaches” such as metformin for hyperglycemia, loperamide for diarrhea, topical hydrocortisone for rash, and steroid mouthwash for stomatitis/mucosal inflammation, he added.
Patients in the triple treatment arm experienced a longer interval before pain worsened, a median of 30.9 versus 18.1 months, and patient-reported outcomes and health-related quality of life measures showed no decrease with the addition of inavolisib, Dr. Juric reported.
Rationale for Using PFS2 as Endpoint
The PFS2 endpoint has emerged with studies of targeted cancer therapies, Kevin Kalinsky, MD, director of the Glenn Family Breast Center at Winship Cancer Institute of Emory University, in Atlanta, said in an interview.
“Presenting PFS2 is not a new thing — we’ve been doing this in other breast cancer studies (of CDK4/6 inhibitors),” said Dr. Kalinsky, a coauthor of the study. “The concern is that you give a drug, and then, after that, things grow so rapidly that then you’re actually not benefiting the patient.
“If you’re giving a targeted agent in the first-line, then the biology changes after that first-line, are you really even making a difference? Or is the drug so toxic that they’re not able to tolerate a next line of treatment?” Dr. Kalinsky continued. “So that’s really the intent of PFS2. The PFS2 included the next line of treatment, so it’s really a first, and second-line representation of treatment. The study presented at ASCO was really about toxicity.”
The study was funded by F. Hoffmann-La Roche Ltd. Dr. Juric disclosed having stock and other ownership interests in PIC Therapeutics, Relay Therapeutics, and Vibliome Therapeutics; consulting or advisory roles with AstraZeneca, Eisai, Genentech, Lilly, MapKure, Novartis, Pfizer, PIC Therapeutics, Relay Therapeutics, and Vibliome Therapeutics; and research funding from Amgen, Arvinas, AstraZeneca, Blueprint Medicines, Eisai, Genentech, Infinity Pharmaceuticals, InventisBio, Novartis, Pfizer, Ribon Therapeutics, Scorpion Therapeutics, Syros Pharmaceuticals, and Takeda.
The U.S. Food and Drug Administration (FDA) recently granted Breakthrough Therapy Designation for inavolisib in combination with palbociclib and fulvestrant based on initial results of the study presented at a December 2023 meeting. The phase 3 results showed the inavolisib-based regimen more than doubled progression-free survival (PFS) compared with the two other drugs alone as first-line treatment, researchers reported.
The expanded analysis of the trial, which was presented at the annual meeting of the American Society of Clinical Oncology, looked at additional endpoints, including PFS2 (defined as time from randomization to end of next-line treatment), time to first chemotherapy, key adverse events (AEs) and patient-reported outcomes (PROs).
“Triple combination of inavolisib, a novel PI3K inhibitor, with palbociclib and fulvestrant, resulted in significant and clinically meaningful improvement in PFS (15.0 vs 7.3 months, hazard ratio [HR] 0.43, P less than .0001),” lead investigator Dejan Juric, MD, reported at the meeting, referring to the initial results.
In additional endpoints, the inavolisib-based triplet also “sustained benefit beyond disease progression, delay in chemotherapy initiation, a manageable safety profile, prolonged time to deterioration in pain severity, and maintained quality of life, supporting the overall conclusion that this triple combination is a promising new treatment option for patients with PIK3CA-mutated HR-positive, HER2-negative metastatic breast cancer,” said the oncologist, of Massachusetts General Hospital Cancer Center and assistant professor at Harvard Medical School in Boston.
Methods and Results
The trial enrolled 325 patients whose disease had progressed during or within 12 months of adjuvant endocrine therapy (ET) with an aromatase inhibitor or tamoxifen and who had not received prior systemic therapy for recurrent LA/mBC. Patients were enrolled from December 2019 to September 2023 and randomized to either the triplet combination of inavolisib with palbociclib and fulvestrant (n = 161) or the doublet therapy of placebo with palbociclib and fulvestrant (n = 164) until discontinuation due to progressive disease or toxicity.
At the analysis cutoff date at the end of September, 57.8% of patients in the experimental triple therapy arm and 70.1% in the doublet arm had discontinued treatment. In addition, “7.5% versus 11.6% of patients died without subsequent therapy,” said Dr. Juric, and 40.4% of those in the triplet arm, and 50% in the doublet arm received subsequent therapy.
In the expanded analysis, at a median follow-up of 21.3 months, the triplet combination was associated with a PFS2 benefit of 8.9 months over the doublet – meaning patients had 24 months versus 15.1 months from randomization to end of next-line treatment (HR = 0.54). There was a similar benefit in time to first chemotherapy.
Hyperglycemia, diarrhea, rash, and mucosal effects are a known toxicity of PI3K inhibition and were experienced more frequently in the inavolisib arm compared with the placebo arm: (59% vs 9%; 48% vs 16%; 25% vs 17%; and 51% vs 27% respectively). However, “in the vast majority of patients these AEs were experienced in a grade 1 or grade 2 level,” and had resolved by the cutoff date, said Dr. Juric.
There was a 6.2% rate of inavolisib discontinuation due to AEs, but most AEs could be managed with “common approaches” such as metformin for hyperglycemia, loperamide for diarrhea, topical hydrocortisone for rash, and steroid mouthwash for stomatitis/mucosal inflammation, he added.
Patients in the triple treatment arm experienced a longer interval before pain worsened, a median of 30.9 versus 18.1 months, and patient-reported outcomes and health-related quality of life measures showed no decrease with the addition of inavolisib, Dr. Juric reported.
Rationale for Using PFS2 as Endpoint
The PFS2 endpoint has emerged with studies of targeted cancer therapies, Kevin Kalinsky, MD, director of the Glenn Family Breast Center at Winship Cancer Institute of Emory University, in Atlanta, said in an interview.
“Presenting PFS2 is not a new thing — we’ve been doing this in other breast cancer studies (of CDK4/6 inhibitors),” said Dr. Kalinsky, a coauthor of the study. “The concern is that you give a drug, and then, after that, things grow so rapidly that then you’re actually not benefiting the patient.
“If you’re giving a targeted agent in the first-line, then the biology changes after that first-line, are you really even making a difference? Or is the drug so toxic that they’re not able to tolerate a next line of treatment?” Dr. Kalinsky continued. “So that’s really the intent of PFS2. The PFS2 included the next line of treatment, so it’s really a first, and second-line representation of treatment. The study presented at ASCO was really about toxicity.”
The study was funded by F. Hoffmann-La Roche Ltd. Dr. Juric disclosed having stock and other ownership interests in PIC Therapeutics, Relay Therapeutics, and Vibliome Therapeutics; consulting or advisory roles with AstraZeneca, Eisai, Genentech, Lilly, MapKure, Novartis, Pfizer, PIC Therapeutics, Relay Therapeutics, and Vibliome Therapeutics; and research funding from Amgen, Arvinas, AstraZeneca, Blueprint Medicines, Eisai, Genentech, Infinity Pharmaceuticals, InventisBio, Novartis, Pfizer, Ribon Therapeutics, Scorpion Therapeutics, Syros Pharmaceuticals, and Takeda.
The U.S. Food and Drug Administration (FDA) recently granted Breakthrough Therapy Designation for inavolisib in combination with palbociclib and fulvestrant based on initial results of the study presented at a December 2023 meeting. The phase 3 results showed the inavolisib-based regimen more than doubled progression-free survival (PFS) compared with the two other drugs alone as first-line treatment, researchers reported.
The expanded analysis of the trial, which was presented at the annual meeting of the American Society of Clinical Oncology, looked at additional endpoints, including PFS2 (defined as time from randomization to end of next-line treatment), time to first chemotherapy, key adverse events (AEs) and patient-reported outcomes (PROs).
“Triple combination of inavolisib, a novel PI3K inhibitor, with palbociclib and fulvestrant, resulted in significant and clinically meaningful improvement in PFS (15.0 vs 7.3 months, hazard ratio [HR] 0.43, P less than .0001),” lead investigator Dejan Juric, MD, reported at the meeting, referring to the initial results.
In additional endpoints, the inavolisib-based triplet also “sustained benefit beyond disease progression, delay in chemotherapy initiation, a manageable safety profile, prolonged time to deterioration in pain severity, and maintained quality of life, supporting the overall conclusion that this triple combination is a promising new treatment option for patients with PIK3CA-mutated HR-positive, HER2-negative metastatic breast cancer,” said the oncologist, of Massachusetts General Hospital Cancer Center and assistant professor at Harvard Medical School in Boston.
Methods and Results
The trial enrolled 325 patients whose disease had progressed during or within 12 months of adjuvant endocrine therapy (ET) with an aromatase inhibitor or tamoxifen and who had not received prior systemic therapy for recurrent LA/mBC. Patients were enrolled from December 2019 to September 2023 and randomized to either the triplet combination of inavolisib with palbociclib and fulvestrant (n = 161) or the doublet therapy of placebo with palbociclib and fulvestrant (n = 164) until discontinuation due to progressive disease or toxicity.
At the analysis cutoff date at the end of September, 57.8% of patients in the experimental triple therapy arm and 70.1% in the doublet arm had discontinued treatment. In addition, “7.5% versus 11.6% of patients died without subsequent therapy,” said Dr. Juric, and 40.4% of those in the triplet arm, and 50% in the doublet arm received subsequent therapy.
In the expanded analysis, at a median follow-up of 21.3 months, the triplet combination was associated with a PFS2 benefit of 8.9 months over the doublet – meaning patients had 24 months versus 15.1 months from randomization to end of next-line treatment (HR = 0.54). There was a similar benefit in time to first chemotherapy.
Hyperglycemia, diarrhea, rash, and mucosal effects are a known toxicity of PI3K inhibition and were experienced more frequently in the inavolisib arm compared with the placebo arm: (59% vs 9%; 48% vs 16%; 25% vs 17%; and 51% vs 27% respectively). However, “in the vast majority of patients these AEs were experienced in a grade 1 or grade 2 level,” and had resolved by the cutoff date, said Dr. Juric.
There was a 6.2% rate of inavolisib discontinuation due to AEs, but most AEs could be managed with “common approaches” such as metformin for hyperglycemia, loperamide for diarrhea, topical hydrocortisone for rash, and steroid mouthwash for stomatitis/mucosal inflammation, he added.
Patients in the triple treatment arm experienced a longer interval before pain worsened, a median of 30.9 versus 18.1 months, and patient-reported outcomes and health-related quality of life measures showed no decrease with the addition of inavolisib, Dr. Juric reported.
Rationale for Using PFS2 as Endpoint
The PFS2 endpoint has emerged with studies of targeted cancer therapies, Kevin Kalinsky, MD, director of the Glenn Family Breast Center at Winship Cancer Institute of Emory University, in Atlanta, said in an interview.
“Presenting PFS2 is not a new thing — we’ve been doing this in other breast cancer studies (of CDK4/6 inhibitors),” said Dr. Kalinsky, a coauthor of the study. “The concern is that you give a drug, and then, after that, things grow so rapidly that then you’re actually not benefiting the patient.
“If you’re giving a targeted agent in the first-line, then the biology changes after that first-line, are you really even making a difference? Or is the drug so toxic that they’re not able to tolerate a next line of treatment?” Dr. Kalinsky continued. “So that’s really the intent of PFS2. The PFS2 included the next line of treatment, so it’s really a first, and second-line representation of treatment. The study presented at ASCO was really about toxicity.”
The study was funded by F. Hoffmann-La Roche Ltd. Dr. Juric disclosed having stock and other ownership interests in PIC Therapeutics, Relay Therapeutics, and Vibliome Therapeutics; consulting or advisory roles with AstraZeneca, Eisai, Genentech, Lilly, MapKure, Novartis, Pfizer, PIC Therapeutics, Relay Therapeutics, and Vibliome Therapeutics; and research funding from Amgen, Arvinas, AstraZeneca, Blueprint Medicines, Eisai, Genentech, Infinity Pharmaceuticals, InventisBio, Novartis, Pfizer, Ribon Therapeutics, Scorpion Therapeutics, Syros Pharmaceuticals, and Takeda.
FROM ASCO 2024