Pfizer: Pfizer Announces Overall Survival Results from Phase 3 PALOMA-2 Trial of IBRANCE® (palbociclib) for the First-Line Treatment of ER+, HER2- Metastatic Breast Cancer

Pfizer Inc. (NYSE:PFE) today announced overall survival (OS) results from the Phase 3 PALOMA-2 trial, which evaluated IBRANCE® (palbociclib) in combination with letrozole compared to placebo plus letrozole for the first-line treatment of postmenopausal women with estrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC). With a median follow-up of 90 months, patients receiving IBRANCE in combination with letrozole had numerically longer OS compared to placebo plus letrozole (median (95% CI) 53.9 months (49.8–60.8) vs median 51.2 months (43.7–58.9)); the results were not statistically significant (Hazard Ratio (HR)=0.956 [95% CI, 0.777–1.177]). The PALOMA-2 trial was designed for a primary endpoint of progression-free survival (PFS) with OS as one of the secondary endpoints. The results will be presented today as an oral presentation at the American Society of Clinical Oncology (ASCO) 2022 Annual Meeting (LBA 1003).

“IBRANCE continues to provide substantial benefit as a first-line treatment for adults with HR+, HER2- mBC based on strong progression-free survival data, which formed the basis of its worldwide approvals,” said Chris Boshoff, M.D., Ph.D., Chief Development Officer, Oncology, Pfizer Global Product Development. “Interpretation of OS in PALOMA-2 is limited by the large and disproportionate censoring of patients with missing survival data between treatment arms. We remain confident in the compelling benefits that IBRANCE plus endocrine therapy offers to this patient population, which is underscored by data from PALOMA-2 showing delayed time to chemotherapy, maintenance of quality of life and a consistent safety profile. Pfizer continues to invest in expanding the treatment options for people living with metastatic breast cancer.”

“IBRANCE transformed the treatment landscape for patients with HR+, HER2- MBC when it was approved in 2015, representing the first new treatment in this patient population in over a decade,” said Richard Finn, M.D., Professor of Medicine at the UCLA David Geffen School of Medicine and Jonsson Comprehensive Cancer Center. “PALOMA-2 enrolled a diverse patient population including patients whose disease was first diagnosed in the metastatic stage as well as those with Disease Free Interval (DFI) less than 12 months from adjuvant treatment and those with greater than 12 months following adjuvant treatment. The median survival of over 50 months in this population represents a significant improvement in the natural history of HR+ breast cancer.”

PALOMA-2 met its primary endpoint of PFS in 2016 and was published in The New England Journal of Medicine in November 2016. The results demonstrated IBRANCE plus letrozole resulted in an improved median PFS of 24.8 months when compared to 14.5 months with placebo plus letrozole (HR=0.580). The PALOMA-2 trial showed that in addition to substantially delaying progressive disease, IBRANCE as first-line treatment, in combination with letrozole, delayed time to chemotherapy (38.1 months vs 29.8 months; HR, 0.73), while maintaining quality of life with no new identified safety issues.

The OS analysis being presented at ASCO included a large proportion of patients with missing survival data (i.e. patients who withdrew consent or were lost to follow-up) and were censored (assumed to be alive) at the time of the analysis: 13% in the treatment arm versus 21% in the control arm. Also of note, 10% of IBRANCE plus letrozole and 2% of placebo plus letrozole patients were still on study treatment at the time of the final analysis. The most common adverse reactions in PALOMA-2 included neutropenia, leukopenia, infections, fatigue and nausea.

IBRANCE continues to be a leader in the CDK4/6 inhibitor class, prescribed to over 450,000 patients across more than 100 countries, and seven out of 10 patients in the U.S. who are prescribed a CDK4/6 inhibitor receiving an IBRANCE prescription.i

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