Expanded Label for Palbociclib in Relapsed, Advanced Breast Cancer

A year following its accelerated approval as frontline treatment for postmenopausal women with estrogen receptor—positive, human epidermal growth factor receptor 2 (HER2)–negative metastatic breast cancer, the FDA has now expanded the use of palbociclib (Ibrance) in combination with fulvestrant for hormone receptor—positive, HER2–negative advanced breast cancer that has progressed on endocrine treatment.

Pfizer had submitted a supplemental new drug application—also known as sNDA—to the FDA in December 2015, that summarized phase 3 data from the PALOMA-3 trial. The trial evaluated palbociclib in combination with fulvestrant versus fulvestrant with placebo, in 521 pre- and postmenopausal women. Trial end point was unacceptable toxicity or disease progression. While none of the trial enrollees were treatment naïve, 80% were postmenopausal and 75% had received prior chemotherapy.

The observed improvement in progression-free survival (PFS) resulted in the current expanded label—median PFS for the palbociclib plus fulvestrant group was 9.5 months, significantly greater than the 4.6 months observed with the placebo plus fulvestrant group (hazard ratio, 0.46; 95% CI, 0.36, 0.59; P<.0001).

Safety evaluation in 345 patients who received palbociclib plus fulvestrant identified the following grade 1-4 adverse reactions as being most common: neutropenia, leukopenia, infections, fatigue, nausea, anemia, stomatitis, headache, diarrhea, thrombocytopenia, constipation, vomiting, alopecia, rash, decreased appetite, and pyrexia. The most common grade 3-4 adverse reactions were neutropenia and leukopenia.

“Today's news gives more women with metastatic breast cancer the opportunity to benefit from this first-in-class medicine,” said Liz Barrett, global president and general manager, Pfizer Oncology, in an associated press release. “Since IBRANCE was approved just over one year ago, physicians across the U.S. have embraced it as a standard of care in the first-line setting. The expanded approval of IBRANCE is supported by a robust body of evidence and underscores Pfizer's continued commitment to addressing the needs of the metastatic breast cancer community. Pfizer is proud to bring forward innovative therapies like IBRANCE that make a meaningful difference in patient’s lives.”