FDA expands Ibrance approval for metastatic breast cancer

The FDA expanded the approval of palbociclib for the treatment of metastatic breast cancer.

Palbociclib (Ibrance, Pfizer) — a cyclin-dependent kinase 4/6 inhibitor — now is approved for use in combination with fulvestrant for the treatment of women with hormone receptor-positive, HER-2–negative metastatic breast cancer who progressed on endocrine therapy.

The agent already had been approved for use in combination with letrozole as initial endocrine-based therapy in postmenopausal women with HR-positive, HER-2–negative advanced or metastatic breast cancer.

The FDA based the expanded approval on results from the phase 3 PALOMA-3 trial, which included 521 pre-, peri- and postmenopausal women with HR-positive, HER-2–negative metastatic breast cancer whose disease progressed during or after endocrine therapy in the adjuvant or metastatic settings. Researchers assigned women 2:1 to fulvestrant plus palbociclib or fulvestrant plus placebo.

Results showed the addition of palbociclib to fulvestrant prolonged median PFS (9.5 months vs. 4.6 months; HR = 0.46; 95% CI, 0.36-0.59). Researchers also reported a higher overall response rate (24.6% vs. 10.9%) and longer duration of response (9.3 months vs. 7.6 months) in the combination group.

“[This] news gives more women with metastatic breast cancer the opportunity to benefit from this first-in-class medicine,” Liz Barrett, global president and general manager of Pfizer Oncology, said in a 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.”

In PALOMA-3, the most common any-grade adverse reactions among palbociclib-treated patients included neutropenia (83% in the combination group vs. 4% for fulvestrant alone), leukopenia (53% vs. 5%), infections (47% vs. 31%), fatigue (41% vs. 29%), nausea (34% vs. 28%), anemia (30% vs. 13%), stomatitis (28% vs. 13%), headache (26% vs 20%), diarrhea (24% vs 19%) and thrombocytopenia (23% vs 0%).