FDA Approves Expanded Indication for Breast Cancer Drug

The FDA approved a new indication that expands the use of palbociclib (Ibrance), a cyclin-dependent kinase 4/6 (CDK 4/6) inhibitor used to treat metastatic breast cancer.

Ibrance is now approved for use in combination with fulvestrant for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer in women with disease progression following endocrine therapy.

The approval followed results of the phase 3 PALOMA-3 trial of Ibrance used in combination with fulvestrant, which more than doubled progression-free survival (PFS) in pretreated patients with HR-positive, HER2-negative breast cancer, delaying disease progression by nearly 5 months.

“Today's news gives more women with metastatic breast cancer the opportunity to benefit from this first-in-class medicine," said President and General Manager of Pfizer, Liz Barrett. “Since Ibrance was approved just over one year ago, physicians across the US 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 patients' lives.”

Ibrance is under evaluation in the phase 3 PALOMA-2 trial in combination with letrozole in postmenopausal women.

The current phase 3 PALOMA-3 trial enrolled 521 women, regardless of menopausal state. The women were randomized 2:1 to receive Ibrance in combination with fulvestrant or the placebo with fulvestrant.

The results of the study showed that the combination of Ibrance and fulvestrant prolonged PFS compared with women who received placebo and fulvestrant.

The median PFS for women in the Ibrance and fulvestrant group was 9.5 months (95% CI: 9.2, 11.0), compared with 4.6 months in the placebo and fulvestrant group (95% CL: 3.5, 5.6) of PFS [HR 0.461 (95% CI: 0.360, 0.591), p <0.0001].

The confirmed overall response rate for patients with measurable disease was 24.6% for the group that was administered Ibrance and fulvestrant, compared to 10.9% for the placebo and fulvestrant group.

The duration of response in the Ibrance and fulvestrant group was 9.3 months compared with 7.6 months for the placebo and fulvestrant group.

Warnings and precautions for Ibrance are neutropenia, pulmonary embolism, and embryo-fetal toxicity.

The most common adverse events were neutropenia (83% vs 4%), 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%), thrombocytopenia (23% vs 0%), constipation (20% vs 16%), vomiting (19% vs 15%), alopecia (18% vs 6%), rash (17% vs 6%), decreased appetite (16% vs 8%), and pyrexia (13% vs 5%).

“There currently is no cure for metastatic breast cancer, so ongoing treatment is usually needed to control the spread of the disease,” said Chief Medical Officer and Breastcancer.org founder, Marisa Weiss, MD. “That's why the availability of a first-of-its-kind treatment option like Ibrance for women dealing with HR+, HER2- metastatic disease represents a very important advance.”