FDA Approves Combination Treatment of Faslodex/Ibrance for Certain Metastatic Breast Cancers

FDA Approves Combination Treatment of Faslodex/Ibrance for Certain Metastatic Breast Cancers

The U.S. Food and Drug Administration (FDA) has approved expanding the use of AstraZeneca’s breast cancer drug Faslodex (fulvestrant), in combination with Pfizer’s Ibrance (palbociclib), to treat advanced breast cancers (BC).

The combination can now be used to treat women with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (MBC) whose disease has progressed after endocrine therapy.

According to a press release, the FDA had initially approved Faslodex as a monotherapy for post-menopausal women with HR+ MBC, whose cancer had progressed after antiestrogen therapy. Data supporting this new decision was collected in the Phase 3 PALOMA-3 clinical trial, which demonstrated an average progression-free survival (PFS) increase of 4.9 months with Faslodex/Ibrance treatment, as opposed to Faslodex/placebo, in women with HR+/HER2-negative MBC whose disease had worsened after endocrine therapy. PFS improvement was not considered to be related to menopausal status.

The study analyzed 521 pre- and post-menopausal women, 74 percent of whom were Caucasian. A total 25 percent of participants had not received any previous therapy in the MBC setting, 60 percent had visceral metastases, and 23 percent had bone-only metastases. Ibrance (palbociclib) was given via oral administration at 125 mg daily for 21 consecutive days, followed by seven days without treatment; Fulvestrant was given intramuscularly at 500 mg on days 1 and 15 of Cycle 1, and then on the first day of each subsequent 28-day cycle.

The most frequent adverse effects reported under the combined regimen were neutropenia (83% for combo versus 4% for fulvestrant), leukopenia (53% for combo versus 5% for fulvestrant), infections (47% for combo versus 31% for fulvestrant), fatigue (41% for combo versus 29% for fulvestrant), nausea (34% for combo versus 28% for fulvestrant), anemia (30% for combo versus 13% for fulvestrant), stomatitis (28% for combo versus 13% for fulvestrant), headache (26% for combo versus 20% for fulvestrant), diarrhea (24% for combo versus 19% for fulvestrant), and thrombocytopenia (23% for combo versus 0% for fulvestrant).

“We believe that advances in cancer treatment will come, in part, from our research building upon existing treatments,” Andrew Coop, vice president for U.S. medical affairs/oncology at AstraZeneca, said in the release. “This new indication adds to the existing body of evidence supporting Faslodex-based therapy for certain metastatic breast cancer patients in an area where there is still a high unmet medical need.”

Advanced or metastatic breast cancer is the most severe stage of BC (also referred to as stage 4), and develops when cancer cells have spread beyond the initial tumor site to other parts of the body, outside of the breast tissue, mostly to the bone, lungs, liver, and brain.