FDA Expands IBRANCE Approval for Maintenance Treatment in HR+, HER2+ Metastatic Breast Cancer

Pfizer said Wednesday that the U.S. Food and Drug Administration approved an expanded use of IBRANCE, or palbociclib, as a frontline maintenance treatment for adults with hormone receptor-positive, HER2-positive locally advanced or metastatic breast cancer after induction therapy.

The new indication allows IBRANCE to be used in combination with trastuzumab, with or without pertuzumab, and endocrine therapy as maintenance treatment following initial therapy. For patients, the decision adds a new option in a metastatic breast cancer subtype where randomized evidence for CDK4/6 inhibitors — a class of medicines that helps slow cancer cell growth — had been limited.

The approval was announced by Pfizer on June 24. A separate FDA press release was not located the same day, although labeling materials reflected the agency action. The decision is based on results from the Phase 3 PATINA, also known as AFT-38, trial, which tested whether adding IBRANCE during maintenance therapy could delay disease progression after induction treatment.

In PATINA, 518 patients were randomly assigned after induction therapy. Of those, 261 received IBRANCE plus anti-HER2 therapy and endocrine therapy, while 257 received anti-HER2 therapy and endocrine therapy alone. The main goal of the study was investigator-assessed progression-free survival, meaning the length of time patients lived without their cancer worsening.

Pfizer said the addition of IBRANCE reduced the risk of disease progression or death by 24%, with a hazard ratio of 0.76. The 95% confidence interval was 0.59 to 0.97, and the one-sided p-value was 0.0134. Median progression-free survival was 44.3 months in the IBRANCE arm, compared with 29.1 months in the control group.

Overall survival was a secondary endpoint and was not yet mature at the time of the announcement and publication, so the results do not show whether the regimen helps patients live longer overall.

Safety in PATINA was described as consistent with IBRANCE’s known profile. The most notable side effect was neutropenia, a drop in infection-fighting white blood cells. In the IBRANCE group, 78% of patients had neutropenia of any grade, 61% had grade 3 or higher neutropenia, and about 0.8% had febrile neutropenia, a more serious complication that involves fever.

The findings matter because the usual first-line treatment for hormone receptor-positive, HER2-positive metastatic breast cancer has been anti-HER2 therapy with chemotherapy, followed by maintenance anti-HER2 therapy plus endocrine therapy. Before this approval, IBRANCE’s U.S. uses were mainly in hormone receptor-positive, HER2-negative advanced or metastatic breast cancer. This action adds a HER2-positive maintenance use and extends a drug class that had been more firmly established in HER2-negative disease.

PATINA results were previously presented at the 2024 San Antonio Breast Cancer Symposium and published in the New England Journal of Medicine in 2026.

“Based on the results from the PATINA study, the addition of IBRANCE in the maintenance phase can meaningfully extend the time patients go without their disease progressing. This approval gives oncologists a new, evidence-based option to optimize maintenance therapy for their patients with HR+, HER2+ disease,” Otto Metzger, M.D., the trial’s principal investigator, said in Pfizer’s press release.

Pfizer said IBRANCE has been prescribed to more than 900,000 patients and is approved in more than 100 countries since its initial 2015 approval.