FDA Expands Pfizer’s Ibrance as Maintenance Therapy for HR-Positive, HER2-Positive Metastatic Breast Cancer

The U.S. Food and Drug Administration on June 24, 2026, approved Pfizer’s palbociclib (Ibrance) as a maintenance therapy for adults with hormone receptor-positive, HER2-positive locally advanced or metastatic breast cancer. The approval allows palbociclib to be used in combination with trastuzumab, with or without pertuzumab, plus endocrine therapy following induction treatment, Pfizer officials said.

The approval expands the use of palbociclib, a CDK4/6 inhibitor marketed as Ibrance by Pfizer Inc., to adult patients with hormone receptor-positive (HR+), HER2-positive (HER2+) locally advanced or metastatic breast cancer as a maintenance therapy following induction treatment, according to the FDA announcement dated June 24, 2026. The newly authorized regimen combines palbociclib with trastuzumab, with or without pertuzumab, plus endocrine therapy, Pfizer officials said in a press release issued the same day.

Median PFS was 44.3 months in the palbociclib group compared to 29.1 months in the control group, with a hazard ratio of 0.75 (95% confidence interval, 0.59 to 0.96; P = 0.02), according to published trial results.

The FDA’s decision was based on data from the PATINA phase III clinical trial, which enrolled 518 patients with HR+/HER2+ metastatic breast cancer. Of these, 261 patients received palbociclib in combination with trastuzumab, pertuzumab, and endocrine therapy, while 257 patients received standard therapy without palbociclib. At a median follow-up of 53.5 months, the trial demonstrated a statistically significant improvement in progression-free survival (PFS) for patients treated with palbociclib.

Additional efficacy outcomes reported in the trial included an objective response rate of 29.2% with palbociclib versus 22.2% in the control arm, and a clinical benefit rate of 89.3% compared with 81.3%, according to an ASCO Post report. The PATINA trial data supported the FDA’s expanded indication, which allows the use of palbociclib as maintenance therapy to prolong disease control after patients have completed initial induction treatment.

The FDA-approved dosing regimen for palbociclib is 125 mg administered orally once daily for 21 consecutive days, followed by a 7-day treatment-free interval, constituting a 28-day cycle. This dosing schedule is to be used in combination with trastuzumab and may include pertuzumab, alongside endocrine therapy, as specified in the agency’s prescribing information.

Safety data from the PATINA trial indicated a higher incidence of grade 3 and 4 adverse events in the palbociclib arm, primarily due to neutropenia. Specifically, 79.7% of patients receiving palbociclib experienced grade 3 adverse events, and 10.0% experienced grade 4 events, compared to 30.6% and 3.6%, respectively, in the standard therapy arm. Pfizer’s prescribing information also includes warnings about severe, life-threatening, or fatal interstitial lung disease (ILD) or pneumonitis associated with CDK4/6 inhibitors like Ibrance. Additionally, venous thromboembolism has been reported in other clinical trial experiences with palbociclib, according to Pfizer’s press materials.

Prior to this expanded approval, Ibrance was authorized for use in HR-positive, HER2-negative advanced or metastatic breast cancer in combination with endocrine therapies. The new indication marks the first FDA approval of palbociclib for HR-positive, HER2-positive metastatic breast cancer, broadening its clinical application. The original approval pathway for Ibrance included Breakthrough Therapy designation and Priority Review in the HR+/HER2-negative metastatic setting.

Pfizer officials described the approval as an expansion of the drug’s label to include maintenance therapy following induction treatment for patients with HR+/HER2+ metastatic breast cancer. The FDA’s decision reflects the agency’s recognition of the clinical benefit demonstrated by the PATINA trial in this patient population.