FDA Approves Pfizer’s Breast Cancer Treatment

On June 24, 2026, Pfizer and FDA announced the approval of a maintenance treatment for adults with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) locally advanced or metastatic breast cancer (MBC).1-2 The combination of palbociclib (IBRANCE) with trastuzumab, with or without pertuzumab, and endocrine therapy has been approved by FDA for use following induction treatment.

Palbociclib, an oral inhibitor of CDKs 4 and 6, is currently used for the “treatment of adult patients with HR+, HER2- advanced or metastatic breast cancer in combination with an aromatase inhibitor as initial endocrine-based therapy; or with fulvestrant in patients with disease progression following endocrine therapy.”1 Other indications include in combination with inavolisib and fulvestrant for the treatment of adult patients with recurring endocrine-resistant, PIK3CA-mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer or after completing adjuvant endocrine therapy.

“Over the past decade, IBRANCE has helped transform metastatic breast cancer treatment, establishing CDK4/6 inhibition as a cornerstone of care,” said Aamir Malik, chief US commercial officer and executive vice president, Pfizer, in a press release.1 “With today’s FDA approval, IBRANCE becomes the first and only CDK4/6 inhibitor indicated for patients with HR+ metastatic breast cancer regardless of HER2 status, extending its impact to patients who continue to face challenges with treatment resistance. This milestone strengthens confidence in IBRANCE as a CDK4/6 inhibitor backbone across combination regimens, reflecting Pfizer's ongoing leadership in delivering meaningful advances for people with breast cancer.”

What Did the Trial Results Show?

FDA approved the treatment based on positive results from the Alliance Foundation Trials (AFT)-sponsored phase 3 PATINA trial, which demonstrated a 24% reduction in the risk of progression or death following induction treatment with palbociclib added to trastuzumab or trastuzumab plus pertuzumab and endocrine therapies compared to anti-HER2 and endocrine therapies alone. The trial was a randomized, open-label global phase 3 study with 518 patients to evaluate the efficacy and safety of palbociclibin combination with anti-HER2 therapy and endocrine therapy compared to anti-HER2 therapy and endocrine therapy alone as a first-line maintenance therapy. Trial results were published in the New England Journal of Medicine.3

According to FDA, “the major efficacy outcome measure was investigator-assessed progression-free survival (PFS) per RECIST version 1.1. Overall survival (OS) was an additional efficacy outcome measure. A statistically significant improvement in investigator-assessed PFS was observed for palbociclib with trastuzumab, with or without pertuzumab, and endocrine therapy compared to trastuzumab, with or without pertuzumab, and endocrine therapy alone (Hazard ratio 0.76 [95% CI: 0.59, 0.97], 1-sided p-value 0.0134). Median PFS could not be adequately described because of censoring. At the time of the PFS analysis, OS data were not mature.”2

“Resistance to dual anti-HER2 and endocrine therapy remains a central clinical challenge for patients with HR+, HER2+ metastatic breast cancer —even after an excellent response to initial treatment,” said Otto Metzger, M.D., principal investigator of the trial for Alliance Foundation Trials and Medical Oncologist at the Dana-Farber Cancer Institute, in a press release.1 “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.”

What Does This Mean for the Industry?

Palbociclib received breakthrough therapy designation for this indication, and the review used the FDA's Assessment Aid. This may indicate a willingness by FDA to expedite CDK4/6 inhibitor reviews in new combinations, which may encourage other manufacturers to invest in similar combinatorial approaches and pursue breakthrough designation strategies.

Because this is a multi-drug regimen that includes a small molecule (palbociclib), two monoclonal antibodies (trastuzumab and pertuzumab), and a hormone therapy, multiple manufacturers across different modalities (oral oncology, biologics/biosimilars) may see an increase in demand simultaneously. There may also be a rise in the complexity of supply chain coordination across drug classes.

The fact that trastuzumab and pertuzumab are biologics with established biosimilar competition and the regimen includes these agents, biosimilar manufacturers of trastuzumab (e.g., Kanjinti, Herzuma, Ogivri) and pertuzumab may find an increase in volume demand, reinforcing the commercial viability of those biosimilar programs.

There may also be an indirect benefit to manufacturers and labs producing diagnostic reagents, IHC/ISH assay kits, and genomic testing platforms, as this drug approval reinforces the importance of HER2 and HR testing as patient selection tools.

References

1. FDA approves Pfizer’s IBRANCE regimen for HR+, HER2+ metastatic breast cancer frontline maintenance. Press release. Pfizer. June 24, 2026. https://www.pfizer.com/news/press-release/press-release-detail/fda-approves-pfizers-ibrance-regimen-hr-her2-metastatic
2. FDA approves palbociclib with trastuzumab, with or without pertuzumab, and endocrine therapy for the maintenance treatment of HR-positive, HER2-positive metastatic breast cancer. Press release. FDA. June 24, 2026. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-palbociclib-trastuzumab-or-without-pertuzumab-and-endocrine-therapy-maintenance
3. Metzger O, Mandrekar S, Goel S, et al. Palbociclib for hormone-receptor–positive, HER2-positive advanced breast cancer. The New England Journal of Medicine. 2026 394 (5) doi: 10.1056/NEJMoa2511218 https://www.nejm.org/doi/full/10.1056/NEJMoa2511218