On October 7, 2026 Pfizer Inc. (NYSE: PFE) reported that the U.S. Food and Drug Administration (FDA) has approved TUKYSA (tucatinib) in combination with trastuzumab and pertuzumab for the maintenance treatment of adults with unresectable locally advanced or metastatic human epidermal growth factor 2-positive (HER2+) breast cancer following induction treatment. The approval expands the use of TUKYSA to frontline, an earlier stage of metastatic disease, offering a new chemotherapy-free maintenance treatment option that may help further delay disease progression.
Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:
Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing
Schedule Your 30 min Free Demo!
"Since its first approval in 2020, TUKYSA has become an important treatment for patients with second-line HER2+ metastatic breast cancer. Today’s FDA approval marks the next chapter for TUKYSA, bringing it into the front-line maintenance setting and offering patients a chemotherapy-free option that can help delay disease progression after initial treatment. This approval reflects Pfizer’s commitment to advancing therapies across the breast cancer treatment journey and delivering meaningful new options for people living with metastatic breast cancer."
– Aamir Malik, Executive Vice President, Chief U.S. Commercial Officer, Pfizer
"The treatment landscape for HER2+ metastatic breast cancer has evolved dramatically over the past decade, but many patients still experience disease progression despite initial benefit from therapy. The HER2CLIMB-05 findings support TUKYSA plus trastuzumab and pertuzumab as a chemotherapy-free maintenance strategy that allows us to target HER2-positive tumors from multiple angles and can help prolong disease control."
– Erika Hamilton, M.D., principal investigator of HER2CLIMB-05 and Chief Development Officer, Late Phase & Director, Breast Cancer Research for Sarah Cannon Research Institute (SCRI)
Key Results from the HER2CLIMB-05 Phase 3 Trial
Prolonged Median Progression-Free Survival (PFS): The primary endpoint analysis showed a 35.9% reduction in the risk of disease progression or death among patients treated with TUKYSA, trastuzumab, and pertuzumab compared to those treated with placebo, trastuzumab, and pertuzumab, following induction treatment, as assessed by the investigator (hazard ratio of 0.64, 95% confidence interval (CI): 0.51-0.80; 2-sided p<0.0001). Median investigator-assessed PFS for patients in the TUKYSA arm was 24.9 months (95% CI, 21.3-not reached) compared to 16.3 months (95% CI, 12.6-18.7) in the placebo arm, representing a difference of 8.6 more months that patients lived without their cancer worsening.
Safety Profile: The safety and tolerability of TUKYSA was generally consistent with its known safety profile, with the exception of increased severity of hepatotoxicity. The majority of hepatotoxicity events were generally asymptomatic and reversible with dose modification and/or discontinuation. The most commonly reported adverse events (≥20%) were diarrhea, musculoskeletal pain, hepatotoxicity, nausea, fatigue, rash, and vomiting. Serious adverse reactions in ≥1% of patients included hepatotoxicity (3.9%), including one patient who experienced a fatal adverse reaction of drug-induced liver injury.
Published Previously: Results from HER2CLIMB-05 were published in the Journal of Clinical Oncology and presented at the 2025 San Antonio Breast Cancer Symposium (SABCS).
About the Phase 3 HER2CLIMB-05 Trial
The HER2CLIMB-05 trial is a randomized, double blind, placebo-controlled, pivotal Phase 3 study evaluating the efficacy and safety of TUKYSA compared to placebo, both in combination with trastuzumab and pertuzumab, as maintenance therapy for patients with HER2+ metastatic breast cancer (MBC) following induction therapy in the front-line setting.
HER2 is overexpressed in up to 15-20% of breast cancers and is associated with poor prognosis, with an estimated five-year survival rate of 41% to 47%, depending on hormone receptor status.1-3
Trial participants who completed induction therapy of trastuzumab, pertuzumab, and a taxane, with no evidence of progression, were randomized to receive TUKYSA in combination with trastuzumab plus pertuzumab (n=326) or placebo in combination with trastuzumab plus pertuzumab (n=328).
The primary endpoint is PFS as assessed by the investigator. Overall survival is a key secondary endpoint.
Continuing Pfizer’s Legacy of Leadership in Breast Cancer
Pfizer has been a leader in breast cancer for over 25 years, and today we have five medicines and one biosimilar approved to treat different subtypes of the disease, reaching over 4.9 million patients worldwide.
In the U.S., TUKYSA is already a National Comprehensive Cancer Network (NCCN) Category 1 second-line plus treatment for HER2+ MBC patients. This approval extends the reach of TUKYSA as part of a front-line maintenance regimen, bringing patients a new option to delay disease progression without the need for continued chemotherapy and helping physicians further individualize treatment plans to best meet the needs of each unique patient.
About TUKYSA (tucatinib)
TUKYSA (tucatinib) is an orally administered tyrosine kinase inhibitor of HER2. TUKYSA is approved in combination with trastuzumab and pertuzumab for the maintenance treatment of adult patients with unresectable locally advanced or metastatic HER2-positive breast cancer following induction treatment. TUKYSA has also been approved in combination with trastuzumab and capecitabine to treat adults with HER2-positive advanced unresectable or MBC, including patients with brain metastases who have received one or more prior anti-HER2 breast cancer treatments in the metastatic setting.
The full U.S. Prescribing Information for TUKYSA can be found here. There may be a delay as the document is updated with the latest information. It will be available as soon as possible. Please check back for the updated full information shortly.
(Press release, Pfizer, OCT 7, 2026, View Source [SID1234673265])