The US Food and Drug Administration (FDA) has approved Pfizer’s Tukysa (tucatinib) along with pertuzumab and trastuzumab as a maintenance therapy for breast cancer.

This regimen is indicated for adults with unresectable locally advanced or metastatic human epidermal growth factor 2-positive (HER2+) disease following induction treatment.

The regulatory decision introduces an oral tyrosine kinase inhibitor to the frontline maintenance setting, providing a chemotherapy-free option intended to delay disease progression.

Regulatory clearance was based on findings from the double-blind, placebo-controlled Phase III HER2CLIMB-05 trial.

Investigators evaluated the three-drug combination against a regimen of pertuzumab, placebo, and trastuzumab in patients who showed no disease progression following taxane-based induction therapy.

In the trial, adding Tukysa lowered the risk of disease progression or death by 35.9% compared to the control arm.

Patients receiving the Tukysa regimen achieved a median investigator-assessed progression-free survival of 24.9 months, compared to 16.3 months for those receiving placebo, marking an 8.6-month extension.

Overall survival remains a key secondary endpoint.

Pfizer executive vice-president and US chief commercial officer Aamir Malik said: “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.”

Adverse events reported in at least 20% of participants included, fatigue, diarrhoea musculoskeletal pain, hepatotoxicity, rash, vomiting, and nausea.

Hepatotoxicity occurred at higher severity than previously observed, though cases were largely asymptomatic and reversible via dose adjustments or treatment halts.

Serious adverse reactions involving hepatotoxicity occurred in 3.9% of patients, including one fatal case of drug-induced liver injury.

Tukysa previously gained US approval alongside capecitabine and trastuzumab for patients with pretreated HER2-positive metastatic disease, including those with brain metastases.

In August 2026, the European Medicines Agency (EMA) validated the marketing authorisation application (MAA) from Pfizer and Valneva for their Lyme disease vaccine candidate, PF-07307405.