Pfizer’s Tukysa combination shows improved survival in breast cancer trial

Pfizer (PFE) announced positive topline results from the Phase 3 HER2CLIMB-05 trial of first-line combination therapy with the tyrosine kinase inhibitor Tukysa – tucatinib – in patients with human epidermal growth factor receptor 2-positive, or HER2+, metastatic breast cancer, or MBC. HER2CLIMB-05 is evaluating Tukysa versus placebo, both in combination with first-line standard-of-care maintenance therapy following chemotherapy-based induction. The trial met its primary endpoint, demonstrating a statistically significant and clinically meaningful improvement in progression-free survival in the Tukysa arm versus the placebo arm. Treatment with Tukysa in combination with trastuzumab and pertuzumab was tolerable, with a safety profile generally consistent with the established safety profiles of each individual therapy. HER2 is overexpressed in up to 15-20% of breast cancers and is associated with poor prognosis, with an estimated five-year survival rate for HER2+ MBC of 41-47%. The majority of HER2+ MBC patients face disease progression within two years of initiating therapy. Results from HER2CLIMB-05 will be presented at a future medical congress and discussed with regulatory authorities. In the U.S., Tukysa is approved by the FDA for use in combination with trastuzumab and capecitabine for adult patients with advanced unresectable or metastatic HER2+ breast cancer. Tukysais not currently approved for first-line treatment.