Pfizer Inc. has announced positive topline results from its 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 (HER2+) metastatic breast cancer (MBC).
HER2CLIMB-05 is evaluating TUKYSA versus placebo, both in combination with first-line standard-of-care maintenance therapy (trastuzumab plus pertuzumab) following chemotherapy-based induction. The trial met its primary endpoint, demonstrating a statistically significant and clinically meaningful improvement in progression-free survival (PFS) by investigator assessment 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+ breast cancer is a particularly challenging subtype, with many patients experiencing disease progression despite effective treatments in the first-line setting,” said Erika Hamilton, principal investigator of HER2CLIMB-05 and director, Breast Cancer Research, Sarah Cannon Research Institute (SCRI).
“The HER2CLIMB-05 results demonstrate that the addition of TUKYSA to first-line maintenance therapy may further lower the risk of disease progression or death, with a treatment that has a well-established safety profile.”
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%, depending on HR status. First-line standard of care maintenance treatment has remained unchanged since 2012, and the majority of HER2+ MBC patients face disease progression within two years of initiating therapy. Until recently, there have been limited advancements for these patients.
“Pfizer aims to help shape the future of front-line treatment for HER2+ MBC, where we see significant opportunity for a chemotherapy-free maintenance approach,” said Johanna Bendell, chief development officer, Oncology, at Pfizer.
“The positive results from HER2CLIMB-05, combined with TUKYSA’s known safety profile in later-line settings, underscore its potential to play a meaningful role in front-line maintenance, where it may benefit a broader population of patients with HER2+ disease. We are grateful to the patients and investigators who contributed to this important research.”
Results from HER2CLIMB-05 will be presented at a future medical congress and discussed with regulatory authorities.
Since its initial approval in 2020, TUKYSA has become a standard of care for HER2+ MBC patients in the third-line setting and has been approved in more than 50 countries. In the US, TUKYSA is approved by the U.S. Food and Drug Administration for use in combination with trastuzumab and capecitabine for adult patients with advanced unresectable or metastatic HER2+ breast cancer, including patients with brain metastases, who have received one or more prior anti-HER2-based regimens in the metastatic setting. TUKYSA is not currently approved for first-line treatment.
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