Tucatinib Plus Ado-Trastuzumab Meets Progression-Free Survival Endpoint in Patients With HER2-Positive Breast Cancer

Seagen announced that a phase 3 clinical trial of tucatinib (Tukysa; Seagen) in combination with the antibody-drug conjugate ado-trastuzumab emtansine (Kadcyla; Genetech) met its primary endpoint of progression-free survival (PFS) in patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer, according to a statement released by the company.

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HER2CLIMB-02 is a global, multicenter, randomized, double-blind, placebo-controlled clinical trial that evaluated tucatinib with ado-trastuzumab emtansine in patients with HER2-positive metastatic and unresectable breast cancer (MBC) who have had prior treatment with a taxane and trastuzumab in any setting.

The primary endpoint was PFS per Responsive Evaluation Criteria in Solid Tumors (RECIST) version 1.1 by investigator assessment. Secondary endpoints included overall survival (OS), PFS by blinded independent committee review (BICR), objective response rate, duration of response, PFS and OS in patients with brain metastases, and safety and tolerability of the regimen.

OS data are not yet mature, according to the statement. Discontinuations due to adverse events were more prevalent in the combination arm of the trial, but there were no new safety signals that emerged for the combination.

Tucatinib is approved in the United States in combination with trastuzumab and capecitabine for adults with advanced unresectable or metastatic HER2-positive breast cancer, including patients with brain metastases who have been treated with 1 or more prior anti-HER2-based regimens in the metastatic setting.

Seagen runs a development program for tucatinib, including a study with registrational intent in the first-line maintenance with trastuzumab and pertuzumab, the HER2CLIMB-05 trial. They also are supporting a cooperative group study in adjuvant high-risk HER2-positive breast cancer in combination with T-DM1.

“We are encouraged by these results for Tukysa in combination with Kadcyla metastatic HER2-positive breast cancer, including in patients with brain metastases,” said Roger Dansey, president of Research and Development and chief medical officer at Seagen, in the statement. “We plan to present the HER2CLIMB-02 data at an upcoming medical meeting and discuss the results with the FDA.”

Reference

Seagen. Seagen phase 3 trial of tukysa (tucatinib) in combination with antibody-drug conjugate ado-trastuzumab emtansine meets primary endpoint of progression-free survival in patients with previously treated HER2-positive metastatic breast cancer. News release. Accessed August 16, 2023. Published August 16, 2023. https://investor.seagen.com/press-releases/news-details/2023/Seagen-Phase-3-Trial-of-TUKYSA-tucatinib-in-Combination-with-Antibody-Drug-Conjugate-ado-trastuzumab-emtansine-Meets-Primary-Endpoint-of-Progression-Free-Survival-in-Patients-with-Previously-Treated-HER2-Positive-Metastatic-Breast-Cancer/default.aspx