Seattle Genetics Announces Submission of Tucatinib New Drug Application to the U.S. FDA for Patients with Locally Advanced or Metastatic HER2-Positive Breast Cancer

Seattle Genetics, Inc. (Nasdaq:SGEN) today announced it has completed the submission of a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for tucatinib. This NDA requests FDA approval of tucatinib in combination with trastuzumab and capecitabine for treatment of patients with locally advanced unresectable or metastatic HER2-positive breast cancer, including patients with brain metastases, who have received at least three prior HER2-directed agents separately or in combination, in the neoadjuvant, adjuvant or metastatic setting. The submission is based on the results of HER2CLIMB, a randomized pivotal trial comparing tucatinib added to trastuzumab and capecitabine versus trastuzumab and capecitabine alone. HER2CLIMB trial results were presented on December 11, 2019 at the 2019 San Antonio Breast Cancer Symposium and published in the New England Journal of Medicine. Tucatinib is an oral, small molecule tyrosine kinase inhibitor (TKI) that is highly selective for HER2.

Tucatinib was recently granted Breakthrough Therapy designation by the FDA in combination with trastuzumab and capecitabine, for treatment of patients with locally advanced unresectable or metastatic HER2-positive breast cancer, including patients with brain metastases, who have been treated with trastuzumab, pertuzumab, and T-DM1. This designation was based on data from the HER2CLIMB trial.

“Today’s submission marks another important milestone for Seattle Genetics and tucatinib, and a potential advance for patients with either locally advanced or metastatic HER2-positive breast cancer, including those with and without brain metastases,” said Roger Dansey, M.D., Chief Medical Officer at Seattle Genetics. “We look forward to working with the FDA on the review of this application.”

About HER2-Positive Breast Cancer

Patients with HER2-positive breast cancer have tumors with high levels of a protein called human epidermal growth factor receptor 2 (HER2), which promotes the aggressive spread of cancer cells. An estimated 271,270 new cases of invasive breast cancer will be diagnosed in the U.S. in 2019.¹ Between 15 and 20 percent of breast cancer cases worldwide are HER2-positive.² Historically, HER2-positive breast cancer tends to be more aggressive and more likely to recur than HER2-negative breast cancer.^{2, 3, 4} In patients with metastatic breast cancer, the most common site of first metastasis is in bone, followed by lung, brain, and liver.^{5, 6} Up to 50 percent of metastatic HER2-positive breast cancer patients develop brain metastases over time.^{2, 7} Despite recent treatment advances, there is still a significant need for new therapies that can impact metastatic disease, especially brain metastases. There are currently no approved therapies demonstrating progression-free survival or overall survival benefit for the treatment of patients with HER2-positive metastatic breast cancer after progression on T-DM1.^{8, 9, 10}