Seagen Inc. announced upcoming data presentations for TUKYSA? (tucatinib) at the San Antonio Breast Cancer Symposium (SABCS), taking place December 7-10, 2021. Seven abstracts including three spotlight posters - highlight the company?s commitment to addressing unmet needs in advanced breast cancer. Two abstracts featured in spotlight poster presentations show: Continued Clinical Benefit in HER2-Positive Metastatic Breast Cancer Patients (MBC) with Active and Stable Brain Metastases. Updated exploratory results from the pivotal HER2CLIMB trial showed that TUKYSA combined with trastuzumab and capecitabine resulted in a robust and durable prolongation of overall survival (OS) that was consistent with results from the primary analysis for HER2-positive metastatic breast cancer patients with brain metastases after an additional 15.6 months of follow-up. The benefit was maintained in patients with active and stable brain metastases. These results will be featured in a spotlight poster (Abstract #PD4-04) presented by Nancy U. Lin, M.D., Director of the Metastatic Breast Cancer Program in the Susan F. Smith Center for Women?s Cancers at Dana-Farber in Boston, MA. Promising Activity of TUKYSA Regimen in HER2-Positive MBC Patients with Leptomeningeal Metastases: A single-arm, investigator-sponsored phase 2 trial (n=17) of TUKYSA combined with trastuzumab and capecitabine represents the first prospective evidence of a systemic regimen demonstrating clinical benefit for HER2-positive breast cancer patients with leptomeningeal metastases, cancer that has spread to the membranes lining the brain and spinal cord. The findings showed a median OS of nearly one year (11.9 months [95% Confidence Interval: 4.1, NR]). Patients with leptomeningeal disease have a historically poor prognosis with median survival of four to five months. The most common treatment for leptomeningeal metastases is radiation therapy. These results will be featured in a spotlight poster (Abstract #PD4-02) presented by Rashmi Murthy, M.D., University of Texas MD Anderson Cancer Center. 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 growth of cancer cells. Up to 50% of metastatic HER2-positive breast cancer patients develop brain metastases over time. In 2020, more than two million new cases of breast cancer were diagnosed worldwide. Between 15% and 20% of breast cancer cases are HER2-positive.