Phase 3 Trial Update of Trastuzumab Emtansine for HER2-Positive Metastatic Breast Cancer

Genentech announced topline results of EMILIA, a randomized Phase 3 study of trastuzumab emtansine (T-DM1) in patients with HER2-positive metastatic breast cancer.

EMILIA (TDM4370g/BO21977) was an international open-label study comparing trastuzumab emtansine alone to lapatinib (Tykerb; GlaxoSmithKline Pharmaceuticals) in combination with Xeloda (capecitabine; Roche Laboratories) in 991 people with HER2-positive metastatic breast cancer whose disease progressed after initial treatment with Herceptin (trastuzumab; Genentech) and a taxane chemotherapy. Participants in the trastuzumab emtansine arm received trastuzumab emtansine 3.6mg/kg every three weeks. Participants in the lapatinib and Xeloda arm received lapatinib 1250mg daily plus Xeloda 2000mg/m2, Days 1–14, every three weeks. The co-primary efficacy endpoints of the study were progression-free survival (PFS) (as assessed by an independent review committee) and OS. Other study endpoints include safety profile, one-year and two-year survival rates, PFS as assessed by investigator, overall response rate, duration of response and quality of life.

The study showed people who received trastuzumab emtansine lived significantly longer without their disease getting worse compared to those who received lapatinib plus Xeloda. Final results for overall survival (OS) are not yet mature. The safety profile of trastuzumab emtansine was consistent with that seen in previous studies.

Trastuzumab emtansine is an investigational medicine known as an antibody-drug conjugate (ADC). It is comprised of the antibody trastuzumab and the chemotherapy DM1 attached together using a stable linker. It is designed to target and inhibit HER2 signaling and deliver the chemotherapy directly inside HER2-positive cancer cells. Trastuzumab emtansine binds to the HER2-positive cancer cells, and is thought to block out-of-control signals that make the cancer grow while also calling on the body’s immune system to attack the cancer cells. Once trastuzumab emtansine is absorbed into those cancer cells, it is designed to destroy them by releasing the DM1.

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