CAMBRIDGE, MA, USA I May 23, 2013 I Merrimack Pharmaceuticals, Inc. (MACK) announced today that the last patient has been enrolled in a Phase 2 randomized, double blind clinical trial of MM-121 in combination with exemestane in postmenopausal women with locally advanced or metastatic estrogen receptor positive (ER+) and/or progesterone receptor positive (PR+), HER2-negative breast cancer. MM-121, a fully human monoclonal antibody that targets ErbB3, is being developed in collaboration with Sanofi.

“In hormone receptor positive breast cancer, exemestane is a popular choice for many women with metastatic disease. However, resistance inevitably develops, and the ongoing challenge is to prevent the progression of these tumors and improve outcomes for these women,” said Akos Czibere, M.D., PhD, Senior Medical Director at Merrimack. “We are hopeful that by combining MM-121 with exemestane, we can block the ErbB3 pathway, which we believe promotes this resistance and, ultimately, prevent the patient’s cancer from progressing.”

This study is designed to evaluate whether MM-121 in combination with exemestane is more effective than exemestane alone. A total of 118 patients were enrolled in the study, which is being conducted in the United States, Canada, Russia and Europe. Top line results from this study are expected in the second half of 2013. Sanofi and Merrimack entered into an exclusive, global license and collaboration agreement for MM-121 in 2009.

About Merrimack

Merrimack is a biopharmaceutical company discovering, developing and preparing to commercialize innovative medicines paired with companion diagnostics for the treatment of cancer. Merrimack applies its systems biology-based approach to biomedical research throughout the research and development process. Merrimack currently has six oncology therapeutics in clinical development.

SOURCE: Merrimack Pharmaceuticals