CAMBRIDGE, Mass., Dec. 12, 2012 (GLOBE NEWSWIRE) -- Merrimack Pharmaceuticals, Inc. (Nasdaq:MACK) today announced enrollment of its first patient in a Phase 1 clinical study of a novel compound for the treatment of advanced solid tumors. MM-141 is a fully human tetravalent antibody designed to target signaling of the P13K/AKT/mTOR pathway driven through IGF-1R and ErbB3 (HER3). It is Merrimack's sixth oncology candidate to enter clinical development. PI3K/AKT/mTOR signaling is often activated in cancers in response to stress induced by chemotherapies or targeted anti-cancer medicines. It is believed to play a significant role in promoting tumor cell survival. "Cancer therapies focused on P13K/AKT/mTOR have not been effective because they have struggled to address the underlying redundancies and adaptations in signaling that drive cancer cell survival," said Ulrik Nielsen, Co-Founder and Chief Scientific Officer of Merrimack. "Merrimack has engineered MM-141 to focus specifically on key pathways of IGF-1R and ErbB3 signaling to address this issue." Merrimack is currently pursuing clinical indications where PI3K/AKT/mTOR inhibitors have demonstrated signs of clinical activity and where IGF-1R and ErbB3 signaling has been shown to play a role in existing or acquired resistance. The Phase 1 study will assess the safety of MM-141 as a monotherapy and in combination with everolimus and docetaxel and to determine the recommended Phase 2 dose. Four sites are currently expected to participate in this trial focusing on patients with advanced solid tumors that have progressed following standard of care therapy. The first patient was dosed at Georgia Cancer Specialists in Atlanta. About Merrimack Pharmaceuticals, Inc. Merrimack Pharmaceuticals is a biopharmaceutical company discovering, developing and preparing to commercialize innovative medicines paired with companion diagnostics for the treatment of serious diseases, with an initial focus on cancer. Merrimack applies Network Biology, its proprietary systems biology-based approach to biomedical research, throughout the research and development process. Merrimack currently has six targeted therapeutic oncology candidates in clinical development.