Sanofi  aventisSanofi-aventis and Merrimack Pharmaceuticals, Inc. announced an exclusive global collaboration and licensing agreement on MM-121, a first-in-class, fully human monoclonal antibody designed to block signalling of the ErbB3 (also known as HER3) receptor, for the management of solid malignancies. MM-121 is currently in phase 1 clinical testing.

Under this agreement, sanofi-aventis will receive an exclusive worldwide license to develop, manufacture and commercialize MM-121. Merrimack will retain potential co-promotion rights in the United States.

"Merrimack's expertise along with their knowledge of biologics development has allowed them to successfully identify ErbB3 as a promising target and rapidly bring MM-121 into clinical development," declared Marc Cluzel, senior vice-president R&D, sanofi-aventis. "MM-121 is a pioneering monoclonal antibody which brings a new innovative approach to sanofi-aventis' oncology portfolio. We are very excited to collaborate with Merrimack on the development of MM-121, which we believe is a very promising compound that will address a significant gap in treating cancer patients."

Under the terms of the agreement, sanofi-aventis agreed to pay Merrimack an upfront cash payment of $60 million for the research, development, manufacturing and commercialization rights. Merrimack is eligible for development and regulatory milestone payments up to $410 million on MM-121, royalties on the worldwide product sales and will receive additional performance milestones of up to $60 million on worldwide sales. Merrimack will participate in the development of MM-121.

The license agreement is subject to antitrust clearance under the Hart-Scott-Rodino Antitrust Improvements Act.

MM-121 is a monoclonal antibody designed to block signalling of the ErbB3 receptor, a member of the epidermal growth factor (EGF) receptor family (also known as ErbB family) which plays a crucial role in the development and evolution of cancer. MM-121 is the first selective ErbB3 antagonist to have entered human clinical development.
 Preclinical data demonstrating MM-121's impact on multiple cancer models (including lung, ovarian, breast, prostate and renal) as both a monotherapy and a combination therapy were presented at the annual meeting of the American Association for Cancer Research in April 2009. The phase 1 trial is being conducted at 3 clinical centres in the United States.

The ErbB3 receptor is a novel target known to be a key mediator of signalling in the ErbB pathway (also known as the EGFR or HER pathway) – a signalling network that impacts a broad array of cancers. ErbB3 and its ligands are expressed and often upregulated in different solid tumours (breast, ovarian) and are associated with metastasis formation and decrease in survival. Importantly, ErbB3 is also involved in the mechanism of resistance to certain treatments such as gefinitib in lung cancer, cetuximab in colon and head & neck cancer, and trastuzumab in breast cancer.

Merrimack Pharma is a biotechnology company focused on the discovery and development of novel treatments for cancer and autoimmune diseases.