Merrimack Pharmaceuticals Initiates Enrollment in a Phase 1/2 Study of MM-111, a Bispecific Antibody ...(ng dynamics between ErbB2 and ErbB3 and...),Health

MM-111 has two antibody arms; a targeting arm that binds to ErbB2 with high affinity and a therapeutic arm that binds to ErbB3 (also known as HER3). Both ErbB2 and ErbB3 are members of the ErbB family of receptors, a complex molecular network whose activation is commonly linked with cancer. In 2003, Merrimack researchers identified ErbB3 as a highly sensitive node in the ErbB signaling network and also found it played a dominant role in activation of the PI3 kinase pathway - a pathway believed to be used by cancer cells to sustain survival. The importance of ErbB3 in cancer progression is now widely appreciated. Preclinical data demonstrating the impact of MM-111 in multiple cancer models were presented at the annual meeting of the American Association for Cancer Research in April.

The current Phase 1/2 study will evaluate the human safety and pharmacokinetics (PK) of MM-111. The Phase 1 portion of the study is enrolling patients with tumors that overexpress ErbB2 while the Phase 2 portion of the study will be restricted to ErbB2 overexpressing (HER2+) breast cancer patients. The first dose was administered at South Texas Accelerated Research Therapeutics (START) where enrollment is currently underway. Fox Chase Cancer Center is expected to participate in the trial this July.

"MM-111 has the potential to help patients who are resistant to currently approved ErbB2 therapies," said William J. Slichenmyer, MD, Senior Vice President and Chief Medical Officer at Merrimack. "Preclinical studies of MM-111 have demonstrated that the bispecific approach shows antitumor activity in a wid
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