Merrimack Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company. The Company is engaged in designing novel treatments for cancer by targeting biomarker-defined cancers. Its clinical programs include MM-121 (seribantumab), MM-141 (istiratumab) and MM-310. MM-121 is a fully human monoclonal antibody that binds to the ErbB3 (HER3) receptor and targets heregulin positive cancers. MM-141 is a fully human tetravalent bispecific antibody designed to block tumor survival signals by targeting receptor complexes containing the insulin-like growth factor 1, or IGF-1, receptor and ErbB3 (HER3) cell surface receptor. MM-310 is an antibody-directed nanotherapeutic that targets the ephrin receptor A2, or EphA2, receptor and contains a novel prodrug of the highly potent chemotherapy docetaxel. The Companyâ€™s preclinical programs include MM-161, ATRi, BCL2/BCLxl, TRAIL, Immuno-oncology and STIMULI.