While investors wait for key data from a Phase II trial with Merrimack Pharmaceuticals Inc.'s HER2 signaling inhibitor MM-121 in breast, ovarian and non-small-cell lung cancer (NSCLC), the company began a Phase II trial with its bispecific antibody, MM-111, which targets the HER2 and HER3 receptors, for advanced gastric, esophageal and gastroesophageal junction (GEJ) cancers.