CAMBRIDGE, Mass., April 29, 2013 (GLOBE NEWSWIRE) -- Merrimack Pharmaceuticals, Inc. (Nasdaq:MACK) announced today that the last patient has been enrolled in the second cohort of a randomized, three-cohort Phase 2 clinical trial of MM-121 in combination with erlotinib for the treatment of non-small cell lung cancer (NSCLC) patients. Developed in collaboration with Sanofi, MM-121 is a fully human monoclonal antibody that targets ErbB3, a cell surface receptor implicated in tumor growth and survival. This cohort (Group A), which focuses on patients with EGFR wild-type tumors, is part of a larger, randomized Phase 2 study evaluating MM-121 in the treatment of three populations of NSCLC patients. The cohort was designed to evaluate if MM-121 in combination with erlotinib is more effective than treatment with erlotinib alone. Patients in Group A have EGFR wild-type NSCLC tumors with recurring or progressive disease following at least one chemotherapy-containing regimen and have not received prior EGFR tyrosine kinase inhibitor therapy. A total of 133 patients were enrolled and final results from this patient group are expected in the second half of 2013. "We are very pleased with the support this study has received from patients, their families and the lung cancer community, which resulted in rapid patient accrual," said Akos Czibere, MD, PhD, Senior Medical Director of the MM-121 program at Merrimack. "We are hopeful that our translational work will help us gain a better understanding of the biomarker profile of NSCLC EGFR wild-type tumors. This could help characterize the role of ErbB3 in this patient population and identify those patients who are likely to benefit most from the addition of MM-121 to erlotinib." A second cohort (Group B) includes patients whose tumors harbor an EGFR mutation and have not received prior EGFR tyrosine kinase inhibitor therapy. The enrollment for the second cohort is ongoing.