Merrimack Pharmaceuticals Completes Enrollment of Second Cohort in Phase 2 Study of MM-121 in Non-Small Cell Lung Cancer

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.

The third cohort (Group C) included patients who were previously treated with an EGFR tyrosine kinase inhibitor and progressed on that therapy. This third cohort is completed and top line results were reported in April 2013.

Sanofi and Merrimack entered into an exclusive, global license and collaboration agreement for MM-121 in 2009.

About Merrimack

Merrimack is a biopharmaceutical company discovering, developing and preparing to commercialize innovative medicines paired with companion diagnostics for the treatment of cancer. Merrimack applies Network Biology, its proprietary systems biology-based approach to biomedical research, throughout the research and development process. Merrimack currently has six targeted therapeutic oncology candidates in clinical development.

Forward-looking statements

To the extent that statements contained in this press release are not descriptions of historical facts, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements include any statements about Merrimack's strategy, future operations, future financial position and future expectations and plans and prospects for Merrimack, and any other statements containing the words "anticipate," "believe," "estimate," "expect," "intend," "may," "plan," "predict," "project," "target," "potential," "will," "would," "could," "should," "continue," and similar expressions. In this press release, Merrimack's forward-looking statements include statements about the potential for MM-121 to provide clinical benefit, the ability of Merrimack to identify patients most likely to respond to treatment and the timing of release of study results. Such forward-looking statements involve substantial risks and uncertainties that could cause Merrimack's clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in the initiation of future clinical trials, availability of data from ongoing clinical trials, expectations for regulatory approvals, development progress of Merrimack's companion diagnostics and other matters that could affect the availability or commercial potential of Merrimack's drug candidates or companion diagnostics. Merrimack undertakes no obligation to update or revise any forward-looking statements. Forward-looking statements should not be relied upon as representing Merrimack's views as of any date subsequent to the date hereof. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Merrimack's business in general, see the "Risk Factors" section of Merrimack's Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 20, 2013 and other reports Merrimack files with the SEC.

CONTACT: Media Contacts: Kathleen Petrozzelli Gallagher, Merrimack 617-441-1043 Liz Bryan, Spectrum 202-955-6222 lbryan@spectrumscience.comSource:Merrimack Pharmaceuticals