Merrimack Pharmaceuticals, Inc. (MACK) Thursday said one cohort of a Phase 2 non-small cell lung cancer or NSCLC study did not meet its primary endpoint. The cohort evaluated MM-121 in combination with erlotinib to treat patients with NSCLC whose disease progressed on an anti-EGFR tyrosine kinase inhibitor.
Elaborating on the study, the firm said the primary objective of the study was to determine the potential of MM-121, a novel signaling inhibitor targeting ErbB3, to modulate or reverse resistance to erlotinib, an EGFR targeted therapy, commonly used in the treatment of NSCLC, in patients who have acquired resistance to EGFR-TKI therapy. Further, primary endpoint of this cohort was to obtain a 40 percent progression free survival rate at four months of treatment, while secondary endpoints included biomarker assessment of patients enrolled in the study.
Commenting on the development, Akos Czibere, Senior Medical Director of the MM-121 program at Merrimack said, "We are disappointed by the overall clinical results in this population, but are encouraged by our preliminary biomarker analysis which we believe will be important for the identification of a predictive diagnostic when analyzed in the context of the overall clinical development program."
MM-121 is a fully human monoclonal antibody that targets ErbB3, a cell surface receptor implicated in tumor growth and survival. Sanofi and Merrimack entered into an exclusive, global license and collaboration agreement for MM-121 in 2009.
Additionally, MM-121 is being evaluated in two additional NSCLC cohorts as well as Phase 2 studies for the treatment of advanced ovarian cancer, hormone-receptor positive breast cancer and HER2 negative breast cancer.
For comments and feedback contact: editorial@rttnews.com
Business News
June 05, 2026 16:18 ET A busy week for economic news flow saw a slew of reports being released that reflected the trends in the U.S. labor market. In Europe, economic growth and inflation data gained attention as the European Central Bank and Bank of England head for policy session later in the month. In Asia, the monetary policy session of the Indian central bank was in focus as the country, a major oil importer, reels under the pressures of a weaker rupee and rising inflation.