CAMBRIDGE, Mass., Dec. 19, 2012 (GLOBE NEWSWIRE) -- Merrimack Pharmaceuticals, Inc. (Nasdaq:MACK) today announced enrollment of its first patient in a cross indication translational study. The study is designed to identify predictive biomarkers associated with the novel compound MM-398 in advanced colorectal, lung and triple-negative breast cancers. Specifically, it aims to establish the feasibility of collecting specialized magnetic resonance-based images (MRI) and tissue-based biomarkers for the purpose of estimating drug delivery to the tumor and patient response to MM-398. A stable, nanotherapeutic encapsulation of the chemotherapy irinotecan, MM-398 is designed to optimize the delivery of irinotecan by increasing levels of the drug deposited in the tumor, extending circulation and thereby enabling preferential activation of the therapy within the tumor. Preclinical research has shown that the length of time MM-398, specifically the active component, SN38, remains within tumors directly correlates with tumor response. Another key to MM-398's activity may be the number of macrophages within a tumor, which have been shown to preferentially internalize liposomes and release their contents. "Our research indicates tumor micro-environments across these clinical indications allow for the deposition of large particles, such as nanotherapeutics. They also have high levels of tumor-associated macrophages, which means MM-398 can be broken down and release increased levels of chemotherapy to the adjacent cancer cells," said Ulrik Nielsen, Co-Founder and Chief Scientific Officer of Merrimack. "We believe this study is the first of its kind to combine the use of both imaging and biomarker diagnostic approaches and we hope that the insights we gain from this study will help to predict response to MM-398 in these hard-to-treat tumors." The cross indication translational study will focus on patients that have progressed following standard of care therapy for colorectal, lung and triple-negative breast cancers. The study is taking place at Scottsdale Healthcare Medical Center in Arizona.