Pomerantz LLP is investigating claims on behalf of investors of Merrimack Pharmaceuticals, Inc. (“Merrimack” or the “Company”) (NASDAQ: MACK). Such investors are advised to contact Robert S. Willoughby at firstname.lastname@example.org or 888-476-6529, ext. On April 4, 2019, Merrimack announced the discontinuation of work on its sole drug candidate in clinical trials, MM-310, citing safety issues. Despite amending the protocol for its Phase 1 study after observing and disclosing signs of peripheral neuropathy in clinical trial participants beginning in November, Merrimack reported that subjects taking MM-310 continued to experience weakness, numbness and extremity pain associated with peripheral neuropathy. On this news, Merrimack’s stock price fell $1.18 per share, or 16.41%, to close at $6.01 per share on April 5, 2019.