Merrimack Scraps Solid Tumor Asset for Safety Reasons and Initiates Layoffs

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In premarket trading, shares of Cambridge, Mass.-based Merrimack Pharmaceuticals have sunk more than 15 percent after the company announced late Thursday that it will discontinue development of an experimental solid tumor treatment and lay off some employees. This is the second round of cuts in less than six months.

Merrimack said it will terminate development of antibody-directed nanotherapeutic, MM-310, after a comprehensive review of safety data from a Phase I study. An examination of the data, which includes the amendment of the clinical protocol, led the company to conclude that the study would not be able to reach an “optimal therapeutic index” for MM-310. Toward the end of 2018, Merrimack announced the observation of “of emerging cumulative grade 3 peripheral neuropathy in three solid tumor patients” following multiple treatments with MM-310. After that observation, the company amended the clinical protocol to change the dosing regimen. Instead of dosing every three weeks, patients in the early-stage trial were dosed every four weeks. However, Merrimack said that dosing change did not help, as data showed MM-310 administered every four weeks “continued to result in significant cumulative peripheral neuropathy, which precludes the study from reaching an optimal therapeutic index for MM-310.”

As a result of the study termination, Merrimack said it will initiate a reduction in its workforce as it closes out clinical activities. The layoffs will be reflective of the company’s “narrowed preclinical pipeline and in line with prior cost-cutting measures,” Merrimack said in its announcement. Merrimack did not disclose in its announcement how many positions are expected to be terminated.

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The latest job cuts come about five months after the company cut 60 percent of its staff after the company halted its Phase II non-small cell lung cancer trial. The SHERLOC trial was assessing its asset MM-121 in combination with chemotherapy drug docetaxel in patients with heregulin positive NSCLC. When Merrimack announced the cuts, the company said at the time that it planned to focus its development efforts on MM-310 in solid tumors, as well as the advancement of its two most promising preclinical candidates, MM-401 and MM-201. The two preclinical candidates are now at the center of Merrimack’s research focus, the company said Thursday. Following the November layoffs, Merrimack announced that it was undertaking a corporate restructuring in order to reduce operational costs and maximize value.

Merrimack Chief Executive Officer Richard Peters said the company has “narrowed the scope” of its pipeline to MM-401 and MM-201, which he described as their “two most promising candidates.” At the American Association for Cancer Research conference in March, the company presented what it called “encouraging data” from the early programs.

Peters said the company is initiating steps to close out remaining clinical activities in order to preserve its resources and cash flow.

“We continue to prudently advance these programs as we work expeditiously to bring our ongoing strategic process to conclusion,” Peters said in a statement.

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