Merrimack 0 for 3 as it dumps cancer drug over safety fears, axes staffers (again)

exit sign
Merrimack's final clinical asset, and yet more staffers, are all headed for the exit. (GH01/ iStock)

Merrimack is dumping another cancer therapy after a recent trial flagged adverse event worries, leading the biotech to swing the ax across its already severely depleted workforce as it gives up on its third and final clinical shot on goal.

The experimental drug on the block is MM-310, an antibody-directed nanotherapeutic in phase 1 for solid tumors. This marks the last of the three clinical drugs Merrimack had in the pipeline since reforming as a clinical-stage R&D biotech back in 2017, and the company is now left with only preclinical assets.

The reason for the latest chop was safety: Last November, the biotech started to see increasing grade 3 peripheral neuropathy (nerve damage, typically in hands/feet) in three solid tumor patients after a series of cycles with MM-310.

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Merrimack tried to head the issue off, tweaking the study’s dosing and rethinking who could be entered into the test, but ongoing data show the drug was still creating “significant cumulative peripheral neuropathy” and therefore had to be stopped.

The biotech says it “plans to work swiftly to close out clinical activities and carry out associated cost-cutting measures and expects to provide an update on these efforts with its first-quarter 2019 financial results.”

This termination will also lead to pink slips for its workforce. Numbers on exactly how far the ax will swing across its staffers are not being released, with the biotech saying in a statement: “Merrimack […] expects to initiate a workforce reduction as it closes out clinical activities, reflective of its narrowed preclinical pipeline and in line with prior cost-cutting measures.”

Alongside these cuts and the culling of MM-310, the company plans to “prudently advance its preclinical immuno-oncology pipeline” that includes MM-401, an agonistic antibody targeting TNFR2, and MM-201, an agonist-Fc fusion protein targeting death receptors 4 and 5.

“We are disappointed that amending the trial protocol does not appear to have solved the cumulative toxicity observed in patients treated with MM-310," said Sergio Santillana, M.D., chief medical officer of Merrimack.

“However, we are grateful to our investigators and patients for their commitment to cancer research, and to our team for all their efforts in supporting the development and clinical evaluation of MM-310.”

Richard Peters, M.D., Merrimack’s CEO and president, added: “As we have narrowed the scope of our pipeline to our two most promising preclinical programs, MM-401 and MM-201, we are initiating steps to close out remaining clinical activities in order to further preserve our resources. We continue to prudently advance these programs as we work expeditiously to bring our ongoing strategic process to conclusion.”

RELATED: Phase 2 flop kills Merrimack pancreatic cancer drug, sinks stock

This rounds off a pretty dismal few years for Merrimack. Back in 2017, the Cambridge, Massachusetts-based biotech was hit when authorities arrested its director of statistical programming. The case alleged Songjiang Wang leaked positive results for three different Merrimack clinical trials to an employee of Akebia Therapeutics, who, in turn, shared tips about a study run by his company.

Later that year, the biotech sold its approved pancreatic cancer drug Onivyde to Ipsen and reduced its headcount by around 80%. The deal transformed Merrimack (now without the Pharmaceuticals) back into a clinical-phase biotech, with three assets and a headcount of 72, down from more than 400 early in 2016. But these three experimental drugs have been falling fast.

In November last year, Merrimack said it would be laying off 60% of its staff and halting development of its lead candidate, MM-121, in response to setbacks in the clinic. That drug failed in non-small cell lung cancer, leading Merrimack to pull the plug on a phase 2 trial of the anti-HER3 antibody in metastatic breast cancer.

A few months before that, Merrimack also canned MM-141 after the pancreatic cancer therapy failed to move the needle in a midphase trial. That left just MM-310, but safety concerns have scuppered this asset, too, leaving the company without any drugs in the clinic and rewinding it back to a startup.

The major restructuring was intended to keep Merrimack operating and raking in milestones from Ipsen while it looked into “strategic alternatives.” By February of this year, Merrimack had made that 60% cut, predominately by eliminating all open positions, while hitting its scientists the hardest and leaving the company with fewer than 30 staff. Now, more cuts are to come as a result of MM-310’s failure, though there are precious few positions left to ax.

The biotech, which has a market cap worth less than $100 million, was down nearly 14% after hours on the news Thursday night.  

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