Merck & Co. was expecting big things from Eisai’s Lenvima in March, when it agreed to shell out up to $5.8 billion on half of the liver cancer drug’s sales. But in the first expansion bid since that deal, Lenvima has hit a snag.

The FDA pushed back its decision on Lenvima as a treatment for previously untreated liver cancer patients, the companies said Friday, noting only that the agency needed "additional time for review of the application." The partners now expect a verdict by Aug. 24, three months after the original decision deadline.

"Eisai, as the marketing authorization holder, is working closely with the FDA to support the continued review of this application," they added in a statement.

The delay marks a reprieve for Bayer, whose Nexavar dominates the first-line liver cancer field. Last year, Eisai unveiled data showing that Lenvima had actually topped the stalwart in a head-to-head showdown—if only slightly—by posting a 13.6-month overall survival benefit compared with Nexavar’s 12.3.

That showing surely factored into Merck’s recent decision to drop a pretty penny on a Lenvima partnership with Eisai. The New Jersey drugmaker handed over $300 million upfront and up to $650 million more for certain rights, along with $450 million in R&D reimbursement. It also pledged $385 million more if the partners nail their clinical and regulatory targets and earmarked $3.97 billion more for Eisai to pocket if the pair hits their sales marks.

Not all of that is riding on success in liver cancer, though. For one, Merck and Eisai in January grabbed the FDA’s breakthrough therapy designation for a combo of Lenvima and Merck immuno-oncology star Keytruda in patients with advanced or metastatic kidney cancer.

As part of the partnership, the companies revealed plans to take the pairing into a slew of new clinical trials, testing it in indications across endometrial cancer, non-small cell lung cancer, head and neck cancer, bladder cancer, melanoma and more.

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