In unexpected blow, Merck halts Keytruda myeloma trial enrollment to probe patient deaths

New Keytruda image
Merck is testing Keytruda in combinations with Celgene's Revlimid and Pomalyst as a treatment for multiple myeloma.

The streak of positive Keytruda updates had to end somewhere. After an onslaught of upbeat trial results and regulatory news, drug maker Merck Monday night announced that it was pausing enrollment on a pair of phase 3 multiple myeloma studies of the med to investigate trial deaths.

The move, which comes at the recommendation of an independent data monitoring committee, comes after “more reports of death” in the Keytruda groups of studies Keynote-183, which is examining a combo of Keytruda with Celgene’s Pomalyst and dexamethasone in previously treated patients, and Keynote-185, which is marrying Keytruda with Celgene’s Revlimid in certain not-yet-treated patients.

Patients already enrolled in those trials will continue to receive treatment, though, Merck said, and the company confirmed to Credit Suisse analyst Vamil Divan that “this is not a clinical hold.”

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Right now, not much else is clear; Merck couldn’t shed light on how many patients have died, or whether investigators observed the imbalance in just one study or both, Divan wrote in a Monday night note to clients. And while the dearth of info makes it “difficult to draw meaningful conclusions,” Divan, for one, is not worried.

“We don’t believe there is anything of major concern here at this time,” he wrote

Keytruda so far has boasted “a clean safety profile,” and considering the number of trials studying the product in “very sick” patient populations, it’s “reasonable to assume that a certain combination or indication could yield a negative safety result, if that is in fact the cause of the imbalance,” he added.

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The blip follows a string of favorable news events for Keytruda, which industry watchers unofficially crowned the PD-1 winner at this month’s American Society of Clinical Oncology annual meeting. And in the weeks leading up to the conference, Keytruda picked up three FDA approvals--as part of a front-line lung cancer chemo combo, in bladder cancer, and in microsatellite instability-high cancer--as well as a priority review in stomach cancer.