Keytruda Side Effects in Multiple Myeloma Combo Treatment Poses Serious Risks: FDA

Combining the cancer drug Keytruda with some other medications to treat multiple myeloma may be deadly for some patients, according to a new warning issued by federal drug regulators. 

The FDA issued a safety alert on August 31, indicating that it has halted two clinical trials, KEYNOTE-183 and KEYNOTE-185, involving the use of Keytruda for multiple myeloma, following a number of patient deaths.

“On July 3, 2017, the FDA required that all patients in these trials be discontinued from further investigation with this drug, because interim results from both trials demonstrated an increased risk of death for patients receiving Keytruda (pembrolizumab) when it was combined with an immunomodulatory agent as compared to the control group,” the agency warned. “Merck & Co., Inc. was made aware of the issue through an external data monitoring committee recommendation and suspended the trials to enrollment on June 12, 2017.”

The trials and risks appeared to be linked to the use of Keytruda in combination with dexamethasone and either of two immunomodulatory agents; lenalidomide or pomalidomide in multiple myeloma clinical trials. Keytruda is currently not approved for use in the treatment of multiple myeloma.

Data from the KEYNOTE-183 trial, which involved about 250 patients, indicates that patients given Keytruda had a 61% increased risk of death, with 29 deaths in the Keytruda arm of the clinical trial, compared to only 21 deaths among the control subjects.

However, data from the KEYNOTE-185 clinical trial, involving about 300 patients, saw an even higher risk, with more than twice as many Keytruda patients dying than those in the control group, 19 to 9. That trial also showed that 54% of the patients given a Keytruda-based drug combination had a 54% chance of severe adverse health effects, compared to only 39% in the control group.

There are a number of other multiple myeloma clinical trials ongoing that either involve Keytruda or similar drugs, known as PD-1/PD-L1 cancer drugs. The FDA is investigating those trials to determine if there is a safety issue with them as well.

The FDA is asking healthcare professionals and patients who experience any adverse events or side effects during Keytruda treatment to report them to the FDA’s MedWatch Adverse Event Reporting Program.