CBC Health Interviews Dr Vincent Rajkumar on Suspension of Pembrolizumab (Keytruda) Trials in Multiple Myeloma
Dr Vincent Rajkumar, Mayo Clinic
Rochester, Minnesota
Keytruda (pembrolizumab) is part of a new class of immune-oncology drugs that recruit the body's own immune system to attack cancer.  

Merck recently announced that the U.S. FDA has placed a clinical hold on two of its trials in multiple myeloma patients, and one cohort of a third multiple myeloma trial, because of more reports of deaths among patients in the Keytruda groups. A second patient cohort in the third trial, exploring a different combination of drugs with Keytruda, is active and currently recruiting patients.
"It's sobering how complex the immune system is," said Dr Vincent Rajkumar, Professor of Medicine at the Mayo Clinic in Rochester, Minnesota. "When you combine two or three of these new immunotherapy type approaches, you are revving up the immune system and so you could get a result which could be lethal. There's a lot of promise, but it comes with a lot of caution as well."
In Canada, Keytruda has been approved for use in a variety of cancers, including some melanoma and lung cancers. Merck has other trials underway looking for new uses against additional cancers.  

"The same drugs that work in one cancer really well might not work in another cancer because each cancer is unique and the effects might be totally different," Dr Rajkumar told CBC Health.  

Merck said in a news release that the FDA has determined that the risk of Keytruda plus the combination drugs outweigh any potential benefit for patients with multiple myeloma. The company had already stopped enrolling patients in the studies last month.  

"These trials have to be done," Dr Rajkumar continued, adding that there are many other successful new therapies recently approved to treat multiple myeloma.  

Because of new treatments that have become available over the past fifteen years, myeloma survival has more than doubled, with an increasing number of patients living longer, productive lives.