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.