Merck & Co. Inc. paused new patient enrollment in two studies exploring Keytruda in combination with other therapies in multiple myeloma, a type of blood cancer, to better understand reports of death among those receiving Keytruda.

The company accepted an external data monitoring committee's recommendation to pause patient enrollment in studies, KEYNOTE-183 and KEYNOTE-185, to collect more information.

Patients enrolled in the two studies would continue to receive treatment while other studies of Keytruda continue unchanged, Merck said.

KEYNOTE-183 is a phase 3 study comparing pomalidomide, sold by Celgene Corp. as Pomalyst, and low-dose dexamethasone with Keytruda to pomalidomide and low-dose dexamethasone alone, in patients with refractory or relapsed and refractory multiple myeloma who have undergone at least two lines of prior treatment.

KEYNOTE-185, is a phase 3 study comparing lenalidomide and low-dose dexamethasone with Keytruda to lenalidomide, sold by Celgene as Revlimid, and low-dose dexamethasone alone, in patients with newly diagnosed and treatment-naive multiple myeloma who are ineligible for a transplant of their own stem cells.

Merck's Keytruda is approved for the treatment of melanoma, lung cancer, head and neck cancer, classical Hodgkin lymphoma, urothelial carcinoma and microsatellite instability-high cancer.