Shares in Merck & Co Inc (NYSE:MRK) slipped in pre-market trade after the pharma giant confirmed it has temporarily stopped enrolling new patients into two late-stage studies testing its Keytruda immunotherapy drug for multiple myeloma.
The decision follows a recommendation by an external data monitoring committee after reports of deaths among those taking Keytruda in the trials.
“The pause is to allow for additional information to be collected to better understand more reports of death in the Keytruda groups,” the company said in the statement.
Patients already enrolled in the studies will continue to receive treatment, Merck added.
PD-1 inhibitor
Keytruda is part of a closely-watched new class of drugs called PD-1 inhibitors that help a patient’s own immune system to fight cancer by blocking a mechanism that tumours use to evade detection.
The drug – which is expected to generate more than US$3bn in sales this year – is already approved to treat a wide range of cancers including lung, bladder and advanced melanoma.
In these two particular trials – KEYNOTE-183 and KEYNOTE-185 – Keytruda was being used in combination with other therapies to treat multiple myeloma; an aggressive and incurable blood cancer that develops in bone marrow.
Shares dipped 1.2% in pre-market trading to trade at US$63.60.