Merck & Co shares slip on Keytruda trial failure

Keytruda (pembrolizumab), the blockbuster immuno-oncology drug from Merck & Co (NYSE: MRK), was approved last year by the US Food and Drug Administration (FDA) to treat hepatocellular carcinoma (HCC) patients previously treated with Bayer's (BAYN: DE) Nexavar (sorafenib).

The FDA granted the accelerated approval based on the Phase II KEYNOTE-224 study, though the Phase III KEYNOTE-240 trial has not yielded such a positive result by failing to meet its co-primary endpoints of overall survival (OS) and progression-free survival (PFS) versus placebo plus best supportive care in patients with advanced HCC who were previously treated with systemic therapy.

These results were announced late on Tuesday and shares in the US pharma giant opened 1% down on Wednesday morning.