NEW YORK – Merck on Monday said it has decided to halt a Phase III study evaluating the combination of its anti-PD-1 therapy pembrolizumab (Keytruda) with ipilimumab (Bristol Myers Squibb's Yervoy) in first-line, metastatic non-small cell lung cancer patients with high PD-L1 expression and no EGFR or ALK alterations.