Shares of Merck rivals Bristol-Myers Squibb ( BMY ) and AstraZeneca ( AZN ) tumbled 5.3% and 2% by Wednesday's close. Merck's Keytruda announcement late Tuesday coincided with its presentation at the JPMorgan Healthcare Conference in San Francisco, one of the drug industry's major annual events. IBD'S TAKE: An event such as the Trump press conference can move stocks, so keep up-to-date on the latest action with IBD's Stocks on the Move. Keytruda plus chemo now has a Prescription Drug Free User Agreement (PDUFA) date of May 10 following the FDA's acceptance of Merck's supplemental Biologics License Agreement (BLA) for accelerated approval. Keytruda is currently approved in first-line non small-cell lung cancer for patients who have a high expression of the PD-L1 protein, which covers about 25%-30% of the NSCLC patient population.