At least eight biotechs gained or lost more than 10% last week after presenting at the American Society of Clinical Oncology meeting in Chicago. Clovis Oncology Inc. (NASDAQ:CLVS) topped the list of gainers after announcing Phase I data for two cancer candidates: CO-1686, a small molecule that inhibits the T790M EGFR mutant and the initial activating EGFR mutations, and rucaparib (CO-338), an oral inhibitor of poly(ADP-ribose) polymerase-1 (PARP-1) and PARP-2. Clovis has rights to CO-1686 from Avila Therapeutics Inc., which was acquired by Celgene Corp. (NASDAQ:CELG), and has exclusive, worldwide rights to rucaparib under a 2011 deal with Pfizer Inc. (NYSE:PFE) (see "Finding a 4-Leaf Clover," A18).

Infinity Pharmaceuticals Inc. (NASDAQ:INFI) and Synta Pharmaceuticals Corp. (NASDAQ:SNTA) fell more than 30% after reporting data that raised concerns from analysts and investors