Highlights of weekly biotech stock moves

Arena Pharmaceuticals Inc. (NASDAQ:ARNA) fell $0.37 (19%) to $1.63 on Friday after FDA has requested additional studies for lorcaserin beyond what the agency asked for in a December meeting to discuss an October complete response letter for the obesity candidate. According to Arena, FDA expressed further concerns about lorcaserin's abuse potential and recommended the company modify and repeat two non-clinical safety studies to provide more information on labeling and scheduling decisions. Nevertheless, Arena said it remains on track to resubmit an NDA by year end.

Arena also said it would cut U.S. headcount by 66 (25%) to about 200. The cuts are expected to save $13.5 million annually. The stock was off $0.27 (14%) on the week...