FDA reviewers gave agency advisors the proverbial chin nod in documents briefing them on Kythera Biopharma Inc.'s submental fat reduction drug, ATX-101 (deoxycholic acid), ahead of a March 9 advisory committee meeting, saying company data support a "favorable benefit-risk assessment" of the injectable, an appraisal that boosted Kythera shares (NASDAQ:KYTH) 25.3 percent to $50 on Thursday.