A Food and Drug Administration panel on Monday recommended approval of Kythera Biopharmaceuticals Inc.’s novel treatment for chin fat. The injectable chemical, ATX-101, dissolves fat and would be the Westlake Village company’s first commercial product. The FDA’s Dermatologic and Ophthalmic Drugs Advisory Committee voted 17-0 in favor of its sale. While the recommendation by the panel of outside experts isn’t binding, the agency usually follows such recommendations. If ATX-101 is approved by the FDA, Kythera plans to launch it during the second half this year. “This milestone demonstrates our commitment to developing first-in-class aesthetic products through a focus on scientific rigor and innovation,” Chief Executive Keith Leonard said in a statement. Last week, in a separate opinion, FDA staff recommended approval of the drug, sending the stock up nearly 22 percent. Shares closed down $1.96, or 3.7 percent, to $51.17 on the Nasdaq.