Rhythm Pharmaceuticals Inc RYTM:NASDAQ

Health care stocks were mostly higher this afternoon, with the NYSE Health Care Index and the SPDR Health Care Select Sector ETF (XLV) both rising 1.0%.

The Nasdaq Biotechnology index, however, was slipping 0.1%.

In company news, Celsion (CLSN) dropped over 16% after the biotechnology company Wednesday plans a $7 million offering of around 1.3 million shares at $5.27 apiece, or 15.3% under Tuesday's closing price.

Rhythm Pharmaceuticals (RYTM) fell almost 17% after the drug maker said it was modifying phase II and phase III testing of setmelanotide drug candidate to treat rare genetic diseases of obesity to focus on rare patient populations that it believes "have the highest likelihood of success."

BioXcel Therapeutics (BTAI) rose almost 12% after Wednesday saying the US Food and Drug Administration has approved its Igalmi sublingual film for the treatment of acute agitation associated with schizophrenia or bipolar I or II disorders in adults. BioXcel shares also were getting a boost from BoA Securities increasing its price target for the stock by $2 to $80.