Health care stocks were narrowly lower this afternoon, with the NYSE Health Care Index and the SPDR Health Care Select Sector ETF (XLV) down around 0.2%. The Nasdaq Biotechnology index also was sinking 1.0%. In company news, Protagonist Therapeutics (PTGX) slumped almost 22% after late Wednesday saying the US Food and Drug Administration plans to rescind the breakthrough therapy designation for its rusfertide drug candidate to treat polycythemia vera.