Protagonist’s stock falls 27% after updating investors about experimental blood disorder drug

Shares of Protagonist Therapeutics Inc. tumbled 27.8% in premarket trading on Thursday, the day after the company disclosed in a securities filing that it expects data from a Phase 2 clinical trial for its ulcerative colitis treatment candidate in the second quarter. It also told investors that the Food and Drug Administration is rescinding the breakthrough therapy designation granted to rusfertide, an experimental treatment for polycythemia vera, which is a rare blood disorder. The company said it is trying to set up a meeting with the FDA to discuss keeping the designation. “We remain confident that rusfertide eventually hits the market; however, we also acknowledge the risk of a black box warning which could reduce its market uptake significantly,” SVB Leerink analysts told investors in a note on Wednesday. Protagonist’s stock is down 25.4% this year, while the S&P 500 has declined 5.8%.

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