Electra Therapeutics priced and upsized its IPO, raising $350 million to support late-stage development of ipsoprubart, a pan-SIRP monoclonal antibody in secondary hemophagocytic lymphohistiocytosis (sHLH). The offering included 23.33 million shares priced at $15 each, with underwriters eligible for a 30-day option that could add additional gross proceeds.