Shares of the rare disease specialist BioCryst Pharmaceuticals (NASDAQ: BCRX) were up by a noteworthy 20% on heavy volume at 9:38 a.m. ET Thursday morning. Although the biotech reported encouraging 2022 second-quarter results prior to today's opening bell, the real needle mover here appears to be the news that the Food and Drug Administration (FDA) has lifted the partial clinical hold on BCX9930. BCX9930 is an oral Factor D inhibitor indicated for a rare blood disease known as paroxysmal nocturnal hemoglobinuria (PNH).