Shares of Bluebird Bio Inc. (NASDAQ:BLUE) fell 37.8% to $28.44 on Feb. 16 as the company temporarily suspended two trials of its experimental gene therapy for sickle cell disease, Lentiglobin (BB-1111), while investigating one unexpected case of acute myeloid leukemia (AML) and another of myelodysplastic syndrome among participants in a phase I/II study of the candidate, called HGB-206. A second patient experienced MDS in 2018.