MorphoSys AG (NASDAQ:MOR) is reportedly facing a burgeoning safety concern surrounding pelabresib, an experimental myelofibrosis treatment. Myelofibrosis is a type of blood cancer characterized by the buildup of scar tissue, called “fibrosis,” in the bone marrow. Physicians participating in MorphoSys’ Phase 3 study have observed instances when patients treated with pelabresib swiftly transitioned from myelofibrosis to acute myeloid leukemia (AML), a more aggressive form of blood cancer. Citing sources familiar with the cases, STAT News noted physicians saw several instances of patients undergoing such rapid progression.  Among 212 patients receiving pelabresib, six serious safety events of “AML transformation” were reported, compared to only two events among 214 patients in the control group. Pelabresib has been the centerpiece of MorphoSys’