A synthetic pladienolide derivative H3B‐8800 was the first compound tested in the spliceosome mutated on hematopoietic cell lines, including SF3B1, SRSF2, and U2AF1.138 In a phase 1 clinical trial, it was tested in 84 patients with myeloid cancers (42 with HR‐MDS or LR‐MDS; 88% with spliceosome mutations of interest) and only 14% of patients experienced reduced transfusion requirement and marrow responses while changes in mutation burden were not seen.139, 140. This evidence concerns the gene SRSF2 and myelodysplastic syndrome.