In conclusion, treatment with H3B-8800 had an acceptable adverse event profile, predictable PK, and modulated splicing, including downregulation of aberrantly spliced TMEM14C. SF3B1 mutation and a high pre-treatment ratio of TMEM14C AJ/CJ were associated with RBC TI in MDS patients. This evidence concerns the gene TMEM14C and myelodysplastic syndrome.