CLINICAL CHARACTERISTICS AND OUTCOMES OF MYELODYSPLASTIC NEOPLASMS AND ACUTE MYELOID LEUKEMIA WITH MECOM REARRANGEMENT: RESULTS FROM A NATIONWIDE MULTICENTER STUDY.

Abstract

Introduction: “AML with MECOM rearrangement” was recently categorized by WHO classification 2022 regardless of blast count, which included those present with MDS and AML into this group. We aim to explore frequency, clinical characteristics, and outcomes in this subtype among Thai myeloid neoplasms. Methods: MDS and AML data was collected from a multicenter study group. MDS and AML with MECOM rearrangements were analyzed and compared with other subtypes. Results: A total of 15 cases with MECOM rearrangement were detected, 5/166 (3%) were MDS while 10/1082 (0.9%) were AML. Eleven of 15 cases (73%) were female. MDS and AML with MECOM rearrangement showed lower hemoglobin, but higher platelet counts compared to others. Three MDS with MECOM rearrangement patients received azacitidine-based regimens and achieved complete hematologic response. In AML cases receiving intensive chemotherapy, MECOM rearrangement subgroup showed lower complete response (CR) rate compared to others (0% vs. 39.6%). Of note, among 10 AML with MECOM rearrangement, 7 patients received intensive chemotherapy but none of them responded. When combining 5 MDS and 10 AML with MECOM rearrangements, survival rate is comparable to the adverse group of AML and the very high risk group MDS with a 1-year survival rate of 27.5% (Figure 1A and 1B). Conclusions: In conclusion, MDS and AML with MECOM rearrangements are rare subtype, more common in female gender and associated with poor prognosis. Chemotherapy should be avoided, hypomethylating agent showed benefit. Novel therapy targeting MECOM gene should be further explored.