Enhanced Survival of Chronic Myelomonocytic Leukemia-Dysplastic over Proliferative Subtype after Allogeneic Hematopoietic Cell Transplant: A Tertiary Center Experience and Literature Review.

Introduction: CMML is a rare neoplasm with overlapping myelodysplastic and myeloproliferative features whose only potential cure is allogeneic hematopoietic cell transplantation (allo-HCT).

Methods: This retrospective study examined 27 CMML patients with high-risk clinical features who underwent first allo-HCT at our institution between 2004 and 2022.

Results: Nineteen patients were diagnosed with the proliferative subtype (CMML-MPN) and 8 with the dysplastic subtype (CMML-MDS). Median OS was 15 months post-HCT (95% CI: 5-71); OS at 1, 3, and 5 years was 52%, 35%, and 35%, respectively. Compared to those with CMML-MPN, patients with CMML-MDS had longer OS (median, 8.6 vs. 0.9 years; p = 0.025), RFS (4.4 vs. 0.5 years; p = 0.021), and GVHD-free, relapse-free survival (GRFS, 9.4 vs. 3.4 months; p = 0.033) as well as lower 1-year NRM (13 vs. 47%; p = 0.043), with the statistical significance of this CMML subtype effect maintained in multivariable models. High-risk cytogenetics were associated with shorter GRFS in the univariable (median, 3.1 vs. 6.2 months; p = 0.013) and multivariable (HR = 4.88; p = 0.006) settings.

Conclusions: Patients who underwent transplant for CMML-MDS experienced substantially better outcomes than those transplanted for CMML-MPN. Future studies are needed for transplantation optimization in CMML, especially CMML-MPN.