Allogeneic hematopoietic stem cell transplantation in patients with germ line DDX41 mutated myeloid malignancies

Germ line DDX41 mutations (DDX41mut) are identified in ∼5% of myeloid malignancies with an excess of blasts, representing a distinct myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) entity. The disease is associated with better outcomes than DDX41 wild-type (DDX41WT) cases, but patients who do not undergo allogeneic hematopoietic stem cell transplantation (HSCT) may experience late relapse. Because of the recent identification of DDX41mut, data on the post-HSCT outcomes remain limited. In this study, we report the HSCT outcomes of 83 patients with DDX41mut MDS/AML. With a median follow-up of 4.4 years, the 2-year leukemia-free survival (LFS) was 68.6% (95% confidence interval [CI], 57.1-77.6) and the 2-year nonrelapse mortality (NRM) was 21.1% (95% CI, 12.9-30.6). We then assessed the impact of DDX41mut using a pair match analysis performed on patients who underwent a transplantation in AML clinical trials. No significant differences were observed between patients with DDX41mut and those with DDX41WT in terms of LFS at 2 years (hazard ratio, 1.06; 95% CI, 0.59-1.90; P = .84), overall survival, NRM, relapse, or graft-versus-host disease incidence. The cumulative incidence of relapse for DDX41mut showed a trend toward a lower relapse rate during the first year then higher after 1 year. Given the familial nature of the disease, we specifically examined patients who relapsed after HSCT with a related donor and identified 7 cases of DDX41mut donor cell leukemia. In this study, HSCT in patients with DDX41mut AML was not associated with an increased risk for toxicity. However, we observed a potential for later relapse, which could potentially be mitigated by selecting related donors based on DDX41 status.