How should myelodysplastic neoplasms with isolated deletion 5q and TP53 multihit alterations be classified?

Myelodysplastic neoplasms (MDS) with TP53 multihit alterations are associated with dismal outcomes. MDS with isolated del(5q) present favorable prognosis but is defined by the absence of TP53 multihit alterations. However, whether TP53 multihit alterations exert the same adverse impact in this genetic context remains uncertain. We retrospectively analyzed the characteristics and outcome of 43 patients with MDS with isolated del(5q) harboring TP53 multihit alterations (MDS-del(5q) TP53 multihit) and compared with 68 patients with low-blast MDS with TP53 multihit and without isolated del(5q) (MDS-LB TP53 multihit). Patients with MDS-del(5q) TP53 multihit showed significantly higher platelet counts, more frequent SF3B1 mutations, were less often classified as high-risk by IPSS-R or IPSS-M, and had significantly better outcomes than patients with MDS-LB TP53 multihit: overall survival of 70.2 vs 13.9 months, and time to acute myeloid leukemia progression (AML) of 31.9 vs 7.2 months, respectively. Moreover, the superior outcomes of MDS-del(5q) TP53 multihit patients persisted significant even when compared with MDS-LB TP53 multihit cases without complex karyotype (survival of 70.2 vs 39.9 months; time to AML progression of 31.9 vs 11.4 months). These findings indicate that, in MDS-del(5q) the adverse impact of TP53 multihit alterations may be less important than in other MDS subtypes.