The mutational landscape in chronic myelomonocytic leukemia and its impact on allogeneic hematopoietic cell transplantation outcomes: a Center for Blood and Marrow Transplantation Research (CIBMTR) analysis

Abstract

Somatic mutations are recognized as an important prognostic factor in chronic myelomonocytic leukemia (CMML). However, limited data are available regarding their impact on outcomes after allogeneic hematopoietic cell transplantation (alloHCT).

In this registry analysis conducted in collaboration with the Center for International Blood and Marrow Transplantation Registry (CIBMTR) database/sample repository, we identified 313 adult patients with CMML (median age: 64 years, range: 28-77) who underwent alloHCT during 2001-2017 and had an available biospecimen in the form of a peripheral blood sample obtained prior to the start of conditioning. In multivariate analysis, a CMML-specific prognostic scoring system (CPSS) score of intermediate-2 (HR=1.46, p=0.049) or high (HR=3.22, p=0.0004) correlated significantly with overall survival (OS). When the molecularly informed CPSS-Mol was applied, a high CPSS-Mol score (HR=2 p=0.0079) correlated significantly with OS. The most common somatic mutations were ASXL1 (62%), TET2 (35%), KRAS/NRAS (33% combined), and SRSF2 (31%). DNMT3A and TP53 mutations were associated with decreased OS (HR=1.70 [95%CI: 1.11-2.60], p=0.0147 and HR=2.72 [95%CI: 1.37-5.39], p=0.0042, respectively) while DNMT3A, JAK2, and TP53 mutations were associated with decreased disease-free survival (DFS) (HR=1.66 [95%CI: 1.11-2.49], p=0.0138, HR=1.79 [95%CI: 1.06- 3.03], p=0.0293, and HR=2.94 [95%CI: 1.50-5.79], p=0.0018 respectively). The only mutation associated with increased relapse was TP53 (HR=2.94, p=0.0201). Nonetheless, the impact specifically of TP53 mutations should be interpreted cautiously given its rarity in CMML. We calculated the goodness of fit measured by Harrell’s C-index for both the CPSS and CPSS-Mol, which were very similar.

In summary, via registry data we have provided the mutational landscape in patients with CMML who underwent alloHCT, and we demonstrated an association between CPSS-Mol and transplant outcomes although without major improvement in the risk prediction beyond the CPSS.