Genomic Landscape and Risk Stratification in Chronic Myelomonocytic Leukemia

PURPOSE

The advent of next-generation sequencing has allowed for the annotation of a vast array of recurrent somatic mutations across human malignancies, ushering in a new era of precision oncology. Chronic myelomonocytic leukemia is recognized as a myelodysplastic/myeloproliferative neoplasm and displays heterogenous clinical and genetic features. Herein, we review what is currently understood regarding the genomic landscape of this disease and discuss how somatic mutations have impacted current risk stratification methods.

RECENT FINDINGS

Genomic studies in chronic myelomonocytic leukemia have identified a characteristic spectrum of cytogenetic and molecular abnormalities. Chromosomal abnormalities are detected in ~30% of patients and somatic gene mutations in up to 90% of patients, most commonly in TET2, SRSF2, and ASXL1. While cytogenetic abnormalities have long been known to impact the prognosis of myeloid neoplasms, recent studies have identified that somatic mutations impact prognosis independent of cytogenetic and clinical variables. This is best exemplified by mutations in ASXL1, which have been uniformly associated with inferior survival. These findings have led to the development of three molecularly inspired prognostic models, in an attempt to more accurately prognosticate in the disease. Our understanding of the genomic landscape of chronic myelomonocytic leukemia continues to evolve, with somatic mutations demonstrating an expanding role in diagnosis, risk stratification, and therapeutic decision-making. Given these findings, molecular profiling by next-generation sequencing should be considered standard of care in all patients.

Autoimmune disease in CMML-the chicken or the egg?

Chronic myelomonocytic leukemia (CMML) is a clonal disorder that is associated with a wide range of systemic inflammatory and autoimmune diseases (SIADs). Approximately 20% of patients with CMML will have an associated SIAD and recognizing this association is critical to the evaluation, prognostication and management of patients with CMML. In this paper, we review the evidence supporting a causative link between these two entities as well as the direction of this relationship. We argue that the data favors CMML as the antecedent and causative disease state with a few notable exceptions. Better understanding of this relationship aids clinicians in the education of their patients and in determining the optimal management approach at the bedside. It is important to recognize opportunities to harmonize the treatments of these disease processes, which may enhance the effectiveness of treatment while reducing the burden of adverse effects from redundant therapies.

Allogeneic hematopoietic stem cell transplant in adult patients with myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap syndromes

MDS/MPN (myelodysplastic syndrome/myeloproliferative neoplasm) overlap syndromes are myeloid malignancies for which allogeneic hematopoietic stem cell transplant (allo-HSCT) is potentially curative. We describe transplant outcomes of 43 patients - 35 with chronic myelomonocytic leukemia, CMML (of which 17 had blast transformation, BT) and eight with MDS/MPN-unclassifiable (MDS/MPN,U). At median follow-up of 21 months, overall survival (OS), cumulative incidence of relapse (CIR) and non-relapse mortality (NRM) were 55%, 29%, and 25% respectively in CMML without BT and 47%, 40%, and 34% respectively in CMML with BT. Higher HSCT-comorbidity index (HSCT-CI >3 versus ≤3; p = 0.015) and splenomegaly (p = 0.006) predicted worse OS in CMML without BT. In CMML with BT, engraftment failure (p = 0.006) and higher HSCT-CI (p = 0.03) were associated with inferior OS, while HSCT within 1-year of diagnosis was associated with improved OS (p = 0.045). In MDS/MPN,U, at median follow-up of 15 months, OS, CIR, and NRM were 62%, 30%, and 14%, respectively.