Molecular Pathogenesis of Chronic Myelomonocytic Leukemia and Potential Molecular Targets for Treatment Approaches

Chronic myelomonocytic leukemia primarily presenting as life-threatening pericardial effusion, Eldoret, Kenya: A case report

Key Clinical Message

Chronic myelomonocytic leukemia, a rare case of hematological malignancy mainly affects the elderly and may present with life threatening pericardial effusion as an initial manifestation. High index of suspicion is hence key for early management.

Abstract

We present a case of an 81-year-old African male who presented with progressive cough, respiratory distress and bilateral lower limb swelling, and was diagnosed with life-threatening pericardial effusion resulting from chronic myelomonocytic leukemia following complete blood count, peripheral blood film, bone marrow aspirate with trephine biopsy, and flow cytometry studies.

Real-World Data on Chronic Myelomonocytic Leukemia: Clinical and Molecular Characteristics, Treatment, Emerging Drugs, and Patient Outcomes

Despite emerging molecular information on chronic myelomonocytic leukemia (CMML), patient outcome remains unsatisfactory and little is known about the transformation to acute myeloid leukemia (AML). In a single-center cohort of 219 CMML patients, we explored the potential correlation between clinical features, gene mutations, and treatment regimens with overall survival (OS) and clonal evolution into AML. The most commonly detected mutations were TET2, SRSF2, ASXL1, and RUNX1. Median OS was 34 months and varied according to age, cytogenetic risk, FAB, CPSS and CPSS-Mol categories, and number of gene mutations. Hypomethylating agents were administered to 37 patients, 18 of whom responded. Allogeneic stem cell transplantation (alloSCT) was performed in 22 patients. Two-year OS after alloSCT was 60.6%. Six patients received targeted therapy with IDH or FLT3 inhibitors, three of whom attained a long-lasting response. AML transformation occurred in 53 patients and the analysis of paired samples showed changes in gene mutation status. Our real-world data emphasize that the outcome of CMML patients is still unsatisfactory and alloSCT remains the only potentially curative treatment. However, targeted therapies show promise in patients with specific gene mutations. Complete molecular characterization can help to improve risk stratification, understand transformation, and personalize therapy.

Multistep pathogenesis of chronic myelomonocytic leukemia in patients

Background

A multistep pathogenesis of myeloid leukemia including mutations in epigenetic, spliceosome, and signaling genes has been recently demonstrated in a preclinical model but is poorly validated in patients.

Methods

Clinical, phenotypic, and biologic features were compared between three distinct molecularly defined CMML cohorts including TET2 monomutated patients (T, n = 10), TET2/SRSF2 bimutated patients (TS, n = 19), and patients who had NRAS mutations in addition to TET2/SRSF2 comutations (TSN, n = 14).

Results

Median survival was 90, 45, and 9 months, respectively (p = .001). Whereas no patient in the T and TS group transformed into acute myeloid leukemia (AML), 6/14 patients in the TSN group had AML at study entry or transformed during follow‐up. Leukocyte counts, blast cell counts, and LDH levels were significantly higher in TSN vs. TS and T, respectively, whereas hemoglobin and platelet values were not significantly different. Increased growth factor‐independent myeloid colony formation was restricted to TSN but not found in T and TS, respectively. The proportion of patients showing in vitro myelomonocytic skewing in T, TS, and TSN was 0%, 56%, and 100%, respectively (p = .010).

Conclusion

Our results demonstrate that the model of multistep pathogenesis in CMML can be recapitulated in patients regarding clinical, phenotypic, and biologic features.