Response to azacitidine treatment was evaluated in a retrospective study of patients with chronic myelomonocytic leukemia (CMML), and in this analysis, more than half of the patients responded to treatment. The results of this study were published in the journal Leukemia Research.

CMML is a hematologic malignancy the World Health Organization (WHO) classifies as a myelodysplastic/myeloproliferative (MDS/MPN) neoplasm, the study investigators explained. A WHO classification system devised in 2017 places patients with CMML into 3 groups, with CMML-0 having the lowest blast percentages in peripheral blood and bone marrow and CMML-2 having the highest blast percentages.

The French-American-British (FAB) classification system categorizes CMML based on leukocyte count, with a leukocyte count of less than 13×109/L denoting the myelodysplastic (MD) subtype and a leukocyte count of 13×109/L or more denoting the myeloproliferative (MP) subtype. Data regarding the efficacy of azacitidine for either MD-CMML or MP-CMML are limited.


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For this retrospective analysis, 91 patients with CMML diagnosed according to WHO or FAB criteria were identified through the Spanish Registry of MDS. Patients had received 1 or more cycles of azacitidine. Study objectives were to assess azacitidine response in patients with CMML and compare responses across CMML subtypes. Responses were assessed between cycles 4 and 6 using overlap MDS/MPN response criteria, which are criteria that have been proposed for considering both MD and MP features in evaluating response.

By FAB criteria, 55% of patients had MD-CMML and 45% had MP-CMML. By WHO criteria, 52% of patients had CMML-0/1 and 48% had CMML-2. Median patient age was 70 years (range, 45 to 84), and 50% of patients were red blood cell transfusion dependent.

Patients received a median of 8 cycles of azacitidine (range, 1 to 70). The overall response rate (ORR) was 58% between cycles 4 and 6. Among 45 patients who were initially transfusion dependent, 22 (49%) reached transfusion independence. A clinical benefit was demonstrated for 22% of the total patient population. ORRs were 60% and 56% in the MD-CMML and MP-CMML groups, respectively.

Using WHO criteria, ORR was 51% in the CMML-0 or CMML-1 group. ORR was 66% in the CMML-2 group. ORRs were also similar for patients across risk groups defined according to the chronic myelomonocytic leukemia-prognostic score system (CPSS).

Grade 3 or 4 azacitidine treatment-related toxicities were reported by 42% of patients. These occurred more commonly in patients with MD-CMML than in patients with MP-CMML (51% vs 32%).

“High ORR according to the overlap-MDS/MPN response criteria was observed regardless of the CMML subtype and the CPSS risk group,” the study investigators concluded.

Reference

Triguero A, Xicoy B, Zamora L, et al. Response to azacitidine in patients with chronic myelomonocytic leukemia according to overlap myelodysplastic/myeloproliferative neoplasms criteria. Leuk Res. Published online March 26, 2022. doi:10.1016/j.leukres.2022.106836