Chronic myelomonocytic leukemia prognostic classification and management: evidence base and current practice

Multicenter validation of the flow measurement of classical monocyte fraction for chronic myelomonocytic leukemia diagnosis

Peripheral blood monocytes include three subsets defined by CD14 and CD16 surface markers. An increase in the CD14⁺⁺CD16^- classical monocyte fraction ≥ 94% of the total monocytes was proposed to rapidly and efficiently distinguish chronic myelomonocytic leukemia from reactive monocytosis. The robustness of this assay required a multicenter validation. The flow cytometry assay designed to quantify peripheral blood monocyte subsets was implemented by multiple diagnosis laboratories in France. A nationwide survey was performed to evaluate its performance. All the 48 French laboratories answered the questionnaire, revealing that 63% use this assay routinely. Central blind reanalysis of 329 cytometry files collected from five laboratories demonstrated an excellent correlation in classical monocyte fraction measurement (r = 0.93; p < 0.0001). The cutoff value of 94% classical monocytes being the critical readout for diagnosis, we then compared 115 patients with classical monocytes ≥ 94% and 214 patients with a fraction < 94% between initial analysis and reanalysis. An agreement was obtained in 311 files. Finally, an overt diagnosis, available for 86 files, confirmed a good sensitivity (93.6%) and specificity (89.7%). This survey demonstrates the robustness of the flow assay with limited variability of classical monocyte percentage between centers, validates the 94% cutoff value, and confirms its sensitivity and specificity.

Blastic Transformation in Mexican Population With Chronic Myelomonocytic Leukemia

BACKGROUND

Chronic myelomonocytic leukemia (CMML) is the most aggressive of chronic leukemias, with short overall survival and a high transformation rate to acute leukemia. We investigated the factors related to blastic transformation in a Mexican population treated at a tertiary referral center.

PATIENTS AND METHODS

The records of patients with a diagnosis of CMML from 2000 to 2015 were reviewed. A total of 54 patients were included, with a median age of 71 years and an overall survival of 16 months. The patients with incomplete data were excluded. IBM SPSS Statistics, version 21.0, software was used to perform the statistical analysis.

RESULTS

The rate of blastic transformation was 33% (18 patients), and the interval time to progression was 9 months (range, 0-87 months). Comparing the patients who did not undergo blastic transformation to those who did, those with progression to acute leukemia tended to be younger (age, 58 vs. 71 years; P = .001), to have a greater peripheral blood blast count (≥ 2% vs. 0%; P = .003), and were more likely to have immature myeloid precursors circulating in the peripheral blood (94% vs. 64%; P = .02). On multivariate analysis, younger age continued to be a statistically significant factor for progression (hazard ratio, 0.97; 95% confidence interval, 0.929-0.987).

CONCLUSION

Mexican patients with CMML that progressed to overt acute leukemia were considerably younger, with a higher tumor burden and short overall survival. In this population, it is important to consider more aggressive treatment at diagnosis, focusing on high-dose chemotherapy and hematopoietic stem cell transplantation within a short period.