Real-world experience with decitabine as a first-line treatment in 306 elderly acute myeloid leukaemia patients unfit for intensive chemotherapy.

Despite widespread use of decitabine to treat acute myeloid leukaemia (AML), data on its effectiveness and safety in the real-world setting are scanty. Thus, to analyze the performance of decitabine in clinical practice, we pooled together patient-level data of three multicentric observational studies conducted since 2013 throughout Italy, including 306 elderly AML patients (median age 75 years), unfit for intensive chemotherapy, treated with first-line decitabine therapy at the registered schedule of 20 mg/m2 /iv daily for 5 days every 4 weeks. Overall response rate (ORR), overall survival (OS) curves, and multivariate hazard ratios (HRs) of all-cause mortality were computed. Overall, 1940 cycles of therapy were administered (median, 5 cycles/patient). A total of 148 subjects were responders and, therefore, ORR was 48.4%. Seventy-one patients (23.2%) had complete remission, 32 (10.5%) had partial remission, and 45 (14.7%) had haematologic improvement. Median OS was 11.6 months for patients with favourable-intermediate cytogenetic risk and 7.9 months for those with adverse cytogenetic risk. Median relapse-free survival after CR was 10.9 months (95% confidence interval [CI]: 8.7-16.0). In multivariate analysis, mortality was higher in patients with adverse cytogenetic risk (HR=1.58; 95% CI: 1.13-2.21) and increased continuously with white blood cell (WBC) count (HR=1.12; 95% CI: 1.06-1.18). A total of 183 infectious adverse events occurred in 136 patients mainly (>90%) within the first five cycles of therapy. This pooled analysis of clinical care studies confirmed, outside of clinical trials, the effectiveness of decitabine as first-line therapy for AML in elderly patients unfit for intensive chemotherapy. An adverse cytogenetic profile and a higher WBC count at diagnosis were, in this real life setting, unfavourable predictors of survival.

Residual Peripheral Blood CD26+ Leukemic Stem Cells in Chronic Myeloid Leukemia Patients During TKI Therapy and During Treatment-Free Remission.

Chronic myeloid leukemia (CML) patients in sustained "deep molecular response" may stop TKI treatment without disease recurrence; however, half of them lose molecular response shortly after TKI withdrawing. Well-defined eligibility criteria to predict a safe discontinuation up-front are still missing. Relapse is probably due to residual quiescent TKI-resistant leukemic stem cells (LSCs) supposedly transcriptionally low/silent and not easily detectable by BCR-ABL1 qRT-PCR. Bone marrow Ph+ CML CD34+/CD38- LSCs were found to specifically co-express CD26 (dipeptidylpeptidase-IV). We explored feasibility of detecting and quantifying CD26+ LSCs by flow cytometry in peripheral blood (PB). Over 400 CML patients (at diagnosis and during/after therapy) entered this cross-sectional study in which CD26 expression was evaluated by a standardized multiparametric flow cytometry analysis on PB CD45+/CD34+/CD38- stem cell population. All 120 CP-CML patients at diagnosis showed measurable PB CD26+ LSCs (median 19.20/µL, range 0.27-698.6). PB CD26+ LSCs were also detectable in 169/236 (71.6%) CP-CML patients in first-line TKI treatment (median 0.014 cells/µL; range 0.0012-0.66) and in 74/112 (66%), additional patients studied on treatment-free remission (TFR) (median 0.015/µL; range 0.006-0.76). Notably, no correlation between BCR-ABL/ABLIS ratio and number of residual LSCs was found both in patients on or off TKIs. This is the first evidence that "circulating" CML LSCs persist in the majority of CML patients in molecular response while on TKI treatment and even after TKI discontinuation. Prospective studies evaluating the dynamics of PB CD26+ LSCs during TKI treatment and the role of a "stem cell response" threshold to achieve and maintain TFR are ongoing.