Identification of Predictive Factors for Overall Survival at Baseline and during Azacitidine Treatment in High-Risk Myelodysplastic Syndromes Treated in the Clinical Practice

Background. 5-Azacitidine (5-AZA) had changed the therapeutic approach to intermediate-2/high IPSS risk myelodysplastic syndromes (MDS) improving the outcome of patients, even in the absence of a complete response. However, real-life experiences have reported contradicting results compared to the AZA001 randomized study. Aim of our analysis was to identify the clinico-biological features at baseline and during treatment associated with the overall survival (OS) and progression-free survival (PFS) at two years in a consecutive cohort of patients treated with hypometylating agent in the clinical practice. Moreover, we propose a new prognostic score for the identification of OS after the first four cycles of therapy.

Patients and Method. We retrospectively analyzed a series of 110 MDS patients treated at a single institution with 5-AZA between September 2003 and January 2017. Patients were diagnosed according to the WHO 2016 criteria. 5-AZA was administered at a dose of 75 mg/m² according to the 5+2+2 schedule every 28 days.

Results. A male predominance was observed (male/female: 66%/34%) with a median age of 70 years (range 38-85). The median dose of 5-AZA received was 135 mg/day (range 105-150) after a median time from diagnosis of 2.3 months (range 0.1-119). Median duration of therapy was 9.5 cycles (range 1-77) with a median time on treatment of 8.5 months (range 1-86.7). OS of the whole cohort was 66.1% (CI 95% 57.2-76.4) at 1 year and 38.3% (CI 95% 29.4-49.9) at 2 years. Seventy-seven patients (70%) performed four cycles of therapy. According to the IWG criteria, 42 patients (54.5%) achieved a complete remission (CR), 11 (14.2%) a partial remission (PR), 17 (22.4%) maintained a stable disease (SD), 2 (2.5%) and 5 (6.4%) presented a progression disease (PD) and a failure, respectively. The 2-year OS was 68% in patients who obtained a CR/PR, 20% in patients with SD and 16% in patients with PD/failure (p<0.001). No differences in terms of OS were observed for gender (p=0.622) and age at baseline (<65years, 65-75 and >75 years, p=0.075). The baseline bone marrow blasts percentage did not impact on OS and PFS (OS, p=0.867; PFS, p=0.611). According to the Revised International Prognostic Score (R-IPSS), 22 (20%), 46 (42.8%) and 42 (38.2%) patients were classified as intermediate, high and very high-risk patients, respectively. We identified that the very high-risk group had an inferior 2-year OS (17%) compared to intermediate-group patients (64%, p<0.001). Indeed, we did not find significant difference according to the IPSS stratification (intermediate 42% vs high-risk 22%, p=0.253). Transfusion-independency at baseline was identified as a favorable prognostic factor on 1-year (66.8%) and 2-year OS (43.4%) compared to patients with transfusion dependency (36.4% and 22.2% if they required 1 unit/month or more than 1 unit at baseline at 2 years, p<0.001). After four cycles received, the persistence of bone marrow blasts >10% identified patients with a worse outcome, with a 2-year OS of 9.4% compared to 60.3% for patients with 0-5% blasts and 44.7% for patients with 5-10% blasts (p=0.002). The occurrence of one infection during the first four cycles impacted on the 2-year OS (31.6% vs 58.3% in patients without, p=0.032). We applied a dynamic prognostic score according to age, cytogenetic risk, transfusion need, number of 5-AZA cycles performed and type of response after the fourth cycle (Table 1): the combination of these variables identified 3 categories of risk with a significantly different 2-year OS: low-risk (72.3%), intermediate (19.8%) and high-risk (8.9%) (p<0.001, Fig. 1).

Conclusions. Our results in a large and consecutive MDS cohort treated outside of clinical trials defined prognostic factors, such as transfusion dependency, persistence of >10% blasts after four cycles and absence of infections, capable of identifying patients with a good outcome. A prognostic score is proposed that requires independent validations in similar cohorts of patients.

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