P073 | RETROSPECTIVE ANALYSIS OF INFECTIONS RELATED TO VENETOCLAX+AZACITIDINE REGIMEN IN ELDERLY AML PATIENTS

Background: the low-intensity regimen of venetoclax (VEN) and azacitidine (AZA) demonstrates favorable efficacy and tolerable safety profile in previously untreated elderly pts with acute myeloid leukemia (AML) unfit for intensive chemotherapy. Nonetheless, these benefits are accompanied by significant cytopenias and infectious complications. Methods: in this retrospective study, 65 treatment-naïve elderly pts diagnosed with AML and treated at our institution between 2017 and 2024 were analyzed. Of these, 35 pts received VEN+AZA as first-line treatment (frontline group) and 30 after progression on prior AZA treatment (R/R group). Overall, 58.5% of pts received antimicrobial prophylaxis. Regarding cycle 1 (C1), 41.5% were treated as inpts, while 58.5% as outpts. Results: the most common infections during C1 were FUO (16.9%), pulmonary infections (15.4%) and sepsis (7.7%). Median OS was 17.2 months (range, 8.8-25.6) in pts who received antimicrobial prophylaxis vs. 14.7 (range, 4.7-24.7) in those who did not (p=.97). OS of pts who developed infections was 12 months (range, 8.6-15.5) vs. 46.4 in those who did not (range, 9.8-83.0; p=0.011). Univariate analysis (UVA) showed that acquired infections significantly impacted OS [HR=2.491, p=0.014, (95%CI, 1.3–4.4)], which was confirmed in multivariate analysis (MVA) for OS [HR=2.5, p=.014, (95%CI 1.2–5.2)] and EFS [HR=1.9, p=.053, (95%CI 0.99-3.7)]. Treatment setting was a crucial predictive factor for infection development during C1 of AZA+VEN in both UVA [HR=.257, p=.016, (95%CI 0.08-0.7)] and MVA [HR=.256, p=.035, (95%CI 0.07-0.9)]. In R/R group, 1-year OS was 71% in pts without infections (95%CI, 71-99) vs. 63% (95%CI, 43-91) in those with (p= 0.027). 1-year EFS was 71% (95%CI, 51-99) vs. 50% (95%CI, 31-82), respectively (p=0.045). 3-month cumulative incidence of infection in frontline group was 79% (95%CI, 51-92) in inpts vs. 50% (95%CI, 23-72) in outpts (p=.043). In R/R group was 75% (95%CI, 36-92) in unfit pts vs. 28% (95%CI, 9.7-50) in those fit (p=.002). In pts <75 years old was 63% (95%CI, 37-81) vs. 75% (95%CI, 2.5-46) in those ≥75 years (p=.0021). Pts with a PLT count at C1d28 ≥100x109/L developed fewer infections compared to those with lower counts [23%, (95%CI, 5.1-49) vs. 65%, (95%CI, 36-83), p=.023]. Conclusions: performing C1 in an inpatient setting is associated with higher risk of infections and poorer survival outcomes. PLT recovery at day 28 plays a protective role, particularly in R/R group.