Outcomes of 3-versus 5-day administration schedule of consolidation cytarabine in adults with acute myeloid leukemia (AML).

7014 Background: Consolidation therapy with intermediate to high-dose cytarabine is critical to prevent relapse in AML. Cytarabine is typically administered every 12 hours on days 1, 3, 5. Two large studies have examined a condensed 3-day administration schedule in patients <60 years and demonstrated a shorter time to absolute neutrophil count (ANC) recovery without compromising long term outcomes. However, use of this regimen in patients ≥60 years has not been evaluated. Here we report our experience with the condensed administration schedule compared with the standard schedule in patients over and under 60 years. Methods: All patients with AML in first complete remission (CR) following intensive induction chemotherapy receiving consolidation at our institution between 1/1/2020 to 12/31/2021 were included in the study. Patients received cytarabine every 12 hours on days 1, 3, 5 (AC135) from 1/1/2020 – 12/31/2020 and cytarabine every 12 hours on days 1, 2, 3 (AC123) from 1/1/2021 – 12/31/2021. All patients received peg-filgrastim support. Data was collected to determine time to ANC recovery >1,000/µL, hemoglobin (Hb) >8g/dL, and platelets >75,000/µL. Comparison of continuous variables between two groups was done using multiple t-tests. Results: Between 1/1/2020 - 12/31/2021, 91 patients received at least one cycle of consolidation with 212 individual encounters. 38 patients received all cycles with AC135, 45 received AC123, and 8 received at least one cycle each of AC123 and AC135. Median age of the AC123 cohort was 50.2 years (range 19-72 years) and 54.3 years for the AC135 cohort (range 22-72 years). For patients ≥60 years of age, 33% (71/213) of the encounters were in the AC123 cohort and the rest in AC135 cohort. Median dose of cytarabine was 5,100 mg/dose in AC123 and 4,600 mg /dose in AC135 (p=0.02). Median time to ANC recovery, hemoglobin, and platelets as well as hospital-related outcomes are described in the table. In patients ≥60 years, median time to ANC recovery was 16.5 vs. 18.6 days (p = 0.03) and platelet recovery was 17.4 vs. 19.7 (p = 0.0008) in AC123 vs AC135 respectively. No neurotoxicity events were noted. Complication rates were similar in both arms. Conclusions: Our study demonstrates that AC123, as compared to AC135, is safe and leads to earlier hematopoietic recovery in adults under and over 60 years. AC123 should be considered the preferred schedule of consolidation therapy administration. [Table: see text]