Background: About 40-50% of older patients (pts) with AML attain complete remission (CR) with induction chemotherapy (IC) but relapse is common.Effective, well-tolerated maintenance treatment (Tx) is needed for older pts in remission who are not eligible for hematopoietic stem cell transplant (HSCT). CC-486 is an oral hypomethylating agent that allows for extended dosing schedules (>7 days [d]/cycle) to sustain therapeutic activity. In the phase III placebo (PBO)-controlled QUAZAR AML-001 trial (NCT01757535), CC-486 maintenance therapy in pts with AML in first remission following IC produced significant improvements in overall and relapse-free survival. Here we report safety and tolerability findings among pt subgroups defined by age at study entry. Methods: Eligible pts were ≥ 55 yrs of age, with de novo or secondary AML, intermediate or poor risk cytogenetics, and ECOG PS ≤ 3; had achieved first CR or CRi after IC ± consolidation; and were not candidates for HSCT. Within 4 mo of CR/CRi, pts were randomized 1:1 to CC-486 300 mg or PBO QD on d 1–14 of repeated 28d Tx cycles. Safety was assessed across 3 age subgroups (≥ 55 to < 65, ≥ 65 to < 75, and ≥ 75 yrs) in pts who received ≥ 1 dose of study drug. Adverse events (AEs) were coded using MedDRA v. 22.0 and graded by NCI-CTCAE v. 4.0. Results: 469 pts (>99% of all enrolled pts) were evaluable for safety (CC-486 n = 236; PBO n = 233). Median age was 68 yrs (range 55-86). Age distribution was similar between the two Tx arms (Table). Between Tx arms, AE rates within each age stratum were similar to rates in the overall study population. The most common AEs (any grade) with CC-486 were GI events, which were more frequent than in the PBO arm across age groups. Within the CC-486 arm, AE rates were generally consistent across age groups, except for constipation, which was > 20% more frequent in pts aged ≥ 75 yrs, and thrombocytopenia, which was ≥ 20% less frequent in this group (Table). Overall, 13% and 4% of pts in the CC-486 and PBO groups discontinued Tx due to AEs. Conclusions: In QUAZAR AML-001, CC-486 was generally well tolerated in all age groups, including elderly pts aged ≥ 75 yrs. Clinical trial information: NCT01757535.