Efficacy and Tolerability of Lenalidomide (len) in Patients (pts) 75 and Older Versus Those Younger Than 75 with Rbc Transfusion-Dependent Low/Int-1-Risk Mds and Del 5Q

6522 Background: LEN is the approved treatment for pts with RBC transfusion-dependent Low/Int-1-risk MDS and del 5q. In 2 multicenter trials (MDS-003/-004) LEN lead to RBC transfusion independence (TI) for ≥ 26 wks in 35–58% of pts and cytogenetic response (CyR) in 25–73%. Most common grade (G) 3–4 adverse events (AE) were neutropenia and thrombocytopenia, a safety concern in elderly pts. We evaluated efficacy and tolerability of LEN in pts ≥ 75 y vs < 75 y in MDS-003/-004 trials. Methods: Pts received LEN 5 mg × 28 d, 10 mg × 21 d, or 10 mg × 28 d (all 28 d cycles). Dose reductions were required for G4 neutropenia (both trials) and platelet counts < 30 x 109/L (MDS-003) or < 25 x 109/L (MDS-004). Results: 32% of the 286 pts were ≥ 75 y. Baseline (BL) characteristics, LEN treatment, and optional G-CSF use are shown in Table. In pts ≥ 75 y vs < 75 y: RBC-TI ≥ 26 wks was 39 vs 47% (P = NS); CyR was 64 vs 54% (P = NS); 2-y AML progression rates were 10 vs 19% (P = NS); 2-y overall survival rates were 62 vs 73% (P = .001); G3–4 AE: neutropenia (63 vs 76%; P = .024), thrombocytopenia (56 vs 49%; P = NS), infection (36 vs 20%; P = .003); median time to recovery to ANC > 1 x 109/L was 0.7 vs 0.7 mo (P = NS) and to platelet counts > 100 x 109/L was 3.3 vs 1.7 mo (P = NS). 59% pts ≥ 75 y and 49% pts < 75 y discontinued LEN due to AE (33 vs 26%; P = NS), lack of effect (32 vs 49%; P = NS), or death (15 vs 6%; P = NS). Dose reduction and discontinuation rates are shown in Table. Conclusions: Pts ≥ 75 y and < 75 y had comparable response and AML progression rates. In pts ≥ 75 y, LEN appears to be well tolerated but the higher infection rate justifies close follow-up. [Table: see text]