Azacitidine Treatment of Lenalidomide-Resistant Myelodysplastic Syndrome with Deletion 5q

Lenalidomide is a highly effective treatment for lower risk transfusion dependent myelodysplastic syndrome (MDS) patients with deletion 5q [del(5q)]. Approximately two thirds of patients become transfusion independent for a median duration of 2 years or longer (List et al, NEJM). Effective treatment alternatives after lenalidomide treatment failure are limited. We examined the response to treatment with azacitidine in del(5q) MDS patients after lenalidomide treatment failure.

MDS patients with del(5q) who were treated with azacitidine after lenalidomide failure were identified through the Moffitt Cancer Center (MCC) MDS database and individual charts reviewed. Data collected included demographics, disease baseline characteristics, duration of response to lenalidomide, responses to azacitidine by international working group (IWG) 2006 criteria, transformation to acute myeloid leukemia (AML), and overall survival (OS). Descriptive statistics were used for analysis and Kaplan Meier estimates were used for OS and AML transformation. All analysis was conducted using SPSS version 19.0 statistical software.

Between July 2005 and June 2011, 18 del(5q) MDS patients treated with azacitidine were identified. The median age was 66 years (50–83), all patients were Caucasian, and male predominance (67%; 12 patients). ECOG performance status was 0–1 in 94% of the patients. The median duration of follow up from date of azacitidine initiation was 645 days. According to the WHO classification, 7 patients (38.9%) had MDS with isolated del(5q), 7 patients (38.9%) refractory cytopenia with multilineage dysplasia (RCMD), 2 patients (11.1%) refractory anemia with excess blasts 1 (RAEB-1), and 2 patients (11.1%) refractory anemia (RA).The international prognostic scoring system (IPSS) risk category was low in 2 (11.2%), intermediate 1 (int-1) in 14 (77.8%), and int-2 in 2 (11.2%) patients. Based on karyotype, 7 patients (38.9%) had isolated del(5 q), 9 (50%) del 5q +1 abnormality, and 2 (11.2%) with del 5q +2 or more cytogenetic abnormality. All patients were transfusion dependent.

The median number of lenalidomide cycles prior to azacitidine was 12 (1–38), with median duration of response 319 days (17–1169). The median number of azacitidine cycles administered was 6 (2–23). The median duration of treatment was 183 days (43–592). The best response to azacitidine by IWG 2006 criteria was one (7.1%) complete response (CR), 2 (5.6%) marrow CR (mCR), 7 (38.9%) hematological improvement (HI), 4 (22.2%) had stable disease, and 4 (22.2%) had progressive disease (PD). The overall response rate was 56%.The HI cell lineage responses were 9 out of 18 (50%) erythroid, 3 out of 13 (23%) HI-P (Platelets), and 2 out 9 (22.2%) HI-N (neutrophils). The median OS was 749 days (95%CI 435–1063) from the time of starting azacitidine. The rate of AML transformation was 27.8% (n=5); median time to AML transformation from azacitidine start was 864 days (95%CI 360–1368).

To our knowledge this is the first report demonstrating the activity of azacitidine in patients with del(5q) MDS after lenalidomide treatment failure. Response rates are similar to those reported in non-del(5q) patients providing azacitidine as an effective option for salvage treatment. Larger cohort of patients is needed to confirm these findings.

Komrokji:Celgene: Honoraria, Research Funding, Speakers Bureau. Lancet:Celgene: Research Funding. List:Celgene: Consultancy.