Bone Marrow Immunological Changes During Treatment with Lenalidomide In Low and Intermediate-1 Risk Myelodysplastic Syndromes with Del(5Q)

Immunological changes have a primary role in the initiation and progression of myelodysplastic syndromes (MDS). Cytokine levels, such as IL-7 and IFN-gamma, are associated with lower-risk disease. Treatment with lenalidomide has proven efficacy in red blood cell (RBC) transfusion-dependent lower-risk MDS patients with del(5q). Lenalidomide exerts anti-angiogenic, anti-proliferative, and pro-erythropoietic effects; in particular, it has been shown that lenalidomide inhibits the proliferation and function of T regulatory cells (Tregs). Finally, MDS patients undergoing lenalidomide treatment experience erythroid responses and suppression of the del(5q) clone.

In a multicenter Italian phase II trial to evaluate safety and efficacy of lenalidomide in primary MDS patients with del(5q) and Low- or Int-1 risk IPSS, we investigated changes in the transcription of cytokines and their receptors during treatment.

The starting dose of lenalidomide was 10 mg p.o once daily on a continuous daily schedule for a maximum of 12 months. Bone marrow (BM) aspirates were obtained on study entry and every 12 weeks. Assays were performed using TaqMan® Low Density Array Fluidic card (TaqMan® Human Array, Applied Biosystems, Foster City, CA, USA) based on Applied Biosystems PRISM® 7900HT comparative ddCT method, according to the manufacturer's instructions. Target gene expression levels were measured in triplicate and normalized against the expression of the 18S housekeeping gene from a BM pool of normal, healthy subjects at all timepoints. Median relative gene expression values in MDS patients were compared to healthy subjects, set as a value of 1.

We report data obtained at baseline and after 12 weeks. Informed consent was obtained in all patients. Twenty-seven patients (5 M, 22 F) were evaluated at baseline and after 12 weeks. Mean age was 72 ± 9 years. Mean Hb level was 8.5 ± 0.9 g/dL and 16 patients were RBC transfusion -dependent (requiring at least 4 RBC transfusions in the preceding 2 months). Seven patients had additional cytogenetic abnormalities. Twenty-one patients (80%) experienced erythroid responses by week 12. Significant variations in gene expression of cytokines and receptors were observed during treatment. Genes significantly regulated during lenalidomide treatment (P < 0.05) are shown in the Table. In particular, FAS, IL-7 and FOXP3 gene were generally under-expressed at baseline and significantly increased after 12 weeks. Accordingly, IL7R was over-expressed in all patients at baseline and its expression was significantly reduced during treatment. Furthermore, IFN-gamma expression increased during therapy.

The protein encoded by FAS gene is a member of the TNF-receptor superfamily and its interaction with its ligand leads to apoptosis. Interleukin (IL)-7 is an essential cytokine that promotes the proliferation and survival of B- and T-lymphocyte progenitors. The IL7R gene on chromosome 5 (5p13) codifies for the IL7 receptor, which blocks apoptosis during differentiation and activation of T lymphocytes. It functions, in part, through the induction of the expression of the antiapoptotic protein Bcl-2. The protein encoded by the FOXP3 gene is a member of transcriptional regulators. Defects in this gene are the cause of X-linked autoimmunity-immunodeficiency syndrome. The results of the present study indicate that lenalidomide may act through immunological changes. Further detailed analyses in these patients may provide new insights into the pathogenesis of MDS with del(5q) and the long-term effects of lenalidomide treatment on immunological changes in BM cells.

Oliva:Celgene: Consultancy.