IKAROS expression in distinct bone marrow cell populations as a candidate biomarker for outcome with lenalidomide-dexamethasone therapy in multiple myeloma.

Immunomodulatory drugs (IMiDs) are a cornerstone in the treatment of multiple myeloma (MM), but specific markers to predict outcome are still missing. Recent work pointed to a prognostic role for IMiD target genes (e.g. CRBN). Moreover, indirect activity of IMiDs on immune cells correlated with outcome, raising the possibility that cell populations in the bone marrow (BM) microenvironment could serve as biomarkers. We therefore analysed gene expression levels of six IMiD target genes in whole BM samples of 44 myeloma patients treated with lenalidomide-dexamethasone. Expression of CRBN (R = 0.30, P = .05), IKZF1 (R = 0.31, P = .04), IRF4 (R = 0.38, P = .01), MCT-1 (R = 0.30, P = .05), and CD147 (R = 0.38, P = .01), but not IKZF3 (R = -0.15, P = .34), was significantly associated with response. Interestingly, IKZF1 expression was elevated in BM environmental cells and thus selected for further investigation by multicolor flow cytometry. High IKAROS protein levels in total BM mononuclear cells (median OS 83.4 vs. 32.2 months, P = .02), CD19+ B cells (median OS 71.1 vs. 32.2 months, P = .05), CD3+ CD8+ T cells (median OS 83.4 vs 19.0 months, P = .008) as well as monocytes (median OS 53.9 vs 18.0 months, P = .009) were associated with superior overall survival (OS). In contrast, IKAROS protein expression in MM cells was not predictive for OS. Our data therefore corroborate the central role of immune cells for the clinical activity of IMiDs and built the groundwork for prospective analysis of IKAROS protein levels in distinct cell populations as a potential biomarker for IMiD based therapies.

Lenalidomide and dexamethasone for acute light chain-induced renal failure: a phase II study.

We prospectively evaluated the activity and tolerance of lenalidomide-dexamethasone in 35 patients with acute light chain-induced renal failure. The lenalidomide dose was adapted to the estimated glomerular filtration rate and dexamethasone was given at high dose in cycle one and at low dose thereafter. Four patients died within the first two cycles, and five discontinued therapy leaving 26 patients for the per-protocol analysis. Responses were observed in 24/35 (68.6%) patients of the intent-to-treat population. Complete response was noted in seven patients (20%), very good partial response in three patients (8.6%), partial response in 14 patients (40%), and minimal response in one patient (2.9%). Renal response was observed in 16 (45.7%) patients: five (14.2%) achieved complete, four (11.4%) partial and seven (20%) minor renal responses. Five of 13 patients who were dialysis dependent at baseline became dialysis independent. The median time to myeloma and to renal response was 28 days for both parameters, while the median time to best myeloma and best renal response was 92 and 157 days, respectively. The median estimated glomerular filtration rate increased significantly in patients with partial response or better from 17.1 mL/min at baseline to 39.1 mL/min at best response (P=0.001). The median progression-free and overall survival was 5.5 and 21.8 months, respectively, in the intent-to-treat population and 12.1 and 31.4 months, respectively, in the per-protocol group. Infections, cardiotoxicity, anemia and thrombocytopenia were the most frequent toxicities. In conclusion, the lenalidomide-dexamethasone regimen achieved rapid and substantial myeloma and renal responses. The trial was registered under EUDRACT number 2008-006497-15.