A randomized phase II study of elotuzumab with lenalidomide and low-dose dexamethasone in patients with relapsed/refractory multiple myeloma.

8020 Background: Elotuzumab (Elo) is a humanized monoclonal IgG1 antibody targeting CS1, a cell surface glycoprotein. CS1 is highly expressed on >95% of multiple myeloma (MM) cells, with lower expression on natural killer cells and little to no expression on normal tissues. A phase 1 trial of Elo plus lenalidomide and low-dose dexamethasone (Elo/Len/Dex) demonstrated an 82% objective response rate (ORR) in patients (pts) with relapsed/refractory (RR) MM (Lonial et al. J Clin Oncol, in press). Methods: In this phase 2 study, previously treated pts with MM were randomized to Elo 10 or 20 mg/kg IV (days 1, 8, 15, and 22 every 28-days in first 2 cycles and days 1 and 15 of subsequent cycles), Len 25 mg PO (days 1-21) and Dex 40 mg PO weekly. Prophylaxis for infusion-related reactions (IRs) was administered prior to each Elo infusion. Treatment continued until disease progression or unacceptable toxicity. The primary objective was to assess efficacy (ORR ≥partial response [PR]) according to IMWG criteria. Resu...