Elotuzumab in combination with lenalidomide and low-dose dexamethasone in relapsed or refractory multiple myeloma: A phase I/II study.

8020 Background: Elotuzumab is a humanized antibody against CS1, a cell surface glycoprotein, which is highly expressed in multiple myeloma (MM). In mouse xenograft MM model, elotuzumab demonstrated significantly enhanced anti-tumor activity when combined with lenalidomide (len) compared to len alone. The study objectives were to evaluate the MTD, safety, PK and efficacy of elotuzumab in combination with len and low dose dexamethasone (dex). Methods: Len (25 mg PO) was given on Days 1-21 of a 28-day cycle. Elotuzumab (IV infusion) in 3 escalating dose cohorts (5, 10 and 20 mg/kg) was given weekly for the first two cycles and then every other week of subsequent cycles. Dex was given weekly at 40 mg PO. First 5 patients were treated for 6 months before a protocol amendment to continue treatment until progression. Results: A total of 29 patients (pts) with a median age of 60 years were enrolled; 28 pts received study drug. Pts had a median of 3 prior MM treatments including thalidomide (59%), bortezomib (69%...