Continuous Elotuzumab, Pomalidomide, and Dexamethasone Maintenance Following Second Autologous Transplantation for Multiple Myeloma: Results of a Prospective Phase 2 Multicenter Trial

Second autologous hematopoietic cell transplantation (AHCT2) is a useful therapeutic modality for fit patients with multiple myeloma who have durable remission after upfront AHCT. Retrospective studies have suggested a significant benefit of incorporating maintenance therapy post-AHCT2, but prospective data on specific regimens are lacking. The purpose of this study was to investigate the use of elotuzumab, pomalidomide, and dexamethasone (EPd) as salvage therapy prior to and maintenance after AHCT2 for relapsed multiple myeloma. This prospective single-arm phase II trial investigating the use of EPd in combination with AHCT2 in patients with relapsed multiple myeloma was conducted at 2 academic centers in North America. The primary outcome was 1-year progression-free survival (PFS). Twenty-five patients were enrolled on the study. Sixteen patients received EPd induction; six patients (38%) progressed during salvage therapy and were removed from the trial prior to AHCT2. Following a planned safety analysis, the protocol was amended, and EPd induction was removed from the study schema. An additional 9 patients underwent induction off-study and were enrolled on trial for AHCT2 and EPd maintenance. A total of 18 patients underwent AHCT2 and received EPd maintenance. Two patients discontinued treatment because of toxicity, one attributed to elotuzumab and the other to pomalidomide. The 1-year PFS was 72%, and the median PFS was 19 months. The study was closed early owing to poor accrual; 6 patients remained on therapy at time of analysis. EPd maintenance after AHCT2 was safe and tolerable. The 1-year PFS and median PFS were similar to values in previous retrospective reports of outcomes following AHCT2. Further studies are needed to define the optimal use of and protocol for AHCT2 in fit patients with relapsed multiple myeloma.