Elotuzumab in Combination With Carfilzomib, Lenalidomide and Dexamethasone (E-KRd) Versus KRd in MM

Multiple myeloma (MM) is a cancer originating from the antibody-secreting plasma cell and characterized by abnormal accumulation of clonal plasma cells in bone marrow. In Europe, 3.8 new cases of MM and 2.2 deaths per 100,000 individuals (age-standardized rate) due to MM were estimated in 2012.

Treatment options for myeloma patients have markedly improved during the last decades.

For frontline treatment, high-dose myeloablative chemotherapy followed by reinfusion of autologous peripheral blood stem cells has been a standard of care since 1996. Introduction of the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide led to improvement in remission rates and survival in newly diagnosed patients. However, high-dose chemotherapy remains essential for achievement of long-lasting remissions even in the era of novel agents.

While high-dose melphalan chemotherapy (HDT) plus autologous stem cell transplant (ASCT) remains a standard in eligible, medically fit subjects, defining an optimal pre- and post HDT approach is subject to rapidly evolving novel-compound based options. In 2010, a group from the U.S. presented results on the combination of lenalidomide, bortezomib, and dexamethasone (VRd) in newly diagnosed patients with an overall response rate of 98%, however without systematic consolidation by HDT. The next-generation proteasome inhibitor carfilzomib is more active and very well tolerated in terms of peripheral neuropathy and gastrointestinal adverse effects. A randomized phase III trial in pretreated myeloma patients found the triple regimen of carfilzomib and lenalidomide/dexamethasone (Rd) to be superior to standard-Rd in terms of depth of response; progression-free survival (PFS) and, most importantly, overall survival (OS). At the 2015 annual meetings of the American Society of Clinical Oncology as well as the European Society of Hematology, this regimen (KRd) was found to be exceptionally effective in a phase 2 trial when given in newly diagnosed patients in a prolonged fashion: patients received four KRd induction cycles prior to HDT. The latter was followed by an additional 4 consolidation and 8 maintenance cycles with KRd, followed by lenalidomide maintenance thereafter. The most appealing effect was the high rate of deep remissions: stringent complete response (sCR) rate increased from 22% following 4 x KRd and HDT to more than 80% following all 18 cycles. Notably, the vast majority of patients in sCR also were negative for minimal residual disease (MRD) as assessed by 10-color flow cytometry. MRD negativity probably has a major impact on long-term disease control as was recently shown in a French prospective trial investigating in the combination of VRd prior and post HDT followed by lenalidomide maintenance.

Of the next-generation compounds, the monoclonal antibodies (moAbs) have recently attracted a lot of interest in MM. The anti-SLAMF7 directed moAb elotuzumab has completed phase III trials in MM patients. One phase III trial in MM patients with one to three prior lines of therapy compared elotuzumab-Rd with standard Rd. The triple combination was shown to significantly prolong PFS in this patient cohort with a greater proportion of patients in at least very good partial response (VGPR) when compared to subjects on Rd. Notably, the rate of infusion-related reactions with this specific moAb was very low, with an overall rate of 10% in premedicated patients and only 1% of Grade 3 severity. Grades 4/5 infusion-related reactions were absent and only 1% of patients on elotuzumab discontinued for infusion-related reactions. Of particular interest is the observation in this trial, that response and PFS were independent of cytogenetic high-risk features, i.e., deletion of chromosome 17p and translocation t(4;14). This effect distinguishes elotuzumab from most, if not all, other drug-based approaches.

The investigators assume that incorporating the moAb into the KRd triple induction regimen should result in an even higher rate of deep (negative for MRD in conjunction with at least very good partial response [VGPR] as defined by the International Myeloma Working Group [IMWG]) with these responses occurring independently of cytogenetic risk. Due to potential interference of elotuzumab with serum immune fixation,the investigators chose VGPR rather than complete response (CR) to exclude false-positive immunofixation results. Furthermore the investigators hypothesize that combining elotuzumab with lenalidomide should prolong PFS further.