A Phase 2 Study to Assess the Feasibility and Tolerance of the Combination of Elotuzumab, Lenalidomide, and Dexamethasone (ERd) in the Induction, Consolidation, and Maintenance Treatment of Transplant-Eligible Patients Newly Diagnosed with Multiple Myeloma (MM)

Background:

The introduction of novel agents such as proteasome inhibitors (PI) and immunomodulatory drugs (IMiDs) with and without corticosteroids has revolutionized treatment (tx) and improved survival rates for MM. IMID/PI triplets such as VRD (bortezomib, lenalidomide, dexamethasone), VTD (bortezomib, thalidomide, dexamethasone), or KRD (carfilzomib, lenalidomide, dexamethasone) are preferred inductions for transplant-eligible patients (pts). Unfortunately, the PI often has unique safety events such as peripheral neuropathy (PN) or cardiac issues that can impact the quality of life. Elotuzumab is a mAb with a dual mechanism of action (tagging MM cells and activating NK cells by binding SLAMF7). The combination of elotuzumab, lenalidomide, and dexamethasone (ERd), is active, well-tolerated, and approved by the FDA for pts with relapsed MM. In this study, we will determine the feasibility of incorporating ERd into a transplant-eligible pt population.

Methods: Pts with newly diagnosed MM requiring chemotherapy planning to undergo autologous stem cell transplantation (ASCT) were enrolled. Induction of elotuzumab at 10 mg/kg was administered IV on days (D) 1, 8, 15, 22 of the 1^st 2 28-day cycles and days 1, 15 of the third and fourth 28-day cycles. Lenalidomide was dosed at 25 mg orally on D 1-21 of each 28 day induction cycle. Dexamethasone was administered IV concurrent with elotuzumab (28mg orally 3-24 hours prior to infusion and 8 mg IV with elotuzumab), with 40 mg orally administered on D 8 and 22 of cycles 3 and 4. After completion of the 4 induction cycles, pts proceeded to mobilization and ASCT though pts who refused transplantation were allowed to proceed directly to consolidation and maintenance if the investigator believed the pt was deriving benefit. 70-120 days after ASCT, 4 cycles of consolidation were administered (dosing similar to cycles 3-4 of induction but with lenalidomide at 15mg). Pts then went on to maintenance with elotuzumab 20 mg/kg IV on D 1, oral lenalidomide 10mg +/- 5 mg D 1-21 and dexamethasone 28mg oral/8 mg IV prior to elotuzumab infusion were dosed in 28-day cycles for up to 24 months.

The primary endpoint was the induction feasibility rate (IFR) defined as the percentage of pts successfully completing 4 cycles of induction tx with ERd and able to start ASCT. Secondary end points were complete response rate (≥nCR), overall response rate (≥PR), progression-free survival (PFS) and overall survival (OS). AEs were assessed according to CTCAE V4 and responses were assessed using the revised IMWG criteria.

Results: 52 pts were enrolled: 56% male, median age 61 ys, 12% RISS III, 21% high-risk cytogenetics [17p del, t(4;14), and/or t(14;16)]. To date, 26 (50%) pts remain on active tx. 4 pts refused transplantation despite being eligible and were excluded from the IFR calculation. The IFR was 69% and the best overall response rate (ORR) was 92% (69% ≥ VGPR). With a median follow up of 20 mos, median PFS and OS for all pts were not reached. The 18 mo PFS and OS were 83% and 89% respectively.

The most common AEs were fatigue (59.6%), diarrhea (42.3%) and nausea (42.3%). PN was seen in 29%, and all events were ≤ G2. There were 28 SAEs in 20 pts, including 12 tx-related SAEs. There was 1 tx-related death due to heart failure in a pt with no history of prior cardiac issues who had subsequent therapy.

29% of pts met the high-risk (HR) criteria (defined as RISS III or high risk cytogenetics) and 29% of pts were considered standard-risk (RISS I and no high-risk cytogenetics). The best ORR was 87% (67% ≥ VGPR) for HR pts and 93% (53% ≥ VGPR) for SR pts and the IFR was 57% for HR pts and 64% for SR pts. The median PFS and OS were 20.5 mos and 22.0 mos respectively for HR pts and have not been reached for SR pts.

Conclusions: ERd induction, consolidation and maintenance was feasible and well tolerated in conjunction with ASCT in transplant-eligible pts. Despite high ORR for all pts, HR patients had inferior PFS and OS. This study supports the continued evaluation of this regimen in SR pts.