Anti-CD3/Anti-SLAMF7 Bispecific Antibody(University of Virginia Foundation)

Background/Aim: Elotuzumab, an anti-SLAMF7 monoclonal antibody, can enhance immune activity via elevated antibody-dependent cellular cytotoxicity and reduced SLAMF7+CD8+CD57+ regulatory T-cells (Tregs). This multicenter observational study investigated the kinetics of lymphocytes in myeloma patients treated with elotuzumab, lenalidomide, and dexamethasone (ERd) by two-color flow cytometry using peripheral blood samples. Patients and Methods: Twenty-one patients were included in this study. The median duration of ERd was 22.6 months, and the cutoff time for long-duration ERd was two years. Results: The CD2+CD16+ and CD16+CD57– NK cells were significantly increased over time in the long-duration ERd group compared to those in the short-duration ERd group (p=0.035 and p<0.001). The CD8+ and CD16–CD57+ lymphocytes, identified as low-activity NK cells or SLAMF7+ Tregs, were significantly increased in the patients whose ERd outcome was progressive disease (PD) compared to those in the non-PD group (p=0.023 and p<0.001). The mean CD4/CD8 ratio and CD19+ lymphocyte counts in the long-duration ERd group were significantly lower than those in the short-duration ERd group, although the kinetics of them did not change over time (p=0.016 and p=0.011). When the cutoff value of CD4/CD8 ratio was 0.792 according to ROC curves, the two-year time to next treatment (TTNT) in the low CD4/CD8 group was significantly longer than that in the high CD4/CD8 group (80.0% vs. 15.0%, p=0.024). Conclusion: The change in NK cells and CD8+ Tregs predicted long-duration ERd and PD, and maintaining low CD4/8 ratio predicted long TTNT, suggesting that these lymphocyte fractions might be biomarkers for a durable therapeutic effect of ERd in myeloma patients.

The aim of this trial was to investigate the addition of the anti-SLAMF7 monoclonal antibody elotuzumab to lenalidomide, bortezomib, and dexamethasone (RVd) in induction and consolidation therapy as well as to lenalidomide maintenance treatment in transplant-eligible patients with newly diagnosed multiple myeloma.

GMMG-HD6 was a phase 3, randomised trial conducted at 43 main trial sites and 26 associated trial sites throughout Germany. Adult patients (aged 18-70 years) with previously untreated, symptomatic multiple myeloma, and a WHO performance status of 0-3, with 3 being allowed only if caused by myeloma disease and not by comorbid conditions, were randomly assigned 1:1:1:1 to four treatment groups. Induction therapy consisted of four 21-day cycles of RVd (lenalidomide 25 mg orally on days 1-14; bortezomib 1·3 mg/m² subcutaneously on days 1, 4, 8, and 11]; and dexamethasone 20 mg orally on days 1, 2, 4, 5, 8, 9, 11, 12, and 15 for cycles 1-2) or, RVd induction plus elotuzumab (10 mg/kg intravenously on days 1, 8, and 15 for cycles 1-2, and on days 1 and 11 for cycles 3-4; E-RVd). Autologous haematopoietic stem-cell transplantation was followed by two 21-day cycles of either RVd consolidation (lenalidomide 25 mg orally on days 1-14; bortezomib 1·3 mg/m² subcutaneously on days 1, 8, and 15; and dexamethasone 20 mg orally on days 1, 2, 8, 9, 15, and 16) or elotuzumab plus RVd consolidation (with elotuzumab 10 mg/kg intravenously on days 1, 8, and 15) followed by maintenance with either lenalidomide (10 mg orally on days 1-28 for cycles 1-3; thereafter, up to 15 mg orally on days 1-28; RVd/R or E-RVd/R group) or lenalidomide plus elotuzumab (10 mg/kg intravenously on days 1 and 15 for cycles 1-6, and on day 1 for cycles 7-26; RVd/E-R or E-RVd/E-R group) for 2 years. The primary endpoint was progression-free survival analysed in a modified intention-to-treat (ITT) population. Safety was analysed in all patients who received at least one dose of trial medication. This trial is registered with ClinicalTrials.gov, NCT02495922, and is completed.

Between June 29, 2015, and on Sept 11, 2017, 564 patients were included in the trial. The modified ITT population comprised 559 (243 [43%] females and 316 [57%] males) patients and the safety population 555 patients. After a median follow-up of 49·8 months (IQR 43·7-55·5), there was no difference in progression-free survival between the four treatment groups (adjusted log-rank p value, p=0·86), and 3-year progression-free survival rates were 69% (95% CI 61-77), 69% (61-76), 66% (58-74), and 67% (59-75) for patients treated with RVd/R, RVd/E-R, E-RVd/R, and E-RVd/E-R, respectively. Infections (grade 3 or worse) were the most frequently observed adverse event in all treatment groups (28 [20%] of 137 for RVd/R; 32 [23%] of 138 for RVd/E-R; 35 [25%] of 138 for E-RVd/R; and 48 [34%] of 142 for E-RVd/E-R). Serious adverse events (grade 3 or worse) were observed in 68 (48%) of 142 participants in the E-RVd/E-R group, 53 (39%) of 137 in the RVd/R, 53 (38%) of 138 in the RVd/E-R, and 50 (36%) of 138 in the E-RVd/R (36%) group. There were nine treatment-related deaths during the study. Two deaths (one sepsis and one toxic colitis) in the RVd/R group were considered lenalidomide-related. One death in the RVd/E-R group due to meningoencephalitis was considered lenalidomide and elotuzumab-related. Four deaths (one pulmonary embolism, one septic shock, one atypical pneumonia, and one cardiovascular failure) in the E-RVd/R group and two deaths (one sepsis and one pneumonia and pulmonary fibrosis) in the E-RVd/E-R group were considered related to lenalidomide or elotuzumab, or both.

Addition of elotuzumab to RVd induction or consolidation and lenalidomide maintenance in patients with transplant-eligible newly diagnosed multiple myeloma did not provide clinical benefit. Elotuzumab-containing therapies might be reserved for patients with relapsed or refractory multiple myeloma.

Bristol Myers Squibb/Celgene and Chugai.