MM-188 Depth of Response of Isatuximab plus Carfilzomib and Dexamethasone in Relapsed Multiple Myeloma: IKEMA Updated Analysis

Abstract

Achieving minimal residual disease negativity (MRD-) in MM is associated with improved survival. Isatuximab (Isa) plus carfilzomib (K) and dexamethasone (d) is approved for relapsed MM patients after ≥1 prior therapy, based on IKEMA interim analysis (NCT03275285). Report updated, longer-term depth of response (DoR) results from IKEMA, including MRD-status. IKEMA, a randomized, open-label, multicenter Phase 3 study, investigates Isa-Kd (n=179) versus Kd (n=123) in relapsed MM patients with 1-3 prior lines of therapy. IV Isa 10 mg/kg was given QW for 4 weeks, followed by Q2W. Both arms received an approved schedule of K (IV) and d (oral/IV). This prespecified analysis evaluated PFS (primary endpoint) at 159 events; secondary endpoints were ≥CR (+stringent CR), MRD-, and ≥CR+MRD-rates, as determined by IRC based on central laboratory data and review of local radiology. MRD status was assessed by NGS (sensitivity threshold ≥10-5) in bone marrow aspirates from patients achieving ≥VGPR. HYDRASHIFT Isa immunofixation (IFE) test, removing Isa interference in IFE, was used to update ≥CR rate. Secondary endpoints were compared between treatment arms using Cochran-Mantel-Haenszel test. One-sided descriptive P-values were provided. All randomized patients not reaching MRD- or without MRD assessment were considered MRD+. At cutoff (14-Jan-2022), with a median follow-up of 44 months, deeper responses were observed in Isa-Kd versus Kd, ≥CR rates 44.1% versus 28.5% (OR: 2.09; 95%CI=1.26-3.48; descriptive P=0.0021). For Isa-Kd versus Kd patients, MRD- (10-5) occurred in 33.5% versus 15.4% (OR: 2.78; 95%CI=1.55-4.99; descriptive P=0.0002), with 26.3% versus 12.2% reaching ≥CR+MRD- (10-5; OR: 2.57; 95%CI=1.35-4.88; P=0.0015); MRD- at 10-6 sensitivity occurred in 10.6% versus 3.3%. MRD- versus MRD+ patients (10-5) had longer mPFS (months); Isa-Kd: not calculable ([NC]; 95%CI=NC-NC) versus 21.7 (95%CI=16.4-27.1); Kd: NC (95%CI=29.2-NC) versus 16.2 (95%CI=13.4-19.5). These results demonstrate clinically meaningful improvement in DoR with Isa-Kd versus Kd. Impressive ≥CR and ≥CR+MRD- (10-5) rates in Isa-Kd versus Kd are the highest reported for proteasome inhibitor-based regimens in relapsed MM. Achieving MRD- led to better outcomes in both arms; Isa-Kd patients had >2-fold higher likelihood of achieving MRD-. Additionally, Isa improved outcomes of MRD+ patients.