Siegel, David

Abstract Chimeric antigen receptor (CAR) T-cell therapy enriched for a memory-like phenotype may persist and function longer than a nonenriched product, thereby improving duration of response (DOR). We conducted a phase I study with bb21217 (NCT03274219), an anti–B-cell maturation antigen CAR T-cell therapy manufactured in the presence of the phosphoinositide 3-kinase inhibitor bb007 to enrich for T cells with a memory-like phenotype, in patients with relapsed/refractory multiple myeloma (N = 72). No new safety concerns were raised with bb21217 therapy (three cases each of grade ≥3 cytokine release syndrome and grade ≥3 neurotoxicity were observed). The objective response rate was 69.4% and the median DOR was 23.8 (95% confidence interval, 16.8–34.8) months. Analysis of the drug product established an association between early memory phenotype and robust expansion and depth of response. Examination of baseline characteristics indicated that tumor burden and prior therapies influenced DOR. The data indicate that generation of CAR T cells early in a disease course when tumor burden is lower and source material exhibits a more naïve phenotype may maximize the clinical benefit potential of the drug product.

Abstract Multiple myeloma is a plasma cell malignancy that is still largely incurable, despite considerable progress in recent years. NF-κB is a well-established therapeutic target in multiple myeloma, but none of the currently available treatment options offer direct, specific pharmacologic targeting of NF-κB transcriptional activity. Thus, we designed a novel direct NF-κB inhibitor (IT848) as a drug candidate with strong potential for clinical translation and conducted comprehensive in vitro and in vivo mechanistic studies in multiple myeloma cell lines, primary multiple myeloma cells, xenograft models, and immunocompetent mouse models of multiple myeloma. Here, we show that IT848 inhibits NF-κB activity through inhibition of DNA binding of all five NF-κB subunits. IT848 treatment of multiple myeloma cell lines and patient samples inhibited proliferation and induced caspase-dependent and independent apoptosis. In addition to direct NF-κB inhibitory effects, IT848 treatment altered the redox homeostasis of multiple myeloma cells through depletion of the reduced glutathione pool, selectively inducing oxidative stress in multiple myeloma but not in healthy cells. Multiple myeloma xenograft studies confirmed the efficacy of IT848 as single agent and in combination with bortezomib. Furthermore, IT848 significantly improved survival when combined with programmed death protein 1 inhibition, and correlative immune studies revealed that this clinical benefit was associated with suppression of regulatory T-cell infiltration of the bone marrow microenvironment. In conclusion, IT848 is a potent direct NF-κB inhibitor and inducer of oxidative stress specifically in tumor cells, displaying significant activity against multiple myeloma cells in vitro and in vivo, both as monotherapy as well as in combination with bortezomib or immune checkpoint blockade.

Abstract Frailty is most prevalent among elderly multiple myeloma (MM) patients, and frail patients have a higher risk of poor outcomes due to reduced performance status or comorbidities. This post hoc analysis assessed efficacy and safety of carfilzomib combinations in frail patients with relapsed and/or refractory MM from the phase 3 ASPIRE (carfilzomib [27 mg/m2]-lenalidomide-dexamethasone [KRd27] vs lenalidomide-dexamethasone [Rd]), ENDEAVOR (carfilzomib [56 mg/m2]-dexamethasone [Kd56] vs bortezomib-dexamethasone [Vd]), and ARROW (once-weekly carfilzomib [70 mg/m2]-dexamethasone [Kd70] vs carfilzomib [27 mg/m2]-dexamethasone [Kd27]) studies. A frailty algorithm incorporating age, Charlson comorbidity index, and performance status classified patients as fit, intermediate, or frail. Results are presented for frail patients (ASPIRE, n = 196; ENDEAVOR, n = 330; ARROW, n = 141). In ASPIRE, median progression-free survival (PFS) (hazard ratio; 95% confidence interval) was 24.1 (KRd27) vs 15.9 months (Rd) (0.78; 0.54-1.12); median overall survival (OS) was 36.4 vs 26.2 months (0.79; 0.57-1.08). In ENDEAVOR, median PFS was 18.7 (Kd56) vs 6.6 months (Vd) (0.50; 0.36-0.68); median OS was 33.6 vs 21.8 months (0.75; 0.56-1.00). In ARROW, median PFS was 10.3 (once-weekly Kd70) vs 6.6 months (twice-weekly Kd27) (0.76; 0.49-1.16). In all 3 studies, rates of grade ≥3 treatment-emergent adverse events were consistent with those observed in the primary studies. The ASPIRE, ENDEAVOR, and ARROW primary analyses demonstrated favorable benefit-risk profiles with carfilzomib-containing regimens compared with controls. Across clinically relevant subgroups, including those by frailty status, consistent efficacy and safety were observed with KRd27, Kd56, and weekly Kd70, and treatment with these regimens should not be restricted by frailty status.