Chanan‐Khan, Asher

PURPOSE At the primary analysis of CASTOR (median follow-up, 7.4 months), daratumumab plus bortezomib and dexamethasone (D-Vd) significantly prolonged progression-free survival versus bortezomib and dexamethasone (Vd) alone in relapsed or refractory multiple myeloma (RRMM). We report updated efficacy and safety results at the final analysis for overall survival (OS). METHODS CASTOR was a multicenter, randomized, open-label, phase III study during which eligible patients with ≥ 1 line of prior therapy were randomly assigned to Vd (up to eight cycles) with or without daratumumab (until disease progression). After positive primary analysis and protocol amendment, patients receiving Vd were offered daratumumab monotherapy after disease progression. RESULTS At a median (range) follow-up of 72.6 months (0.0-79.8), significant OS benefit was observed with D-Vd (hazard ratio, 0.74; 95% CI, 0.59 to 0.92; P = .0075). Median OS was 49.6 months with D-Vd versus 38.5 months with Vd. Prespecified subgroup analyses demonstrated an OS advantage with D-Vd versus Vd for most subgroups, including patients age ≥ 65 years and patients with one or two prior lines of therapy, International Staging System stage III disease, high-risk cytogenetic abnormalities, and prior bortezomib treatment. The most common (≥ 10%) grade 3/4 treatment-emergent adverse events with D-Vd versus Vd were thrombocytopenia (46.1% v 32.9%), anemia (16.0% v 16.0%), neutropenia (13.6% v 4.6%), lymphopenia (10.3% v 2.5%), and pneumonia (10.7% v 10.1%). CONCLUSION D-Vd significantly prolonged OS in patients with RRMM, with the greatest OS benefit observed in patients with one prior line of therapy. To our knowledge, our results, together with the OS benefit observed with daratumumab plus lenalidomide and dexamethasone in the phase III POLLUX study, demonstrate for the first time an OS benefit with daratumumab-containing regimens in RRMM (ClinicalTrials.gov identifier: NCT02136134 [CASTOR]).

AbstractPatients with multiple myeloma (MM) have a lower efficacy from COVID‐19 vaccination and a high rate of mortality from COVID‐19 in hospitalized patients. However, the overall rate and severity of COVID‐19 infection in all settings (including non‐hospitalized patients) and the independent impact of plasma cell‐directed therapies on outcomes needs further study. We reviewed the medical records of 9225 patients with MM or AL amyloidosis (AL) seen at Mayo Clinic Rochester, Arizona, and Florida between 12/01/2019 and 8/31/2021 and identified 187 patients with a COVID‐19 infection (n = 174 MM, n = 13 AL). The infection rate in our cohort was relatively low at 2% but one‐fourth of the COVID‐19 infections were severe. Nineteen (10%) patients required intensive care unit (ICU) admission and 5 (3%) patients required mechanical ventilation. The mortality rate among hospitalized patients with COVID‐19 was 22% (16/72 patients). Among patients that were fully vaccinated at the time of infection (n = 12), two (17%) developed severe COVID‐19 infection, without any COVID‐related death. On multivariable analysis, treatment with CD38 antibody within 6 months of COVID‐19 infection [Risk ratio (RR) 3.6 (95% CI: 1.2, 10.5), p = .02], cardiac [RR 4.1 (95% CI: 1.3, 12.4), p = .014] or pulmonary comorbidities [RR 3.6 (95% CI 1.1, 11.6); p = .029] were independent predictors for ICU admission. Cardiac comorbidity [RR 2.6 (95% CI: 1.1, 6.5), p = .038] was an independent predictor of mortality whereas MM/AL in remission was associated with lower mortality [RR 0.4 (95% CI: 0.2–0.8); p = .008].

Two Letters to Blood address the risks of COVID-19 in populations with precursors of hematological disease. In the first article, Miller and colleagues report on whether clonal hematopoiesis of intermediate potential (CHIP) is associated with adverse outcomes with COVID-19, finding no association between CHIP and 28-day mortality while providing data indirectly linking IL-6 signaling and patient outcomes. In the second article, Ho and colleagues investigate the outcomes of patients with monoclonal gammopathy of undetermined significance (MGUS) with COVID-19, reporting that one-fourth had a severe infection and that on multivariable analysis, adverse outcomes are more likely if immunoparesis is present.

Abstract Purpose: Development of B-cell lymphoma 2 (BCL-2)–specific inhibitors poses unique challenges in drug design because of BCL-2 homology domain 3 (BH3) shared homology between BCL-2 family members and the shallow surface of their protein–protein interactions. We report herein discovery and extensive preclinical investigation of lisaftoclax (APG-2575). Experimental Design: Computational modeling was used to design “lead” compounds. Biochemical binding, mitochondrial BH3 profiling, and cell-based viability or apoptosis assays were used to determine the selectivity and potency of BCL-2 inhibitor lisaftoclax. The antitumor effects of lisaftoclax were also evaluated in several xenograft models. Results: Lisaftoclax selectively binds BCL-2 (Ki < 0.1 nmol/L), disrupts BCL-2:BIM complexes, and compromises mitochondrial outer membrane potential, culminating in BAX/BAK-dependent, caspase-mediated apoptosis. Lisaftoclax exerted strong antitumor activity in hematologic cancer cell lines and tumor cells from patients with chronic lymphocytic leukemia, multiple myeloma, or Waldenström macroglobulinemia. After lisaftoclax treatment, prodeath proteins BCL-2‒like protein 11 (BIM) and Noxa increased, and BIM translocated from cytosol to mitochondria. Consistent with these apoptotic activities, lisaftoclax entered malignant cells rapidly, reached plateau in 2 hours, and significantly downregulated mitochondrial respiratory function and ATP production. Furthermore, lisaftoclax inhibited tumor growth in xenograft models, correlating with caspase activation, poly (ADP-ribose) polymerase 1 cleavage, and pharmacokinetics of the compound. Lisaftoclax combined with rituximab or bendamustine/rituximab enhanced antitumor activity in vivo. Conclusions: These findings demonstrate that lisaftoclax is a novel, orally bioavailable BH3 mimetic BCL-2–selective inhibitor with considerable potential for the treatment of certain hematologic malignancies.

Abstract Over the past decade, significant improvements in survival outcomes have been experienced by multiple myeloma (MM) patients. However, MM remains an incurable disease and patients with triple-class refractory MM have limited treatment options and a dismal prognosis. Chimeric antigen receptor (CAR) T-cell therapy targeting B-cell maturation antigen (BCMA) has transformed the treatment algorithm of relapsed/refractory MM (RRMM), with high overall response rates. Nevertheless, a significant proportion of patients ultimately relapse despite achieving deep remission and show poor outcomes with subsequent treatment post anti-BCMA immunotherapies.1 Iopofosine I-131 (iopofosine) is a first-in-class phospholipid ether radio-conjugate that targets lipid raft microdomains on tumor cells and is internalized. Here we present seven cases of triple class refractory MM patients that relapsed or were refractory to anti-BCMA immunotherapy and treated with iopofosine plus low dose dexamethasone (LoDEX). Patient received a single fractionated cycle of 30mCi/m2 of iopofosine (15 mg/m2 dosed day 1 and day 15) and received LoDEX (40 mg/week for 12 weeks) with an optional second cycle of iopofosine approximately 60 days later. Six of the seven patients achieved the minimum required total administered dose of 60 millicuries (mCi) to be in the evaluable population and 50% achieved a partial response (PR) or better.