CAR-T cell therapy targeting B cell maturation antigen is effective for relapsed/refractory multiple myeloma, including cases with poor performance status

Advances in research on factors affecting chimeric antigen receptor T-cell efficacy

Chimeric antigen receptor T-cell (CAR-T) therapy is becoming an effective technique for the treatment of patients with relapsed/refractory hematologic malignancies. After analyzing patients with tumor progression and sustained remission after CAR-T cell therapy, many factors were found to be associated with the efficacy of CAR-T therapy. This paper reviews the factors affecting the effect of CAR-T such as tumor characteristics, tumor microenvironment and immune function of patients, CAR-T cell structure, construction method and in vivo expansion values, lymphodepletion chemotherapy, and previous treatment, and provides a preliminary outlook on the corresponding therapeutic strategies.

An Assessment of the Effectiveness and Safety of Chimeric Antigen Receptor T-Cell Therapy in Multiple Myeloma Patients with Relapsed or Refractory Disease: A Systematic Review and Meta-Analysis

Multiple myeloma (MM), the second most common hematologic malignancy, remains incurable, and its incidence is rising. Chimeric Antigen Receptor T-cell (CAR-T cell) therapy has emerged as a novel treatment, with the potential to improve the survival and quality of life of patients with relapsed/refractory multiple myeloma (rrMM). In this systematic review and meta-analysis, conducted in accordance with PRISMA guidelines, we aim to provide a concise overview of the latest developments in CAR-T therapy, assess their potential implications for clinical practice, and evaluate their efficacy and safety outcomes based on the most up-to-date evidence. A literature search conducted from 1 January 2019 to 12 July 2023 on Medline/PubMed, Scopus, and Web of Science identified 2273 articles, of which 29 fulfilled the specified criteria for inclusion. Our results offer robust evidence supporting CAR-T cell therapy's efficacy in rrMM patients, with an encouraging 83.21% overall response rate (ORR). A generally safe profile was observed, with grade ≥ 3 cytokine release syndrome (CRS) at 7.12% and grade ≥ 3 neurotoxicity at 1.37%. A subgroup analysis revealed a significantly increased ORR in patients with fewer antimyeloma regimens, while grade ≥ 3 CRS was more common in those with a higher proportion of high-risk cytogenetics and prior exposure to BCMA therapy.

Impact of Frailty on Outcomes after Chimeric Antigen Receptor T Cell Therapy for Patients with Relapsed/Refractory Multiple Myeloma

The literature is limited regarding outcomes in older adults and frail patients receiving BCMA-directed chimeric antigen receptor T cell therapy (CAR-T) for relapsed or refractory multiple myeloma. Here we describe the safety and efficacy of CAR-T in these clinically important subgroups treated in a real-world setting. Frailty was defined as a frail score ≥2 using the simplified frailty index (score based on age + Eastern Cooperative Oncology Group [ECOG] Performance Status + Hematopoietic Cell Transplantation Comorbidity Index [HCT-CI]). Of the 136 patients analyzed (age range, 41 to 81 years), 83 (61%) were considered frail at the time of CAR-T infusion. Compared to the nonfrail group, the frail group had higher proportions of patients with renal insufficiency (18% versus 6%), high-risk cytogenetics (45% versus 35%), extramedullary disease (51% versus 43%), and ECOG Performance Status ≥2 (18% versus 2%), and worse HCT-CI (3 versus 1). Although patients in the frail group had a higher incidence of immune effector cell-associated neurotoxicity syndrome (ICANS) (39% versus 17%), the incidences of all- grade cytokine release syndrome (CRS), as well as high-grade CRS and ICANS, were similar in the 2 groups. With a median follow-up of 7 months, the median progression-free survival was 6.9 months in the frail group versus 11.1 months in the nonfrail group (P = .028). The median overall survival was 14 months in the frail group and was not reached in the nonfrail group (P = .025). This study highlights the tolerable safety and reasonable efficacy of CAR-T for frail myeloma patients in a real-world practice. Although the frail patients did not experience any excessive high-grade toxicities, they did have inferior efficacy outcomes.

Enhancing the safety of CAR-T cell therapy: Synthetic genetic switch for spatiotemporal control

Chimeric antigen receptor T (CAR-T) cell therapy is a promising and precise targeted therapy for cancer that has demonstrated notable potential in clinical applications. However, severe adverse effects limit the clinical application of this therapy and are mainly caused by uncontrollable activation of CAR-T cells, including excessive immune response activation due to unregulated CAR-T cell action time, as well as toxicity resulting from improper spatial localization. Therefore, to enhance controllability and safety, a control module for CAR-T cells is proposed. Synthetic biology based on genetic engineering techniques is being used to construct artificial cells or organisms for specific purposes. This approach has been explored in recent years as a means of achieving controllability in CAR-T cell therapy. In this review, we summarize the recent advances in synthetic biology methods used to address the major adverse effects of CAR-T cell therapy in both the temporal and spatial dimensions.

Effectiveness and safety of anti-BCMA chimeric antigen receptor T-cell treatment in relapsed/refractory multiple myeloma: a comprehensive review and meta-analysis of prospective clinical trials

Background: Chimeric antigen receptor T cells treatment targeting B cell maturation antigen (BCMA) is an emerging treatment option for relapsed/refractory multiple myeloma (RRMM) and has demonstrated outstanding outcomes in clinical studies. Objective: The aim of this comprehensive review and meta-analysis was to summarize the effectiveness and safety of anti-BCMA CAR-T treatment for patients with relapsed/refractory multiple myeloma (RRMM). Our research identifies variables influencing outcome measures to provide additional evidence for CAR-T product updates, clinical trial design, and clinical treatment guidance. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standard was followed for conducting this comprehensive review and meta-analysis, which was submitted to PROSPERO (CRD42023390037). From the inception of the study until 10 September 2022, PubMed, Web of Science, EMBASE, the Cochrane Library, CNKI, and WanFang databases were searched for eligible studies. Stata software (version 16.0) was used to assess effectiveness and safety outcomes. Results: Out of 875 papers, we found 21 relevant trials with 761 patients diagnosed as RRMM and were given anti-BCMA CAR-T treatment. The overall response rate (ORR) for the entire sample was 87% (95% CI: 80-93%) complete response rate (CRR) was 44% (95% CI: 34-54%). The minimal residual disease (MRD) negativity rate within responders was 78% (95% CI: 65-89%). The combined incidence of cytokine release syndrome was 82% (95% CI: 72-91%) and neurotoxicity was 10% (95% CI: 5%-17%). The median progression-free survival (PFS) was 8.77 months (95% CI: 7.48-10.06), the median overall survival (OS) was 18.87 months (95% CI: 17.20-20.54) and the median duration of response (DOR) was 10.32 months (95% CI: 9.34-11.31). Conclusion: According to this meta-analysis, RRMM patients who received anti-BCMA CAR-T treatment have demonstrated both effectiveness and safety. Subgroup analysis confirmed the anticipated inter-study heterogeneity and pinpointed potential factors contributing to safety and efficacy, which may help with the development of CAR-T cell studies and lead to optimized BCMA CAR-T-cell products. Systematic Review Registration: Clinicaltrials.gov, PROSPERO, CRD42023390037.

Identification and Targeting of Mutant Neoantigens in Multiple Myeloma Treatment

Multiple myeloma (MM) is malignant disease characterized by the clonal proliferation of plasma cells in the bone marrow, leading to anemia, immunosuppression, and other symptoms, that is generally hard to treat. In MM, the immune system is likely exposed to neoplasia-associated neoantigens for several years before the tumor onset. Different types of neoantigens have been identified. Public or shared neoantigens derive from tumor-specific modifications often reported in several patients or across diverse tumors. They are intriguing therapeutic targets because they are frequently observed, and they have an oncogenic effect. Only a small number of public neoantigens have been recognized. Most of the neoantigens that have been identified are patient-specific or "private", necessitating a personalized approach for adaptive cell treatment. It was demonstrated that the targeting of a single greatly immunogenic neoantigen may be appropriate for tumor control. The purpose of this review was to analyze the neoantigens present in patients with MM, and to evaluate the possibility of using their presence as a prognostic factor or as a therapeutic target. We reviewed the most recent literature on neoantigen treatment strategies and on the use of bispecific, trispecific, and conjugated antibodies for the treatment of MM. Finally, a section was dedicated to the use of CAR-T in relapsed and refractory patients.

Survival in Patients with Relapsed-Refractory Multiple Myeloma: Indirect Comparison of Six New Treatments

In recent years, new treatments have been studied for relapsed-refractory multiple myeloma (RRMM), including two CAR-T products and a variety of non-CAR-T agents. Since direct comparisons between these innovative treatments are not available, indirect comparisons can be of interest. Reconstruction of individual patient data from Kaplan-Meier graphs (e.g., according to the Shiny method) has been the subject of numerous reports that have fully validated their performance. In the present systematic review, we evaluated six treatments proposed for RRMM, including two CAR-T products (ciltacabtagene autoleucel and idecabtagene vicleucel) and four treatments not based on a CAR-T (melflufen plus dexamethasone, isatuximab plus dexamethasone, selinexor, and belantamab). The endpoint was overall survival (OS). Our results showed statistically significant differences in OS across these treatments. In particular, ciltacabtagene autoleucel showed better OS than idecabtagene vicleucel. As regards non-CAR-T treatments, the ranking in OS was headed by isatuximab plus dexamethasone, followed by belantamab, selinexor, and melflufen plus dexamethasone. In conclusion, while the Shiny method has confirmed its validity in reconstructing individual patient data, our indirect comparisons have offered some original clues to interpret the results of OS published in these studies.

Phase 1 study of C-CAR088, a novel humanized anti-BCMA CAR T-cell therapy in relapsed/refractory multiple myeloma

Background

Anti-B-cell maturation antigen (BCMA) chimeric antigen receptor T-cell (CAR T) therapy showed remarkable efficacy in patients with relapsed or refractory multiple myeloma (RRMM). This phase 1 dose-escalation and expansion study developed C-CAR088, a novel second-generation humanized anti-BCMA CAR T-cell therapy, and assessed the safety and efficacy of three dosages of C-CAR088 in patients with RRMM.

Methods

Patients received lymphodepletion with three doses of cyclophosphamide (300 mg/m²) and three doses of fludarabine (30 mg/m²) on days –5, –4, and –3, followed by an infusion of C-CAR088 on day 0. Doses of 1.0×10⁶, 3.0×10⁶, and 6.0×10⁶ CAR T cells/kg (±20%) were tested in the dose-escalation cohorts and expansion cohorts. The primary endpoint was treatment safety, including the rate of treatment-emergent adverse events after cell infusion. Secondary endpoints were the overall response rate and progression-free survival. The exploratory endpoints were the quantification of C-CAR088 CAR T cells, selection of cytokines and chemokines in blood, and measurement of tumor BCMA expression.

Results

As of July 2, 2021, 31 patients had been infused with C-CAR088. Any grade cytokine release syndrome (CRS) occurred in 29 patients (93.5%), and grade 3 CRS occurred in 3 patients (9.7%). One patient from the high-dose group (4.5–6.0×10⁶ CAR T cells/kg) developed grade 1 neurotoxicity. No dose-limiting toxicities were observed in any dose group, and all adverse events were reversible after proper management. The overall response, stringent complete response, complete response (CR), and very good partial response rates were 96.4%, 46.4%, 10.7%, and 32.1%, respectively. The CR rate in the medium-dose (3.0×10⁶ CAR T cells/kg) and high-dose (4.5–6.0×10⁶ CAR T cells/kg) groups was 54.5% and 71.4%, respectively. In the CR group, 15 (93.7%) patients achieved minimal residual disease (MRD) negativity (test sensitivity >1/10⁻⁵). All seven patients with double-hit or triple-hit multiple myeloma achieved MRD-negative CR.

Conclusions

The present study demonstrated that C-CAR088 had a good safety profile and high antitumor activity in patients with RRMM, constituting a promising treatment option for RRMM.

Trial registration number

NCT03815383, NCT03751293, NCT04295018, and NCT04322292.