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B-cell activating factor belonging to the TNF family (BAFF), also known as B-lymphocyte stimulator (BLyS), plays a crucial role in B-cell development. It has multiple receptors, including BCMA, TACI, and BAFF-R, with diverse roles in different cell types. BAFF induces B-cell proliferation and immunoglobulin secretion, and acts as a survival factor for immature, naive, and activated B cells. Consequently, BAFF-deficient mice often show suppressed humoral responses, while BAFF-overexpressing mice show the higher number of mature B cells and may develop autoimmune-like manifestations and B-cell lymphoproliferative diseases. Elevated BAFF levels are also associated with various hematological malignancies, and its expression correlates with disease progression in some cases. Therefore, BAFF-targeted therapies, such as belimumab, atacicept, and tabalumab, are being explored in clinical trials for conditions like chronic lymphocytic leukemia (CLL) and multiple myeloma. Belimumab, an anti-BAFF monoclonal antibody, is being investigated in combination with rituximab/venetoclax for CLL. Atacicept, a decoy receptor for BAFF and APRIL, showed tolerability in a phase 1b trial for CLL. Tabalumab, another monoclonal antibody targeting BAFF, did not demonstrate significant efficacy in a phase 2 study for relapsed/refractory multiple myeloma. BAFF ligand-based CAR-T cells are designed to target BAFF receptors and show promise in preclinical studies, particularly for B-cell malignancies. The review emphasizes the importance of understanding the roles of BAFF and its receptors in the microenvironment of hematologic malignancies. Targeting BAFF and its receptors presents potential therapeutic avenues, and ongoing clinical trials provide valuable insights., (© 2024. The Author(s).)

The BAFF-APRIL system is crucial for the pathogenesis of systemic lupus erythematosus (SLE) by promoting B cell survival, differentiation and the maintenance of humoral autoimmunity. Here, we investigated the relationship of BCMA expression on B cell subsets with its ligands BAFF and APRIL, together with soluble BCMA, and with clinical and serologic variables in a cohort of 100 SLE patients (86 under conventional and 14 under belimumab therapy) and 30 healthy controls (HCs) using multicolor flow cytometry and ELISA. We found that BCMA expression in SLE patients was significantly increased on all B cell subsets compared to HCs, with all examined components of the BAFF-APRIL system being upregulated. BCMA expression was significantly increased on switched and unswitched memory B cells compared to naïve B cells, both in HCs and SLE. BCMA expression on B cells correlated with plasmablast frequencies, serum anti-dsDNA antibodies and complement consumption, while soluble BCMA correlated with plasmablast frequency, highlighting its potential as a clinical biomarker. Belimumab treatment significantly reduced BCMA expression on most B cell subsets and soluble TACI and contributed to the inhibition of almost the entire BAFF-APRIL system and restoration of B cell homeostasis. These results provide insights into the complex dysregulation of the BAFF-APRIL system in SLE and highlight the therapeutic potential of targeting its components, particularly BCMA, in addition to its use as a biomarker for disease activity.

Despite recent advances in immunotherapies targeting single tumor-associated antigens, patients with multiple myeloma eventually relapse. ISB 2001 is a CD3 + T cell engager (TCE) co-targeting BCMA and CD38 designed to improve cytotoxicity against multiple myeloma. Targeting of two tumor-associated antigens by a single TCE resulted in superior cytotoxic potency across a variable range of BCMA and CD38 tumor expression profiles mimicking natural tumor heterogeneity, improved resistance to competing soluble factors and exhibited superior cytotoxic potency on patient-derived samples and in mouse models. Despite the broad expression of CD38 across human tissues, ISB 2001 demonstrated a reduced T cell activation profile in the absence of tumor cells when compared to TCEs targeting CD38 only. To determine an optimal first-in-human dose for the ongoing clinical trial ( NCT05862012 ), we developed an innovative quantitative systems pharmacology model leveraging preclinical data, using a minimum pharmacologically active dose approach, therefore reducing patient exposure to subefficacious doses of therapies., (© 2024. The Author(s).)

Background: Some challenges still exist with single-target B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T-cell therapies due to variable or negative BCMA expression, although they have yielded remarkable efficacy in relapsed or refractory multiple myeloma. We developed anti-BCMA/GPRC5D bispecific CARs to mitigate the limitations and potentiate the functions of CAR T cells., Methods: This single-arm, phase 1 trial was conducted at the Affiliated Hospital of Xuzhou Medical University (Xuzhou, China). The trial enrolled patients aged 18-75 years with relapsed or refractory multiple myeloma and an Eastern Cooperative Oncology Group performance status of 0-3. Anti-BCMA/GPRC5D bispecific CAR T cells were administered at 0·5 × 10 6 , 1·0 × 10 6 , 2·0 × 10 6 , and 4·0 × 10 6 CAR T cells per kg in the dose-escalation phase, with additional patients included at the dose selected for the dose-expansion phase. The primary endpoint was safety, which included dose-limiting toxicity and maximum tolerated dose. Activity was also evaluated as a secondary endpoint. The maximum tolerated dose was chosen for the dose-expansion phase. Safety and activity analyses were done in all patients who received anti-BCMA/GPRC5D bispecific CAR T cells as defined in the protocol. This trial is registered with ClinicalTrials.gov (NCT05509530) and is complete., Findings: Between Sept 1, 2022, and Nov 3, 2023, 24 patients were enrolled and underwent apheresis. Three patients were excluded after apheresis (two patients discontinued due to rapid disease progression and one patient was withdrawn because of failed manufacture of CAR T cells), so 21 patients were infused with anti-BCMA/GPRC5D bispecific CAR T cells. Median follow-up was 5·8 months (IQR 5·2-6·7). Median age was 62 years (IQR 56-67). Eight (38%) patients were male, and 13 (62%) female. All patients were Chinese. At the 4·0 × 10 6 CAR T cells per kg dose, two patients had dose-limiting toxicities, of whom one died of subarachnoid haemorrhage (which was not considered to be related to the study treatment). The maximum tolerated dose was identified as 2·0 × 10 6 CAR T cells per kg. The most common grade 3 or worse adverse events were haematological toxicities in 19 (90%) patients (except lymphopenia). 15 (71%) patients had cytokine release syndrome, of which all cases were grade 1 or 2. One case of grade 1 immune effector cell-associated neurotoxicity syndrome (ICANS) was observed in a patient who received 4·0 × 10 6 CAR T cells per kg. No ICANS or grade 3 or worse organ toxicities were observed in patients who received 0·5-2·0 × 10 6 CAR T cells per kg. The overall response rate was 86% (18 of 21 patients), with 13 (62%) patients having a complete response or better, and 17 (81%) patients having measurable residual disease negativity. Of the 12 patients who received 2·0 × 10 6 CAR T cells per kg (three in the dose-escalation phase and an addition nine in the dose-expansion phase), the overall response rate was 92% (11 of 12 patients) with nine (75%) patients having a complete response or better., Interpretation: Anti-BCMA/GPRC5D bispecific CAR T cells show a good safety profile and encouraging activity in patients with relapsed or refractory multiple myeloma., Funding: National Natural Science Foundation of China., Translation: For the Chinese translation of the abstract see Supplementary Materials section., Competing Interests: Declaration of interests AHC is a founding member of Shanghai YaKe Biotechnology, a biotechnology company focusing on research and development of tumour cellular immunotherapy. YZ and SP are employed by Shanghai YaKe Biotechnology. All other authors declare no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved, including those for text and data mining, AI training, and similar technologies.)

Competing Interests: We declare no competing interests.

Objectives: This study aims to evaluate the safety and efficacy of BCMA-CD19 compound chimeric antigen receptor T cells (cCAR) to dual reset the humoral and B cell immune system in patients with systemic lupus erythematosus (SLE) with lupus nephritis (LN)., Methods: This is a single-arm open-label multicentre phase 1 study of BCMA and CD19-directed cCAR in patients suffering from SLE/LN with autoantibodies produced by B cells and plasma/long-lived plasma cells. In this clinical trial, we sequentially assigned biopsy-confirmed (classes III-V) LN patients to receive 3×10 6  cCAR cells/kg postcessation of all SLE medications and conditioning. The primary endpoint of safety and toxicity was assessed. Complete immune reset was indicated by B cell receptor (BCR) deep sequencing and flow cytometry analysis. Patient 11 (P11) had insufficient lymphocyte counts and was underdosed as compassionate use., Results: P1 and P2 achieved symptom and medication-free remission (MFR) from SLE and complete remission from lymphoma. P3-P13 (excluding P11) received an initial dose of 3×10 6  cCAR cells /kg and were negative for all autoantibodies, including those derived from long-lived plasma cells, 3 months post-cCAR and the complement returned to normal levels. These patients achieved symptom and MFR with post-cCAR follow-up to 46 months. Complete recovery of B cells was seen in 2-6 months post-cCAR. Mean SLE Disease Activity Index 2000 reduced from 10.6 (baseline) to 2.7 (3 months), and renal function significantly improved in 10 LN patients ≤90 days post-cCAR. cCAR T therapy was well tolerant with mild cytokine-release syndrome., Conclusions: Data suggest that cCAR therapy was safe and effective in inducing MFR and depleting disease-causing autoantibodies in patients with SLE., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ on behalf of EULAR.)

Background: Chimeric antigen receptor (CAR)-T cell has revolutionary efficacy against relapsed/refractory multiple myeloma (R/R MM). However, current CAR-T cell therapy has several limitations including long vein-to-vein time and limited viability., Methods: A 4-1BB-costimulated B-cell maturation antigen (BCMA) CAR-T integrating an independently-expressed OX40 (BCMA-BBZ-OX40) was designed and generated by a traditional manufacturing process (TraditionCART) or instant manufacturing platform (named InstanCART). The tumor-killing efficiency, differentiation, exhaustion, and expansion level were investigated in vitro and in tumor-bearing mice. An investigator-initiated clinical trial was performed in patients with R/R MM to evaluate the outcomes of both TraditionCART and InstanCART. The primary objective was safety within 1 month after CAR-T cell infusion. The secondary objective was the best overall response rate., Results: Preclinical studies revealed that integrated OX40 conferred BCMA CAR-T cells with superior cytotoxicity and reduced exhaustion levels. InstanCART process further enhanced the proliferation and T-cell stemness of BCMA-BBZ-OX40 CAR-T cells. BCMA-BBZ-OX40 CAR-T cells were successfully administered in 22 patients with R/R MM, including 15 patients with TraditionCART and 7 patients with InstanCART. Up to 50% (11/22) patients had a high-risk cytogenetic profile and 36% (8/22) had extramedullary disease. CAR-T therapy caused grade 1-2 cytokine release syndrome in 19/22 (80%) patients, grade 1 neurotoxicity in 2/22 (9%) patients and led to ≥grade 3 adverse events including neutropenia (20/22, 91%), thrombocytopenia (15/22, 68%), anemia (12/22, 55%), creatinine increased (1/22, 5%), hepatic enzymes increased (5/22, 23%), and sepsis (1/22, 5%). The best overall response rate was 100%, and 64% (14/22) of the patients had a complete response or better. The median manufacturing time was shorter for InstanCART therapy (3 days) than for TraditionCART therapy (10 days). Expansion and duration were dramatically higher for InstanCART cells than for TraditionCART cells., Conclusions: BCMA-BBZ-OX40 CAR-T cells were well tolerated and exhibited potent responses in patients with R/R MM. InstanCART shortened the manufacturing period compared to TraditionCART, and improved the cellular kinetics. Our results demonstrated the potency and feasibility of OX40-modified BCMA CAR-T cells using InstanCART technology for R/R MM therapy., Trial Registration Number: This trial was registered at www., Clinicaltrials: gov as #NCT04537442., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: The purpose of this study was to investigate the remodeling of the multiple myeloma microenvironment after B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor T (CAR-T) cell therapy., Experimental Design: We performed single-cell RNA sequencing on paired bone marrow specimens (n = 14) from seven patients with multiple myeloma before (i.e., baseline, "day -4") and after (i.e., "day 28") lymphodepleted BCMA CAR-T cell therapy., Results: Our analysis revealed heterogeneity in gene expression profiles among multiple myeloma cells, even those harboring the same cytogenetic abnormalities. The best overall responses of patients over the 15-month follow-up are positively correlated with the abundance and targeted cytotoxic activity of CD8+ effector CAR-T cells on day 28 after CAR-T cell infusion. Additionally, favorable responses are associated with attenuated immunosuppression mediated by regulatory T cells, enhanced CD8+ effector T-cell cytotoxic activity, and elevated type 1 conventional dendritic cell (DC) antigen presentation ability. DC re-clustering inferred intramedullary-originated type 3 conventional DCs with extramedullary migration. Cell-cell communication network analysis indicated that BCMA CAR-T therapy mitigates BAFF/GALECTIN/MK pathway-mediated immunosuppression and activates MIF pathway-mediated anti-multiple myeloma immunity., Conclusions: Our study sheds light on multiple myeloma microenvironment dynamics after BCMA CAR-T therapy, offering clues for predicting treatment responsivity., (©2024 The Authors; Published by the American Association for Cancer Research.)

Background: On April 18, 2024, the U.S. Food and Drug Administration officially required updating of the "boxed warning" for T cell malignancies for all chimeric antigen receptor T cell (CAR-T) therapies. Given the clinical significance of these therapies, a rigorous safety assessment is paramount. However, comprehensive real-world safety studies have been lacking for the newly marketed CAR-T products idecabtagene vicleucel (ide-cel) and ciltacabtagene autoleucel (cilta-cel), which target B cell maturation antigen, especially regarding the risk of secondary malignancies. Therefore, we aimed to thoroughly analyze the adverse events (AEs) information in the FDA Adverse Event Reporting System (FAERS) database to comprehensively understand the safety risks of ide-cel and cilta-cel., Methods: We extracted AE reports related to ide-cel and cilta-cel from the FAERS database (https://fis.fda.gov/extensions/FPD-QDE-FAERS/FPD-QDE-FAERS.html.) from January 1, 2019 to December 31, 2023. Disproportionality analysis and Bayesian analysis were used to identify risk signals across subgroups and specific cases (including for death and secondary malignancies). Weibull distribution analysis was employed to determine the time to AE onset., Results: A total of 695 AE reports for ide-cel and 848 for cilta-cel were included in the FAERS database. This analysis identified 81 positive signals for ide-cel and 74 for cilta-cel. Notably, comparisons with the drug labels revealed "unexpected signals," including febrile bone marrow aplasia (reporting odds ratio=69.10; confidence interval 39.12-122.03) and plasma cell myeloma (12.45; 8.18-18.95) for ide-cel, and increased serum ferritin (24.98; 8.0-77.58) and large intestine perforation (18.57; 5.98-57.69) for cilta-cel. Both drugs showed a higher AE incidence among male recipients and patients aged ≥65 years, although female recipients faced a greater risk. Most AEs occurred at the early stage of administration. However, secondary malignancies were detected for both drugs, primarily occurring one-year post-administration., Conclusion: This study provides a foundation for understanding the safety profile of CAR-T cell therapy, particularly in relation to the emergence of secondary malignancies. Such insights are helpful for clinical decision-making and the safe and effective utilization of these therapeutic agents., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Liu, Lin, Zhu, Yin, Liu, Lei and Feng.)

Purpose: This study aimed to report the 5-year clinical outcomes of anti-B-cell maturation antigen chimeric antigen receptor (CAR) T-cell (HDS269B) therapy in patients with relapsed/refractory multiple myeloma (RRMM), including those with poor performance status [Eastern Cooperative Oncology Group (ECOG) scores 3 to 4], and to identify factors influencing long-term outcomes., Patients and Methods: Forty-nine patients with RRMM enrolled from 2016 to 2020 received HDS269B (9 × 106 cells/kg) after receiving a conditioning chemotherapy consisting of cyclophosphamide and fludarabine. The overall response, long-term outcomes, and safety were assessed, as were their associations with clinical and disease characteristics., Results: With a median follow-up of 59.0 months, the overall response rate was 77.55%. The median progression-free survival (PFS) and overall survival (OS) were 9.5 months [95% confidence interval (CI), 5.01-13.99] and 20.0 months (95% CI, 11.26-28.74), respectively. The 5-year PFS and OS rates were 21.3% (95% CI, 12.3%-36.7%) and 34.1% (95% CI, 22.7%-51.3%), respectively. Patients with ECOG 0 to 2 had marked longer survival, with a median PFS of 11.0 months and a median OS of 41.8 months. Early minimal residual disease negativity, higher and persistent CAR T-cell expansion, and the absence of extramedullary disease were associated with better survival outcomes. No new CAR T-cell therapy-associated toxicities were observed. Importantly, ECOG scores 0 to 2, prior therapy lines <4, and CAR T-cell persistence at ≥6 months were independently associated with longer OS., Conclusions: HDS269B is effective and safe, especially for patients with ECOG scores 0 to 2. Early CAR T-cell intervention may improve prognosis in patients with RRMM., (©2024 The Authors; Published by the American Association for Cancer Research.)

Idecabtagene vicleucel (ide-cel), a chimeric antigen receptor T-cell therapy targeting B-cell maturation antigen (BCMA), received early access program (EAP) authorization in France in April 2021 for relapsed/refractory multiple myeloma (RRMM). We conducted a real-world registry-based multicentre observational study in 11 French hospitals to evaluate ide-cel outcomes. Data from 176 RRMM patients who underwent apheresis between June 2021 and November 2022 were collected from the French national DESCAR-T registry. Of these, 159 patients (90%) received ide-cel. Cytokine release syndrome occurred in 90% with 2% grade ≥3, and neurotoxicity occurred in 12% with 3% grade ≥3. Over the first 6 months, the best overall response and ≥complete response rates were 88% and 47% respectively. The median progression-free survival (PFS) from the ide-cel infusion was 12.5 months, the median overall survival (OS) was 20.8 months and the estimated OS rate at 12 months was 73.3%. Patients with extra-medullary disease (EMD) had impaired PFS (6.2 months vs. 14.8 months). On multivariable analysis, EMD and previous exposure to BCMA-targeted immunoconjugate or T-cell-redirecting GPRC5D bispecific antibody were associated with inferior PFS. Our study supports ide-cel's feasibility, safety and efficacy in real-life settings, emphasizing the importance of screening for EMD and considering prior treatments to optimize patient selection., (© 2024 The Authors. British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

Introduction: T-cell redirecting bispecific antibodies (BsAbs), targeting B-cell maturation antigen (BCMA) or G-protein - coupled receptor class C group 5 member D (GPRC5D), are efficacious new agents for the treatment of patients with relapsed or refractory MM., Areas Covered: This review discusses the pharmacokinetic properties, efficacy, and safety profile of T-cell redirecting BsAbs in MM, with a special focus on their optimal dosing schedule, resistance mechanisms and future strategies to enhance efficacy, reduce toxicity, and maximize duration of response., Expert Opinion: To further improve the efficacy of BsAbs, ongoing studies are investigating whether combination therapy can enhance depth and duration of response. An important open question is also to what extent response to BsAbs can be improved when these agents are used in earlier lines of therapy. In addition, more evidence is needed on rational de-intensification strategies of BsAb dosing upon achieving a sufficient response, and if (temporary) treatment cessation is possible in patients who have achieved a deep remission (e.g. complete response or minimal residual disease-negative status).

Markers that predict response and resistance to chimeric antigen receptor (CAR) T cells in relapsed/refractory multiple myeloma are currently missing. We subjected mononuclear cells isolated from peripheral blood and bone marrow before and after the application of approved B cell maturation antigen-directed CAR T cells to single-cell multiomic analyses to identify markers associated with resistance and early relapse. Differences between responders and nonresponders were identified at the time of leukapheresis. Nonresponders showed an immunosuppressive microenvironment characterized by increased numbers of monocytes expressing the immune checkpoint molecule CD39 and suppressed CD8 + T cell and natural killer cell function. Analysis of CAR T cells showed cytotoxic and exhausted phenotypes in hyperexpanded clones compared to low/intermediate expanded clones. We identified potential immunotherapy targets on CAR T cells, like PD1, to improve their functionality and durability. Our work provides evidence that an immunosuppressive microenvironment causes resistance to CAR T cell therapies in multiple myeloma., (© 2024. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Importance: Patients with high-risk newly diagnosed multiple myeloma (NDMM) often have poor outcomes with standard treatments, necessitating novel effective frontline therapies to enhance clinical outcomes. GC012F, a B-cell maturation antigen/CD19 dual-targeting chimeric antigen receptor (CAR) T-cell therapy, has been developed on the novel FasTCAR platform. Notably, its use as a frontline therapy for patients with high-risk NDMM who are eligible for transplant has not been thoroughly explored., Objective: To examine the safety, pharmacokinetics, and patient health and survival outcomes associated with GC012F in individuals with NDMM., Design, Setting, and Participants: Patients were enrolled in this single-arm, open-label phase 1 cohort study between June 28, 2021, and June 1, 2023 (the data cutoff date). All patients included in this study were treated at a single center, Shanghai Changzheng Hospital. The patients in the efficacy evaluation were followed up for a minimum period of 3 months., Intervention: Patients underwent 2 cycles of induction therapy, followed by GC012F infusion (at 1 × 105 cells/kg, 2 × 105 cells/kg, or 3 × 105 cells/kg)., Main Outcomes and Measures: The primary goals were to assess the safety, efficacy, and pharmacokinetics of GC012F at various dose levels., Results: Of 22 patients receiving GC012F treatment, 6 experienced mild to moderate cytokine release syndrome (grade 1-2) and none experienced neurotoxic effects. Nineteen patients were included in the efficacy evaluation, and all 19 patients showed stringent complete responses and achieved minimal residual disease negativity. The treatment's effectiveness was consistent across different dose levels. GC012F demonstrated a rapid response, with a median time to first stringent complete response of 84 days (range, 26-267 days) and achieving minimal residual disease negativity within 28 days (range, 23-135 days). The CAR T-cell expansion was robust, with a median peak copy number of 60 652 copies/μg genomic DNA (range, 8754-331 159 copies/μg genomic DNA), and the median time to median peak copy number was 10 days (range, 9-14 days)., Conclusions and Relevance: The findings of this single-arm, open-label phase 1 cohort study suggest that GC012F may be a safe treatment associated with positive health and survival outcomes for patients with high-risk NDMM eligible for transplant. Owing to the small sample size, further studies with larger cohorts and longer follow-up durations are needed.

BCMA-directed chimeric antigen receptor T-cell (CAR T) therapies, including idecabtagene vicleucel (ide-cel) and ciltacabtagene autoleucel (cilta-cel), have transformed the treatment landscape for relapsed-refractory multiple myeloma (RRMM), offering remarkable efficacy with hallmark toxicity risks of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). The FDA mandates a 4-week monitoring period at the treatment center as part of a Risk Evaluation and Mitigation Strategy (REMS) to monitor and manage these toxicities, which, while prudent, may add unnecessary challenges related to access and socioeconomic disparities. We sought to assess CRS and ICANS onset and duration, as well as causes of non-relapse mortality (NRM) in real-world BCMA CAR T recipients in order to better inform future changes to the monitoring guidelines for CAR T recipients. This is a retrospective study across four academic centers that examined 129 ide-cel and cilta-cel recipients that received CAR T cell infusions from May 2021 to June 2023. Infusion and toxicities were managed per institutional guidelines in accordance with previously published guidelines. While differences were noted in the incidence and duration of CRS/ ICANS between ide-cel and cilta-cel, late-onset CRS and ICANS were rare after 2 weeks following infusion (0% and 1.6%, respectively). NRM was driven by hemophagocytic lymphohistiocytosis and infections in the early follow-up period (1.1% until Day 29), then by infections through three months post-infusion (1.2%). Our findings suggest that 25% of patients had to relocate for 4 weeks due to distance from the treatment center. With the low risk of CRS and ICANS after 2 weeks, a flexible shorter monitoring period may be reasonable, emphasizing collaboration with referring oncologists to improve NRM., (Copyright © 2024 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Abstract: The identification and targeting of B-cell maturation antigen (BCMA) through immunotherapeutic strategies such as antibody-drug conjugates, chimeric antigen receptor T cells, and T-cell engagers have revolutionized the care of patients with multiple myeloma (MM). These treatment modalities have improved the survival outcomes of patients with relapsed and/or refractory MM compared with previously established strategies and are moving into earlier lines of therapy. Despite their efficacy, the majority of patients eventually relapse, necessitating additional therapeutic targets for salvage. G-protein-coupled receptor class 5 member D, Fc receptor-homolog 5, and SLAMF7 are some examples of novel targets in development. This expanding armamentarium of immunotherapeutic agents will be crucial to address the unmet need for relapses after BCMA-targeting therapies, particularly antigen-negative relapses. The utilization of sequential T-cell redirective therapies including agents targeting different tumor-associated antigens and combination therapies appears feasible, paving the way for effective chemotherapy-free regimes. Deliberate consideration of treatment timing, preserving T-cell health, overcoming antigenic loss, and comprehension of the complex tumor microenvironment would be key to maximizing therapeutic benefits and minimizing adverse effects. This review summarizes novel targets in development for myeloma beyond BCMA, presenting pivotal safety and efficacy data derived from clinical trials when available and the considerations vital for navigating this expanding landscape of immunotherapeutic options., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

The U.S. Food and Drug Administration (FDA) has reported cases of T-cell malignancies, including CAR-positive lymphomas, in patients receiving B cell maturation antigen (BCMA)- or CD19-targeted autologous CAR-T cell immunotherapy. These reports were derived from clinical trials and/or post-marketing adverse event data. This finding has attracted widespread attention. Therefore, it is essential to explore the potential mechanisms by which chimeric antigen receptor (CAR)-T cell therapy triggers secondary T-cell cancers to further guarantee the safety of CAR-T cell therapy., Competing Interests: Declaration of competing interest The authors declare that there are no conflict of interests, we do not have any possible conflicts of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Serum B-cell maturation antigen (sBCMA) levels can serve as a sensitive biomarker in multiple myeloma (MM). In the research setting, sBCMA levels can be accurately detected by enzyme-linked immunosorbent assay (ELISA), but the approach has not been approved for clinical use. Here, we used a novel chemiluminescence method to assess sBCMA levels in 759 serum samples from 17 healthy donors and 443 patients with plasma cell (PC) diseases including AL amyloidosis, POEMS syndrome, and MM. Serum BCMA levels were elevated 16.1-fold in patients with newly diagnosed MM compared to healthy donors and rare PC diseases patients. Specifically, the sBCMA levels in patients with progressive disease were 64.6-fold higher than those who showed partial response or above to treatment. The sBCMA level also correlated negatively with the response depth of MM patients. In newly diagnosed and relapsed MM patients, survival was significantly longer among those subjects whose sBCMA levels are below the median levels compared with those above the median value. We optimized the accuracy of the survival prediction further by integrating sBCMA level into the Second Revised International Staging System (R2-ISS). Our findings provide evidence that the novel chemiluminescence method is sensitive and practical for measuring sBCMA levels in clinical samples and confirm that sBCMA might serve as an independent prognostic biomarker for MM., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Immunology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Abstract: Teclistamab, an off-the-shelf B-cell maturation antigen (BCMA) × CD3 bispecific antibody that mediates T-cell activation and subsequent lysis of BCMA-expressing myeloma cells, is approved for the treatment of patients with relapsed/refractory multiple myeloma (R/RMM). As a T-cell redirection therapy, clinical outcomes with teclistamab may be influenced by patient immune fitness and tumor antigen expression. We correlated tumor characteristics and baseline immune profiles with clinical response and disease burden in patients with R/RMM from the pivotal phase 1/2 MajesTEC-1 study, focusing on patients treated with 1.5 mg/kg of teclistamab (N = 165). Peripheral blood samples were collected at screening, and bone marrow samples were collected at screening and cycle 3. Better clinical outcomes to teclistamab correlated with higher baseline total T-cell counts in the periphery. In addition, responders (partial response or better) had a lower proportion of immunosuppressive regulatory T cells (Tregs), T cells expressing coinhibitory receptors (CD38, PD-1, and PD-1/TIM-3), and soluble BCMA and a T-cell profile suggestive of a more cytolytic potential, compared with nonresponders. Neither frequency of baseline bone marrow BCMA expression nor BCMA-receptor density was associated with clinical response to teclistamab. Improved progression-free survival was observed in patients with a lower frequency of T cells expressing exhaustion markers and immunosuppressive Tregs. Overall, response to teclistamab was associated with baseline immune fitness; nonresponders had immune profiles suggestive of immune suppression and T-cell dysfunction. These findings illustrate the importance of the contribution of the immune landscape to T-cell redirection therapy response. This trial was registered at www.ClinicalTrials.gov as #NCT03145181/NCT04557098., (© 2024 American Society of Hematology. Published by Elsevier Inc. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Purpose: We present a phase I/II first-in-human trial evaluating the safety and efficacy of 50 mg and 200 mg doses of linvoseltamab, a B-cell maturation antigen × CD3 bispecific antibody in relapsed/refractory multiple myeloma (RRMM)., Methods: Phase II eligible patients had RRMM that either progressed on/after ≥three lines of therapy including a proteasome inhibitor (PI), an immunomodulatory drug (IMiD), and an anti-CD38 antibody or was triple-class (PI/IMiD/anti-CD38) refractory. Phase II treatment was once a week through week 14 and then once every 2 weeks. Phase II 200 mg patients who achieved a ≥very good partial response by week 24 received linvoseltamab once every 4 weeks. The primary end point in phase II was overall response rate (ORR)., Results: Among the 117 patients treated with 200 mg, the median age was 70 years, 39% had high-risk cytogenetics, and 28% had penta-refractory disease. At a median follow-up of 14.3 months, the ORR was 71%, with 50% achieving ≥complete response (CR). In 104 patients treated with 50 mg at a median follow-up of 7.4 months, the ORR was 48%, with 21% achieving ≥CR. The median duration of response (DOR) for 200 mg patients (n = 83) was 29.4 months (95% CI, 19.2 to not evaluable). Among 200 mg patients, the most common adverse events included cytokine release syndrome (35.0% Gr1, 10.3% Gr2, 0.9% Gr3), neutropenia (0.9% Gr2, 18.8% Gr3, 23.1% Gr4), and anemia (3.4% Gr1, 4.3% Gr2, 30.8% Gr3). Immune effector cell-associated neurotoxicity syndrome occurred in 7.7% of patients (2.6% each Gr1, Gr2, Gr3). Infections were reported in 74.4% of patients (33.3% Gr3, 2.6% Gr4); infection frequency and severity declined over time., Conclusion: Linvoseltamab 200 mg induced deep and durable responses, with a median DOR of 29.4 months, in patients with RRMM with an acceptable safety profile.

A better understanding of the roles of the adaptive and innate immune systems in the oncogenesis of cancers including multiple myeloma (MM) has led to the development of novel immune-based therapies. B cell maturation antigen (BCMA), G protein-coupled receptor family C group 5 member D (GPRC5D) and Fc receptor-like protein 5 (FcRL5, also known as FcRH5) are cell-surface transmembrane proteins expressed by plasma cells, and have been identified as prominent immunotherapeutic targets in MM, with promising activity demonstrated in patients with heavily pretreated relapsed and/or refractory disease. Indeed, since 2020, antibody-drug conjugates, bispecific T cell engagers and autologous chimeric antigen receptor T cells targeting BCMA or GPRC5D have been approved for the treatment of relapsed and/or refractory MM. However, responses to these therapies are not universal, and acquired resistance invariably occurs. In this Review, we discuss the various immunotherapeutic approaches targeting BCMA, GPRC5D and FcRL5 that are currently either available or in clinical development for patients with MM. We also review the mechanisms underlying resistance to such therapies, and discuss potential strategies to overcome these mechanisms and improve patient outcomes., (© 2024. Springer Nature Limited.)

Background: The development of CAR-T-cell immunotherapy has notably elevated the efficacy of treating multiple myeloma. Currently, a variety of targets, including BCMA, CS1, CD38, FcRH5, and GPRC5D, are being investigated. Despite these significant advancements, challenges such as antigen escape, limited persistence of CAR-T cells, and the intricate nature of the tumor microenvironment persist, leading to relapses following treatment., Case Presentation: We report the case of a patient with recurrent and refractory multiple myeloma (RRMM) who developed a substantial extramedullary plasmacytoma in the muscles of the lower limb following multiple rounds of radiotherapy and chemotherapy. The patient underwent CAR-T-cell immunotherapy targeting BCMA and CS1; however, the tumor progressed despite treatment. Surgical resection of the extramedullary plasmacytoma was subsequently performed. Upon comparison of the tumor tissue with the adjacent tissue, increased expression of MYBL2 was noted in the tumor tissue, potentially contributing to the lack of improvement in extramedullary relapse after dual-targeted CAR-T cell therapy., Conclusions: In patients with recurrent and refractory multiple myeloma who underwent multiple cycles of chemotherapy and radiotherapy, dual-targeted CAR-T cell therapy aimed at BCMA and CS1 failed to effectively manage extramedullary relapse. Elevated expression of MYBL2 in multiple myeloma correlates with a poorer prognosis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Shi, Wu, Yao, Du and Du.)

Abstract: B-cell maturation antigen (BCMA)-targeting therapeutics have dramatically improved outcomes in relapsed/refractory multiple myeloma (RRMM). However, whether the mechanisms of resistance between these therapies are shared and how the identification of such mechanisms before therapy initiation could refine clinical decision-making remains undefined. We analyzed outcomes for 72 RRMM patients treated with teclistamab, a CD3 × BCMA bispecific antibody, 42% (30/72) of whom had prior BCMA-directed therapy exposure. Malignant plasma cell BCMA expression was present in all BCMA therapy-naïve patients. Prior therapy-mediated loss of plasma cell BCMA expression before teclistamab treatment, measured by immunohistochemistry, was observed in 3 patients, none of whom responded to teclistamab, and 1 of whom also did not respond to ciltacabtagene autoleucel. Whole exome sequencing of tumor DNA from 1 patient revealed biallelic loss of TNFRSF17 following treatment with belantamab mafodotin. Low-to-undetectable peripheral blood soluble BCMA levels correlated with the absence of BCMA expression by bone marrow plasma cells. Thus, although rare, loss of BCMA expression following TNFRSF17 gene deletions can occur following any BCMA-directed therapy and prevents response to subsequent anti-BCMA-directed treatments, underscoring the importance of verifying the presence of a target antigen., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Antibody-producing plasma cells fuel humoral immune responses. They also contribute to autoimmune diseases such as systemic lupus erythematosus or IgA nephropathy. Interleukin-6 and the tumor necrosis factor (TNF) family ligands BAFF (B cell-activating factor) and APRIL (a proliferation-inducing ligand) participate in plasma cell survival. BAFF binds to three receptors, BAFFR (BAFF receptor), TACI (transmembrane activator and CAML interactor), and BCMA (B cell maturation antigen), while APRIL binds to TACI, BCMA, and proteoglycans. However, which ligand-receptor pair(s) are required to maintain plasma cells in different body locations remains unknown. Here, by combining mouse genetic and pharmacological approaches, we found that plasma cells required BCMA and/or TACI but not BAFFR. BCMA responded exclusively to APRIL, while TACI responded to both BAFF and APRIL, identifying three self-sufficient ligand-receptor pairs for plasma cell maintenance: BAFF-TACI, APRIL-TACI, and APRIL-BCMA. Together, these actors accounted for 90% of circulating antibodies. In BAFF-ko mice, the reduction of plasma cells upon APRIL inhibition indicated that APRIL could function in the absence of BAFF-APRIL heteromers. No evidence was found that in the absence of BCMA and TACI, binding of APRIL to proteoglycans would help maintain plasma cells. IL-6, alone or together with BAFF and APRIL, supported mainly splenic plasmablasts and plasma cells and contributed to circulating IgG but not IgA levels. In conclusion, survival factors for plasma cells can vary with body location and with the antibody isotype that plasma cells produce. To efficiently target plasma cells, in particular IgA-producing ones, dual inhibition of BAFF and APRIL is required., Competing Interests: Competing interests statement:P.S. was supported by a research grant from the healthcare business of Merck KGaA, Darmstadt, Germany. Ö.Y. was employee of the healthcare business of Merck KGaA, Darmstadt, Germany at the time of the study. O.D. is employee of Adipogen Life Sciences. Other authors declare no conflict of interest.

Purpose: Bispecific antibodies (BsAb) directed against B-cell maturation antigen (teclistamab) or the orphan G protein-coupled receptor GPRC5D (talquetamab) induce deep and durable responses in heavily pretreated patients with multiple myeloma. However, mechanisms underlying primary and acquired resistance remain poorly understood., Experimental Design: The anti-multiple myeloma activity of teclistamab and talquetamab was evaluated in bone marrow (BM) samples from patients with multiple myeloma. T-cell phenotype and function were assessed in BM/peripheral blood samples obtained from patients with multiple myeloma who were treated with these BsAb., Results: In ex vivo killing assays with 41 BM samples from BsAb-naive patients with multiple myeloma, teclistamab- and talquetamab-mediated multiple myeloma lysis was strongly correlated (r = 0.73, P < 0.0001). Both BsAb exhibited poor activity in samples with high regulatory T-cell (Treg) numbers and a low T-cell/multiple myeloma cell ratio. Furthermore, comprehensive phenotyping of BM samples derived from patients treated with teclistamab or talquetamab revealed that high frequencies of PD-1+ CD4+ T cells, CTLA4+ CD4+ T cells, and CD38+ CD4+ T cells were associated with primary resistance. Although this lack of response was linked to a modest increase in the expression of inhibitory receptors, increasing T-cell/multiple myeloma cell ratios by adding extra T cells enhanced sensitivity to BsAb. Further, treatment with BsAb resulted in an increased proportion of T cells expressing exhaustion markers (PD-1, TIGIT, and TIM-3), which was accompanied by reduced T-cell proliferative potential and cytokine secretion, as well as impaired antitumor efficacy in ex vivo experiments., Conclusions: Primary resistance is characterized by a low T-cell/multiple myeloma cell ratio and Treg-driven immunosuppression, whereas reduced T-cell fitness due to continuous BsAb-mediated T-cell activation may contribute to the development of acquired resistance., (©2024 American Association for Cancer Research.)

In February 2022, the FDA approved ciltacabtagene autoleucel, a chimeric antigen receptor (CAR) T-cell therapy targeting the B-cell maturation antigen, for adult patients with relapsed/refractory multiple myeloma after ≥4 lines of therapy, including an immunomodulatory agent, a proteasome inhibitor, and an anti-CD38 monoclonal antibody. Approval was based on overall response rate (ORR), complete response (CR) rate, and duration of response (DoR) in 97 adult patients in a single-arm, open-label, multicenter phase 2 trial (CARTITUDE-1 [NCT03548207]). Patients received a single infusion of ciltacabtagene autoleucel, preceded by lymphodepleting chemotherapy. Of the 97 patients evaluable, ORR was 97.9% [95% confidence interval (CI), 92.7-99.7] with a stringent CR rate of 78.4% (95% CI, 68.8-86.1). After median follow-up of 18 months, the median DoR was 21.8 months (95% CI, 21.8-not estimable [NE]) in responders (PR or better) and NE (95% CI, 21.8 months-NE) in patients who achieved stringent CR. Serious adverse reactions occurred in 55% of the 97 patients evaluated for safety. Grade 3 or higher cytokine release syndrome (CRS) and neurologic toxicities occurred in 5% and 11% of the patients, respectively, leading to a Risk Evaluation and Mitigation Strategy. Neurologic toxicities included immune effector cell-associated neurologic syndrome, typically seen with CAR-T products, parkinsonism, peripheral neuropathy, cranial nerve palsies, and Guillain-Barré syndrome. One fatal case of hemophagocytic lymphohistiocytosis/macrophage activation syndrome occurred. Prolonged and recurrent grade 3 or 4 cytopenias occurred; a single patient required hematopoietic stem-cell rescue., (©2024 American Association for Cancer Research.)

Abstract: Multiple myeloma is a plasma cell malignancy that is currently incurable with conventional therapies. Following the success of CD19-targeted chimeric antigen receptor (CAR) T cells in leukemia and lymphoma, CAR T cells targeting B-cell maturation antigen (BCMA) more recently demonstrated impressive activity in relapsed and refractory myeloma patients. However, BCMA-directed therapy can fail due to weak expression of BCMA on myeloma cells, suggesting that novel approaches to better address this antigen-low disease may improve patient outcomes. We hypothesized that engineered secretion of the proinflammatory cytokine interleukin-18 (IL-18) and multiantigen targeting could improve CAR T-cell activity against BCMA-low myeloma. In a syngeneic murine model of myeloma, CAR T cells targeting the myeloma-associated antigens BCMA and B-cell activating factor receptor (BAFF-R) failed to eliminate myeloma when these antigens were weakly expressed, whereas IL-18-secreting CAR T cells targeting these antigens promoted myeloma clearance. IL-18-secreting CAR T cells developed an effector-like T-cell phenotype, promoted interferon-gamma production, reprogrammed the myeloma bone marrow microenvironment through type-I/II interferon signaling, and activated macrophages to mediate antimyeloma activity. Simultaneous targeting of weakly-expressed BCMA and BAFF-R with dual-CAR T cells enhanced T-cell:target-cell avidity, increased overall CAR signal strength, and stimulated antimyeloma activity. Dual-antigen targeting augmented CAR T-cell secretion of engineered IL-18 and facilitated elimination of larger myeloma burdens in vivo. Our results demonstrate that combination of engineered IL-18 secretion and multiantigen targeting can eliminate myeloma with weak antigen expression through distinct mechanisms.

Abstract: Multiple myeloma is characterized by frequent clinical relapses after conventional therapy. Recently, chimeric antigen receptor (CAR) T cells targeting B-cell maturation antigen (BCMA) has been established as a treatment option for patients with relapsed or refractory disease. However, although >70% of patients initially respond to this treatment, clinical relapse and disease progression occur in most cases. Recent studies showed persistent expression of BCMA at the time of relapse, indicating that immune-intrinsic mechanisms may contribute to this resistance. Although there were no preexisting T-cell features associated with clinical outcomes, we found that patients with a durable response to CAR T-cell treatment had greater persistence of their CAR T cells than patients with transient clinical responses. They also possessed a significantly higher proportion of CD8+ T-effector memory cells. In contrast, patients with short-lived responses to treatment have increased frequencies of cytotoxic CD4+ CAR T cells. These cells expand in vivo early after infusion but express exhaustion markers (hepatitis A virus cellular receptor 2 [HAVCR2] and T-cell immunoglobulin and mucin domain-containing-3 [TIGIT]) and remain polyclonal. Finally, we demonstrate that nonclassical monocytes are enriched in the myeloma niche and may induce CAR T-cell dysfunction through mechanisms that include transforming growth factor β. These findings shed new light on the role of cytotoxic CD4+ T cells in disease progression after CAR T-cell therapy., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Introduction: Therapeutic strategies against multiple myeloma (MM) have evolved dramatically in recent decades, with unprecedent results in the treatment landscape, culminating in the recent incorporation of novel agents in the anti-myeloma armamentarium., Areas Covered: BCMA represents one of the most promising targets in MM and currently available immune approaches, either approved or under active investigation, are clearly showing their greater potential over standard regimens. In this context, immunotherapies based on chimeric antigen receptor (CAR)-engineered T-cells and bispecific antibodies (BsAbs) have taken center stage, being the ones that are yielding the most promising results in clinical trials. This review focuses on the current landscape of BsAbs and CAR-T, summarizing the latest advances and possible future developments., Expert Opinion: CAR-T and BsAbs anti-BCMA strategies represent breakthrough therapies against MM. However, their inclusion in clinical practice is almost feared, due to the associated limitations, some of which have been addressed here. Meanwhile, all the efforts should be focused on individualizing and choosing the most suitable candidates for each treatment and to understand how to combine, or sequence, these therapies to improve efficacy and minimize toxicity, especially for those patients with limited available treatment options.

Currently available chimeric antigen receptor (CAR)-engineered T-cell therapies targeting B-cell maturation antigen (BCMA), namely, idecabtagene vicleucel and ciltacabtagene autoleucel, have shown marked efficacy against relapsed and refractory multiple myeloma. However, further improvement in CAR-T-cell function is warranted as most patients treated with these products eventually relapse due to various mechanisms such as antigen loss and T-cell dysfunction or disappearance. Strategies for improving CAR-T-cell function include targeting of dual antigens, enhancing cell longevity through genetic modification, and eliminating the immunosuppressive tumor microenvironment. Serious side effects can also occur after CAR-T-cell infusions. Although understanding of the molecular pathogenesis of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome is growing, the unique movement disorder caused by BCMA-targeted therapy is less understood, and its molecular mechanisms must be further elucidated to establish better management strategies. In this article, we will review the current status of BCMA-targeting CAR-T-cell therapy. We will also highlight progress in the development of CAR-T cells targeting other antigens, as well as universal allogeneic CAR-T cells and bispecific antibodies., (© 2024. Japanese Society of Hematology.)

Zevorcabtagene autoleucel () is a fully humanised B cell maturation antigen (BCMA)-targeting specific chimeric antigen receptor (CAR) T-cell therapy being developed by CARsgen for the treatment of multiple myeloma. Zevorcabtagene autoleucel is an autologous CAR T cell comprising a fully human BCMA-specific scFv (25C2), a CD8α hinge region and transmembrane domain, a 4-1BB costimulatory domain and a CD3-ζ T cell activation domain. Zevorcabtagene autoleucel recognizes and induces selective toxicity against BCMA-expressing tumour cells leading to their elimination. In February 2024, zevorcabtagene autoleucel received its first approval in China for the treatment of adults with relapsed or refractory multiple myeloma who have progressed after ≥ 3 prior lines of therapy (including ≥ 1 proteasome inhibitor and an immunomodulatory agent). Clinical studies of zevorcabtagene autoleucel are underway in Canada and the US. This article summarizes the milestones in the development of zevorcabtagene autoleucel leading to this first approval for relapsed or refractory multiple myeloma., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Multiple myeloma (MM) is a plasma cell disease with a preferential bone marrow (BM) tropism. Enforced expression of tissue-specific chemokine receptors has been shown to successfully guide adoptively-transferred CAR NK cells towards the malignant milieu in solid cancers, but also to BM-resident AML and MM. For redirection towards BM-associated chemokine CXCL12, we armored BCMA CAR-NK-92 as well as primary NK cells with ectopic expression of either wildtype CXCR4 or a gain-of-function mutant CXCR4 R334X . Our data showed that BCMA CAR-NK-92 and -primary NK cells equipped with CXCR4 gained an improved ability to migrate towards CXCL12 in vitro . Beyond its classical role coordinating chemotaxis, CXCR4 has been shown to participate in T cell co-stimulation, which prompted us to examine the functionality of CXCR4-cotransduced BCMA-CAR NK cells. Ectopic CXCR4 expression enhanced the cytotoxic capacity of BCMA CAR-NK cells, as evidenced by the ability to eliminate BCMA-expressing target cell lines and primary MM cells in vitro and through accelerated cytolytic granule release. We show that CXCR4 co-modification prolonged BCMA CAR surface deposition, augmented ZAP-70 recruitment following CAR-engagement, and accelerated distal signal transduction kinetics. BCMA CAR sensitivity towards antigen was enhanced by virtue of an enhanced ZAP-70 recruitment to the immunological synapse, revealing an increased propensity of CARs to become triggered upon CXCR4 overexpression. Unexpectedly, co-stimulation via CXCR4 occurred in the absence of CXCL12 ligand-stimulation. Collectively, our findings imply that co-modification of CAR-NK cells with tissue-relevant chemokine receptors affect adoptive NK cell therapy beyond improved trafficking and retention within tumor sites., Competing Interests: AR and UH filed a patent application for the BCMA CAR used in this manuscript PCT/WO2017211900A1. AR and UH receive research funds from Fate Therapeutics San Diego, CA. JR, KM, JG, and BV are employees of Fate Therapeutics. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Moles, Erdlei, Menzel, Massaro, Fiori, Bunse, Schrimpf, Gerlach, Gudipati, Reiser, Mathavan, Goodrich, Huppa, Krönke, Valamehr, Höpken and Rehm.)

Infections are common in plasma cell cancer multiple myeloma (MM) due to disease-related immune deficiencies and cancer treatment. Myeloma cells express Toll-like receptors (TLRs), and TLR activation has been shown to induce proliferative and pro-survival signals in cancer cells. MM is a complex and heterogeneous disease, and expression levels of TLRs as well as downstream signaling components are likely to differ between patients. Here, we show that in a large cohort of patients, TLR1, TLR4, TLR6, TLR9, and TLR10 are the most highly expressed in primary CD138 + cells. Using an MM cell line expressing TLR4 and TLR9 as a model, we demonstrate that TLR4 and TLR9 activation promoted the expression of well-established pro-survival and oncogenes in MM such as MYC , IRF4 , NFKB , and BCL2 . TLR4 and TLR9 activation inhibited the efficacy of proteasome inhibitors bortezomib and carfilzomib, drugs used in the treatment of MM. Inhibiting the autophagosome-lysosome protein degradation pathway by hydroxychloroquine (HCQ) diminished the protective effect of TLR activation on proteasome inhibitor-induced cytotoxicity. We also found that TLR signaling downregulated the expression of TNFRSF17 , the gene encoding for B-cell maturation antigen (BCMA). MYC , BCL2 , and BCL2L1 were upregulated in approximately 50% of primary cells, while the response to TLR signaling in terms of TNFRSF17 expression was dichotomous, as an equal fraction of patients showed upregulation and downregulation of the gene. While proteasome inhibitors are part of first-line MM treatment, several of the new anti-MM immune therapeutic drugs target BCMA. Thus, TLR activation may render MM cells less responsive to commonly used anti-myeloma drugs., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tryggestad, Roseth, Aass, Ørning, Mjelle, Hella and Standal.)

B-cell maturation antigen (BCMA)-targeting immunotherapies (e.g., chimeric antigen receptor T cells (CAR-T) and bispecific antibodies (BsAbs)) have achieved remarkable clinical responses in patients with relapsed and/or refractory multiple myeloma (RRMM). Their use is accompanied by exaggerated immune responses related to T-cell activation and cytokine elevations leading to cytokine release syndrome (CRS) in some patients, which can be potentially life-threatening. However, systematic evaluation of the risk of CRS with BCMA-targeting BsAb and CAR-T therapies, and comparisons across different routes of BsAb administration (intravenous (i.v.) vs. subcutaneous (s.c.)) have not previously been conducted. This study utilized a meta-analysis approach to compare the CRS profile in BCMA-targeting CAR-T vs. BsAb immunotherapies administered either i.v. or s.c. in patients with RRMM. A total of 36 studies including 1,560 patients with RRMM treated with BCMA-targeting CAR-T and BsAb therapies were included in the analysis. The current analysis suggests that compared with BsAbs, CAR-T therapies were associated with higher CRS incidences (88% vs. 59%), higher rates of grade ≥ 3 CRS (7% vs. 2%), longer CRS duration (5 vs. 2 days), and more prevalent tocilizumab use (44% vs. 25%). The proportion of CRS grade ≥ 3 may also be lower (0% vs. 4%) for BsAb therapies administered via the s.c. (3 studies, n = 311) vs. i.v. (5 studies, n = 338) route. This meta-analysis suggests that different types of BCMA-targeting immunotherapies and administration routes could result in a range of CRS incidence and severity that should be considered while evaluating the benefit-risk profiles of these therapies., (© 2024 Pfizer, Inc. Clinical Pharmacology & Therapeutics published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

B-cell-maturation-antigen (BCMA)-directed therapies are highly active for multiple myeloma, but infections are emerging as a major challenge. In this retrospective, single-center analysis we evaluated infectious complications after BCMA-targeted chimeric-antigen-receptor T-cell therapy (CAR-T), bispecific-antibodies (BsAb) and antibody-drug-conjugates (ADC). The primary endpoint was severe (grade ≥3) infection incidence. Amongst 256 patients, 92 received CAR-T, 55 BsAb and 109 ADC. The incidence of severe infections was higher with BsAb (40%) than CAR-T (26%) or ADC (8%), including grade 5 infections (7% vs 0% vs 0%, respectively). Comparing T-cell redirecting therapies, the incidence rate of severe infections was significantly lower with CAR-T compared to BsAb at 1-year (incidence-rate-ratio [IRR] = 0.43, 95%CI 0.25-0.76, P = 0.004). During periods of treatment-emergent hypogammaglobulinemia, BsAb recipients had higher infection rates (IRR:2.27, 1.31-3.98, P = 0.004) and time to severe infection (HR 2.04, 1.05-3.96, P = 0.036) than their CAR-T counterparts. During periods of non-neutropenia, CAR-T recipients had a lower risk (HR 0.44, 95%CI 0.21-0.93, P = 0.032) and incidence rate (IRR:0.32, 95% 0.17-0.59, P < 0.001) of severe infections than BsAb. In conclusion, we observed an overall higher and more persistent risk of severe infections with BsAb. Our results also suggest a higher infection risk during periods of hypogammaglobulinemia with BsAb, and with neutropenia in CAR-T recipients., (© 2024. The Author(s).)

Background: BCMA-directed autologous chimeric antigen receptor T (CAR-T) cells have shown excellent clinical efficacy in relapsed or refractory multiple myeloma (RRMM), however, the current preparation process for autologous CAR-T cells is complicated and costly. Moreover, the upregulation of CD47 expression has been observed in multiple myeloma, and anti-CD47 antibodies have shown remarkable results in clinical trials. Therefore, we focus on the development of BCMA/CD47-directed universal CAR-T (UCAR-T) cells to improve these limitations., Methods: In this study, we employed phage display technology to screen nanobodies against BCMA and CD47 protein, and determined the characterization of nanobodies. Furthermore, we simultaneously disrupted the endogenous TRAC and B2M genes of T cells using CRISPR/Cas9 system to generate TCR and HLA double knock-out T cells, and developed BCMA/CD47-directed UCAR-T cells and detected the antitumor activity in vitro and in vivo., Results: We obtained fourteen and one specific nanobodies against BCMA and CD47 protein from the immunized VHH library, respectively. BCMA/CD47-directed UCAR-T cells exhibited superior CAR expression (89.13-98.03%), and effectively killing primary human MM cells and MM cell lines. BCMA/CD47-directed UCAR-T cells demonstrated excellent antitumor activity against MM and prolonged the survival of tumor-engrafted NCG mice in vivo., Conclusions: This work demonstrated that BCMA/CD47-directed UCAR-T cells exhibited potent antitumor activity against MM in vitro and in vivo, which provides a potential strategy for the development of a novel "off-the-shelf" cellular immunotherapies for the treatment of multiple myeloma., (© 2024. The Author(s).)

CAR-T cell therapy is at the forefront of next-generation multiple myeloma (MM) management, with two B-cell maturation antigen (BCMA)-targeted products recently approved. However, these products are incapable of breaking the infamous pattern of patient relapse. Two contributing factors are the use of BCMA as a target molecule and the artificial scFv format that is responsible for antigen recognition. Tackling both points of improvement in the present study, we used previously characterized VHHs that specifically target the idiotype of murine 5T33 MM cells. This idiotype represents one of the most promising yet challenging MM target antigens, as it is highly cancer- but also patient-specific. These VHHs were incorporated into VHH-based CAR modules, the format of which has advantages compared to scFv-based CARs. This allowed a side-by-side comparison of the influence of the targeting domain on T cell activation. Surprisingly, VHHs previously selected as lead compounds for targeted MM radiotherapy are not the best (CAR-) T cell activators. Moreover, the majority of the evaluated VHHs are incapable of inducing any T cell activation. As such, we highlight the importance of specific VHH selection, depending on its intended use, and thereby raise an important shortcoming of current common CAR development approaches.

Given the global surge in autoimmune diseases, it is critical to evaluate emerging therapeutic interventions. Despite numerous new targeted immunomodulatory therapies, comprehensive approaches to apply and evaluate the effects of these treatments longitudinally are lacking. Here, we leveraged advances in programmable-phage immunoprecipitation methodology to explore the modulation, or lack thereof, of autoantibody profiles, proteome-wide, in both health and disease. Using a custom set of over 730,000 human-derived peptides, we demonstrated that each individual, regardless of disease state, possesses a distinct and complex constellation of autoreactive antibodies. For each individual, the set of resulting autoreactivites constituted a unique immunological fingerprint, or "autoreactome," that was remarkably stable over years. Using the autoreactome as a primary output, we evaluated the relative effectiveness of various immunomodulatory therapies in altering autoantibody repertoires. We found that therapies targeting B cell maturation antigen (BCMA) profoundly altered an individual's autoreactome, while anti-CD19 and anti-CD20 therapies had minimal effects. These data both confirm that the autoreactome comprises autoantibodies secreted by plasma cells and strongly suggest that BCMA or other plasma cell-targeting therapies may be highly effective in treating currently refractory autoantibody-mediated diseases.

Purpose: B-cell maturation antigen (BCMA)-chimeric antigen receptor T-cells (CART) improve results obtained with conventional therapy in the treatment of relapsed/refractory multiple myeloma. However, the high demand and expensive costs associated with CART therapy might prove unsustainable for health systems. Academic CARTs could potentially overcome these issues. Moreover, response biomarkers and resistance mechanisms need to be identified and addressed to improve efficacy and patient selection. Here, we present clinical and ancillary results of the 60 patients treated with the academic BCMA-CART, ARI0002h, in the CARTBCMA-HCB-01 trial., Patients and Methods: We collected apheresis, final product, peripheral blood and bone marrow samples before and after infusion. We assessed BCMA, T-cell subsets, CART kinetics and antibodies, B-cell aplasia, cytokines, and measurable residual disease by next-generation flow cytometry, and correlated these to clinical outcomes., Results: At cut-off date March 17, 2023, with a median follow-up of 23.1 months (95% CI, 9.2-37.1), overall response rate in the first 3 months was 95% [95% confidence interval (CI), 89.5-100]; cytokine release syndrome (CRS) was observed in 90% of patients (5% grades ≥3) and grade 1 immune effector cell-associated neurotoxicity syndrome was reported in 2 patients (3%). Median progression-free survival was 15.8 months (95% CI, 11.5-22.4). Surface BCMA was not predictive of response or survival, but soluble BCMA correlated with worse clinical outcomes and CRS severity. Activation marker HLA-DR in the apheresis was associated with longer progression-free survival and increased exhaustion markers correlated with poorer outcomes. ARI0002h kinetics and loss of B-cell aplasia were not predictive of relapse., Conclusions: Despite deep and sustained responses achieved with ARI0002h, we identified several biomarkers that correlate with poor outcomes., (©2024 American Association for Cancer Research.)

Abstract: For patients with relapsed/refractory multiple myeloma with a relapse after B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T-cell therapy (CAR-T), optimal salvage treatment strategies remain unclear. BCMA-directed CAR-T and bispecific antibodies (BsAbs) are now commercially available, and the outcomes for retreatment with BCMA-directed approaches are not well studied. We performed a retrospective analysis of 68 patients with relapsed disease after BCMA-directed CAR-T to evaluate outcomes and responses to salvage therapies. With a median follow-up of 13.5 months, median overall survival from time of relapse until death was 18 months (95% confidence interval [CI], 13.2 to not reached [NR]). Fifty-eight patients received subsequent myeloma-directed therapies, with a total of 265 lines of therapy (LOTs). The overall response rate for firstline salvage therapy was 41% (95% CI, 28-55). Among all LOTs, high response rates were observed among those receiving another BCMA-directed CAR-T (89%), BCMA-directed BsAbs (60%), CD38-directed combinations (80% when combined with BsAb; 50% when combined with immunomodulatory drugs and/or proteasome inhibitors), and alkylator-combinations (50% overall; 69% with high-dose alkylators). Thirty-four patients received at least 1 line of salvage BCMA-directed therapy; median progression-free survival was 8.3 months (95% CI, 7.9 to NR), 3.6 months (95% CI, 1.4 to NR), and 1 month (95% CI, 0.9 to NR) with median duration of response (DOR) of 8 months, 4.4 months, and 2.8 months for subsequent BCMA-directed CAR-T, BsAb, and belantamab mafadotin, respectively. Retreatment with BCMA-directed CAR-T and BsAbs can be effective salvage options after BCMA-directed CAR-T relapse; however, DORs appear limited, and further studies with new combinations and alternative targets are warranted., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Purpose: Although chimeric antigen receptor T therapy (CAR-T) cells are an established therapy for relapsed/refractory multiple myeloma (RRMM), there are no established models predicting outcome to identify patients who may benefit the most from CAR-T., Patients and Methods: This is an international retrospective observational study including patients with RRMM infused with currently available commercial or academically produced anti-B-cell maturation antigen (BCMA) CAR-T. We describe characteristics and outcomes in Europe (n = 136) and the United States (n = 133). Independent predictors of relapse/progression built a simple prediction model (Myeloma CAR-T Relapse [MyCARe] model) in the training cohort (Europe), which was externally validated (US cohort) and tested within patient- and treatment-specific subgroups., Results: The overall response rate was 87% and comparable between both cohorts, and complete responses were seen in 48% (Europe) and 49% (the United States). The median time to relapse was 5 months, and early relapse <5 months from infusion showed poor survival across cohorts, with the 12-month overall survival of 30% (Europe) and 14% (the United States). The presence of extramedullary disease or plasma cell leukemia, lenalidomide-refractoriness, high-risk cytogenetics, and increased ferritin at the time of lymphodepletion were independent predictors of early relapse or progression. Each factor received one point, forming the three-tiered MyCARe model: scores 0-1 (low risk), scores 2-3 (intermediate risk), and a score of 4 (high risk). The MyCARe model was significantly associated with distinct 5-month incidence of relapse/progression ( P < .001): 7% for low-risk, 27% for intermediate-risk, and 53% for high-risk groups. The model was validated in the US cohort and maintained prognostic utility for response, survival, and outcomes across subgroups., Conclusion: Outcomes of patients with RRMM after CAR-T are comparable between Europe and the United States. The MyCARe model may facilitate optimal timing of CAR-T cells in patient-specific subgroups.