B-cell maturation antigen (BCMA)-targeting therapy is the most common approach to immunotherapy and cellular therapy for multiple myeloma (MM). Three major agents, CAR-T cells, bispecific antibodies, and ADC have been developed as novel therapeutic agents. CAR-T therapy showed favorable efficacy in the treatment of relapsed and refractory MM (RR MM) and was tried in early lines of therapy. Similarly, bispecific antibodies targeting BCMA or other targets have also shown promising effects in treatment of RR MM, and have been now tested in combination with other agents. Although issues such as poor fitness or exhaustion of T cells and increased susceptibility to viral infection remain to be fully resolved, novel immunotherapies and cellular therapies should further improve the prognosis of patients with RR MM.

Objective: The effect of bone marrow soluble B cell maturation antigen (sBCMA) expression on the efficacy and side effects of chimeric antigen receptor (CAR) -modified T-cell-targeting B cell maturation antigen (BCMA) in patients with multiple myeloma (MM) . Methods: This study involved 29 patients with relapsed or refractory MM (RRMM) who received humanized anti-BCMA CAR-T cell clinical trials from January 2018 to December 2021. The expression of sBCMA in bone marrow before and after anti-BCMA CAR-T cell treatment was detected by flow cytometry and compared. Results: ①Two months after BCMA CAR-T cell treatment, 20 patients (68.97%) achieved an overall response (OR), whereas nine patients had stable disease (SD) or miner emission (MR). ②The expression of sBCMA in the bone marrow of 20 patients with OR was higher before treatment than after [26 926 (18 215, 32 488) ng/L vs 9 968 (6 634, 11 459) ng/L; P<0.001]; no significant difference was observed in patients with MR and SD [41 187 (33 816, 47 046) ng/L vs. 33 954 (31 569, 36 256) ng/L; P=0.145]; sBCMA expression in patients with OR before CAR-T cell treatment was lower than in patients with MR and SD (P=0.005). ③No significant linear correlation was found between the peak value of CAR-T cells and sBCMA expression in the bone marrow of all 29 patients with RRMM (R(2)=0.035, P=0.330). ④No significant difference in sBCMA expression was found between grades 0-1 CRS group (13 patients) and grades 2-4 CRS group [16 patients; 32 045 (18 742, 40 801) ng/L vs 29 102 (24 679, 38 776) ng/L, P=0.879], nor between grade 0 ICANS group (22 patients) and grade 1-3 ICANS group [seven patients; 30 073 (19 375, 40 065) ng/L vs 33 816 (22 933, 43 459) ng/L, P=0.763]. Conclusion: sBCMA expression in the bone marrow is related to the efficacy of BCMA CAR-T cell therapy in patients with RRMM, but is not significantly correlated with the severity of adverse events. It may serve as a predictive biomarker for the efficacy of BCMA CAR-T cell therapy in these patients.
目的： 探索多发性骨髓瘤（MM）患者骨髓可溶性B细胞成熟抗原（sBCMA）表达对靶向B细胞成熟抗原（BCMA）的嵌合抗原受体T细胞（CAR-T细胞）治疗疗效及安全性的影响。 方法： 以2018年1月至2021年12月接受人源化抗BCMA CAR-T细胞临床试验的29例复发/难治MM（RRMM）患者为研究对象。流式细胞术检测抗BCMA CAR-T细胞治疗前后骨髓sBCMA的表达并进行差异比较。 结果： ①BCMA CAR-T细胞治疗2个月，20例（68.97%）患者获得总体反应（OR），9例患者仅为病情稳定（SD）或微小缓解（MR）。②20例OR组患者骨髓sBCMA表达治疗前高于治疗后[26 926（18 215, 32 488）ng/L对9 968（6 634, 11 459）ng/L，P<0.001]；而MR+SD组患者骨髓sBCMA表达治疗前后差异无统计学意义[41 187（33 816, 47 046）ng/L对33 954（31 569, 36 256）ng/L，P=0.145]；CAR-T细胞治疗前骨髓sBCMA表达OR组低于MR+SD组患者（P=0.005）。③全部29例RRMM患者CAR-T细胞峰值与骨髓sBCMA表达无明显线性相关性（R(2)=0.035，P=0.330）。④sBCMA表达水平与CAR-T细胞治疗不良事件严重程度的相关性：0~1级细胞因子释放综合征（CRS）组（13例）与2~4级CRS组（16例）比较骨髓sBCMA表达差异无统计学意义[32 045（18 742, 40 801）ng/L对29 102（24 679, 38 776）ng/L，P=0.879]；0级免疫效应细胞相关神经毒性综合征（ICANS）组（22例）与1~3级ICANS组（7例）比较骨髓sBCMA表达差异无统计学意义[30 073（19 375, 40 065）ng/L对33 816（22 933, 43 459）ng/L，P=0.763]。 结论： 骨髓sBCMA表达与RRMM患者接受BCMA CAR-T细胞治疗的疗效有关，但与不良事件严重程度无显著相关性。或可作为RRMM患者接受BCMA CAR-T细胞治疗的疗效预测标志物。.

BACKGROUND: Multiple myeloma (MM) with extramedullary disease (EMD) is rare in clinical practice, and B cell maturation antigen (BCMA) CAR-T cell therapy is a novel therapy for hematologic malignancies. Very few reports have been published on the effect of CAR-T-cell therapy in MM with EMD. Here, we report a case of MM with extramedullary lesions treated with BCMA CAR-T therapy.
METHODS: A 66-year-old female patient presented to our hospital with an enlarged left maxillary gingiva.
METHODS: Diagnosis of indolent MM stage III (DS staging) and stage III (ISS and R ISS) with extramedullary lesions.
METHODS: The patient underwent a clinical trial of humanized anti-BCMA CAR T cell therapy.
RESULTS: Symptoms improved; left gingival hyperplasia and swelling resolved; left buccal mass resolved; and neck and submandibular masses resolved. Pathological examination of the exfoliated masses showed necrotic tissue.
CONCLUSIONS: MM with extramedullary lesions often has limited treatment options, and traditional chemotherapy methods are ineffective; however, BCMA CAR-T cell therapy can significantly improve the symptoms of extramedullary lesions in MM.

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.

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.

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.

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.

BACKGROUND: Despite advances, most patients with multiple myeloma (MM) experience relapse and repeat multiple treatment lines, highlighting an unmet need for patients with relapsed or refractory MM (RRMM). Bispecific antibodies are a new option, but their efficacy and safety in Japanese patients are unknown.
METHODS: This was an analysis of Japanese patients receiving elranatamab monotherapy in MagnetisMM-2 (NCT04798586) and MagnetisMM-3 (NCT04649359). Both studies evaluated a priming dose regimen of elranatamab followed by weekly subcutaneous doses, in patients with disease progression while receiving or who were intolerant to ≥3 prior therapies (≥1 proteasome inhibitor, ≥1 immunomodulatory drug and ≥1 anti-CD38 monoclonal antibody). The primary endpoints were dose limiting toxicities (DLTs) in MagnetisMM-2 and confirmed objective response rate (ORR) in MagnetisMM-3. In both, key secondary endpoints included safety, tolerability, duration of response, time to response, progression-free survival and overall survival.
RESULTS: In MagnetisMM-2 (N = 4) and MagnetisMM-3 (n = 12), median ages were 68.5 and 66.5 years, respectively. No DLTs were observed in MagnetisMM-2. ORRs were 50.0% (95% CI, 6.8-93.2) and 58.3% (95% CI, 27.7-84.8) in MagnetisMM-2 and MagnetisMM-3, respectively. All patients experienced treatment-emergent adverse events in MagnetisMM-2 (grade 3/4: 75.0%) and MagnetisMM-3 (grade 3/4: 100%); cytokine release syndrome occurred in 100% (grade 3/4: 25.0%) and 58.3% (no grade 3/4) of patients, respectively. Neither study reported immune effector cell-associated neurotoxicity syndrome.
CONCLUSIONS: No new safety signals were observed, and ORRs were similar to that of the overall MagnetisMM-3 trial population, supporting further studies of elranatamab in Japanese patients with RRMM. ClinicalTrials.gov identifier: NCT04798586 (MagnetisMM-2), NCT04649359 (MagnetisMM-3).

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.

UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.