Anti-BCMA CAR T-Cell Therapy Research Articles

Single-cell analysis of refractory anti-SRP necrotizing myopathy treated with anti-BCMA CAR-T cell therapy

Immune-mediated necrotizing myopathy (IMNM) is an autoimmune disorder associated with the presence of autoantibodies, characterized by severe clinical presentation with rapidly progressive muscular weakness and elevated levels of creatine kinase, while traditional pharmacological approaches possess varying and often limited effects. Considering the pathogenic role of autoantibodies, chimeric antigen receptor (CAR)-T cells targeting B cell maturation antigen (BCMA) have emerged as a promising therapeutic strategy. We reported here a patient with anti-signal recognition particle IMNM refractory to multiple available therapies, who was treated with BCMA-targeting CAR-T cells, exhibited favorable safety profiles, sustained reduction in pathogenic autoantibodies, and persistent clinical improvements over 18 mo. Longitudinal single-cell RNA, B cell receptor, T cell receptor sequencing analysis presented the normalization of immune microenvironment after CAR-T cell infusion, including reconstitution of B cell lineages, replacement of T cell subclusters, and suppression of overactivated immune cells. Analysis on characteristics of CAR-T cells in IMNM demonstrated a more active expansion of CD8+ CAR-T cells, with a dynamic phenotype shifting pattern similar in CD4+ and CD8+ CAR-T cells. A comparison of CD8+ CAR-T cells in patients with IMNM and those with malignancies collected at different timepoints revealed a more NK-like phenotype with enhanced tendency of cell death and neuroinflammation and inhibited proliferating ability of CD8+ CAR-T cells in IMNM while neuroinflammation might be the distinct characteristics. Further studies are warranted to define the molecular features of CAR-T cells in autoimmunity and to seek higher efficiency and longer persistence of CAR-T cells in treating autoimmune disorders.

Functional Imaging As a Key Diagnostic Tool in the Follow-up of RRMM Patients after CAR-T-Cell Therapy

Introduction: Anti BCMA CAR T-cell therapy (CART) is establishing itself as a new standard of care for relapsed and refractory multiple myeloma (RRMM). However, the optimal follow-up strategy post CART has yet to be determined. Prior studies of our own and others have emphasized the role of functional imaging in monitoring RRMM patients post traditional chemotherapy, revealing residual disease in up to 50 % of otherwise minimal residual disease (MRD) negative patients (Rasche et al. Leukemia 2019). Whether a similar patchy disease pattern is relevant post CART remains unknown. To address this, we implemented a standardized follow-up program post CART, which includes 18F-FDG PET-CT, diffusion-weighted MRI, and bone marrow aspiration with MRD measurements at our center. Methods: We conducted monthly ambulatory visits and serological testing to monitor patients post CART infusion. Additionally, an extended follow-up visit at three months post CART infusion was performed, encompassing whole body PET-CT, whole body diffusion-weighted MRI, and bone marrow aspiration with MRD testing. Response assessments were based on IMWG criteria. MRI classified focal lesions as vital if they exhibited 1) significant diffusion-restriction, 2) a fat fraction less than 20 %, and 3) homogenous hypointensity on T2-weighted images. MRD measurements were performed with flow cytometry with a sensitivity of at least 10 -5 following the Euroflow recommendations. Results: From December 2021 to July 2023 we treated 37 heavily pretreated patients with idecabtagene vicleucel at our center. These patients had a median of 5 prior lines of therapy. High-risk cytogenetics, extra-medullary disease (EMD), and non-secretory disease were seen in 17, 14 and 6 patients, respectively. At data cut off, the ORR, VGPR and CR rates were 78 %, 27 % and 27 %, respectively. We observed primary refractory disease in 14 % of the patients. Among the 22 patients who underwent extended follow-up examinations at three months, the majority achieved MRD negativity, with only 7/22 (32 %) remaining MRD positive after CART. However, functional imaging revealed a higher number of patients with residual disease, with positive results on PET-CT and DW-MRI in 9/22 (41 %) and 10/22 (45 %) of patients, respectively. Notably, 6 of 22 (27 %) patients displayed active lesions on imaging despite MRD negativity at the iliac crest at this time point. Next, we focused on patients who experienced relapse from CART and sought to determine the necessary technology to detect relapse in this setting. Thirteen patients experienced relapse during the study period, and in 8 (61%) of them, functional imaging was the sole method to detect progressive disease. Only 1 patient transitioned from MRD negative to positive during the follow-up period, while the remaining 4 patients showed a significant M protein increase as defined by the IMWG criteria. Conclusion: In our heavily pretreated RRMM population, functional imaging emerged as a crucial diagnostic tool, detecting relapse alone in more than half of the patients. Our data supports inclusion of cross-sectional imaging in a comprehensive follow-plan after CART.

High Efficacy and Safety of Nanobody Based Anti-BCMA CAR-T Cell Therapy in Treating Patients with Relapsed or Refractory Multiple Myeloma

Introduction Refractory or relapsed (R/R) multiple myeloma (MM) is often associated with a poor prognosis following chemotherapy or even transplantation. BCMA-targeted CAR-T therapy has demonstrated notable efficacy in R/R MM. In the past, the overall response rate (ORR) was relatively low at around 60%, but in recent years, advancements in the manufacturing of BCMA-CAR-T products have led to a substantial improvement in efficacy. Here we explore the efficacy and safety of nanobody-based anti-BCMA CAR-T cell therapy in R/R MM from a clinical trial (https://clinicaltrials.gov NCT04447573). Methods Autologous peripheral blood lymphocytes were collected from patients, who subsequently underwent intravenous fludarabine (30mg/m 2/d) and cyclophosphamide (300mg/m 2/d) lymphodepletion chemotherapy from day-5 to day -3. The SL-BCMA CAR molecule, an anti-BCMA CAR-T cell product generated by Senlang Biotechnology, features a structure that includes dual nanobody VHHs targeting BCMA (dVHHs), CD8α hinge region, CD8α transmembrane domain (TMD), co-stimulatory domain (4-1BB), and CD3 zeta domain (CD3ζ). Among them, dVHHs consist of two different VHHs connected by short peptides. The CD8α hinge region provides an effective spatial architecture for the binding of dVHHs and BCMA protein. The first signal of CAR-T cell activation is completed along with the intracellular CD3ζ domain. The 4-1BB intracellular co-stimulatory domain provides co-stimulatory signals for the activation of CAR-T cells. Under the dual signal stimulation, CAR-T cells are activated and expanded. After the BCMA CAR-T cells infusion on day 0, patients underwent evaluations, including immunoglobulin fixed electrophoresis, free light chains in blood and urine, bone marrow penetration, and whole-body PET CT to evaluate the efficacy at the first month, second and third month, and every three months thereafter. Results From April 2021 to May 2023, 21 R/R MM patients in our hospital were treated with SL-BCMA CAR-T, including 10 males and 11 females. The median age is 57 years (30-73 years). Among them, there were 2 cases with Plasma cell leukemia, 10 had extramedullary multiple lesions, and 2 had paralysis caused by central nervous system infiltration. Pre-CAR-T, 11 patients had a prior transplant history including 10 who relapsed after autologous transplantation and 1 who relapsed after allogeneic transplantation. One patient had a rare type of anaplastic Plasma cell tumor. Seven patients presented high-risk factors characterized by FISH abnormalities such as t (4; 14) (p16; q32), t (14; 16) (q32; q23), and 3 had TP53 mutations. The median BCMA expression rate among 19 patients was 53.3% (range: 18.5% -100%), while the remaining 2 patients displayed non-BCMA expression. The median BCMA CAR-T cell dose was 1*10 6/Kg (0.3-2*10 6/Kg). One month following BCMA-CAR-T cell infusion, the ORR was 95%(20/21), and the CR rate was 38% (8/21). The patient who initially showed no response achieved a partial response following a second infusion of BCMA-CAR-T cells. One died at about 2.5 months due to lung infection. Evaluations conducted at the three-month mark showed an ORR of 95% (19/20) and a CR rate of 80% (16/20). One patient relapsed at the second month and underwent salvage allogeneic hematopoietic stem cell transplantation. For the long follow-up data, the median duration of remission was 11 months. Of the 7 deaths, 2 were attributed to infection during disease control, and 5 were due to disease progression. (Figure 1) In terms of side effects, 6 patients developed grade 2 cytokine release syndrome (CRS), and only 1 patient developed grade 3 CRS. Only one patient had grade 1 neurotoxicity. Conclusions The clinical trial demonstrated that BCMA CAR-T therapy, composed of dual nanobody VHHs targeting BCMA (dVHHs), exhibits a high ORR with a manageable safety profile in treating R/R MM patients. This extends even to high-risk patients, such as those with extramedullary lesions, cytogenetics high-risk groups, and patients with plasma cell leukemia or anaplastic plasma cell tumor.

Immune Dynamics Associated with Patient Outcomes Identified By Multimodal Single-Cell Analysis in Multiple Myeloma Patients Receiving Talquetamab Monotherapy

Background: Talquetamab (Tal) is a CD3xGPRC5D bispecific antibody (BiAb) that redirects endogenous T cells to mediate killing of GPRC5D-expressing multiple myeloma (MM) cells. In the recent phase I/II MonumenTAL-1 trial (NCT03399799), Tal showed ≥ 70% response rate when given at the recommended phase 2 doses (RP2D) in heavily pretreated MM patients (Chari A et al., NEJM 2022). However, there is still a need to identify predictive biomarkers and better understand the immune dynamics associated with treatment response and durability with this novel agent. Methods:We identified 30 patients who received Tal monotherapy and had bone marrow (BM) and peripheral blood (PB) samples collected at baseline and PB collected at cycle 3 day 1 (C3D1). Cellular indexing of transcriptomes and epitopes (CITE)-seq was performed to understand transcriptional changes and cell surface proteomics. Total cells were isolated by Ficoll separation from PB and BM samples and were then analyzed separately and only samples of good quality were included in the analysis. Samples were filtered for good quality based on total cell count: at least 1000 cells with more than 500 unique molecular identifiers (UMIs) or genes and less than 4-5 standard deviations above median for UMI, genes and mitochondrial transcripts. A total of 60,851 BM cells (15 pts at baseline) and 299,996 PB cells (23 pts at baseline and 17 pts on C3D1) were analyzed. Downstream analysis was performed using the Seurat R package. All patients included in this study had signed consent for an IRB-approved institutional sub-study (GCO # 18-00456). Results: The 30 patients had a median age of 66.2 years and 57% were female. They received a median of 6 prior lines of therapy, with 83% being triple-class refractory and 50% penta-drug refractory. Only 2 patients were previously treated with anti-BCMA CAR-T cell therapy and none were treated with other BiAbs. 43% of patients had high-risk cytogenetics (including t(4;14), t(14;16) and 17p deletion) and 13% had extramedullary disease at time of initiating therapy. Ten patients (30%) received the recommended phase 2 dose (RP2D) of Tal (0.4 mg/kg weekly or 0.8 mg/kg every other week). Patients were followed for a median of 32.5 months and had a median progression-free survival (PFS) of 6.7 months. 22/30 patients (73%) achieved a partial response (PR) or better, and 14 patients had a short PFS of <150 days. There was no association between the prevalence of different immune cell subsets and depth of response, but rather with PFS. In the baseline BM, a longer PFS was associated with a higher percentage of CD8+ cytotoxic T cells (central memory p=0.00031, effector memory p=0.0022, EMRA p=0.014) and a trend towards higher CD4+ cytotoxic T cells (p=0.072). Of note, we did not find the same associations in the baseline PB samples, which may indicate that the PB may not always reflect the tumor microenvironment in the BM. When we next looked at immune changes in the PB of patients with longer PFS, we found that they exhibited higher percentage of NK cells (p=0.0018 for CD56 low, p=0.04 for CD56 high) and Gamma Delta T cells (p=0.04) at C3D1. Gamma Delta T cells are novel players that warrant further investigation, as they only constitute 1-5% of the T cell repertoire yet are involved in early immune response and do not require major histocompatibility complex (MHC) antigen presentation to function. Profiling of activation and exhaustion markers of these immune subsets is underway. Conclusion: Our findings highlight that the baseline BM immune repertoire and the PB immune changes during Tal treatment may predict long term outcomes. Further in vitro mechanistic studies of T cell function and fitness and validation of these results in independent cohorts will be critical to develop these into predictive biomarkers of long-term response to Tal.

Incidence of Parkinsonism As a Complication of Anti-BCMA CAR-T Cell Therapy in Multiple Myeloma

Introduction: B-cell maturation antigen (BCMA)-directed chimeric antigen receptor T-cell (CAR T) therapy has revolutionized the treatment for relapsed/refractory multiple myeloma (RRMM). Two BCMA-directed CAR T products, Idecabtagene Vicleucel (ide-cel) and Ciltacabtagene Autoleucel (cilta-cel), have received approval from the U.S. Food and Drug Administration (FDA). While these therapies have demonstrated remarkable efficacy, concerns regarding treatment-related neurotoxicities have emerged. The specific adverse effect of Parkinsonism associated with BCMA-directed CAR T therapy has not been adequately studied. Methods: We conducted an analysis utilizing the FDA Adverse Events Reports System (FAERS) database, covering the years 2021-2023. Our search focused on the reported incidence of Parkinsonism associated with BCMA-directed CAR T therapy. Results: Upon reviewing the FDA data, we identified a total of 177 patients with reported nervous system disorders related to Ide-cel therapy. Out of these patients, 2 had reported incidents of Parkinsonism. Similarly, for Cilta-cel therapy, there were 81 patients with reported nervous system disorders, with 5 reported incidents of Parkinsonism. Out of the total 7 reported patients with Parkinsonism, 5 were males, 2 were females, the average age was 67, the average weight was 68.9 kg, and 3 patients were also noted to have associated cytokine release syndrome. Conclusion: Our analysis of FAERS data highlights the occurrence of Parkinsonism associated with BCMA-directed CAR T-cell therapy. Further studies are required to quantify the need for neurological surveillance after initiating treatment with these novel agents.

P-011 Hematopoietic reconstitution and infections after anti-BCMA CAR T-cell therapy in relapsed/ refractory multiple myeloma are associated with pre-CAR-T bridging therapies

P-011 Hematopoietic reconstitution and infections after anti-BCMA CAR T-cell therapy in relapsed/ refractory multiple myeloma are associated with pre-CAR-T bridging therapies

P-036 Real world single center expeirence of long-term toxicities with anti-BCMA CAR T-cell therapy in relapsed and refractory multiple myeloma

P-036 Real world single center expeirence of long-term toxicities with anti-BCMA CAR T-cell therapy in relapsed and refractory multiple myeloma

P-048 Point-of-care anti-BCMA CAR T-cell therapy induces encouraging response rates in relapsed/ refractory multiple myeloma patients mostly with high-risk disease features

P-048 Point-of-care anti-BCMA CAR T-cell therapy induces encouraging response rates in relapsed/ refractory multiple myeloma patients mostly with high-risk disease features

A first-in-human phase 1, multicenter, open-label study of CB-011, a next-generation CRISPR-genome edited allogeneic anti-BCMA immune-cloaked CAR-T cell therapy, in patients with relapsed/refractory multiple myeloma (CAMMOUFLAGE trial).

TPS8063 Background: Autologous CAR-T cell therapies have shown significant benefit in the treatment of adults with relapsed/refractory multiple myeloma (r/r MM). However, these CAR-T cell therapies may have inherent challenges, including functional deficiencies in the patient’s T cells, that could yield an inconsistent or impaired product, as well as require extended time and complexity in manufacturing, thereby limiting patient access and potentially requiring bridging therapy. CB-011 is an allogeneic, off-the-shelf anti-BCMA CAR-T cell therapy derived from healthy donor T cells. A next-generation CRISPR-Cas12a genome-editing technology using CRISPR hybrid RNA-DNA (chRDNA) guides, developed at Caribou to significantly reduce off-target editing, was implemented to generate 4 genome edits in the manufacture of CB-011: (i) the TRAC gene was knocked out to eliminate T cell receptor (TCR) expression and prevent graft versus host disease (GvHD), (ii) the BCMA-specific CAR was site-specifically inserted into the genome at the TRAC locus to eliminate random integration and serves to target the tumor antigen, (iii) the B2M gene was knocked out to eliminate expression of HLA class I molecules to mitigate host T cell cytotoxicity, and (iv) a B2M-HLA-E fusion transgene was site-specifically inserted into the genome at the B2M locus to overcome host NK cell-mediated killing following recognition of “missing self.” This immune cloaking strategy has the potential to allow persistent antitumor activity of the CAR-T cells in the context of antigen engagement. Significant preclinical efficacy in vitro and in vivo supports the clinical evaluation of CB-011. Methods: CB-011 is being evaluated in a multicenter, Phase 1 clinical trial in patients with r/r MM. A 3+3 dose escalation design followed by expansion at the maximum tolerated dose (MTD) and/or the recommended Phase 2 dose (RP2D) is being utilized. Primary objectives are to determine the safety and tolerability of CB-011, and the recommended Phase 2 dose (RP2D). Additional key objectives include preliminary antitumor activity and pharmacokinetics (PK). After concurrently receiving lymphodepletion therapy with cyclophosphamide (300 mg/m2/d) and fludarabine (30 mg/m2/d) for 3 days, patients receive a single dose infusion of CB-011 and are followed for safety and efficacy. Antitumor activity and disease response are measured by International Myeloma Working Group criteria. The CaMMouflage Phase 1 trial is actively enrolling patients and additional information is available on clinicaltrials.gov (NCT05722418). Clinical trial information: NCT05722418 .

Pseudoprogression and Sarcoidosis-like Phenomena after CART-Cells and Bispecific Antibodies in Multiple Myeloma

Introduction: CAR T-cell therapy is establishing itself as a new standard of care in relapsed and refractory multiple myeloma (RRMM). Yet, there are a number of open issues including the lack of data on optimal follow-up assessments post CAR T therapy. Appreciating the high incidence of extramedullary lesions and patchy disease patterns seen in the RRMM setting, whole body 18F-Fluorodeoxyglucose (FDG) PET/CT imaging is increasingly used. Whether FDG is the best tracer in this setting has yet to be determined, as the technique is being based not only on the quantification of increased glucose uptake by tumor cells but also by others such as inflammatory cells. A phenomenon linked to this issue is pseudoprogression, which refers to an increase in the target lesion size due to influx of immune cells that may be misinterpreted as disease relapse. Pseudoprogression is a well-known event after checkpoint blockade therapy, seen in up to 10% of patients with solid cancers. Whether myeloma patients treated with CAR T or bispecific antibodies are at risk for pseudoprogression is, to the best of our knowledge, unknown. Methods: We present a case study of a RRMM patient who experienced pseudoprogression twice during his course of disease treatment that included BCMA CAR T cells Idecabtagene vicleucel and GPRC5DxCD3 bispecific antibody talquetamab. We performed a comprehensive molecular analysis including single cell RNAseq from bronchoalveolar lavage as well as PET imaging using the three PET tracers 18F-FDG, 68Ga-DOTATOC, and 68Ga-Pentixafor (binds to CXCR4) to unravel the biology underlying pseudoprogression in this case. Results: A 61-year-old Caucasian male was diagnosed with biopsy-proven pulmonary MM and treated with BCMA targeting CAR T cells in his 4th line of therapy. Ten days after CAR T infusion, the patient started violent coughing and a FDG-PET revealed full resolution of focal bone lesions but disseminated FDG uptake at the lung and mediastinal lymph nodes reminiscent to sarcoidosis. We performed a PET using 68Ga-DOTATOC that usually detects sarcoidosis with high sensitivity and specificity, which was negative. Negative results were also seen for 68Ga-Pentixafor, which is an alternative tracer to FDG in the detection of MM. Bronchoalveolar lavage (BAL) along with endobronchial ultrasound guided biopsy was done, showing noncaseating granuloma formation in the biopsy without evidence of residual MM cells. Single cell RNA-seq on the BAL sample revealed CD4-positive T cells exhibiting simultaneous expression of genes associated with Th1 T-cells (TBX21, CXCR3, IFNG, TNF) and genes associated with Th17 T-cells (RORC, IL23R, CCR6, CCL20, KLRB1), indicative for a Th1-polarized Th17 phenotype. Furthermore, these cells expressed IL4I1, ABCB1, and CSF210-12 , while IL17A, IL17B, IL17E (IL25), and or IL17F was not expressed, highlighting presence of Th17.1 cells. This cell type has been described to be pro-inflammatory and pathogenic and implicated in several auto-immune diseases, including sarcoidosis. Together, our data suggest a non-infectious, Th17.1 T-cell driven sarcoidosis-like auto-immune phenomenon located in the lungs following anti-BCMA CAR T-cell therapy. Respiratory symptoms completely resolved following high-dose inhalative steroids. The patient relapsed from complete remission (CR), and FDG PET showed the known sarcoidosis-like pulmonary changes, but also revealed a number of new soft-tissue lesions, suspicious for extramedullary relapse. In contrast to the previous scans, these lesions were CXCR4 positive, suggesting a role of using multiple PET tracers in this setting. Later, the patient was enrolled on a trial investigating talquetamab. One week after dosing, the patient experienced severe pain crisis and a diffusion-weighted MRI revealed increase in size of multiple extramedullary lesions, but no new lesions. M- protein levels were decreasing at that time suggesting either mixed response or pseudoprogression. The patient was treated with painkillers and all lesions disappeared on a follow-up scan 6 weeks later, confirming pseudoprogression, and he is in an ongoing CR for 6 months at the time of writing. Conclusion: We present two educating episodes of pseudoprogression in one patient following immune oncology drugs in MM. While one event was transient and self-limiting, the pulmonary manifestations were similar to sarcoidosis and required treatment with steroids.

Patterns of Relapse and Clinical Outcomes in Multiple Myeloma Patients after Anti-BCMA CAR T-Cell Therapy: Implications for Patient's Monitoring after CAR T-Cell Therapy

Patterns of Relapse and Clinical Outcomes in Multiple Myeloma Patients after Anti-BCMA CAR T-Cell Therapy: Implications for Patient's Monitoring after CAR T-Cell Therapy

Disease Characterization and Response Prediction in Myeloma Patients Undergoing Conventional and Cellular Therapies from Circulating Tumor DNA

Background: Multiple myeloma (MM) is characterized by dramatic biological and clinical heterogeneity. Prognostic biomarkers including genomic alterations and bone marrow (BM) minimal residual disease can resolve some of this heterogeneity; however, these rely on invasive tumor sampling which limits their utility. Here we develop and apply plasma cell-free DNA liquid biopsies via Cancer Personalized Profiling by Deep Sequencing (CAPP-Seq) to characterize tumors and quantify treatment response in patients with MM and explore its utility during anti-BCMA CAR T-cell therapy. Methods: We developed a 480 kb MM-specific CAPP-Seq panel, which covers 86 recurrently mutated coding genes as well as other recurrently mutated regions, for disease detection and quantification from circulating tumor DNA (ctDNA). Using this hybrid-capture panel, we profiled 214 plasma, germline and tumor DNA samples from 35 patients including 15 patients undergoing idecabtagene vicleucel (ide-cel) therapy. Samples were sequenced to ultra-high unique molecular depth as previously described (Newman et al, Nat Biotechnol 2016) to quantify ctDNA. Copy number variants (CNVs) were identified using our recently developed method, CANARy (Chabon et al, Nature 2020). Tumor variants and ctDNA levels were identified prior to and following therapy to assess ctDNA dynamics, and were correlated with clinical indices and patient outcomes. Results: We applied CAPP-Seq to samples from 35 patients with newly diagnosed (ND, n=10) or relapsed/refractory (RR, n=25) plasma cell disorders. A median of 87 single-nucleotide variants (SNVs, range 2-283) were detected per case. Among these, a median of 5 mutations/patient were in coding genes such as KRAS (25% of patients), TP53 (25%) and NRAS (19%). Most other SNVs occurred in genomic regions targeted by activation induced deaminase (AID), such as IGH, IGK and IGL. To validate tumor genotyping from plasma, we compared SNVs observed in plasma to paired BM samples in 18 cases. Here, we observed 84% (594/703) of all mutations identified in BM were also present in plasma, including 90% (26/29) of all coding alterations. Interestingly, we detected an additional 259 SNVs in the plasma that were not present in the BM, including KRAS, NRAS, and FAM46C mutations, suggesting ctDNA may better capture spatial tumor heterogeneity. We next utilized CAPP-Seq to quantify disease burden prior to treatment. We detected ctDNA in 97% (31/32) of pretreatment plasma with a median allele frequency of 0.91% (range 0.006 to 36%) and 3.82 log haploid genome equivalents per mL of plasma (hGE/mL). Levels of ctDNA were higher in RRMM compared to NDMM patients (4.26 vs 3.08 log hGE/mL, p=0.02) and correlated with clinical risk factors including R-ISS (stage 1: 2.83 vs stage 2/3: 4.18 log hGE/mL, p=0.01) as well as disease burden measurements including M-spike (rho=0.53, p=0.02) and free light chain ratio (rho=0.40, p=0.03). The fold change in ctDNA level at a median of 36 days from treatment initiation correlated with clinical response (median 0.060 for non-progressors vs 7.0 for progressors, p=0.04). Further, we applied CAPP-Seq to serial samples from 15 patients with RRMM receiving ide-cel. Notably, patients with longer response (>90 days) had significantly lower ctDNA levels at day 28 compared to those with early (<90 days) progression (0.6 vs 4.1 log hGE/mL; p=0.009, Fig 1). Lower ctDNA levels at day 28 predicted longer time to progression (proportional hazard model, p=0.02, HR=1.6). Finally, we assessed clonal evolution upon relapse after ide-cel. In multiple patients we observed emergence of new CNVs in ctDNA, including a case with an emergent loss of chr16, where TNFRSF17 (BCMA) resides (Fig 2). This copy number loss was observed 36 days prior to clinical relapse, was validated through WGS of the relapsed tumor, and resulted in loss of BCMA by immunohistochemistry. Conclusions: Assessment of ctDNA has significant potential utility in MM, as it allows for mutational genotyping, quantification of disease burden, and identification of tumor clonal evolution. Lower levels of ctDNA during treatment and its clearance are associated with improved outcomes, while detection of emergent alterations after targeted therapies may inform subsequent treatment strategies. Use of ctDNA may improve response and relapse prediction and reveal mechanisms of therapy resistance. *SS and DMK are co-senior authors Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Factors associated with infection events after chimeric antigen receptor T-cell therapy for relapsed or refractory multiple myeloma

ObjectivesChimeric antigen receptor (CAR) T-cell therapy is a new and effective method in relapsed or refractory (R/R) multiple myeloma (MM). This study was aimed to explore the risk factors of infection events. MethodsWe retrospectively analyzed 68 patients with R/R MM who received CAR T-cell therapy at the Affiliated Hospital of Xuzhou Medical University from June 2017 to June 2021.35 patients received anti-CD19 combined with anti-BCMA CAR T-cell therapy and 33 patients received anti-BCMA CAR T-cell therapy alone. ResultsInfection events in patients who received ≥4 prior lines of treatment or with grade 3–5 cytokines released syndrome (CRS) mainly occurred within 4 months after CAR T-cell infusion(CTI). The duration of infection-free survival was positively correlated with progression-free survival of patients with R/R MM (R2 = 0.962, p < 0.001) and the first infection event was closely accompanied by the disease relapse or progression. Treatment lines (p = 0.05), duration of ANC<500 cells/mm3 after CTI (p = 0.036), CRS grade (p = 0.007) and treatment response (p < 0.001) were the independent risk factors associated with infection for a multivariable model. The infection incidence was higher in patients with dual CAR T-cell therapy than with mono CAR T-cell therapy18 months after CTI although no statistic differences were observed within 18 months. ConclusionsInfections after CTI were closely associated with more lines of prior treatment, longer duration of ANC<500 cells/mm3, higher grade CRS and poor treatment response. Infections tended to occur in the early stage after CTI in patients with more lines of prior treatment and higher grade CRS.

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

BackgroundAnti-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...

Triple MAPK inhibition salvaged a relapsed post-BCMA CAR-T cell therapy multiple myeloma patient with a BRAF V600E subclonal mutation

BackgroundMultiple Myeloma (MM) is a progressive plasma cell neoplasm characterized by heterogeneous clonal expansion. Despite promising response rates achieved with anti-BCMA CAR-T cell therapy, patients may still relapse and there are currently no clear therapeutic options in post-CAR-T settings. In this report, we present a case of a post-BCMA CAR-T relapsed/refractory (RR) MM patient with skin extramedullary disease (EMD) in which a novel MAPK inhibition combinatorial strategy was implemented based on next-generation sequencing and in vitro experiments.Case presentationA 61-year-old male with penta-refractory MM penta- (IgA lambda), ISS stage 3 with hyperdiploidy, gain of 1q21 and del13 was treated with anti-BCMA CAR-T cell therapy, achieving a best response of VGPR. He progressed after 6 months and was salvaged for a short period with autologous stem cell transplantation. Eventually, he progressed with extramedullary disease manifested as subcutaneous nodules. Based on whole-exome sequencing, we identified a BRAF (V600E) dominant subclone in both bone marrow and cutaneous plasmacytoma. Following in vitro experiments, and according to our previous studies, we implemented a triple MAPK inhibition strategy under which the patient achieved a very good partial response for 110 days, which allowed to bridge him to subsequent clinical trials and eventually achieve a stringent complete response (sCR).ConclusionHere, we show the applicability, effectiveness, and tolerability the triple MAPK inhibition strategy in the context of post-BCMA CAR-T failure in specific subset of patients. The triple therapy could bridge our hospice bound RRMM patient with BRAF (V600E) to further therapeutic options where sCR was achieved. We will further evaluate triple MAPK inhibition in patients with BRAF V600E in a precision medicine clinical trial launching soon.

EE41 Cost-Effectiveness of Anti-BCMA CAR T-Cell Therapy in Triple-Class Refractory Multiple Myeloma

Idecabtagene vicleucel (ide-cel), an anti-BCMA chimeric antigen receptor T-cell (CAR-T) therapy (list price $419,500), was approved in 2021 by the US FDA for triple-class refractory multiple myeloma (MM). Another anti-BCMA CAR T-cell therapy, ciltecabtagene autoleucel (cilta-cel), is undergoing FDA review. We evaluated the cost-effectiveness of ide-cel and cilta-cel (assuming price parity with ide-cel).

Promising therapeutic approaches for relapsed/refractory multiple myeloma

ABSTRACT Objective Treatment strategies for relapsed/refractory MM are particularly complex. In particular, patients who are refractory to the three classes of therapies have limited therapeutic options and poor survival. Fortunately, promising treatments are emerging, but their incorporation into existing treatments still needs to be defined. We will describe the latest trends and emerging developments in the field of therapies for RRMM by analyzing the most recent clinical data and new technologies in drug development. Methods Pubmed, Embase and Cochrane Library were searched to select eligible studies, the clinical data of new promising treatments were reviewed. The key results of the most recent clinical trial were summarized in Table. Results A total of 13 studies were included in the final analysis involving anti-BCMA CAR T-cell therapy, Combined CAR T-cell therapy, antibody-drug conjugates, bispecific Ab therapy and CELMoDs. The key efficacy and side effects of treatments were summarized. Conclusions There is great promise for a set of next-generation of rescue therapies, including CAR T-cell therapy, bispecific antibodies, antibody-drug conjugates, and novel PROteolysis Targeting Chimeras. Emerging new treatments for MM provide more choices for relapsed/refractory multiple myeloma (RRMM). The optimal therapy for each patient should be based on disease-related factors, such as previous therapies, duration of response to prior drugs, clinical and biochemical features of relapse, and the relationship of patient comorbidities with known AE profiles of the different therapies.

A Model Perspective Explanation of the Long-Term Sustainability of a Fully Human BCMA-Targeting CAR (CT103A) T-Cell Immunotherapy.

Different from canonical drugs, CAR T-cells are “living drugs”, which derived from patient’s own blood. Studies of the pharmacokinetics of CAR T-cells could improve our understanding of their efficacy, safety, optimal dosage, and other characterizes. We previously reported a phase I study of a novel fully human BCMA-targeting CAR (CT103A) in 18 patients with relapsed/refractory multiple myeloma. CT103A exhibited extraordinary persistence with low anti-drug antibody positivity. To figure out the pharmacokinetic characterizes and investigate the potential reason of CT103A’s long-term persistence, we established a population pharmacokinetic (PopPK) model of CT103A based on 18 patients cohort by applying nonlinear mixed-effects modeling and analyzed the CAR T-cell clonal evolution. The results suggested that extramedullary spreading was found to impair Cmax and was therefore added as a covariate to the modified model. The model revealed tocilizumab and corticosteroids showed no impact on the CT103A expansion rate. No dominant clone existed in patients with persistently high peripheral CT103A by CAR integration sites analysis. Finally, patients with lower contraction rate constants and higher Cmax as well as memory CT103A fraction could achieve better clinical responses. Taken together, this study developed a PopPK model of a fully human anti-BCMA CAR T-cell therapy, and summarized its model characteristics. We suggested that the long-term persistence of CT103A was attributed to the memory CAR T-cell fraction but not the clonal evolution. This study will improve people’s understanding of pharmacokinetics and PopPK of CAR T-cell immunotherapy.

Efficacy and follow-up of humanized anti-BCMA CAR-T cell therapy in relapsed/refractory multiple myeloma patients with extramedullary-extraosseous, extramedullary-bone related, and without extramedullary disease.

The prognosis of patients with multiple myeloma (MM) with extramedullary disease (EMD) remains poor. A high overall response rate (ORR) has been reported following anti‐B‐cell maturation antigen (BCMA) chimeric antigen receptor (CAR)‐T cell therapy in relapsed/refractory (R/R) patients with MM; however, data on patients with EMD remain limited. Herein, we compared and analyzed the efficacy and long‐term follow‐up of anti‐BCMA CAR‐T cell therapy in R/R MM patients with extramedullary‐extraosseous (EM‐E), extramedullary‐bone related (EM‐B), and without extramedullary disease. No difference in the ORR was observed between the three groups. The long‐term efficacy of anti‐BCMA CAR‐T cell therapy in the EM‐E group was worse than that in patients without EMD and with EM‐B. In the EM‐E group, disease progression was the reappearance of extramedullary lesions without an increase in the MM cell percentage or M protein level. Although no difference in the proportion of CAR‐T cells was detected among the three groups, the EM‐E group might exhibit a relatively high grade of cytokine release syndrome following anti‐BCMA CAR‐T therapy. Interleukin‐6 levels in the without EMD group were lower than those in the EM‐E and EM‐B groups. However, given the small number of cases in the three groups, statistical analysis was not performed.(ChiCTR1800017051 and ChiCTR2000033925).

Updated Phase 1 Results of C-CAR088, an Anti-BCMA CAR T-Cell Therapy in Relapsed or Refractory Multiple Myeloma

▪Background:C-CAR088, an anti-BCMA CAR T-cell therapy, is a novel 2nd generation 4-1BB chimeric antigen receptor T (CAR-T) cell therapy targeting BCMA. Previously presented results from an ongoing study of C-CAR088 in R/R MM (NCT03751293, NCT03815383, NCT04322292, NCT04295018) included a 95.7% overall response rate (ORR) for the dose of 1.0~6.0x10 6 CAR-T cells/kg with a favorable safety profile (Lu, 2020 ASH Oral Presentation #182). Here we present the updated results of the study, with more patients and longer follow up time.Methods:Dose escalation and expansion studies were conducted at four medical centers in China to evaluate the safety and efficacy of C-CAR088 in patients with R/R MM who were previously treated with at least 2 lines of therapy, including proteasome inhibitors (PIs) and IMiDs. C-CAR088 was administered to patients as a single infusion after lymphodepletion with fludarabine (30 mg/m 2) and cyclophosphamide (300 mg/m 2) daily for 3 days. The primary endpoint was the incidence of adverse events (AEs), including dose-limiting toxicities (DLTs), and the secondary endpoints included overall response rate(ORR), duration of response (DOR), and progression-free survival (PFS) by IMWG Uniform Response Criteria.Results:As of July 2nd, 2021, 31 patients had been infused with C-CAR088. The median vein-to-vein time was 18 days. The manufacturing success rate was 100%. 4, 13 and 14 patients were infused with 1.0, 3.0 and 4.5~6.0 x10 6 CAR+ T cells/kg respectively. The median follow-up time for all patients was 8.0 months (0.1-24.2). The median age of patients was 61 years (45-74). The median number of prior lines of therapy was 4 (2-13). There were 25 (80.6%) patients with at least one high risk cytogenetic abnormality and 17 (54.8%) patients with at least two high risk cytogenetic abnormalities. 7 patients (22.6%) received bridging therapy before C-CAR088 therapy.Cytokine release syndrome (CRS) developed in 29/31 (93.5%) patients, grade 1 in 18/31 (58.1%), grade 2 in 8/31 (25.8%) and grade 3 in 3/31 (9.7%) respectively. The median time to the first onset of CRS was 6 days (1-11) and the median duration of CRS was 5 days (2-14). 9/31 (29%) patients used tocilizumab and 6/31 (19.4%) patients used corticosteroids to manage CRS. Only one patient developed a grade 1 neurotoxicity. No DLTs were observed and all adverse events were reversible. One patient died of septic shock on day 2 after receiving C-CAR088.Clinical efficacy was assessed in 28 patients with ≥ 1 month of follow up. Among the 28 patients, 3, 11 and 14 patients were infused with the dose of 1.0 x 10 6 CAR+ T cells/kg 3 x10 6 CAR+ T cells/kg, and 4.5~6x10 6 CAR+ T cells/kg respectively.The ORR was 27/28 (96.4%): 4 (14.3%) achieved CR, 12 (42.9%) achieved sCR and 9 (32.1%) achieved very good partial response (VGPR).At the dose level of 1.0 x10 6 CAR+ T cells/kg, 3(100%) patients achieved VGPR. The median DOR was 3.7 months (1.8-5.8), and the median PFS was 4.6 months (2.7-6.2).The CR rate was 54.5% (6/11) and 71.4% (10/14) in the 3.0 and 4.5~6.0 x10 6 CAR+ T cells/kg cohorts respectively. The median time to CR was 2.0 (0.5-9.5) months. Minimal residual disease (MRD) was testedbyEuroFlow-based flow cytometric analysis in 16 patients who had CR, 15/16 (93.7%) patients were MRD negative with the sensitivity of 10 -5. With a median follow-up of 9.5 months (1.9-24.2) in ≥ 3.0x10 6 CAR+ T cells/kg cohorts, the median DOR and PFS had not been reached. The Kaplan-Meier estimation of PFS at 6 and 12 months was 81.1% (95% CI:65.9% ~99.8%) and 69.5 % (95% CI:51.6 % ~93.6%) respectively.8 patients in the ≥ 3.0x10 6 CAR+ T cells/kg cohorts discontinued the study. 7 discontinued due to disease progression (PD), and 1 discontinued for other anticancer therapy. 4 progressed within 6 months, 2 progressed within 6-12 months, and 1 progressed within 12-24 months.C-CAR088 proliferated and expanded well in patients' blood. The median C max was 734,868 copies/μg gDNA. The median AUC 0~28day was 7,468,779 day·copies/μg gDNA. The median T max was 14 days. The median T last was 84 days. 71% (95% CI: 42%~92%) of patients with C max equal to or greater than the median C max achieved CR/sCR.Conclusion:C-CAR088 has a manageable safety profile, which includes low neurotoxicity rates (with no gr ≥3 events). Deep and durable responses were observed in ≥ 3.0x10 6 CAR-T cells/kg cohorts. Doses of 3.0 and 6.0×10 6 CAR T cells/kg were selected for further study. [Display omitted] DisclosuresZhu: CBMG: Current Employment. Huang: CBMG: Current Employment. Li: CBMG: Current Employment. Lan: CBMG: Current Employment. Chen: CBMG: Current Employment. Humphries: CBMG Ltd: Current Employment. Yao: CBMG: Current Employment, Current holder of stock options in a privately-held company.