B Cell Maturation Antigen CAR-T Cells Research Articles

Patient perspectives on BCMA-targeted therapies for multiple myeloma: a survey conducted in a patient advocacy group.

Advances in multiple myeloma (MM) treatment have shifted the therapeutic landscape. Understanding patients' perspectives can assist physicians in helping patients make informed decisions. This study aimed to understand the patient decision-making process and gain insights into patient perspectives on B-cell maturation antigen (BCMA)-targeted therapies for MM. An 18-question survey was completed by patients with MM enrolled in HealthTree® Cure Hub, an online portal helping patients with plasma cell dyscrasias navigate their disease. From October 28, 2022, to January 12, 2023, 325 patients with MM participated in the survey. The mean age (standard deviation) of the respondents was 66 (8) years; 54% were female and 90% were White. Among 218 patients with complete clinical records in the database, the median (min, max) lines of therapy (LOT) was 2 (1,16). Among 61 (28%) patients who had received ≥4 LOTs, 55 (90%) were triple-class exposed. Of the 290 patients who responded to the question about openness to new therapies, 76 (26%) were open to trying a new therapy immediately and 125 (43%) wanted more information on safety and efficacy. Most respondents reported likely or very likely to try a BCMA CAR T-cell therapy (60%) or a bispecific antibody (74%) and some needed more information to decide (16% for CAR T-cell therapy and 13% for bispecific antibody). The most requested information included efficacy, side effects (SEs), eligibility, and administration process for both CAR T-cell and bispecific therapies. When 2 therapies with the same efficacy and duration of response were offered, 69% of respondents would prefer the therapy with a lower risk of severe SEs but requires continuous dosing with no treatment-free interval, and 31% preferred a therapy given once followed by a treatment-free interval but with a potentially higher risk of severe SEs. To receive an effective therapy, the top acceptable trade-offs included frequent monitoring of SEs and initiating a new therapy in a hospital setting, and the least acceptable compromise was caregiver burden. This study found a high level of openness in patients with MM to try BCMA-targeted therapies. Information on efficacy, safety, availability, and eligibility may assist patients on decision-making.

PD-1 downregulation enhances CAR-T cell antitumor efficiency by preserving a cell memory phenotype and reducing exhaustion

BackgroundDespite the encouraging outcome of chimeric antigen receptor T cell (CAR-T) targeting B cell maturation antigen (BCMA) in managing relapsed or refractory multiple myeloma (RRMM) patients, the therapeutic side effects...

BCMA CAR-T-Cell Therapy in Combination with Long-Term Pomalidomide Is a Safe and Effective Treatment for Relapsed/Refractory Multiple Myeloma

Background: B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor T-cell (CAR-T-cell) therapy has exhibited remarkable efficacy in refractory or relapsed multiple myeloma (R/R MM), but recurrence and rapid progression of disease are still observed in some cases within a short time after treatment. Long-term pomalidomide therapy, which potentiates T-cell functionality and has direct antimyeloma effects, might enhance the efficacy of BCMA CAR-T-cell therapy. Here, we present the efficacy of this combination regimen for R/R MM. Methods: We performed a single-center prospective clinical study that was registered with the Chinese Clinical Trial Registration Center (ChiCTR2000036350). Patients with relpased or refractory multiple myeloma receiving BCMA CAR-T cell infusion were randomized to receive long-term pomalidomide treatment (4 mg/day) one month after infusion. The primary endpoint is overall survival (OS) in R/R MM with long-term pomalidomide administration compared to those without pomalidomide therapy after CAR T-cell infusion. The secondary endpoints include time to progression (TTP) and therapeutic response. Also, the copy numbers of CAR were assessed after infusion. Results: A total of 14 R/R MM patients who received BCMA CAT T-cell therapy, were included in this study. The median age of the enrolled R/R MM patients was 59.5 years (44-71). Five patients had high-risk cytogenetic abnormalities (IGH rearrangement, 1q21 amplification, and P53 deletion) at the time of initial diagnosis. In addition, high-risk genetic alterations were newly detected in patient 2 during first-line therapy. All patients had previously received 3 to 6 lines of treatment with proteasome inhibitors (PIs), immunomodulatory drugs (IMiDs), or anti-CD38 monoclonal antibodies. As shown in Figure 1, all patients had demonstrated progressive disease prior to CAR T-cell infusion. The objective response rate (ORR) of BCMA-CART was 100%. Three months following CAR-T-cell infusion, of the 6 patients receiving pomalidomide, all patients (6/6) achieved VGPR (very good partial response) or CR (complete response）, while only 5 patients (5/8) who did not receive pomalidomide treatment achieved VGPR or better. At a median follow-up of 19.7 months, for the 8 patients who did not receive pomalidomide administration, the median TTP (time to progression) was 4.5 (1-14) months, while the TTP was not reached in patients who received long-term pomalidomide treatment. Moreover, the dynamic abundance of circulating BCMA CAR-T cells was monitored as shown in Figure 2. In patients who received pomalidomide treatment after CAR-T-cell therapy, the CAR copy numbers of circulating CAR-T cells peaked 8 to 10 days after CAR-T-cell infusion, with a peak copy number of up to 10 6. In addition, BCMA CAR-T cells persisted (>1*10 3 copies/µg DNA) for 3 months in vivo. Without pomalidomide administration, BCMA CAR-T cells persisted for up to 2.5 months in the peripheral circulation (results not shown). Conclusion: Our results confirm the efficacy of the long-term oral pomalidomide administration (4 mg/day) after BCMA CAR T-cell infusion in patients with R/R MM. Notably, this combination regieme reduced the recurrence rate and prolonged progression-free survival for R/R MM patients, providing a promising option for treating R/R MM. In addition, oral administration of pomalidomide did not significantly prolong the persistence of BCMA CAR T-cells in vivo. However, data from studies with larger sample sizes are required to draw valid conclusions.

Ablation of Cullin-5 in Primary Human T Cells Improves Tumor Killing and Persistence in BCMA-Targeting CAR-T Cells in a Multiple Myeloma Model

While adoptive T cell therapies have led to remarkable clinical responses in certain subsets of B cell leukemia and lymphoma, many challenges remain that are limiting the efficacy in other hematological malignancies. Compromised T cell function and exhaustion due to chronic antigen exposure can impair the persistence of chimeric antigen receptor (CAR)-T and T-cell-receptor (TCR)-T cells. Gene editing strategies have the potential to circumvent some of these challenges and enhance T cell function. To identify key genes that are involved in regulating T cell dysfunction, we performed a genome-wide CRISPR loss-of-function screen in primary human T cells in conditions that mimic chronic antigen exposure. Primary T cells from two donors were transduced with lentivirus containing a NY-ESO-1 TCR as well as a genome-wide sgRNA library and subsequently CRISPR edited using Cas9-RNP electroporation. These antigen specific TCR-T cells were then co-cultured with the NY-ESO-1+ melanoma cell line A375 at an effector-to-target (E:T) ratio of 1:1 for 48 hours and challenged under the pressure of chronic tumor stimulation for 9 rounds in total. The resulting next-generation sequencing data was then analyzed utilizing the MAGeCK pipeline to identify top scoring hits for validation regarding their role in T cell fitness and persistence. Among the hits with the highest positive fold changes, we found seven genes which are part of the Cullin-RING ligase 5 multi-protein complex (Fig. 1). These hits were then validated in a CAR-T cell context. We first edited primary human T cells by knocking out CUL5 as well as the endogenous TCR. The template for the B Cell Maturation Antigen (BCMA)-specific CAR bb2121 was then delivered to the TRAC locus via CRISPR/Cas9-RNP and adeno-associated virus (AAV). Here, we tested a panel with four CAR modifications, including two different co-stimulatory domains (CD28ζ, 4-1BB), a CAR with mutated immunoreceptor tyrosine-based activation motifs (ITAM) (1XX CAR), and a CAR containing an alternative BCMA-targeting single-chain variable fragment. This panel of CUL5 ablated CAR-T cells were then repeatedly co-cultured with BCMA-expressing tumor cells. After 6 rounds of tumor exposures, CUL5 ablated T cells showed a striking tumor killing advantage compared to control edited cells in a functional tumor killing assay (Fig. 2). Notably, we also observed vastly increased production of the cytotoxic cytokines INF-γand TNF-α in CUL5 ablated cells. Furthermore, the distinct tumor killing advantage of CUL5 KO cells in vitro was reproduced in the context of a CD19-specific CAR, which will be relevant in other clinical settings. Finally, we evaluated the striking tumor killing capacity of CUL5 ablated BCMA-specific CAR-T cells in vivo. For this, NOD.Cg- PrkdcscidIl2rgtm1Wjl/SzJ mice engrafted with luciferase-expressing BCMA+ multiple myeloma cell line OPM2 were treated with this panel of CUL5 ablated and control CAR-T cells and tumor burden was measured via Bioluminescent Imaging (BLI) over time. Mice treated with CUL5 KO BCMA-specific CAR-T cells showed lower median radiance measured by BLI, except for the 1XX CAR condition where both cohorts completely cleared the disease. In addition to the complete tumor clearance in both the control and CUL5 edited cohorts, we observed that the BLI levels in the 1XX CAR treated animals remained stable even after the mice were subjected to five tumor rechallenges. After 90 days, the mice were sacrificed and CAR+ human T cells were isolated from the bone marrow and spleens and phenotypically assessed. Analysis of these samples revealed a significantly higher frequency of CAR+ cells in the mouse bone marrow in the CUL5 KO group compared to control, while there were equivalent numbers in the spleens, suggesting an antigen-specific expansion advantage for the CUL5 KO CAR-T cells. We then co-cultured the isolated BCMA CAR-T cells from the spleens of these mice with OMP2 tumor cells in different E:T ratios and assessed tumor killing. We found a significant advantage in tumor killing of CUL5 ablated T cells compared to control cells in this ex vivo setting, suggesting an improved functional persistence. In summary, our findings identify the CUL5 complex as a novel potential therapeutic target to improve T cell persistence and counteract T cell exhaustion in order to improve the efficacy of adaptive cell immunotherapies for the treatment of BCMA+ hematological malignancies.

Lymphodepletion Enables Successful BCMA CAR-T Cell Engraftment and Tumour Control in the Syngeneic Vk*MYC Model of Aggressive Myeloma

DISCUSSION AND CONCLUSION Chimeric antigen receptor (CAR)-T cells directed against B-cell maturation antigen (BCMA), have yielded impressive results in clinical trials for multiply relapsed/refractory multiple myeloma (MM). However, progression-free survival is short, demonstrating a need for improvements. While numerous advances have been made to improve this treatment modality, these have not always translated to superior clinical outcomes. A major limitation is that novel therapeutics are often not tested in a relevant in vivo model. These novel strategies have been largely tested only in immunodeficient models of MM. To better recapitulate the host-tumour-effector cell interactions, particularly in the TME, we sought to develop a system to study CAR-T cell activity in the Vk*MYC model of MM. Here, we report on the first known successful model of CAR-T cell activity in an immunocompetent model of MM. We sought to identify a BCMA CAR construct that is capable of binding to both human and mouse BCMA. A novel nanobody recognizing BCMA was developed by immunizing llamas with human BCMA and the resulting single-domain antibodies (sdAbs) were subsequently isolated and cloned. These sdAbs were then screened for binding to mouse BCMA. A binder capable of recognizing both human and mouse BCMA was identified and cloned into our murine CAR construct, with CD28 and CD3z signaling domains, herein referred to as sdBCMA2.CD28.CD3z. Murine CAR-T cells were then generated by transducing activated healthy murine splenocytes with a retroviral vector carrying the sdBCMA2.CD28.CD3z construct. These CAR-T cells were then characterized in vitro using standard cytotoxicity, proliferation, and cytokine release assays. To assess activity in an immunocompetent model, female C57BL/6J mice were injected intravenously with Vk12598 Vk*MYC cells. CAR-T cells were later administered intravenously. Mice were bled weekly to quantify M-protein disease burden by serum protein electrophoresis and for phenotypic characterization of circulating cells. When co-cultured with BCMA+ human MM cell lines and with Vk*MYC cell lines, murine sdBCMA2.CD28.CD3z CAR-T cells effectively lysed target cells, proliferated, and released inflammatory cytokines. To assess the in vivo activity of these CAR-T cells, we injected intravenously female C57BL/6J mice with Vk12598 cells, and then administered sdBCMA2.CD28.CD3z CAR-T cells intravenously. While there was some evidence of survival improvement, the median overall survival (mOS) of 35 days compared to 28 days, for CAR-T vs. Mock T-cells, respectively, the difference was non-significant, and the survival benefit was not durable. To address this, we incorporated lymphodepletion by total body irradiation (TBI) followed by CAR-T cell administration the next day. By incorporating lymphodepletion prior to CAR-T cell administration we were able to significantly reduce M-protein surrogates of disease burden, as well as achieve durable remissions in the TBI + CAR-T arm with an mOS not yet reached after experimental day 91, compared to an mOS of 42 days in the TBI + Mock T-cell arm. The addition of TBI also significantly improved the engraftment of CAR-T cells, as assessed by flow cytometry. The TBI + CAR-T arm also had significantly increased IL-6, IL-1b, IL-2, and TNF-a in the serum, compared to the TBI + Mock arm, at 7 days post administration of CAR-T cells. The durable remission achieved using the combination of our novel sdBCMA2.CD28.CD3z CAR-T cells with lymphodepletion is a pivotal advancement in modelling MM CAR-T cell activity in this clinically relevant model system. Our approach represents the first time that CAR-T cells were successfully used to treat the Vk12598 model of MM that faithfully recapitulates relapsed MM. The incorporation of lymphodepletion significantly improves CAR-T cell engraftment, in line with clinical CAR-T cell therapy paradigms. The cytokine profile observed is consistent with the cytokine elevations typically observed after CAR-T cell administration in patients. As our construct is capable of binding to both human and mouse BCMA, we are therefore able to fully characterize our lead assets in a relevant model system. Our strategy will enable further research to dissect host-tumour-effector cell interactions, to better inform the design and characterization of novel CAR-T cell therapies in MM.

C-reactive protein impairs immune response of CD8+ T cells via FcγRIIb-p38MAPK-ROS axis in multiple myeloma

BackgroundC-reactive protein (CRP) is a prototypical acute phase protein in humans with the function of regulating immune cells. Serum CRP levels are elevated in multiple myeloma (MM), associated with MM...

Anti-myeloma efficacy of CAR-iNKT is enhanced with a long-acting IL-7, rhIL-7-hyFc

AbstractMultiple myeloma (MM), a malignancy of mature plasma cells, remains incurable. B-cell maturation antigen (BCMA) is the lead protein target for chimeric antigen receptor (CAR) therapy because of its high expression in most MM, with limited expression in other cell types, resulting in favorable on-target, off tumor toxicity. The response rate to autologous BCMA CAR-T therapy is high; however, it is not curative and is associated with risks of cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome. Outcomes in patients treated with BCMA CAR-T cells (CAR-Ts) may improve with allogeneic CAR T-cell therapy, which offer higher cell fitness and reduced time to treatment. However, to prevent the risk of graft-versus-host disease (GVHD), allogenic BCMA CAR-Ts require genetic deletion of the T-cell receptor (TCR), which has potential for unexpected functional or phenotype changes. Invariant natural killer T cells (iNKTs) have an invariant TCR that does not cause GVHD and, as a result, can be used in an allogeneic setting without the need for TCR gene editing. We demonstrate significant anti-myeloma activity of BCMA CAR-iNKTs in a xenograft mouse model of myeloma. We found that a long-acting interleukin-7 (IL-7), rhIL-7-hyFc, significantly prolonged survival and reduced tumor burden in BCMA CAR-iNKT–treated mice in both primary and re-challenge settings. Furthermore, in CRS in vitro assays, CAR-iNKTs induced less IL-6 than CAR-Ts, suggesting a reduced likelihood of CAR-iNKT therapy to induce CRS in patients. These data suggest that BCMA CAR-iNKTs are potentially a safer, effective alternative to BCMA CAR-Ts and that BCMA CAR-iNKT efficacy is further potentiated with rhIL-7-hyFc.

A distinct cytokine network distinguishes chimeric antigen receptor T cell (CAR-T)–associated hemophagocytic lymphohistiocytosis-like toxicity (carHLH) from severe cytokine release syndrome following CAR-T therapy

Background aimsWith the increasing application of chimeric antigen receptor (CAR)-T cell therapy in various malignancies, an extra toxicity profile has been revealed, including a severe complication resembling hemophagocytic lymphohistiocytosis (HLH), which is usually disguised by severe cytokine release syndrome (CRS). MethodsIn a clinical trial in whom 99 patients received B-cell maturation antigen CAR-T cells, we identified 20 (20.20%) cases of CAR-T cell–associated HLH (carHLH), most of whom possessed a background of severe CRS (grade ≥3). The overlapping features of carHLH and severe CRS attracted us to further explore the differences between them. ResultsWe showed that carHLH can be distinguished by extreme elevation of interferon-γ, granzyme B, interleukin-1RA and interleukin-10, which can be informative in developing prevention and management strategies of this toxicity. Moreover, we developed a predictive model of carHLH with a mean area under the curve of 0.81 ± 0.07, incorporating serum lactate dehydrogenase at day 6 post-CRS and serum fibrinogen at day 3 post-CRS. ConclusionsThe incidence of carHLH in CAR-T recipients might be relatively higher than we previously thought. relatively higher than we previously. A cytokine network distinguished from CRS is responsible for carHLH. And corresponding cytokine-directed therapies, especially targeting IL-10, are worth trying.

P1446: PHASE I STUDY DATA UPDATE OF PHE885, A FULLY HUMAN BCMA-DIRECTED CAR-T CELL THERAPY MANUFACTURED USING THE T-CHARGETM PLATFORM FOR PATIENTS WITH RELAPSED/REFRACTORY (R/R) MULTIPLE MYELOMA (MM)

Background: Chimeric antigen receptor (CAR)-T cell therapy (tx) is approved for treatment of r/r MM. However, prolonged product manufacturing times and a need for longer duration of response are a major obstacle in this population, necessitating fast manufacture of a reliable and durable CAR-T cell product. Aims: Herein we report updated clinical data from a Phase I trial assessing the fully human B-cell maturation antigen (BCMA) CAR-T cell product PHE885 in adult patients (pts) with r/r MM. Methods: This multicenter, open-label study (NCT04318327) characterizes the safety and efficacy of PHE885 manufactured using the novel T-ChargeTM platform, which takes <2 d to manufacture the final product and relies on in vivo expansion after CAR-T cell infusion. Pts with MM r/r to ≥2 prior lines of tx, including an immunomodulatory drug, proteasome inhibitor, and anti-CD38 monoclonal antibody, were eligible. Pts received fludarabine and cyclophosphamide for lymphodepletion prior to a single PHE885 intravenous injection. Primary objectives were safety, including dose-limiting toxicities (DLTs) and adverse events (AEs). Secondary objectives included clinical response, T-ChargeTM process evaluation, and cellular kinetics. Results: At abstract submission, 22 pts were infused with PHE885 at the following fixed doses: 2.5×106 (n=4), 5×106 (n=12), 10×106 (n=5), and 14.3×106 (n=1) CAR-T cells; 15 pts (4 at 2.5×106, 10 at 5×106, and 1 at 14.3×106) were evaluable for safety and efficacy at the data cutoff for the abstract (October 13, 2021). Longer follow up of these 15 pts and data from additional pts treated at doses of 5×106 and 10×106 will be presented at the annual meeting. Of the 15 pts evaluable at data cutoff, DLTs were reported in 3 pts and included asymptomatic grade (gr) 3 transaminitis (n=1, 14.3×106), asymptomatic gr ≥3 elevated pancreatic enzymes (n=1, 5×106), and gr 4 neutropenia (n=1, 2.5×106). Most frequent tx-related gr ≥3 AEs included neutropenia (n=15, 100%), anemia (n=13, 87%), and thrombocytopenia (n=11, 73%). All pts experienced cytokine release syndrome (CRS) per Lee 2014 criteria; 2 had gr ≥3 CRS (n=1, 5×106; n=1, 14.3×106). Median times to CRS onset and resolution were 7 d (range, 4-12 d) and 11 d (range, 9-22 d), respectively. Tocilizumab (n=13, 87%), steroids (n=11, 73%), anakinra (n=4, 27%), and pressors (n=3, 20%) were used to manage CRS. Gr 2 neurotoxicity occurred in 4 pts (27%). Pts had an overall response rate of 93%, stringent complete response in 33%, very good partial response (VGPR) in 20%, and PR in 40%. Of evaluable pts at 3 mo post infusion, 43% (3/7) had minimal residual disease (MRD) at <10–5 sensitivity[JC(1], while 33% (2/6) were MRD negative at <10–6 by next-generation sequencing. Robust expansion of BCMA CAR-T cells was observed in all pts via qPCR and flow cytometry; maximum expansion (geometric mean Cmax) was 316,000 copies/μg by qPCR and 76% of circulating T cells by flow cytometry. Maximum expansion was reached at a median of 14.2 d by qPCR (13.9 d by flow cytometry). Naive-like T cells present in the leukapheresis were preserved during manufacturing of most PHE885 products as measured by flow cytometry, and an increase in naive/Tscm populations is observed in ≥VGPR pts post-infusion. Summary/Conclusion: Low doses of PHE885 manufactured by T-ChargeTM in <2 d have a manageable safety profile and encouraging clinical activity in pts with r/r MM. PHE885 expands rapidly in vivo, persists for prolonged periods, and demonstrates a relatively naive T-cell phenotype.

Clinical features of hemophagocytic syndrome following BCMA CAR-T cell therapy in patients with relapsed/refractory multiple myeloma.

To analyze the clinical features of hemophagocytic syndrome (HLH) following B cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cell therapy in patients with relapsed/refractory multiple myeloma. Ninety-nine patients with relapsed/refractory multiple myeloma (including 3 cases of plasma cell leukemia) undergoing BCMA CAR-T cell therapy (monocentric phaseⅠclinical trial, ChiCTR1800017404) in the First Affiliated Hospital, Zhejiang University School of Medicine from July 2018 to December 2021 were enrolled in the study. The baseline features, laboratory findings, treatment, and clinical response of these patients were analyzed. CAR-T cell associated HLH (carHLH) occurred in 20 patients (20.20%), and the median onset time was 7(0-19) d after cytokine release syndrome (CRS). Patients with carHLH were maily male patients, and manifested as high percentage of abnormal plasma cells, higher incidence of severe CRS (grade 3-4), and robust expansion of CAR-T cells in the peripheral blood (all P<0.05). The levels of interleukin (IL)-6, IL-10 and interferon (IFN)-γ, the peak value of international normalized ratio and D-dimer were elevated, and the valley value of fibrinogen was decreased in patients with carHLH (all P<0.01). All carHLH patients resolved with proper intervention (including 7 cases with tocilizumab, 5 with steroids, 6 with both). The objective response rate in carHLH patients was slightly higher than that in non-carHLH patients [100.0% (17/17) vs. 94.87% (74/78), P>0.05]. The incidence of carHLH is relatively high in BCMA CAR-T cell treated patients, which is closely related to pretreatment tumor cell percentage in bone marrow, expansion of CAR-T cells and the secretion of cytokines. Medication based on tocilizumab and steroids can achieve considerable therapeutic effects in patient with carHLH.

Risk factors of tumor lysis syndrome in relapsed/refractory multiple myeloma patients undergoing BCMA CAR-T cell therapy.

To investigate the risk factors of tumor lysis syndrome (TLS) in relapsed/refractory multiple myeloma (MM) patients undergoing B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cell therapy. The clinical data of 99 relapsed/refractory MM patients receiving BCMA CAR-T cell therapy in the First Affiliated Hospital, Zhejiang University School of Medicine from July 2018 to December 2021 were collected in this study. Univariate analysis and multivariate logistic regression were performed to evaluate the risk factors of TLS following BCMA CAR-T cell therapy. Among the 99 patients, TLS occurred in 17 cases (17.2%) with an onset time of (8.9±3.0) d after BCMA CAR-T cell therapy. All TLS patients developed TLS-related clinical manifestations, including 17 cases with renal dysfunction, 8 cases with arrhythmia. All TLS patients developed cytokine release syndrome (CRS) with an onset of 1.0 (1.0, 6.5) d after CAR-T cell therapy, and 13 cases developed grade 3-4 CRS. The levels of serum uric acid, serum creatinine and the ratio of cases with grade 3-4 CRS were significantly higher in TLS patients than in non-TLS patients (all P<0.05). Multivariate logistic regression revealed that serum creatinine ( OR=1.015, P<0.01) and severe CRS ( OR=9.371, P<0.01) were independent risk factors of TLS. Relapsed/refractory MM patients undergoing BCMA CAR-T therapy shows high incidence of TLS, which are related to elevated levels of serum creatinine and severe CRS. TLS can be prevented clinically by reducing serum creatinine and controlling CRS severity.

Risk factors of acute kidney injury during BCMA CAR-T cell therapy in patients with relapsed/refractory multiple myeloma.

To explore the risk factors of acute kidney injury (AKI) during B cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cell therapy in patients with relapsed/refractory multiple myeloma (MM). The clinical data of 99 patients with relapsed/refractory MM who received BCMA CAR-T cell therapy in the First Affiliated Hospital of Zhejiang University School of Medicine from July 2018 to December 2021 was retrospectively analyzed. Dynamic changes of renal function before and after chemotherapy preconditioning and after CAR-T cell infusion were observed. Logistic regression was used to analyze the independent risk factors associated with the occurrence of AKI. Among 99 patients, the AKI occurred in 25 cases with an incidence rate of 25.3%, and the median time was 8.0 (5.5,11.0) d. The AKI grade 1, 2 and 3 accounted for 8.0%, 12.0% and 36.0%, respectively. Logistic regression analysis showed that serum creatinine (SCr) after chemotherapy preconditioning ( OR=1.020, P<0.001), and the grade of cytokine release syndrome (CRS) ( OR=6.501, P<0.01) were independent risk factors for AKI during treatment. The area under the ROC curve (AUC) of SCr after chemotherapy preconditioning in predicting AKI was 0.800 (95% CI: 0.694-0.904, P<0.001); using 83.0 μmol/L as cut-off value, the sensitivity, specificity and Youden index of SCr were 72.0%, 80.8% and 0.528, respectively. The incidence of AKI in patients with grade 3-4 CRS was 39.1%, while that was 13.2% in patients with CRS<grade 3 ( χ 2=8.767, P<0.01). AKI mostly occurred within 15.0 d after CAR-T cell infusion, causing transient severe renal damage. Patients with abnormal renal function after chemotherapy preconditioning should be alert to the occurrence of AKI, and attention should be paid to the management of the CRS.

BCMA CAR-T Therapy Is Safe and Effective for Refractory/Relapsed Multiple Myeloma With Central Nervous System Involvement.

Central nervous system (CNS) involvement is a rare complication of multiple myeloma (MM) that portends an extremely poor prognosis. Although chimeric antigen receptor (CAR)-T cell therapy is considered a promising strategy for patients with MM, the role of CAR-T cell therapy in MM involving the CNS has not been fully elucidated. In this study, we retrospectively analyzed 4 cases of B-cell maturation antigen CAR-T cell therapy for patients with relapsed/refractory MM involving the CNS. Patients received a range of 2-7 lines of prior therapy, including 1 autologous hematopoietic stem cell transplant. The most common adverse event was cytokine release syndrome, which was observed in all 4 patients, including 2 with grade 1 and 2 with grade 2. No patient was complicated with immune effector cell-associated neurotoxicity syndrome. Within the follow-up (median: 257 d, range: 116-392 d), 3 of 4 patients reached complete remission (CR), and 1 patient reached partial response. At the data cutoff, 1 patient continued to remain in CR at day 220, and the patient with partial response died at day 116. The other 2 patients relapsed at 317 and 111 days with CR durations of 287 and 81 days, respectively. Our results show promising effectiveness and acceptable safety of CAR-T cell therapy for heavily pretreated patients with CNS MM.

Anti B-cell maturation antigen CAR T-cell and antibody drug conjugate therapy for heavily pretreated relapsed and refractory multiple myeloma.

DISCLOSURES: Funding for this summary was contributed by Arnold Ventures, California Health Care Foundation, The Donaghue Foundation, Harvard Pilgrim Health Care, and Kaiser Foundation Health Plan to the Institute for Clinical and Economic Review (ICER), an independent organization that evaluates the evidence on the value of health care interventions. ICER's annual policy summit is supported by dues from AbbVie, Aetna, America's Health Insurance Plans, Anthem, Alnylam, AstraZeneca, Biogen, Blue Shield of CA, Boehringer-Ingelheim, Cambia Health Services, CVS, Editas, Evolve Pharmacy, Express Scripts, Genentech/Roche, GlaxoSmithKline, Harvard Pilgrim, Health Care Service Corporation, HealthFirst, Health Partners, Humana, Johnson & Johnson (Janssen), Kaiser Permanente, LEO Pharma, Mallinckrodt, Merck, Novartis, National Pharmaceutical Council, Pfizer, Premera, Prime Therapeutics, Regeneron, Sanofi, Spark Therapeutics, uniQure, and United Healthcare. Beinfeld, Fluetsch, and Pearson are employed by ICER. Ollendorf received funding from ICER for work on this summary and reports consulting and other personal fees from EMD Serono, Amgen, Analysis Group, Aspen Institute/University of Southern California, GalbraithWight, Cytokinetics, Executive Insight, Sunovion, University of Colorado, World Health Organization, and Eli Lilly, unrelated to this work. Lee and McQueen received funding from ICER for work on this summary.

A transgene-encoded truncated human epidermal growth factor receptor for depletion of anti- B-cell maturation antigen CAR-T cells

BackgroundChimeric antigen receptor T cells (CAR-T) against B-cell maturation antigen (BCMA) has been used to treat multiple myeloma (MM). CAR-T cells co-expressing a truncated human EGFR (tEGFR) has been proposed for in vivo cell ablation. MethodsWe designed and tested a novel anti-BCMA CAR. We transduced T cells with retroviral vectors encoding CAR and tEGFR. The anti-BCMA-CAR-transduced T cells were evaluated for the functions including cytokine production, proliferation, cytotoxicity, and in vivo tumor eradication of BCMA. Cetuximab was used for in vivo cell ablation. ResultsThe CAR-T cells could specifically recognize BCMA, and anti-BCMA CAR-T cells could exhibit interferon-γ and cytotoxicity specifically produced by BCMA and eradicate tumor in vivo. Cetuximab could mediate antibody-dependent cellular cytotoxicity and in vivo elimination. ConclusionsWe confirm that BCMA is a suitable target for CAR- T cells and tEGFR is a effective tool for cellular ablation.

A Fully-Human Armored BCMA CAR Boosts Function of CD4+ CAR-T Cells and Resists TGF-β Suppression in Pre-Clinical Models of Multiple Myeloma

The B-cell maturation antigen (BCMA) is an immunotherapy target selectively expressed on multiple myeloma cells (MM). Despite recent success of experimental BCMA CAR-T cell therapy, clinical remissions in MM are often short, in part due to low persistence of the BCMA CAR-T cells. Additionally, immunosuppressive factors, notably TGF-β, are known to be elevated in the peripheral blood and tumor microenvironment in the bone marrow of MM patients, potentially contributing to the lack of durability of CAR-T cell therapy. We aimed to develop a fully-human BCMA CAR with long-term persistence and functional resistance to the suppressive effects of TGF-β. Initially, two fully human single chain variable fragments (scFv) specific for BCMA, derived by biopanning of a yeast display human scFv library, were characterized in a CAR format. Each of the two scFvs was cloned into a lentiviral vector CAR backbone, comprised of the CD8 hinge and transmembrane domain, 4-1BB co-stimulatory domain and CD3ζ signaling domain, and termed BCMA1 and BCMA2, respectively. BCMA2 and BCMA1 T cells, generated by lentiviral vector transduction of primary human T cells, exhibited high CAR expression at multiplicities of infection 10 to 40 (BCMA1: 64-81%; BCMA2: 84-94%), and consistently demonstrated potent cytotoxicity in an overnight co-culture with BCMA+ MM cell lines RPMI-8226 and MM1.S, but not the BCMA- 293T cells. BCMA2 CAR showed robust proliferative capacity in response to repeated, long-term exposure to MM1.S target cells, concordant with the sustained CD4 T-cell subset and high IL-2 production during the course of repeated exposure to target cells. This is in contrast to BCMA1, that showed precipitous decrease in CD4+ T-cell subset upon co-culture with MM cells, resulting in a CAR T-cell population dominated by CD8+ T-cells. Furthermore, the BCMA2 demonstrated prolonged potency in clearing tumor cells compared to BCMA1, even after continuous 20-day exposure to target cells. This was further confirmed in a mouse intradermal RPMI-8226 xenograft tumor model, in which infusion of BCMA2 T-cells resulted in the rapid and complete eradication of tumors, while BCMA1 showed a slower decline in tumor burden. To further improve the efficacy of the BCMA2, specifically within the TGF-β-rich immunosuppressive tumor microenvironment, we developed an armored BCMA2 CAR variant, which co-expresses the dominant negative TGF-β RII bicistronically via a 2A sequence (BCMA2-TbnegCAR). In a 10 day-long co-culture assay with MM1.S targets in the presence of spiked 10 ng/ml TGF-β, BCMA2-TbnegCAR retained high proliferative capacity and potent cytotoxicity, while the unarmored BCMA2 had diminished proliferation and substantially reduced cytokine and granzyme B production. Consistently, in the in vivo intradermal tumor model that utilizes RPMI-8226, which is a MM cell line that endogenously produces TGF-β, we observed that BCMA2-TbnegCAR treatment resulted in higher T-cell counts in the tumors and an earlier decrease of tumor burden compared to infusion with BCMA2, further demonstrating the increased efficacy and potency of the BCMA2-TbnegCAR. In conclusion, we have designed and characterized a new fully-human BCMA2-TbnegCAR, with a novel scFv that exhibits robust proliferative capacity and persistent cytotoxicity, and remains functionally resistant to the immunosuppressive effects of TGF-β. This novel BCMA CAR can potentially improve the effectiveness and durability of the current BCMA CAR-T cell therapy. Disclosures Alabanza: Lentigen, a Miltenyi Biotec Company: Current Employment, Patents &amp; Royalties: CAR-T immunotherapy. Vu:Lentigen, a Miltenyi Biotec Company: Current Employment, Patents &amp; Royalties: CAR-T immunotherapy. Wu:Lentigen, a Miltenyi Biotec Company: Current Employment. Zhu:Lentigen, a Miltenyi Biotec Company: Current Employment, Patents &amp; Royalties: CAR-T immunotherapy. Dropulic:Lentigen, a Miltenyi Biotec Company: Current Employment, Patents &amp; Royalties: CAR-T immunotherapy. Schneider:Lentigen, a Miltenyi Biotec Company: Current Employment, Patents &amp; Royalties.

Novel Therapies for the Treatment of Patients with Relapsed/Refractory Multiple Myeloma: A Review of Clinical Trials

Introduction: Multiple myeloma (MM) is a neoplastic proliferation of plasma cells. It is the second most common hematological malignancy in the US. Although it is associated with poor prognosis, newer therapies have improved outcomes in MM patients. This review aims to describe novel therapies used for the treatment of relapsed/refractory multiple myeloma (RRMM). Methods: A literature search was performed on Embase and clinicaltrials.gov using the keyword "Multiple Myeloma" from 1/1/2016 to 6/25/2020 for identifying ongoing clinical trials in the treatment of RRMM. After detailed scrutiny, we included 23 ongoing clinical trials (N=4362). We excluded case reports, case series, review articles, meta-analysis, and observational studies. Results: We summarized the interim results from ongoing clinical trials evaluating treatment of RRMM under following newer categories of drugs: Immunomodulatory drugs In a phase 1b/IIa trial (NCT02773030, N=51) evaluating the efficacy of a novel immunomodulators, iberdomide CC-220 + dexamethasone (Dex) yielded an overall response rate (ORR) of 31%, clinical benefit (CB) was seen in 51% of the patients, and disease control (DC) in 88% of the patients and it was well tolerated by RRMM patients. There are other ongoing clinical trials evaluating the efficacy of Avadomide (CC-122), CC-92480 in RRMM. Alkylating agents In a phase I/II trial (NCT01897714, N=45), melphalan-flufenamide (melflufan) + Dex yielded an ORR of 31%, it was well tolerated with 49% CB. Phase III OCEAN trial (NCT03151811, N=450) is currently ongoing to compare melflufen + Dex vs. pomalidomide (Pom) + Dex. Apoptotic agents A phase 3 trial BELLINI (NCT02755597, N=291) evaluated the efficacy of veneteclox (Ven, Bcl-2 inhibitor) by randomizing patients to either Ven or Placebo arm. With a median follow up of 28.6 months (m), progression free survival (PFS) was 23.2m in the Ven arm vs. 11.4m in placebo. The interim results from a phase I/II trial (NCT03314181, N=104) of Ven + daratumumab (Dara) + Dex showed ORR of 96% with ≥ very good partial response (VGPR) of 96%. The addition of Bortezomib (Bor) to VenDaraDex had a slightly low ORR of 92%, with ≥VGPR of 79%. Another phase I/II trial (NCT01794520, N=117) is in progress to assess the efficacy and safety of Ven as monotherapy. Monoclonal Antibodies (MoAb) A phase I/II trial (NCT01421186, N=91) evaluated the efficacy of MOR202, which is a novel MoAb. MOR202 was evaluated in three arms; MOR202 + Dex, MOR202 + Lenalidomide (Len) + Dex and MOR202 + Pom + Dex. The interim analysis showed the ORR of 65% with MOR202 + Len + Dex which was better than ORR of 48% with MOR202 + Pom + Dex, while the use of MOR202 + Dex yielded only 28% ORR. Antibody-drug conjugate (ADC) Four ongoing trials are evaluating the efficacy of ADC (belantamab mafodotin), and the interim results are available for two trials. In phase II DREAMM-2 trial (NCT03525678, N=221) evaluating 2 doses of GSK2857916, 2.5mg/kg dose yielded ORR of 31% while 3.4mg/kg showed ORR of 34%. Another phase I trial (NCT02064387, N=79) evaluated belantamab mafodotin in RRMM and other hematologic malignancies expressing B-cell maturation antigen (BCMA). The results were promising with ORR of 60%. Bispecific T-cell engagers (BiTE) Phase I trial of BiTE AMG 420 (NCT02514239, N=43) showed favorable results with ORR 70%, and CR 12%. The interim results from another phase I trial (NCT03486067, N=115) which evaluated the efficacy of BiTE CC-93269 showed 43% ORR and CR 17%. CAR-T Cell therapy CAR-T cell therapy is also being studied in RRMM with JNJ-68284528 directed against BCMA in a phase Ib trial (NCT03548207, N=118). The interim analysis of 29 response evaluable patients out of 118 reported 100% ORR with stringent CR 76%. PK13 Inhibitors In a phase I/II study (NCT00401011, N=84) evaluating perifosine + Bor +/- Dex, ORR of 41% was observed in Bor RR patients, and therapy was well tolerated with PFS of 6.4m and mOS of 25m. Conclusion: This review demonstrates novel and promising therapies which are currently in early phase clinical trials for the treatment of RRMM. Based on interim results, Iberdomide, melflufan, Ven, MoAb MOR202, ADC belantamab mafodotin, BiTE Molecule AMG 420, BCMA CAR-T cell therapy and perifosine have shown promising early activity and safety data in RRMM patients. Additional exploratory clinical trials are needed to confirm the efficacy and safety of these agents. Disclosures Anwer: Incyte, Seattle Genetics, Acetylon Pharmaceuticals, AbbVie Pharma, Astellas Pharma, Celegene, Millennium Pharmaceuticals.: Honoraria, Research Funding, Speakers Bureau.

Safety and Efficacy of Anti-Bcma CAR-T Cells for Relapsed/Refractory Multiple Myeloma: A Systematic Review of Literature

Background: Multiple myeloma (MM) is a plasma cell disorder and demonstrates overexpression of B cell maturation antigen (BCMA). Our objective is to evaluate the safety and efficacy of chimeric antigen receptor T cells (CAR-T) against BCMA in patients with relapsed/refractory multiple myeloma (RRMM). Methods: We conducted a systematic literature search using PubMed, Cochrane, Clinicaltrials.gov, and Embase databases. We also searched for data from society meetings. A total of 935 articles were identified, and 610 were screened for relevance. Results: Data from thirty-one original studies with a total of 871 patients (pts) were included based on defined eligibility criteria, see Table 1. Hu et al. reported an overall response rate (ORR) of 100% in 33 pts treated with BCMA CAR-T cells including 21 complete response (CR), 7 very good partial response (VGPR), 4 partial response (PR). Moreover, 32 pts achieved minimal residual disease (MRD) negative status. Chen et al. reported ORR of 88%, 14% CR, 6% VGPR, and 82% MRD negative status with BCMA CAR-T therapy in 17 RRMM pts. In another clinical trial by Han et al. BCMA CAR-T therapy demonstrated an ORR of 100% among 7 evaluable pts with 43% pts having ≥ CR and 14% VGPR. An ORR of 100% with 64% stringent CR (sCR) and 36% VGPR was reported with novel anti-BCMA CART cells (CT103A). Similarly, Li et al. reported ORR of 87.5%, sCR of 50%, VGPR 12.5%, and PR 25% in 16 pts. BCMA targeting agent, JNJ-4528, showed ORR of 91%, including 4sCR, 2CR, 10MRD, and 7VGPR. CAR-T- bb2121 demonstrated ORR of 85%, sCR 36%, CR 9%, VGPR 57%, and MRD negativity of 100% (among 16 responsive pts). GSK2857916, a BCMA targeting CAR-T cells yielded ORR of 60% in both clinical trials. Three studies utilizing bispecific CART cells targeting both BCMA &amp; CD38 (LCARB38M) reported by Zhao et al., Wang et al., and Fan et al. showed ORR of 88%, 88%, &amp; 100% respectively. Topp et al. reported ORR of 31% along with 5 ≥CR and 5 MRD negative status in 42 pts treated with Bi T-cells Engager BiTE® Ab BCMA targeting antigen (AMG420). One clinical trial presented AUTO2 CART cells therapy against BCMA with an ORR of 43%, VGPR of 14%, and PR of 28%. CT053CAR-BCMA showed 14sCR and 5CR with a collective ORR of 87.5% and MRD negative status of 85% in 24 and 20 evaluable pts, respectively. Likewise, Mikkilineni et al. reported an ORR of 83%, sCR of 16.7%, and VGPR &amp; PR of 25% and 41% in 12 pts treated with FHVH-BCMA T cells. Similar results are also reported in other clinical trials of BCMA targeting CART therapy (Table 1). The most common adverse effects exhibited were grade 1-3 hematologic (cytopenia) and cytokine release syndrome (CRS) (mostly reversible with tocilizumab). Conclusion: Initial data from ongoing clinical trials using BCMA targeting CAR-T therapy have yielded promising results both in terms of improved outcome and tolerable toxicity profiles. Although two phase 3 trails are ongoing, additional data is warranted to further ensure the safety and efficacy of anti-BCMA CAR-T cells therapy in pts with RRMM for future use. Disclosures Anwer: Incyte, Seattle Genetics, Acetylon Pharmaceuticals, AbbVie Pharma, Astellas Pharma, Celegene, Millennium Pharmaceuticals.: Honoraria, Research Funding, Speakers Bureau.

Dual Targeting to Overcome Current Challenges in Multiple Myeloma CAR T-Cell Treatment.

In the era of highly promising novel targeted-immunotherapy strategies for multiple myeloma (MM), the first series of clinical trials with CAR T-cells targeting the plasma cell-specific B-cell maturation antigen (BCMA) have shown excellent response rates. In the long-term, however, MM appears to escape the therapy likely due to initial low and heterogeneous expression or downregulation of BCMA expression. Several other molecules targeted by CAR T-cells in MM are expressed at high levels on MM cells, but many of these attractive targets are also expressed on various, sometimes vital non-malignant cells, posing major risks for on-target, off-tumor side effects. CAR T-cell therapy for MM therefore faces two urgent challenges: (i) improving the efficacy of BCMA CAR T-cells and (ii) establishing a MM-selectivity even when CAR T-cells are directed against not entirely MM-specific target antigens. In this review, we will outline the current attempts to tackle these challenges, with a specific focus on how dual CAR targeting might be applied to tackle both issues.

Safety and efficacy of CAR-T cell targeting BCMA in patients with multiple myeloma coinfected with chronic hepatitis B virus

BackgroundReactivation of hepatitis B virus (HBV) infection is a well-recognized complication in patients with chronic or resolved HBV infection undergoing anticancer therapy. There is a risk of HBV reactivation after...