Successful Treatment of Relapsed/Refractory Extramedullary Multiple Myeloma With Anti-BCMA CAR-T Cell Therapy Followed by Haploidentical Hematopoietic Stem Cell Transplantation: A Case Report and a Review of the Contemporary Literature

T-cell redirection therapy after allogeneic stem cell transplantation in multiple myeloma: When the cure fails!

Allogeneic stem cell transplant remains an option for patients with myeloma. Given the unfortunate inevitability of the majority of patients, relapsing salvage therapy options are needed. Although there is a potential concern for subsequent T-cell redirection therapy in these patients, Hammons et al. provide a retrospective look at patients treated this way with no new significant adverse safety or efficacy signal. Commentary on: Hammons et al. Chimeric antigen receptor and bispecific T-cell engager therapies in multiple myeloma patients with prior allogeneic transplantation. Br J Haematol 2024;204:887-891.

Four-year follow-up of LCAR-B38M in relapsed or refractory multiple myeloma: a phase 1, single-arm, open-label, multicenter study in China (LEGEND-2)

Background

LCAR-B38M is a chimeric antigen receptor T cell product with two binding domains targeting B cell maturation antigen. Our previous reports showed a remarkable efficacy of LCAR-B38M in patients with relapsed/refractory multiple myeloma (RRMM) at a median follow-up of 2 years. Here, we report long-term safety and efficacy data from a median follow-up of 4 years.

Methods

LEGEND-2 was a phase 1, single-arm, open-label study conducted in four registered sites in China. Seventy-four participants with RRMM received LCAR-B38M treatment. Lymphodepletion was performed using cyclophosphamide or cyclophosphamide plus fludarabine. LCAR-B38M, at a median dose of 0.513 × 10⁶ cells/kg, was intravenously administered either in three split infusions or in a single infusion. The primary objective was the safety of LCAR-B38M, and the secondary objective was efficacy.

Results

As of May 25, 2021, the median follow-up was 47.8 months. All patients experienced ≥ 1 adverse events (AEs). Grade ≥ 3 AEs were observed in 45/74 (60.8%) patients. Cytokine release syndrome (CRS) occurred in 68/74 (91.9%) cases; 7 (9.5%) had grade ≥ 3 CRS. One patient experienced grade 1 central nervous system toxicity. The overall response rate was 87.8%. Fifty-four out of 74 (73.0%) patients achieved complete response. The median progression-free survival was 18.0 months, and the median overall survival for all patients was not reached. The median duration of response was 23.3 months. Four patients experienced viral infection more than 6 months post-infusion, and four patients developed second primary non-hematological malignancies at a median time of 11.5 months post-CAR-T cell transfer.

Conclusions

The 4-year follow-up data of LCAR-B38M therapy demonstrated a favorable long-term safety profile and a durable response in patients with RRMM.

Trial registration Clinicaltrials.gov NCT03090659 (retrospectively registered on March 27, 2017); ChiCTR-ONH-17012285.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13045-022-01301-8.

Patient selection for CAR T or BiTE therapy in multiple myeloma: Which treatment for each patient?

Multiple myeloma (MM) is a plasma cell malignancy that affects an increasing number of patients worldwide. Despite all the efforts to understand its pathogenesis and develop new treatment modalities, MM remains an incurable disease. Novel immunotherapies, such as CAR T cell therapy (CAR) and bispecific T cell engagers (BiTE), are intensively targeting different surface antigens, such as BMCA, SLAMF7 (CS1), GPRC5D, FCRH5 or CD38. However, stem cell transplantation is still indispensable in transplant-eligible patients. Studies suggest that the early use of immunotherapy may improve outcomes significantly. In this review, we summarize the currently available clinical literature on CAR and BiTE in MM. Furthermore, we will compare these two T cell-based immunotherapies and discuss potential therapeutic approaches to promote development of new clinical trials, using T cell-based immunotherapies, even as bridging therapies to a transplant.

Current Role of Allogeneic Stem Cell Transplantation in Multiple Myeloma

Major progress in the treatment of multiple myeloma has been made in the last several years. However, myeloma remains incurable and patients with high-risk cytogenetics or advanced stage disease have an even worsen survival. Only allogeneic transplantation may have curative potential in some patients. However, the high non-relapse mortality and incidence of chronic graft-versus-host disease have raised controversy regarding this procedure. In this review, we will address the role of upfront and delayed allogeneic transplant.

Cellular Immunotherapies for Multiple Myeloma: Current Status, Challenges, and Future Directions

Multiple myeloma (MM) remains incurable due to relapse, although the use of proteasome inhibitors, immunomodulatory drugs, CD38-targeting antibodies, and autologous stem cell transplantation (auto-SCT) significantly improve the clinical outcomes of patients with newly diagnosed MM. In recent years, the introduction of chimeric antigen receptor T-cell (CAR T-cell) therapy has brought hope to patients with refractory and relapsed MM. The graft-versus-myeloma effect of allogeneic SCT provides the possibility for curing a subset of MM patients. In this review, we summarize the recent advances and challenges of cellular immunotherapies for MM, focusing on auto-SCT, allogeneic SCT, and CAR T-cell approaches. We also discuss future directions, and propose a specific algorithm for cellular therapies for MM and probability of minimal residual disease-directed therapy.

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).