Highly proliferative and functional PD-1+ and TIM-3+ T cells are transiently increased in multiple myeloma following autologous hematopoietic stem cell transplantation

T-cell exhaustion in multiple myeloma

INTRODUCTION

Chimeric Antigen Receptor (CAR) T-cells and Bispecific Antibodies (BsAb) are the leading platforms for redirecting the immune system against cells expressing the specific antigen, revolutionizing the treatment of hematological malignancies, including multiple myeloma (MM). In MM, drug-resistant relapses are the main therapy-limiting factor and the leading cause of why the disease is still considered incurable. T-cell-engaging therapies hold promise in improving the treatment of MM. However, the effectiveness of these treatments may be hindered by T-cell fitness. T-cell exhaustion is a condition of a gradual decline in effector function, reduced cytokine secretion, and increased expression of inhibitory receptors due to chronic antigen stimulation.

AREAS COVERED

This review examines findings about T-cell exhaustion in MM in the context of T-cell redirecting BsAbs and CAR-T treatment.

EXPERT OPINION

The fitness of T-cells has become an important factor in the development of T-cell redirecting therapies. The way T-cell exhaustion relates to these therapies could affect the further development of CAR and BsAbs technologies, as well as the strategies used for clinical use. Therefore, this review aims to explore the current understanding of T-cell exhaustion in MM and its relationship to these therapies.

Immune Checkpoints and targeted agents in relapse and graft-versus-host disease after hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for malignant hematologic disorders. Novel anti-infection agents have successfully decreased the risk of fatal infections post-HSCT in recent years, but the relapse of primary disease and graft-versus-host disease (GVHD) remain the major causes of death for transplant recipients, and significantly deteriorate the quality of life. Thus, it is crucial to maintain the immune homeostasis in transplant recipients and balance the graft-versus-leukemia (GVL) effect and GVHD.

METHODS

We reviewed the recently published literatures on immune checkpoint (IC) and targeted agents in relapse and GVHD after allogeneic HSCT RESULTS: Emerging data suggest that IC is an attractive target to modulate immune responses, and accumulating evidences of IC-targeted agents have been published for the treatment of malignancies and autoimmune disorders. The unique mechanism of IC-targeted agents, which affects the immune homeostasis of the transplant recipient by modulating alloreactivity, minimizes the risk of organ toxicity and immunosuppression associated with conventional therapy CONCLUSION: There is an increase in literature reporting the application of immune checkpoint-targeted agents in HSCT settings, and an overview will benefit further exploration in this field.

Different expression patterns of VISTA concurrent with PD-1, Tim-3, and TIGIT on T cell subsets in peripheral blood and bone marrow from patients with multiple myeloma

V-type immunoglobulin domain-containing suppressor of T cell activation (VISTA) is considered as an immunosuppressive factor and potential therapeutic target for anticancer therapy. However, little is known about VISTA expression and its role in immunosuppression in multiple myeloma (MM). In this study, VISTA expression and co-expression with programmed cell death receptor-1 (PD-1), T cell immunoglobulin mucin-domain-containing-3 (Tim-3), and T cell immunoglobulin and ITIM domain (TIGIT) in CD3+, CD4+, CD8+, and regulatory T (Treg) cells were analyzed in patients with MM by multi-color fluorescent flow cytometry of peripheral blood (PB) and bone marrow (BM) samples from 36 patients with MM and compared to 36 PB samples and 10 BM samples from healthy individuals (HIs), which served as controls. The results demonstrated a significant increased percentage of VISTA co-expression with PD-1, Tim-3, and TIGIT in CD3+, CD4+, CD8+, and Treg cells in PB from MM patients compared with HIs. A similar trend for VISTA+CD8+ T cells was found in BM. Moreover, a trend of a high percentage on VISTA expression and co-expression in PB rather than BM was found. Furthermore, significant positive correlations existed for VISTA expression concurrent with PD-1, Tim-3, and TIGIT in T cell subsets and clinical indicators, including Revised International Staging System (R-ISS) staging of multiple myeloma, Eastern Cooperative Oncology Group (ECOG) score, and beta-2-microglobulin (β2-MG). In conclusion, higher VISTA expression concurrent with PD-1, Tim-3, and TIGIT on T cells, particularly in the PB of patients with MM, may result in T cell exhaustion and dysfunction and be closely associated with disease progression and clinical indicators. Thus, VISTA may be considered a potential target for reversing T cell exhaustion and improving T cell function in MM.