Immune Functions of Signaling Lymphocytic Activation Molecule Family Molecules in Multiple Myeloma

The role of signaling lymphocyte activation molecule family receptors in hematologic malignancies

PURPOSE OF REVIEW

In this review, we provide an overview of the current understanding of SLAM-family receptors in hematologic malignancies. We highlighted their contribution to the disease pathogenesis and targeting strategies to improve therapeutic outcomes.

RECENT FINDINGS

Emerging studies have reported the tumor-promoting role of SLAM-family receptors in various hematologic malignancies, including chronic lymphocytic leukemia, acute myeloid leukemia, and multiple myeloma. Specifically, they regulate the interaction between malignant cells and the tumor microenvironment to promote apoptosis resistance, therapeutic resistance, impairment of antitumor and tumor progression.

SUMMARY

SLAM-family receptors promote the progression of hematologic malignancies by regulating the interaction between malignant cells and the tumor microenvironment. This provides the rationale that SLAM-targeted therapies are appealing strategies to enhance therapeutic outcomes in patients.

The numerous facets of 1q21+ in multiple myeloma: Pathogenesis, clinicopathological features, prognosis and clinical progress (Review)

Multiple myeloma (MM) is a malignant neoplasm characterized by the clonal proliferation of abnormal plasma cells (PCs) in the bone marrow and recurrent cytogenetic abnormalities. The incidence of MM worldwide is on the rise. 1q21+ has been found in ~30-40% of newly diagnosed MM (NDMM) patients.1q21+ is associated with the pathophysiological mechanisms of disease progression and drug resistance in MM. In the present review, the pathogenesis and clinicopathological features of MM patients with 1q21+ were studied, the key data of 1q21+ on the prognosis of MM patients were summarized, and the clinical treatment significance of MM patients with 1q21+ was clarified, in order to provide reference for clinicians to develop treatment strategies targeting 1q21+.

SLAMF7 predicts prognosis and correlates with immune infiltration in serous ovarian carcinoma

OBJECTIVE

Signaling lymphocytic activation molecule family members (SLAMFs) play a critical role in immune regulation of malignancies. This study aims to investigate the prognostic value and function of SLAMFs in ovarian cancer (OC).

METHODS

The expression analysis of SLAMFs was conducted based on The Cancer Genome Atlas Ovarian Cancer Collection (TCGA-OV) and Gene Expression Omnibus (GEO) databases. Immunohistochemistry (IHC) was further performed on tissue arrays (n=98) to determine the expression of SLAMF7. Kaplan-Meier plotter and multivariate Cox regression model were used to evaluate the correlation of SLAMF7 expression with survival outcomes of patients. The molecular function of SLAMF7 in OC was further investigated using Gene Set Enrichment Analysis (GSEA).

RESULTS

SLAMF7 mRNA expression were significantly upregulated in OC tumor tissue compared to normal tissue. IHC revealed that SLAMF7 expression was located in the interstitial parts of tumor tissue, and higher SLAMF7 expression was associated with favorable survival outcomes. GSEA demonstrated that SLAMF7 is involved immune-related pathways. Further analysis showed that SLAMF7 had a strong correlation with the T cell-specific biomarker (CD3) but not with the B cell (CD19, CD22, and CD23) and natural killer cell-specific biomarkers (CD85C, CD336, and CD337). Furthermore, IHC analysis confirmed that SLAMF7 was expressed in tumor-infiltrating T cells, and the IHC score of SLAMF7 was positively correlated with CD3 (r=0.85, p<0.001).

CONCLUSION

SLAMF7 is expressed in the interstitial components of clinical OC tissue, and higher SLAMF7 expression indicated a favorable prognosis for patients with OC. Additionally, SLAMF7 is involved in T-cell immune infiltration in OC.

Killer instincts: natural killer cells as multifactorial cancer immunotherapy

Natural killer (NK) cells integrate heterogeneous signals for activation and inhibition using germline-encoded receptors. These receptors are stochastically co-expressed, and their concurrent engagement and signaling can adjust the sensitivity of individual cells to putative targets. Against cancers, which mutate and evolve under therapeutic and immunologic pressure, the diversity for recognition provided by NK cells may be key to comprehensive cancer control. NK cells are already being trialled as adoptive cell therapy and targets for immunotherapeutic agents. However, strategies to leverage their naturally occurring diversity and agility have not yet been developed. In this review, we discuss the receptors and signaling pathways through which signals for activation or inhibition are generated in NK cells, focusing on their roles in cancer and potential as targets for immunotherapies. Finally, we consider the impacts of receptor co-expression and the potential to engage multiple pathways of NK cell reactivity to maximize the scope and strength of antitumor activities.

SLAM Modification as an Immune-Modulatory Therapeutic Approach in Cancer

In the field of oncology, the Signaling Lymphocyte Activation Molecule (SLAM) family is emerging as pivotal in modulating immune responses within tumor environments. The SLAM family comprises nine receptors, mainly found on immune cell surfaces. These receptors play complex roles in the interaction between cancer and the host immune system. Research suggests SLAM's role in both enhancing and dampening tumor-immune responses, influencing the progression and treatment outcomes of various cancers. As immunotherapy advances, resistance remains an issue. The nuanced roles of the SLAM family might provide answers. With the rise in technologies like single-cell RNA sequencing and advanced imaging, there is potential for precise SLAM-targeted treatments. This review stresses patient safety, the importance of thorough clinical trials, and the potential of SLAM-focused therapies to transform cancer care. In summary, SLAM's role in oncology signals a new direction for more tailored and adaptable cancer treatments.

Mechanisms of Action and Limitations of Monoclonal Antibodies and Single Chain Fragment Variable (scFv) in the Treatment of Cancer

Monoclonal antibodies are among the most effective tools for detecting tumor-associated antigens. The U.S. Food and Drug Administration (FDA) has approved more than 36 therapeutic antibodies for developing novel alternative therapies that have significant success rates in fighting cancer. However, some functional limitations have been described, such as their access to solid tumors and low interaction with the immune system. Single-chain variable fragments (scFv) are versatile and easy to produce, and being an attractive tool for use in immunotherapy models. The small size of scFv can be advantageous for treatment due to its short half-life and other characteristics related to the structural and functional aspects of the antibodies. Therefore, the main objective of this review was to describe the current situation regarding the mechanisms of action, applications, and limitations of monoclonal antibodies and scFv in the treatment of cancer.

SLAM-family receptors come of age as a potential molecular target in cancer immunotherapy

The signaling lymphocytic activation molecule (SLAM) family receptors were discovered in immune cells for the first time. The SLAM-family receptors are a significant player in cytotoxicity, humoral immune responses, autoimmune diseases, lymphocyte development, cell survival, and cell adhesion. There is growing evidence that SLAM-family receptors have been involved in cancer progression and heralded as a novel immune checkpoint on T cells. Previous studies have reported the role of SLAMs in tumor immunity in various cancers, including chronic lymphocytic leukemia, lymphoma, multiple myeloma, acute myeloid leukemia, hepatocellular carcinoma, head and neck squamous cell carcinoma, pancreas, lung, and melanoma. Evidence has deciphered that the SLAM-family receptors may be targeted for cancer immunotherapy. However, our understanding in this regard is not complete. This review will discuss the role of SLAM-family receptors in cancer immunotherapy. It will also provide an update on recent advances in SLAM-based targeted immunotherapies.

The levels of serum soluble CD86 are correlated with the expression of CD86 variant 3 gene and are prognostic indicators in patients with myeloma

We previously showed that cell-surface CD86 expressed on multiple myeloma (MM) cells contributed to not only tumor growth but also antitumor cytotoxic T-lymphocyte responses mediated by induction of IL-10-producing CD4⁺ T cells. The soluble form of CD86 (sCD86) was also detected in serum from patients with MM. Thus, to determine whether sCD86 levels are a useful prognostic factor, we investigated the association of serum sCD86 levels with disease progression and prognosis in 103 newly diagnosed patients with MM. Serum sCD86 was detected in 71% of the patients with MM but was only rarely detected in patients with monoclonal gammopathy of undetermined significance and healthy controls, and the level was significantly increased in patients with advanced-stage MM. When we examined differences in clinical characteristics according to the level of serum sCD86, those in the high (≥2.18 ng/mL, n = 38) group exhibited more aggressive clinical characteristics, with shorter overall survival times compared with those in the low (<2.18 ng/mL, n = 65) group. On the other hand, it was difficult to stratify the patients with MM into different risk groups based on the expression levels of cell-surface CD86. The levels of serum sCD86 were significantly correlated with the expression levels of the messenger RNA (mRNA) transcripts of CD86 variant 3, which lack exon 6, resulting in a truncated transmembrane region, and its variant transcripts were upregulated in the high group. Thus, our findings suggest that sCD86 can be easily measured in peripheral blood samples and is a useful prognostic marker in patients with MM.

Multiplex proteomics using proximity extension assay for the identification of protein biomarkers predictive of acute graft-vs.-host disease in allogeneic hematopoietic cell transplantation

OBJECTIVES

Allogeneic hematopoietic cell transplantation (HCT) is associated with acute graft-vs.-host disease (aGVHD). The presented study applied a novel multiplex antibody-based proximity extension assay (PEA) proteomic platform that can detect thousands of serum proteins simultaneously for the identification of potential biomarkers of aGVHD.

METHODS

Serum samples from 28 patients who underwent allogeneic HCT for acute myeloid leukemia (AML) were analyzed; 17 were diagnosed with grade II-IV aGVHD while 11 patients were not. Samples collected on day -6, day 0, +14, +30, +60 and +90 post-HCT were analyzed for the relative concentrations of 552 proteins. The concentration of each protein from baseline to the closest time point before onset of aGVHD, or to the latest time point in control patients, was documented.

RESULTS

Individualized analysis identified 26 proteins demonstrating ≥3-fold increase at aGVHD onset compared to baseline, eliminating proteins with a similar increase in controls. Another approach used paired t-testing and logistic regression that identified a four-marker panel, including SLAMF7, IL-1ra, BTN3A2 and DAB2, where individual log-likelihood ratios ranged from 3.99 to 8.15 (logistic regression, p=0.004-0.046). When combined, the four-marker panel demonstrated an area under the curve (AUC) of 0.90 (95% CI: 0.78-1.00; p=0.0006) with high negative predictive value of 81.8% and positive predictive value of 86.7%. All four markers play a physiological role in immune regulation. Among these, three were also present in the individualized analysis (SLAMF7, IL-1ra and BTN3A2).

CONCLUSIONS

We conclude that serum proteins identified using multiplex proteomics, particularly SLAMF7, IL-1ra, BTN3A2 and DAB2, may potentially predict aGVHD.

CD229 interacts with RASAL3 to activate RAS/ERK pathway in multiple myeloma proliferation

Multiple myeloma (MM) is an incurable plasma cell malignancy, while CAR-T therapy offers a new direction for the treatment of MM. Recently, signaling lymphocytic activation molecule family 3 (CD229), a cell surface immune receptor belonging to the signaling lymphocyte activating molecule family (SLAMF), is emerging as a CAR-T therapeutic target in MM. However, a clear role of CD229 in MM remains elusive. In this study, MM patients with elevated CD229 expression achieved poor prognosis by analyzing MM clinical databases. In addition, CD229 promoted MM cell proliferation in vitro as well as in xenograft mouse model in vivo. Mechanism study revealed that CD229 promoted MM cell proliferation by regulating the RAS/ERK signaling pathway. Further exploration employed co-immunoprecipitation coupled with mass spectrometry to identify RASAL3 as an important downstream protein of CD229. Additionally, we developed a co-culture method combined with the immunofluorescence assay to confirm that intercellular tyrosine phosphorylation mediated self-activation of CD229 to activate RAS/ERK signaling pathway via interacting with RASAL3. Taken together, these findings not only demonstrate the oncogenic role of CD229 in MM cell proliferation, but also illustrate the potential of CD229 as a promising therapeutic target for MM treatment.

Chromosomal 1q21 abnormalities in multiple myeloma: a review of translational, clinical research, and therapeutic strategies

INTRODUCTION

Multiple myeloma (MM) remains an incurable disease with a median overall survival of approximately 5 years. Gain or amplification of 1q21 (1q21+) occurs in around 40% of patients with MM and generally portends a poor prognosis. Patients with MM who harbor 1q21+ are at increased risk of drug resistance, disease progression, and death. New pharmacotherapies with novel modes of action are required to overcome the negative prognostic impact of 1q21+. Areas covered: This review discusses the detection, biology, prognosis, and therapeutic targeting of 1q21+ in newly diagnosed and relapsed MM. Patients with MM and 1q21+ tend to present with higher tumor burden, greater end-organ damage, and more co-occurring high-risk cytogenetic abnormalities than patients without 1q21+. The chromosomal rearrangements associated with 1q21+ result in dysregulation of genes involved in oncogenesis. Identification and characterization of the 1q21+ molecular targets are needed to inform on prognosis and treatment strategy. Clinical trial data are emerging that addition of isatuximab to combination therapies may improve outcomes in patients with 1q21+ MM. Expert opinion: In the next 5 years, the results of ongoing research and trials are likely to focus on the therapeutic impact and treatment decisions associated with 1q21+ in MM.