Progress of research on PD-1/PD-L1 in leukemia

Targeting the Immune Microenvironment in Chronic Lymphocytic Leukemia: An Evolving Therapeutic Strategy

Although small molecule inhibitors that target the aberrant signaling pathways and molecular defects of chronic lymphocytic leukemia (CLL) result in improved survival benefits vs. traditional chemoimmunotherapy or chemotherapy, treatment resistance may result later, reflecting the intrinsic tumor heterogeneity, persistence of the leukemic clone, and presence of the tumor microenvironment, which supports the survival of the disease clone. Patients with CLL have immune-related abnormalities in T lymphocyte subset composition, immune synapse formation, and other immune dysregulations. Cellular interactions between the disease clone and its microenvironment provide therapeutic opportunities to target these tumor pathogenesis pathways, potentially improving the patient's immune functions and clinical outcomes of targeted therapies. At present, despite the lack of response of immune checkpoint inhibitors in CLL, they showed promising efficacy in patients with Richter transformation. Together with CD19-targeted chimeric antigen receptor-modified T cell (CAR-T) therapy, novel bispecific antibodies and other immunotherapies are being investigated to improve survival outcomes for patients with relapsed or refractory (R/R) CLL, as exemplified by epcoritamab, a bispecific antibody that recently demonstrated initial efficacy in R/R CLL and in patients in high-risk CLL subgroups, including those with TP53 aberrations and unmutated genes that encode immunoglobulin variable heavy chain region (IGHV). Furthermore, to address the immune escape of cancer cells and issues that impact the durability of single-targeted T cell-redirected therapies, novel strategies such as trispecific antibodies and combination therapies are being investigated to increase tumor specificity or immune cell activation. In summary, there is emerging evidence that immunotherapies may counteract the immunosuppressive microenvironment of CLL, improve clinical responses, decrease the risk of infection, and overcome treatment resistance.

Prognostic value of CD47 overexpression measured by flow cytometry in acute myeloid leukemia

The glycoprotein CD47 is an innate immune checkpoint ubiquitously expressed on all healthy cells to prevent themselves from phagocytosis. CD47 binds to its receptor SIRPα on macrophages, thus producing a signal transduction cascade which inhibits phagocytosis. CD47 is overexpressed on various solid and hematologic malignancies in order to escape the immune system. High expression of CD47 in patients with AML has been associated with poor prognosis, however, there is no standard technique to assess CD47 expression on AML blasts in clinical practice and the real prognostic value of CD47 overexpression varies among studies in the current literature. In this study, CD47 expression was evaluated by flow cytometry on AML blasts from bone marrow samples at diagnosis and reported in terms of median fluorescence intensity (MFI). Flow cytometry analysis demonstrated the expression of CD47 in all AML patients with a median MFI on leukemic blasts of 16.8 (range 2-693.63). CD47 levels on AML blasts correlated with WBC count (rs 0.403, p = 0.016), BM blasts percentage (rs 0.494, p = 0.003), PB blasts percentage (rs 0.482, p = 0.003) and LDH levels (rs 0.382, p = 0.028) and higher expression of CD47 was associated with reduced survival with a hazard ratio of 1.04 (CI: 1.01-1.08, p = 0.047). Further studies with larger sample sizes are necessary to better define the real prognostic value of CD47 overexpression in the complexity of AML tumor microenvironment and, possibly, to identify a subgroup of patients who could derive maximum benefit from emerging CD47-SIRPα blocking therapies.

Programmed Cell Death-1 and Programmed Cell Death Ligand-1 in Childhood Acute B-Lymphoblastic Leukemia: Expression and Significance as Biomarker

INTRODUCTION

This study aimed to assess programmed death-1 (PD-1) and programmed death ligand-1 (PDL-1) expression in newly diagnosed pediatric cases of acute B-lymphoblastic leukemia (B-ALL) and at 6 months of treatment and to explore their value as biomarkers.

METHODS

Fifty newly diagnosed B-ALL patients and 30 controls were recruited. Bone marrow samples or peripheral blood were obtained from children at diagnosis and 6 months after cytotoxic therapy. Flow cytometric analysis of obtained samples was done and the PD-1, PDL-1, and CD3 (cluster of differentiation) expressions were recorded.

RESULTS

Percentages of PD-1, PDL-1, and CD3 in the control and B-ALL groups at initial presentation were 7.9% ± 2.8% vs. 16.45% ± 7.7% (p = 0.023), 8.6% ± 3.4% vs. 19.05% ± 13.7% (p < 0.001), and 30.8% ± 1.2% vs. 11.05% ± 7.3% (p < 0.001), respectively. CD3 expression increased significantly at 6 months; PD-1 and PDL-1 expression showed insignificant decrease from initial presentation. There was a negative correlation between PD-1 and HB level (p = 0.03) and a positive correlation between PD-1 and PDL-1 at 6 months of treatment (p = 0.002). Remission rates increased significantly with the decrease of PD-1and PDL-1.

CONCLUSION

Initially, PD-1 and PDL-1 were higher in patients than in controls and decreased 6 months after treatment. PD-1 and PDL-1 expression was associated with increased remission rates, implicating that modulation of PD-1 and PDL-1 expression may be a therapeutic approach for B-ALL. Moreover, this study created a new method for the assessment of PD-1 and PDL-1 in B-ALL.

CLINICAL TRIAL

Trial Registration: NCT05428111.

A New Histology-Based Prognostic Index for Acute Myeloid Leukemia: Preliminary Results for the "AML Urayasu Classification"

Background: This study was aimed at elucidating the mechanisms underlying the development of treatment resistance in patients with acute myeloid leukemia (AML) other than M3 myeloid leukemia in order to devise ways to overcome treatment resistance and improve the treatment outcomes in these patients. Methods: For this study, we randomly selected 35 patients with AML who had received combined cytarabine plus idarubicin treatment for new-onset AML at our hospital. We performed immunohistochemical analysis of biopsy specimens obtained from the patients to investigate the expressions of 23 treatment-resistance-related proteins, and retrospectively analyzed the correlations between the expression profiles of the resistance proteins and the patient survival. Results: The following four proteins were identified as being particularly significant in relation to treatment resistance and patient prognosis: (1) p53; (2) multidrug resistance-associated protein 1 (MRP1; idarubicin extracellular efflux pump); (3) aldo-keto reductase family 1 member B10 (AKR1B10; idarubicin-inactivating enzyme); and (4) AKR1B1 (competitive inhibitor of AKR1B10). Based on our findings, we propose the following Urayasu classification for AML, which we believe would be very useful for accurately stratifying patients with AML according to the predicted prognosis: Group 1 (n = 22, 63%): p53(-)/MRP1(-) associated with AKR1B10(+)/AKR1B1(+) or AKR1B10(-)/AKR1B1(-); 5-year overall survival (OS), 82%-100%; Group 2 (n = 9, 26%): p53(-)/MRP1(-) associated with AKR1B10(+)/AKR1B1(-); 5-year OS, 68%; Group 3 (n = 4, 11%): p53(+) or MRP1(+); median survival, 12-14 months; 2-year OS, 0%. Conclusions: The Urayasu classification for AML is useful for predicting the prognosis of patients with AML. Group 1 in this classification included twice as many patients as that included in the Favorable prognosis group in the AML prognostic classification proposed by the European Leukemia Net. As the Urayasu classification for AML is based on the mechanisms of resistance to chemotherapy, it is not only useful for prognostic stratification of the patients, but also provides insights for developing more effective treatments for AML.

Role of PD-1/PD-L1 signaling axis in oncogenesis and its targeting by bioactive natural compounds for cancer immunotherapy

Cancer is a global health problem and one of the leading causes of mortality. Immune checkpoint inhibitors have revolutionized the field of oncology, emerging as a powerful treatment strategy. A key pathway that has garnered considerable attention is programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1). The interaction between PD-L1 expressed on tumor cells and PD-1 reduces the innate immune response and thus compromises the capability of the body's immune system. Furthermore, it controls the phenotype and functionality of innate and adaptive immune components. A range of monoclonal antibodies, including avelumab, atezolizumab, camrelizumab, dostarlimab, durvalumab, sinitilimab, toripalimab, and zimberelimab, have been developed for targeting the interaction between PD-1 and PD-L1. These agents can induce a broad spectrum of autoimmune-like complications that may affect any organ system. Recent studies have focused on the effect of various natural compounds that inhibit immune checkpoints. This could contribute to the existing arsenal of anticancer drugs. Several bioactive natural agents have been shown to affect the PD-1/PD-L1 signaling axis, promoting tumor cell apoptosis, influencing cell proliferation, and eventually leading to tumor cell death and inhibiting cancer progression. However, there is a substantial knowledge gap regarding the role of different natural compounds targeting PD-1 in the context of cancer. Hence, this review aims to provide a common connection between PD-1/PD-L1 blockade and the anticancer effects of distinct natural molecules. Moreover, the primary focus will be on the underlying mechanism of action as well as the clinical efficacy of bioactive molecules. Current challenges along with the scope of future research directions targeting PD-1/PD-L1 interactions through natural substances are also discussed.

T-Cell Immunoglobulin and Mucin Domain 3 (TIM-3) Gene Expression as a Negative Biomarker of B-Cell Acute Lymphoblastic Leukemia

B-cell acute lymphoblastic leukemia (B-ALL) accounts for 85% of all childhood ALL. Malignancies exhaust T and B cells, resulting in an increased expression of immune checkpoint receptors (ICRs), such as T-cell immunoglobulin and mucin domain 3 (TIM-3). TIM-3 has been found to be dysregulated in different types of cancer. However, there is a lack of rigorous studies on the TIM-3 expression in B-ALL. The current study aimed to measure the expression of TIM-3 at the gene and protein levels and evaluate the potential of TIM-3 as a biomarker in B-ALL. A total of 28 subjects were recruited between 2021 and 2023, comprising 18 subjects diagnosed with B-ALL and 10 non-malignant healthy controls. The B-ALL patients were divided into three groups: newly diagnosed (four patients), in remission (nine patients), and relapse/refractory (five patients). The expression levels of TIM-3 were evaluated using the real-time qPCR and ELISA techniques. The results revealed that the TIM-3 expression was significantly downregulated in the malignant B-ALL patients compared to the non-malignant healthy controls in the mRNA (FC = -1.058 ± 0.3548, p = 0.0061) and protein blood serum (p = 0.0498) levels. A significant TIM-3 gene reduction was observed in the relapse/refractory cases (FC = -1.355 ± 0.4686, p = 0.0327). TIM-3 gene expression allowed for significant differentiation between patients with malignant B-ALL and non-malignant healthy controls, with an area under the curve (AUC) of 0.706. The current study addressed the potential of reduced levels of TIM-3 as a negative biomarker for B-ALL patients.

Identification of a Novel hsa_circ_0058058/miR-324-5p Axis and Prognostic/Predictive Molecules for Acute Myeloid Leukemia Outcome by Bioinformatics-Based Analysis

Acute myeloid leukemia (LAML) is one of the most prevalent hematological malignancies. In recent years, while targeted approaches have shown promise in the fight against cancer, the treatability and prognosis of patients remain inadequate due to the shortage of drugs. Noncoding RNAs, especially circular RNA (circRNA) and microRNA (miRNA), have been shown to play a unique role in tumor development. This study aims to identify the disease-associated circRNA-miRNA-mRNA network by bioinformatic analysis and investigate the mechanisms in the development and progression of LAML. Additionally, it reveals the promising roles of these molecules as a diagnostic biomarker and therapeutic target for LAML treatment. Using various bioinformatics approaches, we identified the hsa_circ_0058058/miR-324-5p axis in LAML and its possible functions in LAML development. According to our results, hsa circ-0058058 can regulate the expression of AP1G1 and SP1 through miR-324-5p to support angiogenesis, the cell cycle, and DNA replication processes. Downregulation of hsa circ-0058058 may contribute to the anticancer functions of miR-324-5p on LAML tumorigenesis, and upregulation of miR-324-5p can abolish the oncogenic effects of AP1G1 and SP1 on LAML tumorigenesis. Additionally, highly enriched pathways indicated possible interactions between molecules underlying LAML pathology. Targeted molecules within this network may be able to function as therapeutic and diagnostic biomarkers for disease, while more research and clinical confirmation are needed.

Association of Polymorphisms in PD-1 and LAG-3 Genes with Acute Myeloid Leukemia

Background and objectives: Acute myeloid leukemia (AML) is a hematological malignancy characterized by uncontrolled proliferation of immature myeloid cells. Immune checkpoint molecules such as programmed cell death protein 1 (PD-1) and lymphocyte activation gene-3 (LAG-3) are essential for controlling anti-tumor immune responses. This study aims to explore the correlation between specific genetic variations (SNPs) in the PDCD1 (rs2227981) and LAG3 (rs12313899) genes and the likelihood of developing AML in the Saudi population. Material and methods: total of 98 Saudi AML patients and 131 healthy controls were genotyped for the PDCD1 rs2227981 and LAG3 rs12313899 polymorphisms using TaqMan genotyping assays. A logistic regression analysis was conducted to evaluate the relationship between the SNPs and AML risk using several genetic models. Results: The results revealed a significant association between the PDCD1 rs2227981 polymorphism and increased AML risk. In AML patients, the frequency of the G allele was considerably greater than in healthy controls (OR = 1.93, 95% CI: 1.31-2.81, p = 0.00080). The GG and AG genotypes were associated with a very high risk of developing AML (p < 0.0001). In contrast, no significant association was observed between the LAG3 rs12313899 polymorphism and AML risk in the studied population. In silico analysis of gene expression profiles from public databases suggested the potential impact of PDCD1 expression levels on the overall survival of AML patients. Conclusions: This study provides evidence for the association of the PDCD1 rs2227981 polymorphism with an increased risk for AML in the Saudi population.

Galectin-9, a pro-survival factor inducing immunosuppression, leukemic cell transformation and expansion

Leukemia is a malignancy of the bone marrow and blood originating from self-renewing cancerous immature blast cells or transformed leukocytes. Despite improvements in treatments, leukemia remains still a serious disease with poor prognosis because of disease heterogeneity, drug resistance and relapse. There is emerging evidence that differentially expression of co-signaling molecules play a critical role in tumor immune evasion. Galectin-9 (Gal-9) is one of the key proteins that leukemic cells express, secrete, and use to proliferate, self-renew, and survive. It also suppresses host immune responses controlled by T and NK cells, enabling leukemic cells to evade immune surveillance. The present review provides the molecular mechanisms of Gal-9-induced immune evasion in leukemia. Understanding the complex immune evasion machinery driven by Gal-9 expressing leukemic cells will enable the identification of novel therapeutic strategies for efficient immunotherapy in leukemic patients. Combined treatment approaches targeting T-cell immunoglobulin and mucin domain-3 (Tim-3)/Gal-9 and other immune checkpoint pathways can be considered, which may enhance the efficacy of host effector cells to attack leukemic cells.