DNA demethylation in PD-1 gene promoter induced by 5-azacytidine activates PD-1 expression on Molt-4 cells

PD-1 regulation in immune homeostasis and immunotherapy

Harnessing the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis is pivotal in autoimmunity and cancer immunotherapy. PD-1 receptors on immune cells engage with one of its ligands, PD-L1 or PD-L2, expressed on antigen-presenting cells or tumor cells, driving T-cell dysfunction and tumor immune escape. Thus, targeting PD-1/PD-L1 revitalizes cytotoxic T cells for cancer elimination. However, a majority of cancer patients don't respond to PD-1/PD-L1 blockade, and the underlying mechanisms remain partially understood. Recent studies have revealed that PD-1 expression levels or modifications impact the effectiveness of anti-PD-1/PD-L1 treatments. Therefore, understanding the molecular mechanisms governing PD-1 expression and modifications is crucial for innovating therapeutic strategies to enhance the efficacy of PD-1/PD-L1 inhibition. This article presents a comprehensive overview of advancements in PD-1 regulation and highlights their potential in modulating immune homeostasis and cancer immunotherapy, aiming to refine clinical outcomes.

Pediatric acute myeloid leukemia: Insight into genetic landscape and novel targeted approaches

Acute myeloid leukemia (AML) is a very heterogeneous hematological malignancy that accounts for approximately 20% of all pediatric leukemia cases. The outcome of pediatric AML has improved over the last decades, with overall survival rates reaching up to 70%. Still, AML is among the leading types of pediatric cancers by its high mortality rate. Modulation of standard therapy, like chemotherapy intensification, hematopoietic stem cell transplantation and optimized supportive care, could only get this far, but for the significant improvement of the outcome in pediatric AML, development of novel targeted therapy approaches is necessary. In recent years the advances in genomic techniques have greatly expanded our knowledge of the AML biology, revealing molecular landscape and complexity of the disease, which in turn have led to the identification of novel therapeutic targets. This review provides a brief overview of the genetic landscape of pediatric AML, and how it's used for precise molecular characterization and risk stratification of the patients, and also for the development of effective targeted therapy. Furthermore, this review presents recent advances in molecular targeted therapy and immunotherapy with an emphasis on the therapeutic approaches with significant clinical benefits for pediatric AML.

Novel immune directed therapies in myelodysplastic syndromes and acute myeloid leukemia

PURPOSE OF REVIEW

Therapies that target the immune system are increasingly used across oncology, including in hematologic malignancies such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). While allogeneic transplant has been a key therapy in these cancers, new approaches that target the immune system are being explored including immune checkpoint therapies, antibody-drug conjugates, and cellular therapies.

RECENT FINDINGS

This review outlines updates in the preclinical rationale for immune directed therapies in MDS and AML, as well as recent clinical trials exploring these therapies. This manuscript summarizes the development of therapies targeting T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) and CD47, which are being evaluated in late phase studies in MDS and AML. It also reviews the landscape of other immune based therapies including antibody-drug conjugates, chimeric antigen receptor-T cells, bispecific antibodies, and tumor vaccines.

SUMMARY

The treatment landscape in MDS and AML is rapidly changing; with a goal of improving the quality and duration of responses, a number of immune based therapies are under investigation. This review outlines recent advances with these therapies as well as some of the challenges that remain to incorporate them into leukemia care.

Lymphocyte Exhaustion in AML Patients and Impacts of HMA/Venetoclax or Intensive Chemotherapy on Their Biology

Simple Summary

Patients with acute myeloid leukemia (AML) are routinely treated with either intensive chemotherapy or DNA hypomethylating agents (HMA) in combination with the Bcl-2 inhibitor, venetoclax. While both treatment regimens are highly cytotoxic to the aggressive AML tumor cells, they are also toxic to immune cells. Therefore, we sought to establish the detrimental impacts of these therapies on lymphocytes and their recovery over time in AML patients. Even prior to treatment initiation, the patients were found to have exhausted lymphocytes in peripheral blood, and additional signs of exhaustion were noted after treatment with HMA/venetoclax. In fact, the lymphocytes were still suppressed for two to three months after the initiation of induction therapy. Furthermore, T cells in a subset of patients subsequently found to be resistant to venetoclax therapy exhibited a higher expression of perforin and CD39 and more pronounced IFN-γ production.

Abstract

Acute myeloid leukemia (AML) is an aggressive malignancy that requires rapid treatment with chemotherapies to reduce tumor burden. However, these chemotherapies can compromise lymphocyte function, thereby hindering normal anti-tumor immune responses and likely limiting the efficacy of subsequent immunotherapy. To better understand these negative impacts, we assessed the immunological effects of standard-of-care AML therapies on lymphocyte phenotype and function over time. When compared to healthy donors, untreated AML patients showed evidence of lymphocyte activation and exhaustion and had more prevalent CD57⁺NKG2C⁺ adaptive NK cells, which was independent of human cytomegalovirus (HCMV) status. HMA/venetoclax treatment resulted in a greater fraction of T cells with effector memory phenotype, inhibited IFN-γ secretion by CD8⁺ T cells, upregulated perforin expression in NK cells, downregulated PD-1 and 2B4 expression on CD4⁺ T cells, and stimulated Treg proliferation and CTLA-4 expression. Additionally, we showed increased expression of perforin and CD39 and enhanced IFN-γ production by T cells from pre-treatment blood samples of venetoclax-resistant AML patients. Our results provide insight into the lymphocyte status in previously untreated AML patients and the effects of standard-of-care treatments on their biology and functions. We also found novel pre-treatment characteristics of T cells that could potentially predict venetoclax resistance.

Research advances in nanomedicine, immunotherapy, and combination therapy for leukemia

In the past decade, clinical and laboratory studies have led to important new insights into the biology of leukemia and its treatment. This review describes the progress of leukemia research in the United States in recent years. Whereas the traditional method of treatment is chemotherapy, it is nonselective and could induce systemic toxicities. Thus, in parallel with research on new chemotherapies, great emphasis has been placed on developing immunotherapies. Here, we will review the current immunotherapies available in research and development that overcome current challenges, specifically looking in the field of chimeric antigen receptor T-cell (CAR-T) therapies, checkpoint inhibitors, and antibody-drug conjugates. With about 100 clinical trials for CAR-T therapies and 30 in checkpoint inhibitors for leukemia treatment, scientists are trying to make these technologies cheaper, faster, and more feasible. Further describing the delivery of these therapeutics, we look at the current progress, clinical, and preclinical status of nano-based medicines such as liposomes, polymeric micelles, and metal nanoparticles. Taking advantage of their physicochemical and biologic properties, nanoparticles have been shown to increase the efficacy of commonly administered chemotherapies with reduced adverse effects.

Current Advances in Immunotherapy for Acute Leukemia: An Overview of Antibody, Chimeric Antigen Receptor, Immune Checkpoint, and Natural Killer

Recently, due to the application of hematopoietic stem cell transplantation and small molecule inhibitor, the survival of acute leukemia is prolonged. However, the 5 year survival rate remains low due to a high incidence of relapse. Immunotherapy is expected to improve the prognosis of patients with relapsed or refractory hematological malignancies because it does not rely on the cytotoxic mechanisms of conventional therapy. In this paper, the advances of immunotherapy in acute leukemia are reviewed from the aspects of Antibody including Unconjugated antibodies, Antibody-drug conjugate and Bispecific antibody, Chimeric Antigen Receptor (CARs), Immune checkpoint, Natural killer cells. The immunological features, mechanisms and limitation in clinic will be described.

A Review of Efficacy and Safety of Checkpoint Inhibitor for the Treatment of Acute Myeloid Leukemia

Immune checkpoint inhibitors (ICIs) as positive modulators of immune response have revolutionized the treatment of cancer and have achieved impressive efficacy in melanoma and numerous solid tumor malignancies. These agents are being investigated in acute myeloid leukemia (AML) to further enhance response rate as induction therapy and to improve relapse-free survival (RFS) post chemotherapy and bone marrow transplantation. PD-1 and CTLA-4 are the two most actively investigated checkpoint receptors, which play a role in different stages of anti-tumor immune response. This study reviews data from ongoing phase I, II clinical trials evaluating PD-1 and CTLA-4 inhibitors on AML patients and discusses especially efficacy and adverse events as well as prospects of these drugs in treating AML. Single anti-PD-1 monoclonal antibody infusion shows rather modest clinical efficacy. While combinations of PD-1 inhibitor with hypomethylating agents (HMAs) represent encouraging outcome for relapsed/refractory (R/R) AML patients as well as for elderly patients as first-line therapy option. Adding PD-1 inhibitor to traditional induction therapy regimen is also safe and feasible. CTLA-4 inhibitor ipilimumab exhibits specific potency in treating relapsed AML patients with extramedullary disease in later post-transplantation stage. In terms of side effects, irAEs found in these trials can mostly be appropriately managed with steroids but are occasionally fatal. More rationally designed combinational therapies are under investigation in ongoing clinical trials and will further advance our understanding of checkpoint inhibitors as well as lead us to the most appropriate application of these agents.

Treponema denticola increases MMP-2 expression and activation in the periodontium via reversible DNA and histone modifications

Host-derived matrix metalloproteinases (MMPs) and bacterial proteases mediate destruction of extracellular matrices and supporting alveolar bone in periodontitis. The Treponema denticola dentilisin protease induces MMP-2 expression and activation in periodontal ligament (PDL) cells, and dentilisin-mediated activation of pro-MMP-2 is required for cellular fibronectin degradation. Here, we report that T. denticola regulates MMP-2 expression through epigenetic modifications in the periodontium. PDL cells were treated with epigenetic enzyme inhibitors before or after T. denticola challenge. Fibronectin fragmentation, MMP-2 expression, and activation were assessed by immunoblot, zymography, and qRT-PCR, respectively. Chromatin modification enzyme expression in T. denticola-challenged PDL cells and periodontal tissues were evaluated using gene arrays. Several classes of epigenetic enzymes showed significant alterations in transcription in diseased tissue and T. denticola-challenged PDL cells. T. denticola-mediated MMP-2 expression and activation were significantly reduced in PDL cells treated with inhibitors of aurora kinases and histone deacetylases. In contrast, DNA methyltransferase inhibitors had little effect, and inhibitors of histone acetyltransferases, methyltransferases, and demethylases exacerbated T. denticola-mediated MMP-2 expression and activation. Chronic epigenetic changes in periodontal tissues mediated by T. denticola or other oral microbes may contribute to the limited success of conventional treatment of chronic periodontitis and may be amenable to therapeutic reversal.

Epigenetic and Genetic Regulation of PDCD1 Gene in Cancer Immunology

Utilizing biology of PD-1: PD-L1 interaction related pathways for cancer immunotherapy is an emerging concept in cancer research. However, there is limited literature on epigenetic regulation of PD1 gene (PDCD1). Promising data from clinical trials of PD/PDl-1 immunotherapy in melanoma, renal cancers, colorectal and lung cancers has generated a lot of hope for successful treatment of patients. Immunotherapy in cancers has a significant role in strategizing NCI's Cancer Moonshot Program of US NIH and FDA policies. The cost of the treatment by immunotherapy is extremely high. This preview presents a concise compilation of current knowledge on how the PD-1 gene is regulated in different cancers and infections. We have also discussed about epigenetic regulation of PDCD1 gene, especially the effect of different epigenetic inhibitors of DNA methylation and histone modifications at different steps in PD-1 regulation.

Targeting Immune Checkpoints in Hematologic Malignancies

The use of antibodies that target immune checkpoint molecules on the surface of T-lymphocytes and/or tumor cells has revolutionized our approach to cancer therapy. Cytotoxic-T-lymphocyte antigen (CTLA-4) and programmed cell death protein 1 (PD-1) are the two most commonly targeted immune checkpoint molecules. Although the role of antibodies that target CTLA-4 and PD-1 has been established in solid tumor malignancies and Food and Drug Administration approved for melanoma and non-small cell lung cancer, there remains a desperate need to incorporate immune checkpoint inhibition in hematologic malignancies. Unlike solid tumors, a number of considerations must be addressed to appropriately employ immune checkpoint inhibition in hematologic malignancies. For example, hematologic malignancies frequently obliterate the bone marrow and lymph nodes, which are critical immune organs that must be restored for appropriate response to immune checkpoint inhibition. On the other hand, hematologic malignancies are the quintessential immune responsive tumor type, as proven by the success of allogeneic stem cell transplantation (allo-SCT) in hematologic malignancies. Also, sharing an immune cell lineage, malignant hematologic cells often express immune checkpoint molecules that are absent in solid tumor cells, thereby offering direct targets for immune checkpoint inhibition. A number of clinical trials have demonstrated the potential for immune checkpoint inhibition in hematologic malignancies before and after allo-SCT. The ongoing clinical studies and complimentary immune correlatives are providing a growing body of knowledge regarding the role of immune checkpoint inhibition in hematologic malignancies, which will likely become part of the standard of care for hematologic malignancies.

V‑set and transmembrane domain‑containing 1 is silenced in human hematopoietic malignancy cell lines with promoter methylation and has inhibitory effects on cell growth

Numerous leukocyte differentiation antigens act as important markers for research, diagnosis, triage and eventually treatment targets for hematopoietic malignancies. V‑set and transmembrane domain‑containing 1 (VSTM1) was identified by immunogenomic analysis as a potential leukocyte differentiation antigen gene. VSTM1 is located at 19q13.4 on human chromosomes, an important genomic region prone to genetic and epigenetic modifications in numerous hematopoietic malignancies. VSTM1‑v1, a primary splicing form encoded by VSTM1, is a type I transmembrane molecule with an extracellular immunoglobulin V‑like domain and two cytoplasmic immunoreceptor tyrosine-based inhibitory motifs. In the present study, VSTM1 expression was examined in normal human peripheral leukocytes and hematopoietic tumor cell lines; in addition, the aberrant methylation of the VSTM1 gene was evaluated using methylation‑specific polymerase chain reaction (MSP). The results of the present study demonstrated that VSTM1 was widely expressed in normal human peripheral blood leukocytes, including granulocytes and monocytes, in concurrence with previous studies, as well as lymphocytes; in addition, the molecular size and expression levels of VSTM1 varied considerably between leukocytes. However, VSTM1 was undetectable in numerous hematopoietic tumor cell lines following promoter hypermethylation. The effects of pharmacologically‑induced demethylation of the VSTM1 gene and promoter region were analyzed using MSP and biosulfite genomic sequencing, and the results revealed that VSTM1 expression was restored in methylation‑silenced Jurkat cells. In addition, CKK‑8 assays revealed that VSTM1‑v1 overexpression in Jurkat cells resulted in growth suppression. Furthermore, the inhibitory effect on cell growth was enhanced following antibody‑induced cross‑linking of VSTM1‑v1. In conclusion, the results of the present study indicated that promoter methylation silenced VSTM1 and negatively regulated cell growth in human hematopoietic malignancy cell lines.