Development of small molecule drugs targeting immune checkpoints

Immune checkpoint inhibitors(ICIs)are used to relieve and refuel anti-tumor immunity by blocking the interaction,transcription,and translation of co-inhibitory immune checkpoints or degrading co-inhibitory immune checkpoints.Thousands of small molecule drugs or biological materials,especially antibody-based ICIs,are actively being studied and antibodies are currently widely used.Limitations,such as anti-tumor efficacy,poor membrane permeability,and unneglected tolerance issues of antibody-based ICIs,remain evident but are thought to be overcome by small molecule drugs.Recent structural studies have broadened the scope of candidate immune checkpoint molecules,as well as innovative chemical inhibitors.By way of comparison,small molecule drug-based ICIs represent superior oral bioavailability and favorable pharmacokinetic features.Several ongoing clinical trials are exploring the synergetic effect of ICIs and other therapeutic strategies based on multiple ICI functions,including immune regulation,anti-angiogenesis,and cell cycle regulation.In this review we summarized the current progression of small molecule ICIs and the mechanism underlying immune checkpoint proteins,which will lay the foundation for further exploration.

Multiple Defects of Cell Cycle Checkpoints in U937-ASPI3K, an U937 Cell Mutant Stably Expressing Anti-Sense ATM Gene cDNA

(Ataxia-telangiectasia mutated gene (ATM) functions in control of cell cycle checkpoints in responding to DNA damage and protects cells from undergoing apoptosis. Knock-out within tumor cells of endogenous ATM will achieve therapeutic benefits and enable a better understanding of the decisive mechanisms of cell death or survival in response to DNA damaging agents. ) In present paper, we sought to characterize the cell cycle checkpoint profiles in U937-ASPI3K, a U937 cell mutant that was previously established with endogenous ATM knock-out phenotype. Syn- chronized U937-ASPI3K was exposed to 137Cs irradiation, G1, S. G2/M cell cycle checkpoint pro- files were evaluated by determining cell cycle kinetics, p53/p21 protein, cyclin dependent kinase 2 (CDK2) and p34CDC2 kinase activity in response to irradiation. U937-ASPI3K exhibited multiple defects in cell cycle checkpoints as defined by failing to arrest cells upon irradiation. The accumulation of cellular p53/p21 protein and inhibition of CDK kinase was also abolished in U937-ASPI3K. It was concluded that the stable expression of anti-sense PI3K cDNA fragment completely abolished multiple cell cycle checkpoints in U937-ASPI3K, and hence U937-ASPI3K with an AT-like phenotype could serves as a valuable model system for investigating the signal transduction pathway in responding to DNA damaging-based cancer therapy.

Metabolic checkpoints in neurodegenerative T helper 17（TH17） and neuroregenerative regulatory T(Treg) cells as new therapeutic targets for multiple sclerosis

The central nervous system (CNS) is an immune-privileged site with tightly-regulated immune responses, a concept proposed by Nobel Laureate Sir Peter Medawar in 1960. Under physiological conditions, only a few T lymphocytes conducting immunosurveillance can infiltrate the CNS.

NK cell checkpoints and immune therapy in fatty liver disease

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis(NAFLD and NASH,respectively)are becoming a global epidemic manifested by metabolic syndrome,hepatic fibrosis,and cirrhosis,as well as hepatocellular carcinoma(HCC).Natural killer(NK)cells play an important role in the natural history of the disease as anti-fibrotic and anti-tumor protection.NK cells directly kill activated myofibroblasts to prevent fibrosis progression.However,NK cell functional impairment develops along with insulin resistance and deterioration to cirrhosis and HCC.Metabolic checkpoints have been identified that affect NK cell function and killing.Insulin resistance has been directly identified within NK cells,as they decrease expression of insulin receptors.The normal NK cell activation by insulin is therefore effected.Furthermore,Nerologin-4(NLG4)is overexpressed in impaired NK cells from NAFLD donors with advanced fibrosis.NLG4 overexpression impairs NK cell function and contributes to fibrosis progression.Intracellular NK cell depletion of mT OR,NMDAR activation by liver environmental enrich agonists up-regulates NLG4 expression.NLG4 causes a downstream cascade of intracellular scaffolding proteins to depress the killing function via f-actin remodeling.Berra neuroxin is a defined ligand for NLG4 and is found in target cells including activated fibrotic myofibroblasts and HCC cells.This overexpression further enhanced the NLG4 effect to impair NK cell killing.Other NK cells immune checkpoints have been identified.Targeting metabolic checkpoints activate NK cells to reconstitute their killing effects as anti-fibrotic or anti-tumor.Moreover,NLG4 NK expression and an occult urea assay with myofibroblasts has been identified as a biomarker tool in fibrogenesis.

Understanding the function and dysfunction of the immune system in lung cancer: the role of immune checkpoints

Survival rates for metastatic lung cancer, including non-small cell lung cancer （NSCLC） and small cell lung cancer （SCLC）, are poor with S-year survivals of less than 5%. The immune system has an intricate and complex relationship with tumorigenesis; a groundswell of research on the immune system is leading to greater understanding of how cancer progresses and presenting new ways to halt disease progress. Due to the extraordinary power of the immune system-- with its capacity for memory, exquisite specificity and central and universal role in human biology--immunotherapy has the potential to achieve complete, long-lasting remissions and cures, with few side effects for any cancer patient, regardless of cancer type. As a result, a range of cancer therapies are under development that work by turning our own immune cells against tumors. However deeper understanding of the complexity of immunomodulation by tumors is key to the development of effective immunotherapies, especially in lung cancer.

Myeloid checkpoints for cancer immunotherapy

Myeloid checkpoints are receptors on the myeloid cell surface which can mediate inhibitory signals to modulate anti-tumor immune activities.They can either inhibit cellular phagocytosis or suppress T cells and are thus involved in the pathogenesis of various diseases.In the tumor microenvironment,besides killing tumor cells by phagocytosis or activating anti-tumor immunity by tumor antigen presentation,myeloid cells could execute protumor efficacies through myeloid checkpoints by interacting with counter-receptors on other immune cells or cancer cells.In summary,myeloid checkpoints may be promising therapeutic targets for cancer immunotherapy.

Current state and future of co-inhibitory immune checkpoints for the treatment of glioblastoma

In the interaction between a tumor and the immune system,immune checkpoints play an important role,and in tumor immune escape,co-inhibitory immune checkpoints are important.Immune checkpoint inhibitors(ICIs)can enhance the immune system's killing effect on tumors.To date,impressive progress has been made in a variety of tumor treatments;PD1/PDL1 and CTLA4 inhibitors have been approved for clinical use in some tumors.However,glioblastoma(GBM)still lacks an effective treatment.Recently,a phase III clinical trial using nivolumab to treat recurrent GBM showed no significant improvement in overall survival compared to bevacizumab.Therefore,the use of immune checkpoints in the treatment of GBM still faces many challenges.First,to clarify the mechanism of action,how different immune checkpoints play roles in tumor escape needs to be determined;which biomarkers predict a benefit from ICIs treatment and the therapeutic implications for GBM based on experiences in other tumors also need to be determined.Second,to optimize combination therapies,how different types of immune checkpoints are selected for combined application and whether combinations with targeted agents or other immunotherapies exhibit increased efficacy need to be addressed.All of these concerns require extensive basic research and clinical trials.In this study,we reviewed existing knowledge with respect to the issues mentioned above and the progress made in treatments,summarized the state of ICIs in preclinical studies and clinical trials involving GBM,and speculated on the therapeutic prospects of ICIs in the treatment of GBM.

Targeting immune checkpoints:how to use natural killer cells for fighting against solid tumors

Natural killer(NK)cells are unique innate immune cells that mediate antiviral and anti-tumor responses.Thus,they might hold great potential for cancer immunotherapy.NK cell adoptive immunotherapy in humans has shown modest efficacy.In particular,it has failed to demonstrate therapeutic efficiency in the treatment of solid tumors,possibly due in part to the immunosuppressive tumor microenvironment(TME),which reduces NK cell immunotherapy’s efficiencies.It is known that immune checkpoints play a prominent role in creating an immunosuppressive TME,leading to NK cell exhaustion and tumor immune escape.Therefore,NK cells must be reversed from their dysfunctional status and increased in their effector roles in order to improve the efficiency of cancer immunotherapy.Blockade of immune checkpoints can not only rescue NK cells from exhaustion but also augment their robust anti-tumor activity.In this review,we discussed immune checkpoint blockade strategies with a focus on chimeric antigen receptor(CAR)-NK cells to redirect NK cells to cancer cells in the treatment of solid tumors.

Prognostic characterization of copper death-related immune checkpoint genes and analysis of immunologic and pharmacologic therapy in bladder cancer

Objective:Copper death-induced tumor cell death and immune checkpoint blockade therapy are highly selective.Combining their advantages and understanding their characteristics in bladder cancer is very important for the development of new targeted therapy.The identification of bladder cancer by screening the characteristic genes of copper death-related immune checkpoints provide a theoretical basis for the selection of adjuvant treatment options and the application of new targets.Methods:The expression samples of normal bladder tissue and bladder cancer were obtained from TCGA and GEO databases,and 13 cop-per death genes and 79 immune checkpoint genes were extracted from previous studies.The mRNA expression of prognostic genes was verified by qPCR.The copper death-related immune checkpoint genes were screened by correlation analysis to construct a prognostic model,and the differences in the efficacy of immunotherapy and chemotherapy between the high-risk group and the low-risk group were evaluated.Results:A prognostic model consisting of BTNL9,CD160,TNFRSF14 and TNFRSF18 was constructed.Its reliable predictive ability was proved in both databases,and qPCR showed that the expression levels of the four genes were significantly different between the normal group and the cancer cell group.The effect of immunotherapy in the lowrisk group was better than that in the high-risk group.Patients in the high-risk group had better chemotherapy efficacy.Conclusion:The copper death-related immune checkpoint gene model can accurately predict the prognosis of patients.Drug and immune analysis provide a basis for clinical treatment,and the discovery of potential targets provides a new solution for clinical decision-making.

Pembrolizumab autoimmune related diabetes:Moving forward,keep learning

Immune checkpoint inhibitors(and more specifically programmed cell death 1/programmed cell death ligand 1 inhibitors as Pembrolizumab)initiated a revolution in the field of melanoma and have now expanded to several tumor subtypes and in increasingly broader clinical contexts,including the adjuvant and neoadjuvant setting,with potentially curable patients and prolonged survival.The side effects related to these drugs include a wide spectrum of manifestations,with endocrinological adverse events being some of the most frequent.Pembrolizumab-induced type 1 diabetes mellitus is an infrequent but potentially serious and not clearly reversible side effect that possesses characteristic clinical features and has high morbidity and mortality,with a chronic impact on quality of life.The etiopathogenesis of this phenomenom needs to be further investigated and a collaborative effort through the involvement of oncologists and other medical specialists is necessary for the correct identification and management of patients at risk.

Immune checkpoint inhibitor-associated gastritis:Patterns and management

Immune checkpoint inhibitors(ICIs)are widely used due to their effectiveness in treating various tumors.Immune-related adverse events(irAEs)are defined as adverse effects resulting from ICI treatment.Gastrointestinal irAEs are a common type of irAEs characterized by intestinal side effects,such as diarrhea and colitis,which may lead to the cessation of ICIs.Although irAE gastritis is rarely reported,it may lead to serious complications such as gastrorrhagia.Furthermore,irAE gastritis is often difficult to identify early due to its diverse symptoms.Although steroid hormones and immunosuppressants are commonly used to reverse irAEs,the best regimen and dosage for irAE gastritis remains uncertain.In addition,the risk of recurrence of irAE gastritis after the reuse of ICIs should be considered.In this editorial,strategies such as early identification,pathological diagnosis,mana-gement interventions,and immunotherapy rechallenge are discussed to enable clinicians to better manage irAE gastritis and improve the prognosis of these patients.

Human NK cells: surface receptors, inhibitory checkpoints, and translational applications

NK cells play important roles in innate defenses against viruses and in the control of tumor growth and metastasis.The regulation/induction of NK cell function is mediated by an array of activating or inhibitory surface receptors.In humans,major activating receptors involved in target cell killing are the natural cytotoxicity receptors(NCRs)and NKG2D.Activating receptors recognize ligands that are overexpressed or expressed de novo upon cell stress,viral infection,or tumor transformation.The HLA-class I-specific inhibitory receptors,including KIRs recognizing HLA-class I allotypic determinants and CD94/NKG2A recognizing the class-Ib HLA-E,constitute a fail-safe mechanism to avoid unwanted NK-mediated damage to healthy cells.Other receptors such as PD-1,primarily expressed by activated T lymphocytes,are important inhibitory checkpoints of immune responses that ensure T-cell tolerance.PD-1 also may be expressed by NK cells in cancer patients.Since PD-1 ligand(PD-L1)may be expressed by different tumors,PD-1/PD-L1 interactions inactivate both T and NK cells.Thus,the reliable evaluation of PD-L1 expression in tumors has become a major issue to select patients who may benefit from therapy with mAbs disrupting PD-1/PD-L1 interactions.Recently,NKG2A was revealed to be an important checkpoint controlling both NK and T-cell activation.Since most tumors express HLA-E,mAbs targeting NKG2A has been used alone or in combination with other therapeutic mAbs targeting PD-1 or tumor antigens(e.g.,EGFR),with encouraging results.The translational value of NK cells and their receptors is evidenced by the extraordinary therapeutic success of haploidentical HSCT to cure otherwise fatal high-risk leukemias.

Immunotherapy of gastric cancer:Present status and future perspectives

In this editorial,we comment on the article entitled“Advances and key focus areas in gastric cancer immunotherapy:A comprehensive scientometric and clinical trial review(1999-2023),”which was published in the recent issue of the World Journal of Gastroenterology.We focused on the results of the authors’bibliometric analysis concerning gastric cancer immunotherapy,which they analyzed in depth by compiling the relevant publications of the last 20 years.Before that,we briefly describe the most recent data concerning the epidemiological parameters of gastric cancer(GC)in different countries,attempting to give an interpretation based on the etiological factors involved in the etiopathogenesis of the neoplasm.We then briefly discuss the conservative treatment(chemotherapy)of the various forms of this malignant neoplasm.We describe the treatment of resectable tumors,locally advanced neoplasms,and unresectable(advanced)cases.Special attention is given to modern therapeutic approaches with emphasis on immunotherapy,which seems to be the future of GC treatment,especially in combination with chemotherapy.There is also a thorough analysis of the results of the study under review in terms of the number of scientific publications,the countries in which the studies were conducted,the authors,and the scientific centers of origin,as well as the clinical studies in progress.Finally,an attempt is made to draw some conclusions and to point out possible future directions.

Molecular insights into clinical trials for immune checkpoint inhibitors in colorectal cancer:Unravelling challenges and future directions

Colorectal cancer(CRC)is a complex disease with diverse etiologies and clinical outcomes.Despite considerable progress in development of CRC therapeutics,challenges remain regarding the diagnosis and management of advanced stage metastatic CRC(mCRC).In particular,the five-year survival rate is very low since mCRC is currently rarely curable.Over the past decade,cancer treatment has significantly improved with the introduction of cancer immunotherapies,specifically immune checkpoint inhibitors.Therapies aimed at blocking immune checkpoints such as PD-1,PD-L1,and CTLA-4 target inhibitory pathways of the immune system,and thereby enhance anti-tumor immunity.These therapies thus have shown promising results in many clinical trials alone or in combination.The efficacy and safety of immunotherapy,either alone or in combination with CRC,have been investigated in several clinical trials.Clinical trials,including KEYNOTE-164 and CheckMate 142,have led to Food and Drug Administration approval of the PD-1 inhibitors pembrolizumab and nivolumab,respectively,for the treatment of patients with unresectable or metastatic microsatellite instability-high or deficient mismatch repair CRC.Unfortunately,these drugs benefit only a small percentage of patients,with the benefits of immunotherapy remaining elusive for the vast majority of CRC patients.To this end,primary and secondary resistance to immunotherapy remains a significant issue,and further research is necessary to optimize the use of immunotherapy in CRC and identify biomarkers to predict the response.This review provides a comprehensive overview of the clinical trials involving immune checkpoint inhibitors in CRC.The underlying rationale,challenges faced,and potential future steps to improve the prognosis and enhance the likelihood of successful trials in this field are discussed.

Predictive model using four ferroptosis-related genes accurately predicts gastric cancer prognosis

BACKGROUND Gastric cancer(GC)is a common malignancy of the digestive system.According to global 2018 cancer data,GC has the fifth-highest incidence and the thirdhighest fatality rate among malignant tumors.More than 60%of GC are linked to infection with Helicobacter pylori(H.pylori),a gram-negative,active,microaerophilic,and helical bacterium.This parasite induces GC by producing toxic factors,such as cytotoxin-related gene A,vacuolar cytotoxin A,and outer membrane proteins.Ferroptosis,or iron-dependent programmed cell death,has been linked to GC,although there has been little research on the link between H.pylori infection-related GC and ferroptosis.AIM To identify coregulated differentially expressed genes among ferroptosis-related genes(FRGs)in GC patients and develop a ferroptosis-related prognostic model with discrimination ability.METHODS Gene expression profiles of GC patients and those with H.pylori-associated GC were obtained from The Cancer Genome Atlas and Gene Expression Omnibus(GEO)databases.The FRGs were acquired from the FerrDb database.A ferroptosis-related gene prognostic index(FRGPI)was created using least absolute shrinkage and selection operator–Cox regression.The predictive ability of the FRGPI was validated in the GEO cohort.Finally,we verified the expression of the hub genes and the activity of the ferroptosis inducer FIN56 in GC cell lines and tissues.RESULTS Four hub genes were identified(NOX4,MTCH1,GABARAPL2,and SLC2A3)and shown to accurately predict GC and H.pylori-associated GC.The FRGPI based on the hub genes could independently predict GC patient survival;GC patients in the high-risk group had considerably worse overall survival than did those in the low-risk group.The FRGPI was a significant predictor of GC prognosis and was strongly correlated with disease progression.Moreover,the gene expression levels of common immune checkpoint proteins dramatically increased in the highrisk subgroup of the FRGPI cohort.The hub genes were also confirmed to be highly overexpressed in GC cell lines and tissues and were found to be primarily localized at the cell membrane.The ferroptosis inducer FIN56 inhibited GC cell proliferation in a dose-dependent manner.CONCLUSION In this study,we developed a predictive model based on four FRGs that can accurately predict the prognosis of GC patients and the efficacy of immunotherapy in this population.

Revolutionizing gastric cancer treatment:The potential of immunotherapy

Gastric cancer,a prevalent malignancy worldwide,ranks sixth in terms of frequency and third in fatality,causing over a million new cases and 769000 annual deaths.Predominant in Eastern Europe and Eastern Asia,risk factors include family medical history,dietary habits,tobacco use,Helicobacter pylori,and Epstein-Barr virus infections.Unfortunately,gastric cancer is often diagnosed at an advanced stage,leading to a grim prognosis,with a 5-year overall survival rate below 5%.Surgical intervention,particularly with D2 Lymphadenectomy,is the mainstay for early-stage cases but offers limited success.For advanced cases,the National Comprehensive Cancer Network recommends chemotherapy,radiation,and targeted therapy.Emerging immunotherapy presents promise,especially for unresectable or metastatic cases,with strategies like immune checkpoint inhibitors,tumor vaccines,adoptive immunotherapy,and nonspecific immunomodulators.In this Editorial,with regards to the article“Advances and key focus areas in gastric cancer immunotherapy:A comprehensive scientometric and clinical trial review”,we address the advances in the field of immunotherapy in gastric cancer and its future prospects.

Managing immune checkpoint inhibitor-associated gastritis: Insights and strategies

Immune checkpoint inhibitors(ICIs)are widely used due to their effectiveness in treating various tumors.Immune-related adverse events(irAEs)are defined as adverse effects resulting from ICI treatment.Gastrointestinal irAEs are a common type of irAEs characterized by intestinal side effects,such as diarrhea and colitis,which may lead to the discontinuation of ICIs.

Blockade of CD300A enhances the ability of human NK cells to lyse hematologic malignancies

Objective: The human cluster of differentiation(CD)300A, a type-I transmembrane protein with immunoreceptor tyrosine-based inhibitory motifs, was investigated as a potential immune checkpoint for human natural killer(NK) cells targeting hematologic malignancies(HMs).Methods: We implemented a stimulation system involving the CD300A ligand, phosphatidylserine(PS), exposed to the outer surface of malignant cells. Additionally, we utilized CD300A overexpression, a CD300A blocking system, and a xenotransplantation model to evaluate the impact of CD300A on NK cell efficacy against HMs in in vitro and in vivo settings. Furthermore, we explored the association between CD300A and HM progression in patients.Results: Our findings indicated that PS hampers the function of NK cells. Increased CD300A expression inhibited HM lysis by NK cells. CD300A overexpression shortened the survival of HM-xenografted mice by impairing transplanted NK cells. Blocking PS–CD300A signals with antibodies significantly amplified the expression of lysis function-related proteins and effector cytokines in NK cells, thereby augmenting the ability to lyse HMs. Clinically, heightened CD300A expression correlated with shorter survival and an “exhausted” phenotype of intratumoral NK cells in patients with HMs or solid tumors.Conclusions: These results propose CD300A as a potential target for invigorating NK cell-based treatments against HMs.

DNA damage response-related immune activation signature predicts the response to immune checkpoint inhibitors: from gastrointestinal cancer analysis to pan-cancer validation

Objective: DNA damage response(DDR) deficiency has emerged as a prominent determinant of tumor immunogenicity. This study aimed to construct a DDR-related immune activation(DRIA) signature and evaluate the predictive accuracy of the DRIA signature for response to immune checkpoint inhibitor(ICI) therapy in gastrointestinal(GI) cancer.Methods: A DRIA signature was established based on two previously reported DNA damage immune response assays. Clinical and gene expression data from two published GI cancer cohorts were used to assess and validate the association between the DRIA score and response to ICI therapy. The predictive accuracy of the DRIA score was validated based on one ICI-treated melanoma and three pan-cancer published cohorts.Results: The DRIA signature includes three genes(CXCL10, IDO1, and IFI44L). In the discovery cancer cohort, DRIA-high patients with gastric cancer achieved a higher response rate to ICI therapy than DRIA-low patients(81.8% vs. 8.8%;P < 0.001), and the predictive accuracy of the DRIA score [area under the receiver operating characteristic curve(AUC) = 0.845] was superior to the predictive accuracy of PD-L1 expression, tumor mutational burden, microsatellite instability, and Epstein–Barr virus status. The validation cohort demonstrated that the DRIA score identified responders with microsatellite-stable colorectal and pancreatic adenocarcinoma who received dual PD-1 and CTLA-4 blockade with radiation therapy. Furthermore, the predictive performance of the DRIA score was shown to be robust through an extended validation in melanoma, urothelial cancer, and pan-cancer.Conclusions: The DRIA signature has superior and robust predictive accuracy for the efficacy of ICI therapy in GI cancer and pancancer, indicating that the DRIA signature may serve as a powerful biomarker for guiding ICI therapy decisions.