Current research insights into the role of CTLA-4 in hepatitis B virus (HBV) infection.

Chronic hepatitis B virus (HBV) infection is a significant global public health concern, and the clearance of HBV is closely linked to the activity of HBV-specific T cells, which is regulated by various co-suppressor molecules. Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is among these co-suppressor molecules which induces T cell exhaustion by competitively inhibiting CD28 and dampening the function of HBV-specific T cells. CTLA-4 also plays a role in the regulation of T helper (Th) cell differentiation and influences cytokine release. In addition, CTLA-4 can impact glucose metabolism in hepatocellular carcinoma through its interaction with T regulatory (Treg) cells. This review aims to provide a comprehensive overview of the existing literature related to the role of CTLA-4 in HBV patients across different subsets of T cells. Additionally, we propose a discussion on the possible mechanisms through which CTLA-4 may contribute to HBV infection, as well as the development of HBV-induced cirrhosis and hepatocellular carcinoma.

Advanced cervix cancer patient with chemotherapy-induced grade IV myelosuppression achieved complete remission with cadonilimab: A case report.

BACKGROUND: The prognosis for patients with advanced metastatic cervix cancer (MCC) is poor, and this disease continues to pose a considerable therapeutic challenge. Despite the administration of first-line regimens consisting of cisplatin, paclitaxel, and bevacizumab, survival rates for patients with metastasis remain poor. The emergence of bispecific antibodies (BsAbs) offers a novel treatment option for patients diagnosed with MCC. CASE SUMMARY: In this report, we present a patient with MCC who was treated with cadonilimab monotherapy at a dose of 6 mg/kg every two weeks after chemotherapy was proven to be intolerable. The patient exhibited a sustained complete response for a duration of 6 months, demonstrating an optimistic outlook. CONCLUSION: This case illustrates the considerable efficacy of cadonilimab for treating advanced MCC. Therefore, BsAb therapy is a promising strategy for effectively treating patients with advanced MCC and should be considered as an option when patients are intolerant to standard chemotherapy.

Antibody-Conjugated Nanogel with Two Immune Checkpoint Inhibitors for Enhanced Cancer Immunotherapy.

Cancer immunotherapy by immune checkpoint inhibitors (ICIs) acts on antitumor responses by stimulating the immune system to attack cancer cells. However, this powerful therapy is hampered by its high treatment cost and limited efficacy. Here, it is shown that the development of an antibody-conjugated nanogel (ANGel), consisting of N-isopropylacrylamide-co-acrylic acid and antibody-binding protein (protein A), potentiates the efficacy of two ICI monoclonal antibodies (mAbs) (cytotoxic-T-lymphocyte-associated antigen 4 and programmed death ligand-1 mAbs). Compared with mAb treatment alone, treatment with a bispecific ANGel surface-conjugated with the mAbs significantly decreases both the survival of Michigan Cancer Foundation-7 (MCF-7) and M D Anderson-Metastatic Breast-231 (MDA-MB-231) breast cancer cells in vitro and the burden of 4T1-luciferase-2-derived orthotopic syngeneic tumors in vivo. The bispecific ANGel is also more potent than the conventional treatment at prolonging survival in animals with triple-negative breast cancer. The advantage of the bispecific ANGel over other engineered bispecific antibodies arises not only from the adaptability to link multiple antibodies quickly and easily, but also from the capability to maintain the anticancer effect steadily at subcutaneously delivered tumor site. This finding has an important implication for cancer immunotherapy, opening a new paradigm to treat solid tumors.

KN046, a bispecific antibody against PD-L1 and CTLA-4, plus chemotherapy as first-line treatment for metastatic NSCLC: A multicenter phase 2 trial.

KN046, a bispecific antibody targeting PD-L1 and CTLA-4, presents a promising therapeutic option for metastatic non-small cell lung cancer (NSCLC). In this multicenter phase 2 trial, patients with nonsquamous (non-sq) NSCLC receive pemetrexed, whereas those with sq-NSCLC receive paclitaxel, plus KN046 and carboplatin. Following four cycles, maintenance therapy includes KN046 with pemetrexed for non-sq-NSCLC and KN046 for sq-NSCLC. The objective response rate is 46.0%, and the median duration of response is 8.1 months. The median progression-free and overall survival are 5.8 and 26.6 months, respectively. The common adverse events include anemia (87.4%), loss of appetite (72.4%), and neutropenia (70.1%). The most prevalent immune-related adverse event is pruritus (28.7%). These findings indicate that first-line treatment with KN046 and chemotherapy is effective and tolerable in metastatic NSCLC patients, warranting further investigation in a larger phase 3 trial. The trial is registered at ClinicalTrials.gov (NCT04054531).

Association of lung immune prognostic index with survival outcomes in patients with metastatic renal cell carcinoma treated with nivolumab plus ipilimumab.

OBJECTIVE: Lung immune prognostic index is based on derived neutrophil-to-lymphocyte ratio and lactate dehydrogenase level. Lung immune prognostic index has reported association with survival outcomes in patients with various malignancies undergoing treatment with immune checkpoint inhibitors. However, the prognostic impact of pre-treatment lung immune prognostic index in patients with metastatic renal cell carcinoma receiving nivolumab plus ipilimumab treatment remains unclear. This study examines the association between lung immune prognostic index and outcomes in this setting. METHODS: We retrospectively evaluated 156 patients with metastatic renal cell carcinoma treated with nivolumab plus ipilimumab at eight institutions. We assessed the associations between pre-treatment lung immune prognostic index and survival outcomes including progression-free survival, second progression-free survival (PFS2), cancer-specific survival and overall survival. RESULTS: Patients were classified into good (n = 84, 54%), intermediate (n = 52, 33%) and poor (n = 20, 13%) lung immune prognostic index groups. Progression-free survival did not significantly differ between lung immune prognostic index groups, but there was significant difference in PFS2, cancer-specific survival and overall survival. In multivariable Cox proportional hazard analyses, high pre-treatment lung immune prognostic index was a significant predictor of poor PFS2 (vs. good group, intermediate group: P = 0.01 and poor group: P = 0.04) and poor overall survival (vs. good group, intermediate group: P = 0.01 and poor group: P < 0.01). Moreover, the patients with poor lung immune prognostic index had significantly poorer cancer-specific survival than those with good LIPI (P < 0.01). CONCLUSIONS: High pre-treatment LIPI is suggested by our results to be a significant independent predictor of poor prognosis in patients receiving nivolumab plus ipilimumab for metastatic renal cell carcinoma.

Clinical Utility of Inflammatory and Nutritious Index as Therapeutic Prediction of Nivolumab plus Ipilimumab in Advanced Non-Small Cell Lung Cancer.

INTRODUCTION: Biomarkers for predicting the outcome of ipilimumab plus nivolumab (Nivo-Ipi) treatment in cancer patients have not been identified. Herein, we investigated the prognostic significance of inflammatory and nutritional markers in patients with advanced non-small cell lung cancer (NSCLC) receiving Nivo-Ipi. METHODS: Our study retrospectively analyzed 101 patients with advanced NSCLC who received Nivo-Ipi at a single institution. Inflammatory and nutritional indices were correlated with patient outcomes and included the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), systemic immune-inflammation index (SII), prognostic nutritional index (PNI), advanced lung cancer inflammation index (ALI), and Glasgow prognostic score (GPS). RESULTS: The NLR significantly correlated with the PLR, SII, PNI, ALI, and GPS. Regarding therapeutic efficacy, the NLR, SII, and PNI predicted a partial response, and all indices predicted progressive disease. In subgroup analyses, the SII, PNI, and ALI predicted the outcome of patients with adenocarcinoma, whereas only the PNI predicted the outcome of patients with non-adenocarcinoma. The PNI and SII were the most useful indices in patients with a programmed death ligand-1 expression level of <1% and ≥1%, respectively. CONCLUSION: The NLR, PLR, SII, PNI, ALI, and GPS were significantly associated with the outcome of Nivo-Ipi treatment in patients with NSCLC. The PNI was the most suitable marker regardless of histological type. The SII and PNI were the most promising markers for patients with and without PD-L1 expression, respectively.

Expansion of Pathogenic Cardiac Macrophages in Immune Checkpoint Inhibitor Myocarditis.

BACKGROUND: Immune checkpoint inhibitors (ICIs), antibodies targeting PD-1 (programmed cell death protein 1)/PD-L1 (programmed death-ligand 1) or CTLA4 (cytotoxic T-lymphocyte-associated protein 4), have revolutionized cancer management but are associated with devastating immune-related adverse events including myocarditis. The main risk factor for ICI myocarditis is the use of combination PD-1 and CTLA4 inhibition. ICI myocarditis is often fulminant and is pathologically characterized by myocardial infiltration of T lymphocytes and macrophages. Although much has been learned about the role of T-cells in ICI myocarditis, little is understood about the identity, transcriptional diversity, and functions of infiltrating macrophages. METHODS: We used an established murine ICI myocarditis model (Ctla4+/-Pdcd1-/- mice) to explore the cardiac immune landscape using single-cell RNA-sequencing, immunostaining, flow cytometry, in situ RNA hybridization, molecular imaging, and antibody neutralization studies. RESULTS: We observed marked increases in CCR2 (C-C chemokine receptor type 2)+ monocyte-derived macrophages and CD8+ T-cells in this model. The macrophage compartment was heterogeneous and displayed marked enrichment in an inflammatory CCR2+ subpopulation highly expressing Cxcl9 (chemokine [C-X-C motif] ligand 9), Cxcl10 (chemokine [C-X-C motif] ligand 10), Gbp2b (interferon-induced guanylate-binding protein 2b), and Fcgr4 (Fc receptor, IgG, low affinity IV) that originated from CCR2+ monocytes. It is important that a similar macrophage population expressing CXCL9, CXCL10, and CD16α (human homologue of mouse FcgR4) was expanded in patients with ICI myocarditis. In silico prediction of cell-cell communication suggested interactions between T-cells and Cxcl9+Cxcl10+ macrophages via IFN-γ (interferon gamma) and CXCR3 (CXC chemokine receptor 3) signaling pathways. Depleting CD8+ T-cells or macrophages and blockade of IFN-γ signaling blunted the expansion of Cxcl9+Cxcl10+ macrophages in the heart and attenuated myocarditis, suggesting that this interaction was necessary for disease pathogenesis. CONCLUSIONS: These data demonstrate that ICI myocarditis is associated with the expansion of a specific population of IFN-γ-induced inflammatory macrophages and suggest the possibility that IFN-γ blockade may be considered as a treatment option for this devastating condition.

Herpesvirus entry mediator as a potential biomarker in breast cancer compared with conventional cytotoxic T­lymphocyte­associated antigen 4.

Breast cancer (BC) is the most common cancer in women worldwide, with 2.3 million cases recorded in 2020. Despite improvements in cancer treatment, patients with BC still succumb to the disease, due to regional and distant metastases when diagnosed at later stages. Several immune checkpoint inhibitors have been approved for BC treatment, based on their expression and role in maintaining immunosurveillance against tumors. The present study aimed to evaluate the expression of 12 immune checkpoints in patients with BC, and assess their role as diagnostic and therapeutic markers. Expression levels were measured using reverse transcription-quantitative polymerase chain reaction. Among the 12 immune markers, herpesvirus entry mediator (HVEM) was found to be significantly upregulated in patients with malignant BC compared to non-malignant controls, with a relative fold change (FC) of 1.46 and P=0.012. A similar finding was observed for cytotoxic T-lymphocyte-associated antigen 4 (CTLA4; FC=1.47 and P=0.035). In addition, receiver operating characteristic curve analysis revealed that HVEM expression allowed significant differentiation between groups, with an area under the curve of 0.74 (P=0.013). Upregulation in both HVEM and CTLA4 was revealed to be significantly associated with the human epidermal growth factor receptor-2 (HER2)-enriched phenotype (FC=3.53, P=0.009 and FC=5.98, P=0.002, respectively), while only HVEM was significantly associated with the triple-negative phenotype (FC=2.07, P=0.016). Furthermore, HVEM was significantly higher in patients with grade III tumors (FC=1.88, P=0.025) and negative vascular invasion (FC=1.67, P=0.046) compared with non-malignant controls. Serum protein levels were assessed by multiplex immunoassay, and a significant increase in HVEM was detected in patients with malignant BC compared with that in non-malignant controls (P=0.035). These data indicated that HVEM may serve as a potential biomarker and target for immunotherapy, especially for certain types of BC.

Therapeutic modalities and clinical outcomes in a large cohort with LRBA deficiency and CTLA4 insufficiency.

BACKGROUND: LPS-responsive beige-like anchor (LRBA) deficiency (LRBA-/-) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA4) insufficiency (CTLA4+/-) are mechanistically overlapped diseases presenting with recurrent infections and autoimmunity. The effectiveness of different treatment regimens remains unknown. OBJECTIVE: Our aim was to determine the comparative efficacy and long-term outcome of therapy with immunosuppressants, CTLA4-immunoglobulin (abatacept), and hematopoietic stem cell transplantation (HSCT) in a single-country multicenter cohort of 98 patients with a 5-year median follow-up. METHODS: The 98 patients (63 LRBA-/- and 35 CTLA4+/-) were followed and evaluated at baseline and every 6 months for clinical manifestations and response to the respective therapies. RESULTS: The LRBA-/- patients exhibited a more severe disease course than did the CTLA4+/- patients, requiring more immunosuppressants, abatacept, and HSCT to control their symptoms. Among the 58 patients who received abatacept as either a primary or rescue therapy, sustained complete control was achieved in 46 (79.3%) without severe side effects. In contrast, most patients who received immunosuppressants as primary therapy (n = 61) showed either partial or no disease control (72.1%), necessitating additional immunosuppressants, abatacept, or transplantation. Patients with partial or no response to abatacept (n = 12) had longer disease activity before abatacept therapy, with higher organ involvement and poorer disease outcomes than those with a complete response. HSCT was performed in 14 LRBA-/- patients; 9 patients (64.2%) showed complete remission, and 3 (21.3%) continued to receive immunosuppressants after transplantation. HSCT and abatacept therapy gave rise to similar probabilities of survival. CONCLUSIONS: Abatacept is superior to immunosuppressants in controlling disease manifestations over the long term, especially when started early, and it may provide a safe and effective therapeutic alternative to transplantation.

Circulating Th2-biased T follicular helper cells impede antiviral humoral responses during chronic hepatitis B infection through upregulating CTLA4.

Failure in curing chronic hepatitis B (CHB) caused by hepatitis B virus (HBV) can lead to functional impairment of B cells. Cytotoxic T-lymphocyte associated antigen 4 (CTLA4) regulates B cell and T follicular helper (Tfh) cell differentiation. In addition, Tfh cells play a critical role in helping B cells generate antibodies upon pathogen exposure. Here, we analyzed the global and HBsAg-specific B cells and circulating Tfh (cTfh) cells using samples from treatment-naïve and Peg-IFN-α-treated CHB patients and healthy subjects. Compared to healthy subjects, CTLA4 expression was significantly increased in cTfh cells, from CHB patients. The frequency of CTLA4+cTfh2 cells was negatively correlated with that of HBsAg-specific resting memory B cells. Importantly, inhibition of CTLA4 restored HBsAb secretion and promoted plasma cell differentiation. In addition, CTLA4+cTfh2 cells from CHB patients were ineffective in providing B cell help. Both expression of CTLA4 in cTfh and cTfh2 cells and ratios of CLTA4+cTfh and CTLA4+cTfh2 cells were significantly decreased in Peg-IFN-α-treated CHB patients who showed complete responses. Thus, our results highlighted that cTh2-biased T follicular helper cells could impede antiviral humoral responses during chronic HBV infection by upregulating CTLA4, suggesting that further optimizing potent Tfh cell responses may promote functional cure of CHB.

Correlation of CTLA-4 polymorphism and the risk of gastric cancer in a Chinese Bai population.

Cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) is involved in the regulation of immune responses mediated by T cells. This study aimed to explore the correlation between CTLA-4 gene polymorphisms and the risk of gastric cancer (GC) in the Bai minority population of southwestern China. A total of 422 GC patients and 397 healthy controls (HC) were included in this case-control study. Four single nucleotide polymorphism sites of CTLA-4 gene (rs231775, rs733618, rs16840252 and rs3087243) were selected and analysed. The results showed a significant difference in the rs733618 loci between GC and HC groups. The frequency of the rs733618 polymorphism 'TC' genotype was significantly lower in GC group compared to the HC group [odds ratio (OR), 95% confidence interval (CI): .47 (.35-.63), p < .001]. GC cases with dominant genetic model 'TC + CC' had a 47% reduced risk of GC [OR, 95%CI: .53 (.40-.71), p < .001]. Subgroup analyses revealed that the rs733618 'TC + CC' genotype was associated with a lower risk of GC in male patients [OR, 95%CI: .42 (.31-.58), p < .001], those aged ≤60 years old [OR, 95%CI: .27 (.18-.42), p < .001], non-drinkers [OR, 95%CI: .21 (.13-.33), p < .001], non-smokers [OR, 95%CI: .38 (.25-.57), p < .001] and individuals without Helicobacter pylori infection [OR, 95%CI: .16 (.10-.26), p < .001]. Further multivariated analyses indicated that individuals with the 'TC + CC' rs733618 genotype who were aged ≤60 years old [OR, 95%CI: .42 (.29-.83), p = .032] and had no H. pylori infection [OR, 95%CI: .35 (.28-.76), p = .018] were found to have a protective effect against GC. Additionally, soluble CTLA-4 were significantly lower in GC patients with 'TC' and 'TC + CC' genotypes (all p < .05). Our findings suggest that the rs733618 polymorphism of CTLA-4 gene may play a critical role in the prevention of GC.

The impact of PD-L1 as a biomarker of cancer responses to combo anti-PD-1/CTLA-4.

Combination therapy of solid tumors with immune checkpoint inhibitors (ICIs) is a promising and rapidly evolving area of clinical research. Combo nivolumab-ipilimumab therapy has demonstrated potent efficacy in recent years, and PD-L1 expression profile has shown to play a key role in determining the most optimal immunotherapeutic regimen in advanced cancer patients. Here, the focus is over the impact of PD-L1 on combo nivolumab-ipilimumab in advanced solid cancer patients. Interpretations of this review indicate that patient responses to combo nivolumab-ipilimumab can be affected from different levels of PD-L1 expression states. A point required attention is the variations in responses among diverse cancer types or between different doses of the immunotherapy drugs. In general, higher rates of responses are seen with higher PD-L1 expression levels in many cancer types. This, however, is not coincided with survival of patients. Taken all into consideration, it could be asserted that considering PD-L1 as a solo biomarker may not be reliable for predicting clinical efficacy of combo nivolumab-ipilimumab. Thus, a search for other biomarkers or combination of PD-L1 with other factors may be considered for predicting patient responses.

The Expression of CTLA-4 in Breast Tumors and Tumor-Infiltrating Leukocytes Affects Patients' Systemic Inflammatory Status and Varies According to Their Molecular Subtypes.

Recent evidence has pointed out that the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) expression is a poor prognosis factor. However, the implications of CTLA-4 expression on circulating inflammatory mediators are unclear for breast cancer. Tumor biopsies and blood samples were collected from 117 breast cancer patients. Oxidative stress parameters were evaluated in plasma samples by measuring the lipoperoxidation profile and nitric oxide metabolites (NOx). Interleukins 12 (IL-12) and 4 (IL-4) were assessed by ELISA. CTLA-4 expression was determined by immunofluorescence assessed by its labeling in tumor-infiltrating leukocytes (TILs) or breast tumors. Correlations between CTLA-4 expression in breast tumors with TCD4/TCD8 infiltrating lymphocyte and inflammation-related genes were performed using data from TIMER 2.0/TCGA databases (n = 2160). CTLA-4 expression in TILs significantly correlated to triple-negative breast tumors. Patients carrying CTLA-4-positive tumors exhibited lower plasmatic NOx levels, and those expressing CTLA-4 in TILs had reduced levels of IL-12 in plasma. No changes in either IL-4 or lipid peroxidation profiles were detected concerning any CTLA4 status. Compared to the Luminal A ones, oxidative stress parameters and cytokines were observed in patients bearing triple-negative tumors. CTLA-4 expression in all breast cancer subtypes positively correlated to TCD4/TCD8 lymphocyte infiltrates, as well as to the pro-inflammatory genes IL12A, IL4, NFKB1, NFKB2, NOS1, NOS2, and NOS3. CTLA-4 expression in both tumor and TILs can affect the systemic inflammatory status of breast cancer patients, especially antitumor molecules such as IL-12 and NOx that correlate to more aggressive disease.

Reinstating immunogenicity using bispecific anti-checkpoint/agent inhibitors.

Immune checkpoint inhibitor (ICI) resistance demands for acquisition of novel strategies in order to broaden the therapeutic repertoire of advanced cancers. Bispecific antibodies can be utilized as an emerging therapeutic paradigm and a step forward in cancer immunotherapy. Synchronous inhibition of programmed death-1 (PD-1), programmed death-ligand 1 (PD-L1) or cytotoxic T lymphocyte associated antigen-4 (CTLA-4), or with other agents can expand antibody selectivity and improve therapeutic window through tightening cell-to-cell bridge (a process called immunological synapse) within tumor immune microenvironment (TIME). There is evidence of higher potency of this co-targeting approach over combined single-agent monoclonal antibodies in reinvigorating anti-tumor immune responses, retarding tumor growth, and improving patient survival. In fact, immunological synapses formed by interactions of such bispecific agents with TIME cells directly mediate cytotoxicity against tumor cells, and durable anti-tumor immune responses are predictable after application of such agents. Besides, lower adverse events are reported for bispecific antibodies compared with individual checkpoint inhibitors. These are all indicative of the importance of exploiting novel bispecific approach as a replacement for conventional combo checkpoint inhibitor therapy particularly for tumors with immunosuppressive or cold immunity. Study in this area is still continued, and in the future more will be known about the importance of this bispecific approach in cancer immunotherapy.

Immune mediated colitis: a surgical perspective.

BACKGROUND: This study aims to review and summarize the current up to date literature that explore the current treatment approaches to immune mediated colitis and the role of surgical specialties in the landscape of management. METHODS: A narrative review of papers was performed following a literature search through Medline, EMBASE and Cochrane Central databases pertaining to immune mediated colitis as an adverse event of cancer immunotherapy. RESULTS: Current guidelines for the diagnosis and treatment of immune mediated colitis mirror the approach to the workup of inflammatory bowel disease and guided by treating oncology and gastroenterology specialties. Immune mediated colitis however relies on surgical specific skills as a consequence of obtaining a diagnosis as well as in the management of complications that may arise. CONCLUSION: Immune mediate colitis management has largely been under the purview of medical specialties. This review explores the current landscape of managing immune mediated colitis from a surgical perspective and highlights key areas in which surgeons can engage in the multidisciplinary care of this condition. To facilitate prompt diagnosis and management of immune-mediated colitis, there is an increasing necessity for surgeons to become familiar with the latest multidisciplinary approaches and recommendations.

Indoleamine 2,3-dioxygenase 1 in circumventing checkpoint inhibitor responses: Updated.

Metabolic alterations occur commonly in tumor cells as a way to adapt available energetic sources for their proliferation, survival and resistance. Indoleamine 2,3-dioxygenase 1 (IDO1) is an intracellular enzyme catalyzing tryptophan degradation into kynurenine. IDO1 expression shows a rise in the stroma of many types of human cancers, and it provides a negative feedback mechanism for cancer evasion from immunosurveillance. Upregulation of IDO1 correlates with cancer aggression, poor prognosis and shortened patient survival. The increased activity of this endogenous checkpoint impairs effector T cell function, increases regulatory T cell (Treg) population and induces immune tolerance, so its inhibition potentiates anti-tumor immune responses and reshapes immunogenic state of tumor microenvironment (TME) presumably through normalizing effector T cell activity. A point is that the expression of this immunoregulatory marker is upregulated after immune checkpoint inhibitor (ICI) therapy, and that it has inducible effect on expression of other checkpoints. These are indicative of the importance of IDO1 as an attractive immunotherapeutic target and rationalizing combination of IDO1 inhibitors with ICI drugs in patients with advanced solid cancers. In this review, we aimed to discuss about the impact of IDO1 on tumor immune ecosystem, and the IDO1-mediated bypass of ICI therapy. The efficacy of IDO1 inhibitor therapy in combination with ICIs in advanced/metastatic solid tumors is also a focus of this paper.

PD-1 and CTLA-4 exert additive control of effector regulatory T cells at homeostasis.

At homeostasis, a substantial proportion of Foxp3+ T regulatory cells (Tregs) have an activated phenotype associated with enhanced TCR signals and these effector Treg cells (eTregs) co-express elevated levels of PD-1 and CTLA-4. Short term in vivo blockade of the PD-1 or CTLA-4 pathways results in increased eTreg populations, while combination blockade of both pathways had an additive effect. Mechanistically, combination blockade resulted in a reduction of suppressive phospho-SHP2 Y580 in eTreg cells which was associated with increased proliferation, enhanced production of IL-10, and reduced dendritic cell and macrophage expression of CD80 and MHC-II. Thus, at homeostasis, PD-1 and CTLA-4 function additively to regulate eTreg function and the ability to target these pathways in Treg cells may be useful to modulate inflammation.

Activated CTLA-4-independent immunosuppression of Treg cells disturbs CTLA-4 blockade-mediated antitumor immunity.

Combination therapy with anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and anti-programmed death-1 (PD-1) monoclonal antibodies (mAbs) has dramatically improved the prognosis of patients with multiple types of cancer, including renal cell carcinoma (RCC). However, more than half of RCC patients fail to respond to this therapy. Regulatory T cells (Treg cells) are a subset of highly immunosuppressive CD4+ T cells that promote the immune escape of tumors by suppressing effector T cells in the tumor microenvironment (TME) through various mechanisms. CTLA-4 is constitutively expressed in Treg cells and is regarded as a key molecule for Treg-cell-mediated immunosuppressive functions, suppressing antigen-presenting cells by binding to CD80/CD86. Reducing Treg cells in the TME with an anti-CTLA-4 mAb with antibody-dependent cellular cytotoxicity (ADCC) activity is considered an essential mechanism to achieve tumor regression. In contrast, we demonstrated that CTLA-4 blockade without ADCC activity enhanced CD28 costimulatory signaling pathways in Treg cells and promoted Treg-cell proliferation in mouse models. CTLA-4 blockade also augmented CTLA-4-independent immunosuppressive functions, including cytokine production, leading to insufficient antitumor effects. Similar results were also observed in human peripheral blood lymphocytes and tumor-infiltrating lymphocytes from patients with RCC. Our findings highlight the importance of Treg-cell depletion to achieve tumor regression in response to CTLA-4 blockade therapies.

Microwave ablation combined with anti-PD-1/CTLA-4 therapy induces an antitumor immune response to renal cell carcinoma in a murine model.

The study was designed to evaluate the efficiency of microwave ablation (MWA) in combination with anti-programmed death receptor 1 (anti-PD-1)/cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) in renal cell carcinoma (RCC) treatment. After tumors were established on C57/BL6 mice, MWA treatment and/or immune checkpoint inhibitor (ICI) treatment to the mice were performed. Tumor volume was recorded every 7 days. A rechallenge test was conducted on mice with tumors in the left kidney to explore the systemic establishment of antitumor immunity on day 7. In this study, during the 21-day observation period, tumors were continued to grow in all groups. However, compared with the tumor growth rate in MWA or control group, the rate in the ICI or MWA+ICI groups was decreased. Moreover, the population of CD8+T-cells was increased only in the MWA+ICI group, while that of regulatory T cells was decreased in the MWA, ICI, and MWA+ICI groups. Additionally, the MWA+ICI group had the highest interferon-γ level among all groups. Furthermore, histopathological examination revealed that CTLA-4 expression in distant tumors was reduced in the ICI and MWA + ICI groups. MWA treatment increased PD-L1/PD-1 expression; however, after the combination treatment with ICI, PD-L1/PD-1 expression was decreased. According to the rechallenge test, mice (16.7%) in the MWA group, ICI group (50%), and MWA+ICI group (66.7%) exhibited successful tumor rejection, whereas no mice in the control group exhibited the capability of tumor rejection. Overall, the systemic antitumor immunity induced by MWA was boosted when combined with anti-PD-1/CTLA-4 treatment in an RCC murine model.