TIGIT-CD226-PVR axis: advancing immune checkpoint blockade for cancer immunotherapy

Colorectal cancer-associated fibroblasts inhibit effector T cells via NECTIN2 signaling

Cancer-associated fibroblasts play a crucial role within the tumor microenvironment. However, a comprehensive characterization of CAF in colorectal cancer (CRC) is still missing. We combined scRNA-seq and spatial proteomics to decipher fibroblast heterogeneity in healthy human colon and CRC at high resolution. Analyzing nearly 23,000 fibroblasts, we identified 11 distinct clusters and verified them by spatial proteomics. Four clusters, consisting of myofibroblastic CAF (myCAF)-like, inflammatory CAF (iCAF)-like and proliferating fibroblasts as well as a novel cluster, which we named "T cell-inhibiting CAF" (TinCAF), were primarily found in CRC. This new cluster was characterized by the expression of immune-interacting receptors and ligands, including CD40 and NECTIN2. Co-culture of CAF and T cells resulted in a reduction of the effector T cell compartment, impaired proliferation, and increased exhaustion. By blocking its receptor interaction, we demonstrated that NECTIN2 was the key driver of T cell inhibition. Analysis of clinical datasets showed that NECTIN2 expression is a poor prognostic factor in CRC and other tumors. In conclusion, we identified a new class of immuno-suppressive CAF with features rendering them a potential target for future immunotherapies.

A novel signature constructed by cuproptosis-related RNA methylation regulators suggesting downregulation of YTHDC2 may induce cuproptosis resistance in colorectal cancer

BACKGROUND

A newly identified type of cell death due to intracellular copper accumulation is known as cuproptosis and RNA methylation is a post-transcriptional modification mechanism, both of which perform vital roles in the immune microenvironment of colorectal cancer (CRC), but the link between the two needs more research.

METHODS

TCGA database provided RNA-seq data and details clinically of CRC samples. Cuproptosis-related RNA methylation regulators (CRRMRs) were identified by correlation analysis. We screened 6 CRRMRs for prognostic model construction by employing LASSO-Cox regression analysis and calculated risk scores by CRRMRs (CuMS). GSE39582 and GSE38832 cohort were used as external validation sets. This research concentrated on the connection between the prognostic model and somatic mutation, anti-cancer drug sensitivity, immune infiltration, immune checkpoint expression. In addition, we investigated the differential expression of YTHDC2 in epithelial cell subpopulations by single-cell analysis with GSE166555, calculated cuproptosis scores and performed pathway enrichment. In vitro experiments were performed to explore the consequences of knockdown of YTHDC2 on CRC cell proliferation and migration, as well as changes in CRC cell viability in response to elesclomol after knockdown of YTHDC2. In vivo experiments, we constructed the cell line-derived xenograft model to further validate the results of the in vitro experiments.

RESULTS

The prognosis of CRC can be predicted by CuMS, which GSE39582 and GSE38832 confirmed. Two CuMS groups showed different tumor mutation burden (TMB) and immune infiltration. CuMS was connected to emerging immune checkpoints CD47 and PVR, therefore, it can be clinically complementary to TMB and microsatellite instability (MSI) status. In single-cell analysis, a subpopulation of epithelial cells with high YTHDC2 expression had a high cuproptosis score. In vitro experiments, knocking down YTHDC2 promoted cell proliferation and migration in CRC, and weaken the inhibitory effect of elesclomol and elesclomol-Cu on cell viability, which in vivo experiments validated.

CONCLUSION

We developed a prognostic model constructed by 6 CRRMRs to assess overall survival and immune microenvironment of CRC patients. YTHDC2 might regulate cuproptosis in multiple ways.

Phase I pharmacokinetic, safety, and preliminary efficacy study of tiragolumab in combination with atezolizumab in Chinese patients with advanced solid tumors

PURPOSE

Tiragolumab is an immunoglobulin G1 monoclonal antibody targeting the immune checkpoint T cell immunoreceptor with immunoglobulin and immunoreceptor ITIM domains. Targeting multiple immune pathways may improve anti-tumor responses. The phase I YP42514 study assessed the pharmacokinetics (PK), safety, and preliminary efficacy of tiragolumab plus atezolizumab in Chinese patients with advanced solid tumors.

METHODS

Adult patients from mainland China with Eastern Cooperative Oncology Group performance score 0/1, life expectancy of ≥ 12 weeks, and adequate hematologic/end organ function were eligible. Patients received tiragolumab 600 mg and atezolizumab 1200 mg intravenous every 3 weeks. Key endpoints were PK (serum concentrations of tiragolumab and atezolizumab) and safety. Results from this study were compared with the global phase I study, GO30103 (NCT02794571).

RESULTS

In this study, 20 patients received a median of five doses of tiragolumab plus atezolizumab. Median age was 57.5 years, 85.0% of patients were male and the most common tumor type was non-small cell lung cancer. Exposures in Chinese patients were comparable to the global GO30103 population: geometric mean ratio was 1.07 for Cycle 1 tiragolumab area under the concentration-time curve0-21 and 0.92 and 0.93 for Cycle 1 peak and trough atezolizumab exposure, respectively. Treatment-related adverse events were consistent across the Chinese and global populations. Two patients (10.0%) in this study achieved a partial response.

CONCLUSION

In this study, tiragolumab plus atezolizumab was tolerable and demonstrated preliminary anti-tumor activity. There were no meaningful differences in the PK or safety of tiragolumab plus atezolizumab between the Chinese and global populations.

CLINICAL TRIAL REGISTRATION NUMBER

China Clinical Trial Registry Identifier CTR20210219/YP42514. Date of registration 16 March 2021.

A Novel Epigenetic Strategy to Concurrently Block Immune Checkpoints PD-1/PD-L1 and CD155/TIGIT in Hepatocellular Carcinoma

Tumor microenvironment is an intricate web of stromal and immune cells creating an immune suppressive cordon around the tumor. In hepatocellular carcinoma (HCC), Tumor microenvironment is a formidable barrier towards novel immune therapeutic approaches recently evading the oncology field. In this study, the main aim was to identify the intricate immune evasion tactics mediated by HCC cells and to study the epigenetic modulation of the immune checkpoints; Programmed death-1 (PD-1)/ Programmed death-Ligand 1 (PD-L1) and T cell immunoreceptor with Ig and ITIM domains (TIGIT)/Cluster of Differentiation 155 (CD155) at the tumor-immune synapse. Thus, liver tissues, PBMCs and sera were collected from Hepatitis C Virus (HCV), HCC as well as healthy individuals. Screening was performed to PD-L1/PD-1 and CD155/TIGIT axes in HCC patients. PDL1, CD155, PD-1 and TIGIT were found to be significantly upregulated in liver tissues and peripheral blood mononuclear cells (PBMCs) of HCC patients. An array of long non-coding RNAs (lncRNAs) and microRNAs validated to regulate such immune checkpoints were screened. The lncRNAs; CCAT-1, H19, and MALAT-1 were all significantly upregulated in the sera, PBMCs, and tissues of HCC patients as compared to HCV patients and healthy controls. However, miR-944-5p, miR-105-5p, miR-486-5p, miR-506-5p, and miR-30a-5p were downregulated in the sera and liver tissues of HCC patients. On the tumor cell side, knocking down of lncRNAs-CCAT-1, MALAT-1, or H19-markedly repressed the co-expression of PD-L1 and CD155 and accordingly induced the cytotoxicity of co-cultured primary immune cells. On the immune side, ectopic expression of the under-expressed microRNAs; miR-486-5p, miR-506-5p, and miR-30a-5p significantly decreased the transcript levels of PD-1 in PBMCs with no effect on TIGIT. On the other hand, ectopic expression of miR-944-5p and miR-105-5p in PBMCs dramatically reduced the co-expression of PD-1 and TIGIT. Finally, all studied miRNAs enhanced the cytotoxic effects of PBMCs against Huh7 cells. However, miR-105-5p showed the highest augmentation for PBMCs cytotoxicity against HCC cells. In conclusion, this study highlights a novel co-targeting strategy using miR-105-5p mimics, MALAT-1, CCAT-1 and H19 siRNAs to efficiently hampers the immune checkpoints; PD-L1/PD-1 and CD155/TIGIT immune evasion properties in HCC.

Non-viral vector-based genome editing for cancer immunotherapy

Despite the exciting promise of cancer immunotherapy in the clinic, immune checkpoint blockade therapy and T cell-based therapies are often associated with low response rates, intrinsic and adaptive immune resistance, and systemic side effects. CRISPR-Cas-based genome editing appears to be an effective strategy to overcome these unmet clinical needs. As a safer delivery platform for the CRISPR-Cas system, non-viral nanoformulations have been recently explored to target tumor cells and immune cells, aiming to improve cancer immunotherapy on a gene level. In this review, we summarized the efforts of non-viral vector-based CRISPR-Cas-mediated genome editing in tumor cells and immune cells for cancer immunotherapy. Their design rationale and specific applications were highlighted.

A non-comparative, randomized, phase II trial of atezolizumab or atezolizumab plus tiragolumab for programmed death-ligand 1-positive recurrent cervical cancer (SKYSCRAPER-04)

OBJECTIVE

To evaluate tiragolumab (anti-TIGIT) and atezolizumab (anti-PD-L1) as second- or third-line therapy for PD-L1-positive persistent/recurrent cervical cancer.

METHODS

In the open-label, non-comparative, randomized phase II SKYSCRAPER-04 trial (NCT04300647), patients with PD-L1-positive (SP263 tumor area positivity ≥5%) recurrent/persistent cervical cancer after 1-2 chemotherapy lines (≥1 platinum-based) were randomized 3:1 to atezolizumab 1200 mg with/without tiragolumab 600 mg every 3 weeks until disease progression or unacceptable toxicity. Stratification factors were performance status, prior (chemo)radiotherapy, and disease status. The primary endpoint was independent review committee-assessed confirmed objective response rate per RECIST v1.1 in patients receiving tiragolumab plus atezolizumab. An objective response rate ≥21% (one-sample z-test p≤0.0245) was required for statistical significance versus a historical reference.

RESULTS

Protocol-defined independent review committee-assessed objective response rates were 19.0% (95% CI 12.6 to 27.0) in 126 patients receiving tiragolumab plus atezolizumab (p=0.0787 vs historical reference) and 15.6% (95% CI 6.5 to 29.5) in 45 atezolizumab-treated patients. Response rates were higher in PD-L1high (tumor area positivity ≥10%) than PD-L1low (tumor area positivity 5%-9%) subgroups with both regimens. At 8.5 months' median follow-up, independent review committee-assessed progression-free survival was 2.8 months (95% CI 1.7 to 4.1) with tiragolumab plus atezolizumab and 1.9 months (95% CI 1.5 to 3.0) with atezolizumab. In post hoc analyses (10.4 months' median follow-up), median overall survival was 11.1 months (95% CI 9.6 to 14.5) with the combination and 10.6 months (95% CI 6.9 to 13.8) with atezolizumab (crossover permitted). In the combination group, 3% of patients had adverse events requiring treatment discontinuation and 8% had grade ≥3 adverse events of special interest; corresponding values in the single-agent arm were 4% and 11%. There were no treatment-related deaths or new safety findings.

CONCLUSION

The objective response rate with the tiragolumab-plus-atezolizumab combination was numerically higher than the historical reference but did not reach statistical significance.

Immune checkpoint inhibitors and neurotoxicity: a focus on diagnosis and management for a multidisciplinary approach

INTRODUCTION

Although immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, the consequential over activation of the immune system is often complicated by adverse events that can affect several organs and systems, including the nervous system. The precise pathophysiology underlying neurological irAEs (n-irAEs) is not completely known. Around 3.8% of patients receiving anti-CTLA-4 agents, 6.1% of patients receiving anti-PD-1/PD-L1, and 12% of patients receiving combination therapies have n-irAEs. Most n-irAEs are low-grade, while severe toxicities have rarely been reported. in this article, we performed an updated literature search on immuno-related neurotoxicity on main medical research database, from February 2017 to December 2023.

AREAS COVERED

We have also compared the latest national and international guidelines on n-irAEs management with each other in order to better define patient management.

EXPERT OPINION

A multidisciplinary approach appears necessary in the management of oncological patients during immunotherapy. Therefore, in order to better manage these toxicities, we believe that it is essential to collaborate with neurologists specialized in the diagnosis and treatment of n-irAEs, and that a global neurological assessment, both central and peripheral, is necessary before starting immunotherapy, with regular reassessment during treatment.

Targeting SCD triggers lipotoxicity of cancer cells and enhances anti-tumor immunity in breast cancer brain metastasis mouse models

Breast cancer brain metastases (BCBM) are a significant cause of mortality and are incurable. Thus, identifying BCBM targets that reduce morbidity and mortality is critical. BCBM upregulate Stearoyl-CoA Desaturase (SCD), an enzyme that catalyzes the synthesis of monounsaturated fatty acids, suggesting a potential metabolic vulnerability of BCBM. In this study, we tested the effect of a brain-penetrant clinical-stage inhibitor of SCD (SCDi), on breast cancer cells and mouse models of BCBM. Lipidomics, qPCR, and western blot were used to study the in vitro effects of SCDi. Single-cell RNA sequencing was used to explore the effects of SCDi on cancer and immune cells in a BCBM mouse model. Pharmacological inhibition of SCD markedly reshaped the lipidome of breast cancer cells and resulted in endoplasmic reticulum stress, DNA damage, loss of DNA damage repair, and cytotoxicity. Importantly, SCDi alone or combined with a PARP inhibitor prolonged the survival of BCBM-bearing mice. When tested in a syngeneic mouse model of BCBM, scRNAseq revealed that pharmacological inhibition of SCD enhanced antigen presentation by dendritic cells, was associated with a higher interferon signaling, increased the infiltration of cytotoxic T cells, and decreased the proportion of exhausted T cells and regulatory T cells in the tumor microenvironment (TME). Additionally, pharmacological inhibition of SCD decreased engagement of immunosuppressive pathways, including the PD-1:PD-L1/PD-L2 and PVR/TIGIT axes. These findings suggest that SCD inhibition could be an effective strategy to intrinsically reduce tumor growth and reprogram anti-tumor immunity in the brain microenvironment to treat BCBM.

T-reg transcriptomic signatures identify response to check-point inhibitors

Regulatory T cells (Tregs) is a subtype of CD4+ T cells that produce an inhibitory action against effector cells. In the present work we interrogated genomic datasets to explore the transcriptomic profile of breast tumors with high expression of Tregs. Only 0.5% of the total transcriptome correlated with the presence of Tregs and only four transcripts, BIRC6, MAP3K2, USP4 and SMG1, were commonly shared among the different breast cancer subtypes. The combination of these genes predicted favorable outcome, and better prognosis in patients treated with checkpoint inhibitors. Twelve up-regulated genes coded for proteins expressed at the cell membrane that included functions related to neutrophil activation and regulation of macrophages. A positive association between MSR1 and CD80 with macrophages in basal-like tumors and between OLR1, ABCA1, ITGAV, CLEC5A and CD80 and macrophages in HER2 positive tumors was observed. Expression of some of the identified genes correlated with favorable outcome and response to checkpoint inhibitors: MSR1, CD80, OLR1, ABCA1, TMEM245, and ATP13A3 predicted outcome to anti PD(L)1 therapies, and MSR1, CD80, OLR1, ANO6, ABCA1, TMEM245, and ATP13A3 to anti CTLA4 therapies, including a subgroup of melanoma treated patients. In this article we provide evidence of genes strongly associated with the presence of Tregs that modulates the response to check point inhibitors.

Blocking CD226 regulates type 2 innate lymphoid cell effector function and alleviates airway hyperreactivity

BACKGROUND

Type 2 innate lymphoid cells (ILC2s) play a pivotal role in type 2 asthma. CD226 is a costimulatory molecule involved in various inflammatory diseases.

OBJECTIVE

We aimed to investigate CD226 expression and function within human and mouse ILC2s, and to assess the impact of targeting CD226 on ILC2-mediated airway hyperreactivity (AHR).

METHODS

We administered IL-33 intranasally to wild-type mice, followed by treatment with anti-CD226 antibody or isotype control. Pulmonary ILC2s were sorted for ex vivo analyses through RNA sequencing and flow cytometry. Next, we evaluated the effects of CD226 on AHR and lung inflammation in wild-type and Rag2-/- mice. Additionally, we compared peripheral ILC2s from healthy donors and asthmatic patients to ascertain the role of CD226 in human ILC2s.

RESULTS

Our findings demonstrated an inducible expression of CD226 in activated ILC2s, enhancing their cytokine secretion and effector functions. Mechanistically, CD226 alters intracellular metabolism and enhances PI3K/AKT and MAPK signal pathways. Blocking CD226 ameliorates ILC2-dependent AHR in IL-33 and Alternaria alternata-induced models. Interestingly, CD226 is expressed and inducible in human ILC2s, and its blocking reduces cytokine production. Finally, we showed that peripheral ILC2s in asthmatic patients exhibited elevated CD226 expression compared to healthy controls.

CONCLUSION

Our findings underscore the potential of CD226 as a novel therapeutic target in ILC2s, presenting a promising avenue for ameliorating AHR and allergic asthma.

Hemin blocks TIGIT/PVR interaction and induces ferroptosis to elicit synergistic effects of cancer immunotherapy

The immune checkpoint TIGIT/PVR blockade exhibits significant antitumor effects through activation of NK and CD8+ T cell-mediated cytotoxicity. Immune checkpoint blockade (ICB) could induce tumor ferroptosis through IFN-γ released by immune cells, indicating the synergetic effects of ICB with ferroptosis in inhibiting tumor growth. However, the development of TIGIT/PVR inhibitors with ferroptosis-inducing effects has not been explored yet. In this study, the small molecule Hemin that could bind with TIGIT to block TIGIT/PVR interaction was screened by virtual molecular docking and cell-based blocking assay. Hemin could effectively restore the IL-2 secretion from Jurkat-hTIGIT cells. Hemin reinvigorated the function of CD8+ T cells to secrete IFN-γ and the elevated IFN-γ could synergize with Hemin to induce ferroptosis in tumor cells. Hemin inhibited tumor growth by boosting CD8+ T cell immune response and inducing ferroptosis in CT26 tumor model. More importantly, Hemin in combination with PD-1/PD-L1 blockade exhibited more effective antitumor efficacy in anti-PD-1 resistant B16 tumor model. In summary, our finding indicated that Hemin blocked TIGIT/PVR interaction and induced tumor cell ferroptosis, which provided a new therapeutic strategy to combine immunotherapy and ferroptosis for cancer treatment.

Single-Cell Profiling Reveals Immune-Based Mechanisms Underlying Tumor Radiosensitization by a Novel Mn Porphyrin Clinical Candidate, MnTnBuOE-2-PyP5+ (BMX-001)

Manganese porphyrins reportedly exhibit synergic effects when combined with irradiation. However, an in-depth understanding of intratumoral heterogeneity and immune pathways, as affected by Mn porphyrins, remains limited. Here, we explored the mechanisms underlying immunomodulation of a clinical candidate, MnTnBuOE-2-PyP5+ (BMX-001, MnBuOE), using single-cell analysis in a murine carcinoma model. Mice bearing 4T1 tumors were divided into four groups: control, MnBuOE, radiotherapy (RT), and combined MnBuOE and radiotherapy (MnBuOE/RT). In epithelial cells, the epithelial-mesenchymal transition, TNF-α signaling via NF-кB, angiogenesis, and hypoxia-related genes were significantly downregulated in the MnBuOE/RT group compared with the RT group. All subtypes of cancer-associated fibroblasts (CAFs) were clearly reduced in MnBuOE and MnBuOE/RT. Inhibitory receptor-ligand interactions, in which epithelial cells and CAFs interacted with CD8+ T cells, were significantly lower in the MnBuOE/RT group than in the RT group. Trajectory analysis showed that dendritic cells maturation-associated markers were increased in MnBuOE/RT. M1 macrophages were significantly increased in the MnBuOE/RT group compared with the RT group, whereas myeloid-derived suppressor cells were decreased. CellChat analysis showed that the number of cell-cell communications was the lowest in the MnBuOE/RT group. Our study is the first to provide evidence for the combined radiotherapy with a novel Mn porphyrin clinical candidate, BMX-001, from the perspective of each cell type within the tumor microenvironment.

Immune checkpoints in autoimmune vasculitis

Giant cell arteritis (GCA) is a prototypic autoimmune disease with a highly selective tissue tropism for medium and large arteries. Extravascular GCA manifests with intense systemic inflammation and polymyalgia rheumatica; vascular GCA results in vessel wall damage and stenosis, causing tissue ischemia. Typical granulomatous infiltrates in affected arteries are composed of CD4+ T cells and hyperactivated macrophages, signifying the involvement of the innate and adaptive immune system. Lesional CD4+ T cells undergo antigen-dependent clonal expansion, but antigen-nonspecific pathways ultimately control the intensity and duration of pathogenic immunity. Patient-derived CD4+ T cells receive strong co-stimulatory signals through the NOTCH1 receptor and the CD28/CD80-CD86 pathway. In parallel, co-inhibitory signals, designed to dampen overshooting T cell immunity, are defective, leaving CD4+ T cells unopposed and capable of supporting long-lasting and inappropriate immune responses. Based on recent data, two inhibitory checkpoints are defective in GCA: the Programmed death-1 (PD-1)/Programmed cell death ligand 1 (PD-L1) checkpoint and the CD96/CD155 checkpoint, giving rise to the "lost inhibition concept". Subcellular and molecular analysis has demonstrated trapping of the checkpoint ligands in the endoplasmic reticulum, creating PD-L1low CD155low antigen-presenting cells. Uninhibited CD4+ T cells expand, release copious amounts of the cytokine Interleukin (IL)-9, and differentiate into long-lived effector memory cells. These data place GCA and cancer on opposite ends of the co-inhibition spectrum, with cancer patients developing immune paralysis due to excessive inhibitory checkpoints and GCA patients developing autoimmunity due to nonfunctional inhibitory checkpoints.

Mn-Anti-CTLA4-CREKA-Sericin Nanotheragnostics for Enhanced Magnetic Resonance Imaging and Tumor Immunotherapy

The integration of magnetic resonance imaging (MRI), cGAS-STING, and anti-CTLA-4 (aCTLA-4) based immunotherapy offers new opportunities for tumor precision therapy. However, the precise delivery of aCTLA-4 and manganese (Mn), an activator of cGAS, to tumors remains a major challenge for enhanced MRI and active immunotherapy. Herein, a theragnostic nanosphere Mn-CREKA-aCTLA-4-SS (MCCS) is prepared by covalently assembling Mn2+, silk sericin (SS), pentapeptide CREKA, and aCTLA-4. MCCS are stable with an average size of 160 nm and is almost negatively charged or neutral at pH 5.5/7.4. T1-weighted images showed MCCS actively targeted tumors to improve the relaxation rate r1 and contrast time of MRI. This studies demonstrated MCCS raises reactive oxygen species levels, activates the cGAS-STING pathway, stimulates effectors CD8+ and CD80+ T cells, reduces regulatory T cell numbers, and increases IFN-γ and granzyme secretion, thereby inducing tumor cells autophagy and apoptosis in vitro and in vivo. Also, MCCS are biocompatible and biosafe. These studies show the great potential of Mn-/SS-based integrative material MCCS for precision and personalized tumor nanotheragnostics.

Anti-TIGIT antibody improves PD-L1 blockade through myeloid and Treg cells

Tiragolumab, an anti-TIGIT antibody with an active IgG1κ Fc, demonstrated improved outcomes in the phase 2 CITYSCAPE trial (ClinicalTrials.gov: NCT03563716 ) when combined with atezolizumab (anti-PD-L1) versus atezolizumab alone1. However, there remains little consensus on the mechanism(s) of response with this combination2. Here we find that a high baseline of intratumoural macrophages and regulatory T cells is associated with better outcomes in patients treated with atezolizumab plus tiragolumab but not with atezolizumab alone. Serum sample analysis revealed that macrophage activation is associated with a clinical benefit in patients who received the combination treatment. In mouse tumour models, tiragolumab surrogate antibodies inflamed tumour-associated macrophages, monocytes and dendritic cells through Fcγ receptors (FcγR), in turn driving anti-tumour CD8+ T cells from an exhausted effector-like state to a more memory-like state. These results reveal a mechanism of action through which TIGIT checkpoint inhibitors can remodel immunosuppressive tumour microenvironments, and suggest that FcγR engagement is an important consideration in anti-TIGIT antibody development.

TIGIT: A potential immunotherapy target for gynecological cancers

Gynecological cancer represents a significant global health challenge, and conventional treatment modalities have demonstrated limited efficacy. However, recent investigations into immune checkpoint pathways have unveiled promising opportunities for enhancing the prognosis of patients with cancer. Among these pathways, TIGIT has surfaced as a compelling candidate owing to its capacity to augment the immune function of NK and T cells through blockade, thereby yielding improved anti-tumor effects and prolonged patient survival. Global clinical trials exploring TIGIT blockade therapy have yielded promising preliminary findings. Nevertheless, further research is imperative to comprehensively grasp the potential of TIGIT-based immunotherapy in optimizing therapeutic outcomes for gynecological cancers. This review primarily delineates the regulatory network and immunosuppressive mechanism of TIGIT, expounds upon its expression and therapeutic potential in three major gynecological cancers, and synthesizes the clinical trials of TIGIT-based cancer immunotherapy. Such insights aim to furnish novel perspectives and serve as reference points for subsequent research and clinical application targeting TIGIT in gynecological cancers.

T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain as a promising immune checkpoint target for the treatment of SLE

Immune checkpoints (ICs) play a pivotal role in orchestrating immune regulation, crucial for the maintenance of immune tolerance and prevention of autoimmune diseases. One noteworthy example among these immune regulators is T cell immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT). The TIGIT pathway's inhibition or the absence of TIGIT has been linked to the hyperactivation and excessive proliferation of T cells, rendering individuals more susceptible to autoimmune diseases and exacerbating inflammatory responses. Conversely, the activation of TIGIT has exhibited promising outcomes in ameliorating autoimmune disorders, as observed in murine models of systemic lupus erythematosus (SLE). Consequently, a judicious exploration of the co-inhibitory axis appears warranted for the effective management of pathogenic immune responses in SLE. In light of compelling evidence, this review undertakes a comprehensive examination of TIGIT's characteristics within the context of autoimmunity, offering insights into its potential as a therapeutic target for SLE.

Engaging stimulatory immune checkpoint interactions in the tumour immune microenvironment of primary liver cancers - how to push the gas after having released the brake

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the first and second most common primary liver cancer (PLC). For decades, systemic therapies consisting of tyrosine kinase inhibitors (TKIs) or chemotherapy have formed the cornerstone of treating advanced-stage HCC and CCA, respectively. More recently, immunotherapy using immune checkpoint inhibition (ICI) has shown anti-tumour reactivity in some patients. The combination regimen of anti-PD-L1 and anti-VEGF antibodies has been approved as new first-line treatment of advanced-stage HCC. Furthermore, gemcibatine plus cisplatin (GEMCIS) with an anti-PD-L1 antibody is awaiting global approval for the treatment of advanced-stage CCA. As effective anti-tumour reactivity using ICI is achieved in a minor subset of both HCC and CCA patients only, alternative immune strategies to sensitise the tumour microenvironment of PLC are waited for. Here we discuss immune checkpoint stimulation (ICS) as additional tool to enhance anti-tumour reactivity. Up-to-date information on the clinical application of ICS in onco-immunology is provided. This review provides a rationale of the application of next-generation ICS either alone or in combination regimen to potentially enhance anti-tumour reactivity in PLC patients.

Coordinated Immune Cell Networks in the Bone Marrow Microenvironment Define the Graft versus Leukemia Response with Adoptive Cellular Therapy

Understanding how intra-tumoral immune populations coordinate to generate anti-tumor responses following therapy can guide precise treatment prioritization. We performed systematic dissection of an established adoptive cellular therapy, donor lymphocyte infusion (DLI), by analyzing 348,905 single-cell transcriptomes from 74 longitudinal bone-marrow samples of 25 patients with relapsed myeloid leukemia; a subset was evaluated by protein-based spatial analysis. In acute myelogenous leukemia (AML) responders, diverse immune cell types within the bone-marrow microenvironment (BME) were predicted to interact with a clonally expanded population of ZNF683 + GZMB + CD8+ cytotoxic T lymphocytes (CTLs) which demonstrated in vitro specificity for autologous leukemia. This population, originating predominantly from the DLI product, expanded concurrently with NK and B cells. AML nonresponder BME revealed a paucity of crosstalk and elevated TIGIT expression in CD8+ CTLs. Our study highlights recipient BME differences as a key determinant of effective anti-leukemia response and opens new opportunities to modulate cell-based leukemia-directed therapy.

Neoantigen Cancer Vaccines and Different Immune Checkpoint Therapies Each Utilize Both Converging and Distinct Mechanisms that in Combination Enable Synergistic Therapeutic Efficacy

The goal of therapeutic cancer vaccines and immune checkpoint therapy (ICT) is to eliminate cancer by expanding and/or sustaining T cells with anti-tumor capabilities. However, whether cancer vaccines and ICT enhance anti-tumor immunity by distinct or overlapping mechanisms remains unclear. Here, we compared effective therapeutic tumor-specific mutant neoantigen (NeoAg) cancer vaccines with anti-CTLA-4 and/or anti-PD-1 ICT in preclinical models. Both NeoAg vaccines and ICT induce expansion of intratumoral NeoAg-specific CD8 T cells, though the degree of expansion and acquisition of effector activity was much more substantial following NeoAg vaccination. Further, we found that NeoAg vaccines are particularly adept at inducing proliferating and stem-like NeoAg-specific CD8 T cells. Single cell T cell receptor (TCR) sequencing revealed that TCR clonotype expansion and diversity of NeoAg-specific CD8 T cells relates to their phenotype and functional state associated with specific immunotherapies employed. Effective NeoAg vaccines and ICT required both CD8 and CD4 T cells. While NeoAg vaccines and anti-PD-1 affected the CD4 T cell compartment, it was to less of an extent than observed with anti-CTLA-4, which notably induced ICOS+Bhlhe40+ Th1-like CD4 T cells and, when combined with anti-PD-1, a small subset of Th2-like CD4 T cells. Although effective NeoAg vaccines or ICT expanded intratumoral M1-like iNOS+ macrophages, NeoAg vaccines expanded rather than suppressed (as observed with ICT) M2-like CX3CR1+CD206+ macrophages, associated with the vaccine adjuvant. Further, combining NeoAg vaccination with ICT induced superior efficacy compared to either therapy in isolation, highlighting the utility of combining these modalities to eliminate cancer.

SKYSCRAPER-02: Tiragolumab in Combination With Atezolizumab Plus Chemotherapy in Untreated Extensive-Stage Small-Cell Lung Cancer

PURPOSE

The phase III SKYSCRAPER-02 study determined whether the benefits of atezolizumab plus carboplatin and etoposide (CE) could be enhanced by the addition of tiragolumab in untreated extensive-stage small-cell lung cancer (ES-SCLC). We report final progression-free survival (PFS) and overall survival (OS) analyses.

METHODS

Patients received tiragolumab 600 mg/placebo, plus atezolizumab 1,200 mg and CE (four cycles), then maintenance tiragolumab/placebo plus atezolizumab. Primary end points were investigator-assessed PFS and OS in patients without history/presence of brain metastases (primary analysis set [PAS]). Additional end points included PFS and OS in all patients regardless of brain metastases status (full analysis set [FAS]), response, and safety.

RESULTS

Four hundred ninety patients were randomly assigned (FAS): 243 to tiragolumab arm and 247 to control arm. At the cutoff date (February 6, 2022; median duration of follow-up, 14.3 months [PAS] and 13.9 months [FAS]), final analysis of PFS in the PAS (n = 397) did not reach statistical significance (stratified hazard ratio [HR], 1.11; P = .3504; median, 5.4 months tiragolumab v 5.6 months control). At the cutoff date (September 6, 2022; median duration of follow-up, 21.2 months [FAS]), median OS in the PAS at final OS analysis was 13.1 months in both arms (stratified HR, 1.14; P = .2859). Median PFS and OS in the FAS were consistent with the PAS. The proportion of patients with immune-mediated adverse events (AEs) in the tiragolumab and control arms was 54.4% and 49.2%, respectively (grade 3/4: 7.9% and 7.7%). AEs leading to treatment withdrawal occurred in 8.4% and 9.3% of tiragolumab- and control-treated patients, respectively.

CONCLUSION

Tiragolumab did not provide additional benefit over atezolizumab and CE in untreated ES-SCLC. The combination was well tolerated with no new safety signals.

Targeting TIGIT for cancer immunotherapy: recent advances and future directions

As a newly identified checkpoint, T cell immunoreceptor with immunoglobulin and tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is highly expressed on CD4+ T cells, CD8+ T cells, natural killer (NK) cells, regulatory T cells (Tregs), and tumor-infiltrating lymphocytes (TILs). TIGIT has been associated with NK cell exhaustion in vivo and in individuals with various cancers. It not only modulates NK cell survival but also mediates T cell exhaustion. As the primary ligand of TIGIT in humans, CD155 may be the main target for immunotherapy due to its interaction with TIGIT. It has been found that the anti-programmed cell death protein 1 (PD-1) treatment response in cancer immunotherapy is correlated with CD155 but not TIGIT. Anti-TIGIT alone and in combination with anti-PD-1 agents have been tested for cancer immunotherapy. Although two clinical studies on advanced lung cancer had positive results, the TIGIT-targeted antibody, tiragolumab, recently failed in two new trials. In this review, we highlight the current developments on TIGIT for cancer immunotherapy and discuss the characteristics and functions of TIGIT.

Inhibitors of Immune Checkpoints: Small Molecule- and Peptide-Based Approaches

The revolutionary progress in cancer immunotherapy, particularly the advent of immune checkpoint inhibitors, marks a significant milestone in the fight against malignancies. However, the majority of clinically employed immune checkpoint inhibitors are monoclonal antibodies (mAbs) with several limitations, such as poor oral bioavailability and immune-related adverse effects (irAEs). Another major limitation is the restriction of the efficacy of mAbs to a subset of cancer patients, which triggered extensive research efforts to identify alternative approaches in targeting immune checkpoints aiming to overcome the restricted efficacy of mAbs. This comprehensive review aims to explore the cutting-edge developments in targeting immune checkpoints, focusing on both small molecule- and peptide-based approaches. By delving into drug discovery platforms, we provide insights into the diverse strategies employed to identify and optimize small molecules and peptides as inhibitors of immune checkpoints. In addition, we discuss recent advances in nanomaterials as drug carriers, providing a basis for the development of small molecule- and peptide-based platforms for cancer immunotherapy. Ongoing research focused on the discovery of small molecules and peptide-inspired agents targeting immune checkpoints paves the way for developing orally bioavailable agents as the next-generation cancer immunotherapies.

Astragalus Polysaccharide Alleviates Ulcerative Colitis by Regulating the Balance of mTh17/mTreg Cells through TIGIT/CD155 Signaling

The balance between memory Th17 cells (mTh17) and memory Treg cells (mTreg) plays a key role in the pathogenesis of ulcerative colitis (UC), and TIGIT signaling is involved in the differentiation of mTh17/mTreg cells. Astragalus polysaccharide (APS) has good immunomodulatory and anti-inflammatory effects. Here, the regulatory effects and potential mechanisms of APS on mTh17/mTreg cells in UC are explored. A UC model was induced with dextran sulfate sodium (DSS) and treated simultaneously with APS (200 mg/kg/day) for 10 days. After APS treatment, the mice showed a significant increase in colonic length and a significant decrease in colonic weight, colonic weight index and colonic weight/colonic length, and more intact mucosa and lighter inflammatory cell infiltration. Notably, APS significantly down-regulated the percentages of Th17 (CD4+CCR6+), cmTh17 (CD4+CCR7+CCR6+) and emTh17 (CD4+CCR7-CCR6+) cells and significantly up-regulated the percentages of cmTreg (CD4+CCR7+Foxp3+) and emTreg (CD4+CCR7-Foxp3+) cells in the mesenteric lymph nodes of the colitis mice. Importantly, APS reversed the expression changes in the TIGIT molecule on mTh17/mTreg cells in the colitis mice with fewer CD4+CCR6+TIGIT+, CD4+CCR7-CCR6+TIGIT+ and CD4+CCR7-CCR6+TIGIT+ cells and more CD4+Foxp3+TIGIT+, CD4+CCR7-Foxp3+TIGIT+ and CD4+CCR7-Foxp3+TIGIT+ cells. Meanwhile, APS significantly inhibited the protein expression of the TIGIT ligands CD155, CD113 and CD112 and downstream proteins PI3K and AKT in the colon tissues of the colitis mice. In conclusion, APS effectively alleviated DSS-induced UC in mice by regulating the balance between mTh17/mTreg cells, which was mainly achieved through regulation of the TIGIT/CD155 signaling pathway.

Lymphocyte subsets and inflammatory factors as predictors of immunotherapy efficacy in patients with hepatocellular carcinoma

We aimed to investigate the correlation between lymphocyte subpopulations expressing inhibitor receptors, IL-6 levels, and the efficacy of immunotherapy in patients with hepatocellular carcinoma. Blood samples were prospectively collected before and after immunotherapy from patients with intermediate and advanced hepatocellular carcinoma who were treated with immunotherapy at the Fifth Medical Center of the PLA General Hospital from August 2022 to October 2023. According to the efficacy of the patients, patients were divided into effective and ineffective groups, with 40 in the effective group and 44 in the ineffective group. We compared changes in lymphocyte subsets and IL-6 levels between the two groups. Optimal cut-off value was determined using ROC curves. Then, patients were categorized into high and low groups based on cut-off value, and the disease control rates and progression free survival were compared. Before immunotherapy, there were no significant differences in the baseline levels of lymphocyte subsets (PD1 + TIM3 + T/T, TIGIT + T/T, TIM3 + T/T, CTLA4 + T/T, LAG3 + T/T, PD1 + T/T) and IL-6 between the two groups (P > 0.05). After immunotherapy, the levels of PD1 + TIM3 + T/T, TIGIT + T/T, and IL-6 in the effective group were lower than those in the ineffective group and these differences were statistically significant (P = 0.001, P = 0.008, P = 0.000). However, the levels of other lymphocyte subsets showed no significant difference. Using the ROC curve to assess efficacy prediction, PD1 + TIM3 + T/T, TIGIT + T/T and IL-6 demonstrated high predictive ability (AUC = 0.79, AUC = 0.81, AUC = 0.78). The predictive value of efficacy was further improved when all three factors were combined (AUC = 0.92, P = 0.000). Based on the ROC curve, we identified optimal cut-off value for three factors. Notably, patients with values below the optimal cut-off value had higher disease control rate and progression free survival. The levels of PD1 + TIM3 + T/T, TIGIT + T/T, and IL-6 after 2 cycles of immunotherapy may serve as predictors of treatment efficacy in patients with hepatocellular carcinoma.

Knockout of the inhibitory receptor TIGIT enhances the antitumor response of ex vivo expanded NK cells and prevents fratricide with therapeutic Fc-active TIGIT antibodies

BACKGROUND

Inhibitory receptor T-cell Immunoreceptor with Ig and ITIM domains (TIGIT) expressed by Natural Killer (NK) and T cells regulates cancer immunity and has been touted as the next frontier in the development of cancer immunotherapeutics. Although early results of anti-TIGIT and its combinations with antiprogrammed death-ligand 1 were highly exciting, results from an interim analysis of phase III trials are disappointing. With mixed results, there is a need to understand the effects of therapeutic anti-TIGIT on the TIGIT+ immune cells to support its clinical use. Most of the TIGIT antibodies in development have an Fc-active domain, which binds to Fc receptors on effector cells. In mouse models, Fc-active anti-TIGIT induced superior immunity, while Fc receptor engagement was required for its efficacy. NK-cell depletion compromised the antitumor immunity of anti-TIGIT indicating the essential role of NK cells in the efficacy of anti-TIGIT. Since NK cells express TIGIT and Fc-receptor CD16, Fc-active anti-TIGIT may deplete NK cells via fratricide, which has not been studied.

METHODS

CRISPR-Cas9-based TIGIT knockout (KO) was performed in expanded NK cells. Phenotypic and transcriptomic properties of TIGIT KO and wild-type (WT) NK cells were compared with flow cytometry, CyTOF, and RNA sequencing. The effect of TIGIT KO on NK-cell cytotoxicity was determined by calcein-AM release and live cell imaging-based cytotoxicity assays. The metabolic properties of TIGIT KO and WT NK cells were compared with a Seahorse analyzer. The effect of the Fc-component of anti-TIGIT on NK-cell fratricide was determined by co-culturing WT and TIGIT KO NK cells with Fc-active and Fc-inactive anti-TIGIT.

RESULTS

TIGIT KO increased the cytotoxicity of NK cells against multiple cancer cell lines including spheroids. TIGIT KO NK cells upregulated mTOR complex 1 (mTORC1) signaling and had better metabolic fitness with an increased basal glycolytic rate when co-cultured with cancer cells compared with WT NK cells. Importantly, TIGIT KO prevented NK-cell fratricide when combined with Fc-active anti-TIGIT.

CONCLUSIONS

TIGIT KO in ex vivo expanded NK cells increased their cytotoxicity and metabolic fitness and prevented NK-cell fratricide when combined with Fc-active anti-TIGIT antibodies. These fratricide-resistant TIGIT KO NK cells have therapeutic potential alone or in combination with Fc-active anti-TIGIT antibodies to enhance their efficacy.

New insights into the stemness of adoptively transferred T cells by γc family cytokines

T cell-based adoptive cell therapy (ACT) has exhibited excellent antitumoral efficacy exemplified by the clinical breakthrough of chimeric antigen receptor therapy (CAR-T) in hematologic malignancies. It relies on the pool of functional T cells to retain the developmental potential to serially kill targeted cells. However, failure in the continuous supply and persistence of functional T cells has been recognized as a critical barrier to sustainable responses. Conferring stemness on infused T cells, yielding stem cell-like memory T cells (TSCM) characterized by constant self-renewal and multilineage differentiation similar to pluripotent stem cells, is indeed necessary and promising for enhancing T cell function and sustaining antitumor immunity. Therefore, it is crucial to identify TSCM cell induction regulators and acquire more TSCM cells as resource cells during production and after infusion to improve antitumoral efficacy. Recently, four common cytokine receptor γ chain (γc) family cytokines, encompassing interleukin-2 (IL-2), IL-7, IL-15, and IL-21, have been widely used in the development of long-lived adoptively transferred TSCM in vitro. However, challenges, including their non-specific toxicities and off-target effects, have led to substantial efforts for the development of engineered versions to unleash their full potential in the induction and maintenance of T cell stemness in ACT. In this review, we summarize the roles of the four γc family cytokines in the orchestration of adoptively transferred T cell stemness, introduce their engineered versions that modulate TSCM cell formation and demonstrate the potential of their various combinations. Video Abstract.

Anti-TIGIT Antibody Tiragolumab Alone or With Atezolizumab in Patients With Advanced Solid Tumors: A Phase 1a/1b Nonrandomized Controlled Trial

Importance

Inhibition of the T-cell immunoreceptor with Ig and ITIM domains (TIGIT)/poliovirus receptor pathway may amplify the antitumor immune response of atezolizumab in programmed death ligand 1-selected tumors.

Objective

To evaluate the safety and antitumor activity of the anti-TIGIT antibody tiragolumab and its combination with atezolizumab in patients with advanced solid tumors.

Design, Setting, and Participants

The GO30103 open-label, first-in-human phase 1a/1b dose-escalation and dose-expansion nonrandomized controlled trial was conducted at 13 sites in 6 countries (Australia, Canada, France, Korea, Spain, and the US). The start dates were May 23, 2016, for phase 1a and October 11, 2016, for phase 1b. Patients were aged 18 years or older with measurable disease at baseline. The clinical cutoff date was October 1, 2021. Data analysis was performed on January 24, 2022.

Interventions

Patients received fixed-dose intravenous tiragolumab on day 1 of each 21-day cycle (2 mg escalating to 1200 mg) in phase 1a, plus fixed-dose intravenous atezolizumab (1200 mg every 3 weeks) in phase 1b. Patients were treated until disease progression, loss of clinical benefit, or development of unacceptable toxicity.

Main Outcomes and Measures

The primary end points included the safety, tolerability, and recommended phase 2 dose (RP2D) of tiragolumab or combination tiragolumab plus atezolizumab. The secondary end point included the investigator-assessed objective response rate (ORR). Counts and percentages are used for categorical variables, and medians and ranges are used for continuous variables.

Results

Among the phase 1a (n = 24) and 1b (n = 49) dose-escalation cohorts, the median age was 60 (range, 40-77) and 54 (range, 25-81) years, respectively. More than half of patients were women (14 of 24 [58%] and 25 of 49 [51%]), and more than a third (10 [42%] and 18 [37%]) had received 4 or more prior cancer therapies. No dose-limiting toxicities occurred, and the maximum tolerated dose of tiragolumab was not reached (NR). The most frequent treatment-related adverse events (AEs) were fatigue (5 of 24 [21%]) in phase 1a and pruritus (5 of 49 [10%]) in phase 1b; the majority of AEs were grade 1 or 2. Immune-mediated AEs occurred in 4 of 24 (17%) and 29 of 49 (59%) patients during phases 1a and 1b, respectively (primarily grade 1 or 2). The RP2D of tiragolumab was 600 mg intravenously every 3 weeks, which was tested in phase 1b dose expansion. The confirmed ORR was 0% during phase 1a, with evidence of antitumor activity in 6% of patients (n = 3) during phase 1b. The safety profile of combination tiragolumab plus atezolizumab in phase 1b was similar in the dose-escalation and dose-expansion cohorts. The confirmed ORR was 46% (6 of 13) in the non-small cell lung cancer (NSCLC) cohort (median duration of response [DOR], NR) and 28% (5 of 18) in the esophageal cancer (EC) cohort (median DOR, 15.2 [95% CI, 7.0 to NR] months).

Conclusions and Relevance

In this nonrandomized controlled trial, tiragolumab was well tolerated with or without atezolizumab; no new safety signals were observed. Preliminary antitumor activity was demonstrated for the combination regimen in patients with cancer immunotherapy-naive metastatic NSCLC or EC.

Trial Registration

ClinicalTrials.gov Identifier: NCT02794571.

Integrated single-cell and bulk sequencing analyses with experimental validation identify the prognostic and immunological implications of CD226 in pan-cancer

PURPOSE

CD226 (DNAM-1) is an activating receptor mainly expressed in CD8 + and NK cells. CD226 deficiency and blockade have been shown to impair tumor suppression, while enhanced CD226 expression positively correlated with the increased efficacy of immune checkpoint blockade (ICB) therapies. However, the detailed function and role of CD226 in pan-cancer are largely unknown and require further in-depth investigation. Therefore, this study aims to investigate the biological functions of CD226, its role in tumor immunity, and its potential to predict prognosis and immunotherapy response in pan-cancer.

METHODS

By taking advantage of single-cell and bulk sequencing analyses, we analyzed the expression profile of CD226, its correlation with patient prognosis, immune infiltration level, immune-related genes, tumor heterogeneity, and stemness in pan-cancer. We also investigated the biological functions of CD226 using gene set enrichment analysis (GSEA) and evaluated its predictive value in response to immunotherapy and small-molecule targeted drugs. In addition, we validated the expression of CD226 in tumor-infiltrating CD8 + and NK cells and studied its association with their functions using a murine B16F10 melanoma model.

RESULTS

CD226 exhibited differential expression across most tumor types, and its elevated expression was associated with improved clinical outcomes in multiple cancer types. CD226 is closely correlated with numerous tumor-infiltrating immune cells, tumor stemness, and heterogeneity in most cancers. Furthermore, based on single-cell sequencing analysis, CD226 expression was found to be higher on effector CD4 + T cells than naïve CD4 + T cells, and its expression level was decreased in exhausted CD8 + T cells relative to effector CD8 + T cells in multiple cancer types. Additionally, flow cytometric analysis demonstrated that CD226 was highly correlated with the function of tumor-infiltrating NK and CD8 + T cells in murine B16F10 melanoma. Moreover, GSEA analysis revealed that CD226 was closely associated with T cell activation, natural killer cell mediated immunity, natural killer cell-mediated cytotoxicity, and T cell receptor signaling pathway. Finally, CD226 showed promising predictive potential for responsiveness to both ICB therapies and various small-molecule targeted drugs.

CONCLUSION

CD226 has shown great potential as an innovative biomarker for predicting patient prognosis, immune infiltration levels, and the function of tumor-infiltrating CD8 + T cells, as well as immunotherapy response. Additionally, our findings suggest that the optimal modification of CD226 expression and function, combined with current ICBs, could be a promising strategy for tumor immunotherapy.

SHP2: A Pleiotropic Target at the Interface of Cancer and Its Microenvironment

The protein phosphatase SHP2/PTPN11 has been reported to be a key modulator of proliferative pathways in a wide range of malignancies. Intriguingly, SHP2 has also been described as a critical regulator of the tumor microenvironment. Based on this evidence SHP2 is considered a multifaceted target in cancer, spurring the notion that the development of direct inhibitors of SHP2 would provide the twofold benefit of tumor intrinsic and extrinsic inhibition. In this review, we will discuss the role of SHP2 in cancer and the tumor microenvironment, and the clinical strategies in which SHP2 inhibitors are leveraged as combination agents to improve therapeutic response.

SIGNIFICANCE

The SHP2 phosphatase functions as a pleiotropic factor, and its inhibition not only hinders tumor growth but also reshapes the tumor microenvironment. Although their single-agent activity may be limited, SHP2 inhibitors hold the potential of being key combination agents to enhance the depth and the durability of tumor response to therapy.

Identification of Nectin Family Interactive Gene Panel and Stratification of Clinical Outcomes in Patients with Pancreatic Cancer

BACKGROUND

Although patient-risk stratification is important for selecting individualized treatment for pancreatic ductal adenocarcinoma (PDAC), predicting the oncologic outcomes after surgery remains a challenge. In this study, we identified a nectin family gene panel (NFGP) that can accurately stratify oncologic outcomes in patients with PDAC.

STUDY DESIGN

Comprehensive analysis of the expression of 9 nectin family genes identified the NFGP, which was assessed for predictive performance in 2 independent public cohorts (The Cancer Genome Atlas [TCGA] n = 176; International Cancer Genome Consortium [ICGC] n = 89). It was subsequently trained and validated for the in-house training cohort without neo-adjuvant therapy (NAT, n = 213) and the validation cohort with NAT (n = 307).

RESULTS

Using the Cox regression model, NFGP derived from 9 nectin family genes accurately stratified overall survival (OS) in TCGA (p = 0.038) and ICGC (p = 0.005). We subsequently optimized NFGP, which robustly discriminated postoperative prognosis, OS (p = 0.014) and relapse-free survival ([RFS] p = 0.006) in the training cohort. The NFGP was successfully validated in an independent validation cohort (OS: p < 0.001; RFS: p = 0.004). Multivariate analysis demonstrated the NFGP was an independent prognostic factor for OS and RFS in the training (p = 0.028 and 0.008, respectively) and validation (p < 0.001 and 0.013, respectively) cohorts. The subcohort analyses showed that the predictive performance of NFGP is applicable to the patients' subcohort according to resectability or adjuvant therapy status. Additionally, a combination model of NFGP score and CA19-9 level emerged with improved accuracy for predicting prognosis.

CONCLUSIONS

This study established the predictive significance of NFGP for oncologic outcomes after surgery in PDAC. Our data demonstrate its clinical impact as a potent biomarker for optimal patient selection for individualized treatment strategies.

Combinatorial blockade for cancer immunotherapy: targeting emerging immune checkpoint receptors

The differentiation, survival, and effector function of tumor-specific CD8+ cytotoxic T cells lie at the center of antitumor immunity. Due to the lack of proper costimulation and the abundant immunosuppressive mechanisms, tumor-specific T cells show a lack of persistence and exhausted and dysfunctional phenotypes. Multiple coinhibitory receptors, such as PD-1, CTLA-4, VISTA, TIGIT, TIM-3, and LAG-3, contribute to dysfunctional CTLs and failed antitumor immunity. These coinhibitory receptors are collectively called immune checkpoint receptors (ICRs). Immune checkpoint inhibitors (ICIs) targeting these ICRs have become the cornerstone for cancer immunotherapy as they have established new clinical paradigms for an expanding range of previously untreatable cancers. Given the nonredundant yet convergent molecular pathways mediated by various ICRs, combinatorial immunotherapies are being tested to bring synergistic benefits to patients. In this review, we summarize the mechanisms of several emerging ICRs, including VISTA, TIGIT, TIM-3, and LAG-3, and the preclinical and clinical data supporting combinatorial strategies to improve existing ICI therapies.

NK Receptors Replace CD28 As the Dominant Source of Signal 2 for Cognate Recognition of Cancer Cells by TAA-specific Effector CD8+ T Cells

CD28-driven "signal 2" is critical for naïve CD8+ T cell responses to dendritic cell (DC)-presented weak antigens, including non-mutated tumor-associated antigens (TAAs). However, it is unclear how DC-primed cytotoxic T lymphocytes (CTLs) respond to the same TAAs presented by cancer cells which lack CD28 ligands. Here, we show that NK receptors (NKRs) DNAM-1 and NKG2D replace CD28 during CTL re-activation by cancer cells presenting low levels of MHC I/TAA complexes, leading to enhanced proximal TCR signaling, immune synapse formation, CTL polyfunctionality, release of cytolytic granules and antigen-specific cancer cell killing. Double-transduction of T cells with recombinant TCR and NKR constructs or upregulation of NKR-ligand expression on cancer cells by chemotherapy enabled effective recognition and killing of poorly immunogenic tumor cells by CTLs. Operational synergy between TCR and NKRs in CTL recognition explains the ability of cancer-expressed self-antigens to serve as tumor rejection antigens, helping to develop more effective therapies.

Molecular and structural basis of TIGIT: Nectin-4 interaction, a recently discovered pathway crucial for cancer immunotherapy

TIGIT (T cell immunoglobulin and ITIM domain) is an inhibitory receptor expressed on T and NK cells that interact with cell surface glycoprotein belonging to the nectin and nectin-like family of cell adhesion molecules, particularly nectin-2 and nectin-like 5 (PVR). Nectin-4 has been recently identified as a novel ligand for TIGIT and the interaction among them inhibits NK cell cytotoxicity. In this study, biophysical experiments were conducted to decipher the mechanism of this novel interaction, followed by structure-guided mutagenesis studies to map the nectin-4 binding interface on TIGIT. Using surface plasmon resonance, we deduced that TIGIT recognizes the membrane distal ectodomain of nectin-4 and the interaction is weaker than the well-characterized TIGIT: nectin-2 interaction. Deciphering the molecular basis of this newly identified interaction between TIGIT and nectin-4 will provide us important insight into the manipulation of this inhibitory signaling pathway, especially targeting cancer cells overexpressing nectin-4 that evade the immune surveillance of the body.

CD155 and its receptors in cancer immune escape and immunotherapy

In recent years, there have been multiple breakthroughs in cancer immunotherapy, with immune checkpoint inhibitors becoming the most promising treatment strategy. However, available drugs are not always effective. As an emerging immune checkpoint molecule, CD155 has become an important target for immunotherapy. This review describes the structure and function of CD155, its receptors TIGIT, CD96, and CD226, and summarizes that CD155 expressed by tumor cells can upregulate its expression through the DNA damage response pathway and Ras-Raf-MEK-ERK signaling pathway. This review also elaborates the mechanism of immune escape after binding CD155 to its receptors TIGIT, CD96, and CD226, and summarizes the current progress of immunotherapy research regarding CD155 and its receptors. Besides, it also discusses the future direction of checkpoint immunotherapy.

Development and evaluation of nanobody tracers for noninvasive nuclear imaging of the immune-checkpoint TIGIT

Introduction

T cell Ig and ITIM domain receptor (TIGIT) is a next-generation immune checkpoint predominantly expressed on activated T cells and NK cells, exhibiting an unfavorable prognostic association with various malignancies. Despite the emergence of multiple TIGIT-blocking agents entering clinical trials, only a fraction of patients responded positively to anti-TIGIT therapy. Consequently, an urgent demand arises for noninvasive techniques to quantify and monitor TIGIT expression, facilitating patient stratification and enhancing therapeutic outcomes. Small antigen binding moieties such as nanobodies, are promising candidates for such tracer development.

Methods

We generated a panel of anti-human or anti-mouse TIGIT nanobodies from immunized llamas. In addition, we designed a single-chain variable fragment derived from the clinically tested monoclonal antibody Vibostolimab targeting TIGIT, and assessed its performance alongside the nanobodies. In vitro characterization studies were performed, including binding ability and affinity to cell expressed or recombinant TIGIT. After Technetium-99m labeling, the nanobodies and the single-chain variable fragment were evaluated in vivo for their ability to detect TIGIT expression using SPECT/CT imaging, followed by ex vivo biodistribution analysis.

Results

Nine nanobodies were selected for binding to recombinant and cell expressed TIGIT with low sub-nanomolar affinities and are thermostable. A six-fold higher uptake in TIGIT-overexpressing tumor was demonstrated one hour post- injection with Technetium-99m labeled nanobodies compared to an irrelevant control nanobody. Though the single-chain variable fragment exhibited superior binding to TIGIT-expressing peripheral blood mononuclear cells in vitro, its in vivo behavior yielded lower tumor-to-background ratios at one hour post- injection, indicating that nanobodies are better suited for in vivo imaging than the single-chain variable fragment. Despite the good affinity, high specificity and on-target uptake in mice in this setting, imaging of TIGIT expression on tumor- infiltrating lymphocytes within MC38 tumors remained elusive. This is likely due to the low expression levels of TIGIT in this model.

Discussion

The excellent affinity, high specificity and rapid on-target uptake in mice bearing TIGIT- overexpressing tumors showed the promising diagnostic potential of nanobodies to noninvasively image high TIGIT expression within the tumor. These findings hold promise for clinical translation to aid patient selection and improve therapy response.

TIGIT-Fc fusion protein alleviates murine lupus nephritis through the regulation of SPI-B-PAX5-XBP1 axis-mediated B-cell differentiation

OBJECTIVES

T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is a newly discovered immune checkpoint (IC) that exhibits immunosuppressive function in the regulation of immune system. Activation of TIGIT signaling has emerged as a promising approach for autoimmune disease immunotherapy, such as systemic lupus erythematosus (SLE).

METHODS

We generated a chimeric protein, TIGIT-immunoglobulin (Ig), by fusing the extracellular domain of murine TIGIT to the Fc region of mouse IgG2a, which was used to investigated the effect of activating the TIGIT signaling in murine lupus models (MRL/lpr and chronic graft-versus-host disease mice). Treated mice were harvested, and samples of serum, kidney, and spleen were collected for outcome evaluation. In vitro treatment of TIGIT-Ig in B cells was used for exploring the roles of TIGIT in toll-like receptor 7 (TLR7)-mediated B cell differentiation and antibody production.

RESULTS

TIGIT-Ig treatment delayed disease progression in both lupus models, accompanied by a decrease in the production of anti-double stranded DNA antibodies (anti-dsDNA), proteinuria, proteinuria/creatinine, and Ig kidney deposition. Additionally, the group treated with TIGIT-Ig displayed a decreased proportion of T helper cell (Th)1 cells, T follicular helper (Tfh) cells, and B-cell subsets, including germinal center B cells (GC B), plasmablasts, and plasma cells, compared to the group treated with control IgG. Interestingly, we also observed an increased proportion of Tregs in the spleen of the TIGIT-Ig group. We have discovered a new way in which activating the TIGIT pathway can regulate B-cell differentiation through the SPI-B-PAX5-XBP1 pathway, resulting in a reduction in autoantibodies.

CONCLUSION

Together, TIGIT may be a promising IC target for SLE treatment.

Microbiota-dependent regulation of costimulatory and coinhibitory pathways via innate immune sensors and implications for immunotherapy

Our bodies are inhabited by trillions of microorganisms. The host immune system constantly interacts with the microbiota in barrier organs, including the intestines. Over decades, numerous studies have shown that our mucosal immune system is dynamically shaped by a variety of microbiota-derived signals. Elucidating the mediators of these interactions is an important step for understanding how the microbiota is linked to mucosal immune homeostasis and gut-associated diseases. Interestingly, the efficacy of cancer immunotherapies that manipulate costimulatory and coinhibitory pathways has been correlated with the gut microbiota. Moreover, adverse effects of these therapies in the gut are linked to dysregulation of the intestinal immune system. These findings suggest that costimulatory pathways in the immune system might serve as a bridge between the host immune system and the gut microbiota. Here, we review mechanisms by which commensal microorganisms signal immune cells and their potential impact on costimulation. We highlight how costimulatory pathways modulate the mucosal immune system through not only classical antigen-presenting cells but also innate lymphocytes, which are highly enriched in barrier organs. Finally, we discuss the adverse effects of immune checkpoint inhibitors in the gut and the possible relationship with the gut microbiota.

Cancer immunotherapies: advances and bottlenecks

Immunotherapy has ushered in a new era in cancer treatment, and cancer immunotherapy continues to be rejuvenated. The clinical goal of cancer immunotherapy is to prime host immune system to provide passive or active immunity against malignant tumors. Tumor infiltrating leukocytes (TILs) play an immunomodulatory role in tumor microenvironment (TME) which is closely related to immune escape of tumor cells, thus influence tumor progress. Several cancer immunotherapies, include immune checkpoint inhibitors (ICIs), cancer vaccine, adoptive cell transfer (ACT), have shown great efficacy and promise. In this review, we will summarize the recent research advances in tumor immunotherapy, including the molecular mechanisms and clinical effects as well as limitations of immunotherapy.

TIGIT can inhibit T cell activation via ligation-induced nanoclusters, independent of CD226 co-stimulation

TIGIT is an inhibitory receptor expressed on lymphocytes and can inhibit T cells by preventing CD226 co-stimulation through interactions in cis or through competition of shared ligands. Whether TIGIT directly delivers cell-intrinsic inhibitory signals in T cells remains unclear. Here we show, by analysing lymphocytes from matched human tumour and peripheral blood samples, that TIGIT and CD226 co-expression is rare on tumour-infiltrating lymphocytes. Using super-resolution microscopy and other techniques, we demonstrate that ligation with CD155 causes TIGIT to reorganise into dense nanoclusters, which coalesce with T cell receptor (TCR)-rich clusters at immune synapses. Functionally, this reduces cytokine secretion in a manner dependent on TIGIT's intracellular ITT-like signalling motif. Thus, we provide evidence that TIGIT directly inhibits lymphocyte activation, acting independently of CD226, requiring intracellular signalling that is proximal to the TCR. Within the subset of tumours where TIGIT-expressing cells do not commonly co-express CD226, this will likely be the dominant mechanism of action.

Clinical Significance of Nectins in HCC and Other Solid Malignant Tumors: Implications for Prognosis and New Treatment Opportunities-A Systematic Review

The nectin family comprises four proteins, nectin-1 to -4, which act as cell adhesion molecules. Nectins have various regulatory functions in the immune system and can be upregulated or decreased in different tumors. The literature research was conducted manually by the authors using the PubMed database by searching articles published before 2023 with the combination of several nectin-related keywords. A total of 43 studies were included in the main section of the review. Nectins-1-3 have different expressions in tumors. Both the loss of expression and overexpression could be negative prognostic factors. Nectin-4 is the best characterized and the most consistently overexpressed in various tumors, which generally correlates with a worse prognosis. New treatments based on targeting nectin-4 are currently being developed. Enfortumab vedotin is a potent antibody-drug conjugate approved for use in therapy against urothelial carcinoma. Few reports focus on hepatocellular carcinoma, which leaves room for further studies comparing the utility of nectins with commonly used markers.

Diverging prognostic effects of CD155 and CD73 expressions in locally advanced triple-negative breast cancer

Background

Immune checkpoint inhibition, combined with novel biomarkers, may provide alternative pathways for treating chemotherapy-resistant triple-negative breast cancer (TNBC). This study investigates the expression of new immune checkpoint receptors, including CD155 and CD73, which play a role in T and natural killer (NK) cell activities, in patients with residual TNBC after neoadjuvant chemotherapy (NAC).

Methods

The expression of biomarkers was immunohistochemically examined by staining archival tissue from surgical specimens (n = 53) using specific monoclonal antibodies for PD-L1, CD155, and CD73.

Results

Of those, 59.2% (29/49) were found to be positive (>1%) for PD-L1 on the tumour and tumour-infiltrating lymphocytes (TILs), while CD155 (30/53, 56.6%) and CD73 (24/53, 45.3%) were detected on tumours. Tumour expressions of CD155 and CD73 significantly correlated with PD-L1 expression on the tumour (p = 0.004 for CD155, p = 0.001 for CD73). Patients with CD155 positivity ≥10% were more likely to have a poor chemotherapy response, as evidenced by higher MDACC Residual Cancer Burden Index scores and Class II/III than those without CD155 expression (100% vs 82.6%, p = 0.03). At a median follow-up time of 80 months (range, 24-239), patients with high CD73 expression showed improved 10-year disease-free survival (DFS) and disease-specific survival (DSS) rates compared to those with low CD73 expression. In contrast, patients with CD155 (≥10%) expression exhibited a decreasing trend in 10-year DFS and DSS compared to cases with lower expression, although statistical significance was not reached. However, patients with coexpression of CD155 (≥10%) and low CD73 were significantly more likely to have decreased 10-year DFS and DSS rates compared to others (p = 0.005).

Conclusion

These results demonstrate high expression of CD73 and CD155 in patients with residual tumours following NAC. CD155 expression was associated with a poor response to NAC and poor prognosis in this chemotherapy-resistant TNBC cohort, supporting the use of additional immune checkpoint receptor inhibitor therapy. Interestingly, the interaction between CD155 and CD73 at lower levels resulted in a worse outcome than either marker alone, which calls for further investigation in future studies.

Clinical significance of CD155 expression and correlation with cellular components of tumor microenvironment in gastric adenocarcinoma

Introduction

CD155 is recently emerging as a promising target in malignancies. However, the relationship between CD155 expression and tumor microenvironment (TME) cell infiltration in gastric adenocarcinoma (GAC) has rarely been clarified.

Methods

We measured CD155 expression in specimens of gastric precancerous disease and GAC by immunohistochemistry. The association of CD155 expression with GAC progression and cells infiltration in TME was evaluated through 268 GAC tissues and public dataset analysis.

Results

We showed that the expression of CD155 was positively correlated with the pathological development of gastric precancerous disease (r = 0.521, P < 0.0001). GAC patients with high CD155 expression had a poorer overall survival (P = 0.033). Moreover, CD155 expression correlated with aggressive clinicopathological features including tumor volume, tumor stage, lymph node involvement, and cell proliferation (P <0.05). Remarkably, CD155 expression positively related to the infiltration of CD68+ macrophages in TME (P = 0.011). Meanwhile, the positive correlation was observed between CD155 and CD31 (P = 0.026). In addition, patients with high CD155 expression combined with low CD3, CD4, CD8, IL-17, IFN-γ or CD19 expression as well as those with high CD155 and α-SMA expression showed significantly worse overall survival (P < 0.05).

Conclusions

CD155 may play a pivotal role in the development of GAC through both immunological and non-immunological mechanisms and be expected to become a novel target of immunotherapy in GAC patients.

Combined Blockade of TIGIT and PD-L1 Enhances Anti-Neuroblastoma Efficacy of GD2-Directed Immunotherapy with Dinutuximab Beta

Immunotherapies against high-risk neuroblastoma (NB), using the anti-GD2 antibody (Ab) dinutuximab beta (DB), significantly improved patient survival. Ab-dependent cellular cytotoxicity (ADCC) is one of the main mechanisms of action and it is primarily mediated by NK cells. To further improve antitumor efficacy, we investigated here a combinatorial immunotherapy with DB and the double immune checkpoint blockade of T-cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) and programmed cell death ligand-1 (PD-L1). The effects of ADCC, mediated by DB against NB cells on NK-cell activity, and the expression of TIGIT and CD226 and their ligands CD112 and CD155, as well as of PD-1 and PD-L1 on NB and effector cells, were investigated using flow cytometry. ADCC was assessed with a calcein-AM-based cytotoxicity assay. The efficacy of a combinatorial immunotherapy with DB, given as a long-term treatment, and the double immune checkpoint blockade of TIGIT and PD-L1 was shown using a resistant murine model of NB, followed by an analysis of the tumor tissue. We detected both TIGIT ligands, CD112 and CD155, on all NB cell lines analyzed. Although ADCC by DB resulted in a strong activation of NK cells leading to an effective tumor cell lysis, a remarkable induction of PD-L1 expression on NB cells, and of TIGIT and PD-1 on effector cells, especially on NK cells, was observed. Additional anti-TIGIT or anti-PD-L1 treatments effectively inhibited tumor growth and improved survival of the mice treated with DB. The superior antitumor effects were observed in the "DB + double immune checkpoint blockade" group, showing an almost complete eradication of the tumors and the highest OS, even under resistant conditions. An analysis of tumor tissue revealed both TIGIT and TIGIT ligand expression on myeloid-derived suppressor cells (MDSCs), suggesting additional mechanisms of protumoral effects in NB. Our data show that the targeting of TIGIT and PD-L1 significantly improves the antitumor efficacy of anti-GD2 immunotherapy, with DB presenting a new effective combinatorial treatment strategy against high-risk tumors.

Fc-competent multispecific PDL-1/TIGIT/LAG-3 antibodies potentiate superior anti-tumor T cell response

The landscape of current cancer immunotherapy is dominated by antibodies targeting PD-1/PD-L1 and CTLA-4 that have transformed cancer therapy, yet their efficacy is limited by primary and acquired resistance. The blockade of additional immune checkpoints, especially TIGIT and LAG-3, has been extensively explored, but so far only a LAG-3 antibody has been approved for combination with nivolumab to treat unresectable or metastatic melanoma. Here we report the development of a PDL1 × TIGIT bi-specific antibody (bsAb) GB265, a PDL1 × LAG3 bsAb GB266, and a PDL1 × TIGIT × LAG3 tri-specific antibody (tsAb) GB266T, all with intact Fc function. In in vitro cell-based assays, these antibodies promote greater T cell expansion and tumor cell killing than benchmark antibodies and antibody combinations in an Fc-dependent manner, likely by facilitating T cell interactions (bridging) with cancer cells and monocytes, in addition to blocking immune checkpoints. In animal models, GB265 and GB266T antibodies outperformed benchmarks in tumor suppression. This study demonstrates the potential of a new generation of multispecific checkpoint inhibitors to overcome resistance to current monospecific checkpoint antibodies or their combinations for the treatment of human cancers.

Self-delivery of TIGIT-blocking scFv enhances CAR-T immunotherapy in solid tumors

Chimeric antigen receptor T cell therapy has become an important immunotherapeutic tool for overcoming cancers. However, the efficacy of CAR-T cell therapy in solid tumors is relatively poor due to the complexity of the tumor microenvironment and inhibitory immune checkpoints. TIGIT on the surface of T cells acts as an immune checkpoint by binding to CD155 on the tumor cells' surface, thereby inhibiting tumor cell killing. Blocking TIGIT/CD155 interactions is a promising approach in cancer immunotherapy. In this study, we generated anti-MLSN CAR-T cells in combination with anti-α-TIGIT for solid tumors treatment. The anti-α-TIGIT effectively enhanced the efficacy of anti-MLSN CAR-T cells on the killing of target cells in vitro. In addition, we genetically engineered anti-MSLN CAR-T cells with the capacity to constitutively produce TIGIT-blocking single-chain variable fragments. Our study demonstrated that blocking TIGIT significantly promoted cytokine release to augment the tumor-killing effect of MT CAR-T cells. Moreover, the self-delivery of TIGIT-blocking scFvs enhanced the infiltration and activation of MT CAR-T cells in the tumor microenvironments to achieve better tumor regression in vivo. These results suggest that blocking TIGIT effectively enhances the anti-tumor effect of CAR-T cells and suggest a promising strategy of combining CAR-T with immune checkpoints blockade in the treatment of solid tumors.

Co-inhibition of TIGIT and PD-1/PD-L1 in Cancer Immunotherapy: Mechanisms and Clinical Trials

Over the past decade, immune checkpoint inhibitors (ICIs) have emerged as a revolutionary cancer treatment modality, offering long-lasting responses and survival benefits for a substantial number of cancer patients. However, the response rates to ICIs vary significantly among individuals and cancer types, with a notable proportion of patients exhibiting resistance or showing no response. Therefore, dual ICI combination therapy has been proposed as a potential strategy to address these challenges. One of the targets is TIGIT, an inhibitory receptor associated with T-cell exhaustion. TIGIT has diverse immunosuppressive effects on the cancer immunity cycle, including the inhibition of natural killer cell effector function, suppression of dendritic cell maturation, promotion of macrophage polarization to the M2 phenotype, and differentiation of T cells to regulatory T cells. Furthermore, TIGIT is linked with PD-1 expression, and it can synergize with PD-1/PD-L1 blockade to enhance tumor rejection. Preclinical studies have demonstrated the potential benefits of co-inhibition of TIGIT and PD-1/PD-L1 in enhancing anti-tumor immunity and improving treatment outcomes in several cancer types. Several clinical trials are underway to evaluate the safety and efficacy of TIGIT and PD-1/PD-L1 co-inhibition in various cancer types, and the results are awaited. This review provides an overview of the mechanisms of TIGIT and PD-1/PD-L1 co-inhibition in anti-tumor treatment, summarizes the latest clinical trials investigating this combination therapy, and discusses its prospects. Overall, co-inhibition of TIGIT and PD-1/PD-L1 represents a promising therapeutic approach for cancer treatment that has the potential to improve the outcomes of cancer patients treated with ICIs.

Toxicities associated with immune checkpoint inhibitors: a systematic study

BACKGROUND

Available evidence shows that the incidence of toxicities associated with cancer immunotherapy, such as programmed cell death 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1)-related toxicities, is estimated to be between 0.3 and 1.3%.

OBJECTIVE

This systematic review aimed to investigate cancer patients' susceptibility to toxicities associated with PD-1/PD-L1 inhibitors and establish a clinically relevant landscape of side effects of PD-1/PD-L1 inhibitors.

DATA SOURCES

Relevant publications from PubMed, Embase, Cochrane Library, Web of Science, and China National Knowledge Infrastructure (CNKI) between 2014 and 2019.

STUDY ELIGIBILITY CRITERIA, PARTICIPANTS, AND INTERVENTIONS

We searched randomized controlled trials (RCTs) reporting treatment-related toxicities associated with PD-1 and PD-L1 inhibitors in the treatment of cancers. The primary endpoint was to assess the difference in the incidences of toxicities between cancer patients who did and did not receive PD-1/PD-L1 inhibitors. A total of 29 RCTs, incorporating 8576 patients, met the eligibility criteria.

STUDY APPRAISAL AND SYNTHESIS METHODS

We calculated the pooled relative risks and corresponding 95% CIs using a random-effects model and assessed the heterogeneity between different groups. The subgroup analyses were conducted based on cancer type, toxicity grade (severity), system and organ, treatment regimens in the intervention arm and the control arm, PD-1/PD-L1 inhibitor drug type, and cancer type.

RESULTS

A total of 11 categories (e.g. endocrine toxicity), and 39 toxicity types (e.g. hyperthyroidism) were identified. For toxicities at any grade, those treated with PD-1/PD-L1 inhibitors were at lower risks for gastrointestinal toxicity, hematologic toxicity, and treatment event leading to discontinuation; and were at higher risks for respiratory toxicity (all P <0.05). Those treated with PD-1/PD-L1 inhibitors were at lower risks for fatigue, asthenia, and peripheral edema and were at higher risks for pyrexia, cough, dyspnea, pneumonitis, and pruritus.

LIMITATIONS

The present research is a meta-analysis at the study level rather than at the patient level; insights on risk factors associated with the development of toxicities cannot be found in our study. There was a possible overlap in Common Terminology Criteria for Adverse Events (CTCAE) definitions which prevents understanding the true rates of specific toxicities.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

For most toxicity types based on system and organ, the incidence proportions for patients in the intervention arm were lower than those in the control arm, which suggested the general safety of PD-1/PD-L1 inhibitors against conventional chemotherapy and cytotoxic t-lymphocyte-associated protein 4 (CTLA-4) inhibitors. Future research should focus on taking effective targeted measures to decrease the risks of different toxicities for different patient populations.

SYSTEMATIC REVIEW REGISTRATION NUMBER

We registered the research protocol with PROSPERO (registration number CRD42019135113).