Systems biology informed neural networks (SBINN) predict response and novel combinations for PD-1 checkpoint blockade

Anti-PD-1 immunotherapy has recently shown tremendous success for the treatment of several aggressive cancers. However, variability and unpredictability in treatment outcome have been observed, and are thought to be driven by patient-specific biology and interactions of the patient's immune system with the tumor. Here we develop an integrative systems biology and machine learning approach, built around clinical data, to predict patient response to anti-PD-1 immunotherapy and to improve the response rate. Using this approach, we determine biomarkers of patient response and identify potential mechanisms of drug resistance. We develop systems biology informed neural networks (SBINN) to calculate patient-specific kinetic parameter values and to predict clinical outcome. We show how transfer learning can be leveraged with simulated clinical data to significantly improve the response prediction accuracy of the SBINN. Further, we identify novel drug combinations and optimize the treatment protocol for triple combination therapy consisting of IL-6 inhibition, recombinant IL-12, and anti-PD-1 immunotherapy in order to maximize patient response. We also find unexpected differences in protein expression levels between response phenotypes which complement recent clinical findings. Our approach has the potential to aid in the development of targeted experiments for patient drug screening as well as identify novel therapeutic targets.

Ovarian Cancer-Associated Ascites Have High Proportions of Cytokine-Responsive CD56bright NK Cells

Ovarian cancer is the most lethal gynecological malignancy, with serous histotype as the most prevalent epithelial ovarian cancer (EOC). Peritoneal ascites is a frequent comorbidity in advanced EOC. EOC-associated ascites provide a reliable sampling source for studying lymphocytes directly from tumor environment. Herein, we carried out flow cytometry-based analysis to readdress issues on NK and T lymphocyte subsets in women with advanced EOC, additionally evaluating phenotypic modulation of their intracellular pathways involved in interleukin (IL)-2 and IL-15 signaling. Results depicted ascites as an inflammatory and immunosuppressive environment, presenting significantly (p < 0.0001) higher amounts of IL-6 and IL-10 than in the patients' blood, as well as significantly (p < 0.05) increased expression of checkpoint inhibitory receptors (programmed death protein-1, PD-1) and ectonucleotidase (CD39) on T lymphocytes. However, NK lymphocytes from EOC-associated ascites showed higher (p < 0.05) pS6 phosphorylation compared with NK from blood. Additionally, in vitro treatment of lymphocytes with IL-2 or IL-15 elicited significantly (p < 0.001) phosphorylation of the STAT5 protein in NK, CD3 and CD8 lymphocytes, both from blood and ascites. EOC-associated ascites had a significantly (p < 0.0001) higher proportion of NK CD56bright lymphocytes than blood, which, in addition, were more responsive (p < 0.05) to stimulation by IL-2 than CD56dim NK. EOC-associated ascites allow studies on lymphocyte phenotype modulation in the tumor environment, where inflammatory profile contrasts with the presence of immunosuppressive elements and development of cellular self-regulating mechanisms.

Expression of Programmed Death Receptor 1 (PD-1) Gene and Its Ligand (PD-L1) in Patients with Laryngeal Cancer

(1) Background: The interaction of the programmed death receptor (PD-1) with its ligand 1 (PD-L1) allows cancer cells to escape from the control of the immune system. Research evaluating the expression of immune checkpoint genes in the tissues of laryngeal tumors may contribute to the introduction of new effective immunotherapeutic methods in this group of neoplasms. The aim of this study was to evaluate the expression of the gene for the programmed death receptor (PD-1) and its ligand (PD-L1) in laryngeal tumors (T1, T2, T3) in patients without lymph node involvement and distant metastases. (2) Methods: The study included 73 patients: 39 of them were diagnosed with carcinoma planoepiteliale keratodes (study group) and 34 with nasal septal deviation undergoing septoplasty (control group). Biological material for molecular tests (Real time PCR) was collected during surgical procedures. Furthermore, all study participants completed a questionnaire regarding, among others, smoking and body weight. (3) Results: Gene expression for programmed death receptor 1 (PD-1) and its ligand 1 (PD-L1) was, statistically, significantly higher (p < 0.0001) in tumor tissue than in unchanged mucosa. Moreover, it was found that the greater the tumor size, the higher the expression level of the tested molecules. (4) Conclusions: Although further research on the role of the PD-1/PD-L1 pathway in laryngeal tumors is necessary, the presented reports are promising and may constitute a contribution to considerations on the introduction of targeted immunotherapy with anti-PD1 and anti-PD-L1 monoclonal antibodies in the treatment of these tumors.

Impacts of pembrolizumab therapy on immune phenotype in patients with high-grade neuroendocrine neoplasms

High grade neuroendocrine neoplasms (G3 NENs) are rare aggressive tumors with limited treatment options. Twenty-one previously treated patients with metastatic extra-pulmonary G3 NENs were treated with pembrolizumab. Baseline tumor samples were assessed for PD-L1 and tumor infiltrating lymphocytes (TIL). Peripheral blood samples drawn pre-treatment, prior to cycle three, and at disease progression were analyzed by flow cytometry. One patient achieved partial response, two had stable disease, and 18 exhibited progressive disease. The partially responding patient did not progress after 392 days, and the median progression-free survival (PFS) was 59 days. Longer PFS correlated independently with higher pre-treatment peripheral blood T-cell counts and lower pre-treatment activation state (CD69 expression) of naïve T cells and NK cells. Peripheral T-cell viability was reduced in patients with greater TILs. Post-treatment, T cells had reduced numbers of CD4+ cells, reduced PD-1 expression, increased activation of effector (CD62L-) cells, and increased expression of TIGIT. Baseline TIGIT expression on peripheral T cells also correlated positively with Ki67 in tumor. Patients with higher baseline T-cell expression of TIM-3 had shorter PFS. Despite limited activity of pembrolizumab, this study highlights the immune phenotype in this rare tumor type before and after treatment. High baseline peripheral T-cell count and reduced activation of T and NK cell subsets were associated with improved outcomes. Furthermore, increased post-treatment TIGIT and elevated baseline TIM-3 expression suggest that these may limit the efficacy of pembrolizumab, providing a rationale for combination immunotherapy (PD-1 with TIGIT and/or TIM-3 antibodies) to treat extra-pulmonary G3 NENs.

Blockade of the co-inhibitory molecule PD-1 unleashes ILC2-dependent antitumor immunity in melanoma

Group 2 innate lymphoid cells (ILC2s) are essential to maintain tissue homeostasis. In cancer, ILC2s can harbor both pro-tumorigenic and anti-tumorigenic functions, but we know little about their underlying mechanisms or whether they could be clinically relevant or targeted to improve patient outcomes. Here, we found that high ILC2 infiltration in human melanoma was associated with a good clinical prognosis. ILC2s are critical producers of the cytokine granulocyte-macrophage colony-stimulating factor, which coordinates the recruitment and activation of eosinophils to enhance antitumor responses. Tumor-infiltrating ILC2s expressed programmed cell death protein-1, which limited their intratumoral accumulation, proliferation and antitumor effector functions. This inhibition could be overcome in vivo by combining interleukin-33-driven ILC2 activation with programmed cell death protein-1 blockade to significantly increase antitumor responses. Together, our results identified ILC2s as a critical immune cell type involved in melanoma immunity and revealed a potential synergistic approach to harness ILC2 function for antitumor immunotherapies.

Significance of PD1 Alternative Splicing in Celiac Disease as a Novel Source for Diagnostic and Therapeutic Target

Background

We have focused on the alteration of the PD-1/PD-L1 pathway in celiac disease and discussed the roles of the PD1 pathway in regulating the immune response. We explored the idea that the altered mRNA splicing process in key regulatory proteins could represent a novel source to identify diagnostic, prognostic, and therapeutic targets in celiac disease.

Methods

We characterized the PD1 mRNA variants' profile in CD patients and in response to gluten peptides' incubation after in vitro experiments. Total RNA from whole blood was isolated, and the coding region of the human PD-1 mRNA was amplified by cDNA PCR.

Results

PCR amplification of the human PD-1 coding sequence revealed an association between the over-expression of the sPD-1 protein and the PD-1Δex3 transcript in celiac disease. Thus, we have found three novel alternative spliced isoforms, two of which result in a truncated protein and the other isoform with a loss of 14 aa of exon 2 and complete exon 3 (Δ3) which could encode a new soluble form of PD1 (sPD-1).

Conclusions

Our study provides evidence that dietary gluten can modulate processes required for cell homeostasis through the splicing of pre-mRNAs encoding key regulatory proteins, which represents an adaptive mechanism in response to different nutritional conditions.

Transmembrane adaptor protein PAG is a mediator of PD-1 inhibitory signaling in human T cells

The inhibitory receptor PD-1 is expressed on T cells to inhibit select functions when ligated. The complete signaling mechanism downstream of PD-1 has yet to be uncovered. Here, we discovered phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG) is phosphorylated following PD-1 ligation and associate this with inhibitory T cell function. Clinical cohort analysis correlates low PAG expression with increased survival from numerous tumor types. PAG knockdown in T cells prevents PD-1-mediated inhibition of cytokine secretion, cell adhesion, CD69 expression, and ERK204/187 phosphorylation, and enhances phosphorylation of SRC527 following PD-1 ligation. PAG overexpression rescues these effects. In vivo, PAG contributes greatly to the growth of two murine tumors, MC38 and B16, and limits T cell presence within the tumor. Moreover, PAG deletion sensitizes tumors to PD-1 blockade. Here PAG is established as a critical mediator of PD-1 signaling and as a potential target to enhance T cell activation in tumors.

Identification ACTA2 and KDR as key proteins for prognosis of PD-1/PD-L1 blockade therapy in melanoma

Programmed cell death protein 1 (PD-1) /programmed cell death ligand 1 (PD-L1) blockade is an important therapeutic strategy for melanoma, despite its low clinical response. It is important to identify genes and pathways that may reflect the clinical outcomes of this therapy in patients. We analyzed clinical dataset GSE96619, which contains clinical information from five melanoma patients before and after anti-PD-1 therapy (five pairs of data). We identified 704 DEGs using these five pairs of data, and then the number of DEGs was narrowed down to 286 in patients who responded to treatment. Next, we performed KEGG pathway enrichment and constructed a DEG-associated protein-protein interaction network. Smooth muscle actin 2 (ACTA2) and tyrosine kinase growth factor receptor (KDR) were identified as the hub genes, which were significantly downregulated in the tumor tissue of the two patients who responded to treatment. To confirm our analysis, we demonstrated similar expression tendency to the clinical data for the two hub genes in a B16F10 subcutaneous xenograft model. This study demonstrates that ACTA2 and KDR are valuable responsive markers for PD-1/PD-L1 blockade therapy.

Enfortumab vedotin after PD-1 or PD-L1 inhibitors in cisplatin-ineligible patients with advanced urothelial carcinoma (EV‑201): a multicentre, single-arm, phase 2 trial

BACKGROUND

Locally advanced or metastatic urothelial carcinoma is generally incurable and has scarce treatment options, especially for cisplatin-ineligible patients previously treated with PD-1 or PD-L1 therapy. Enfortumab vedotin is an antibody-drug conjugate directed at Nectin-4, a protein highly expressed in urothelial carcinoma. We aimed to evaluate the efficacy and safety of enfortumab vedotin in the post-immunotherapy setting in cisplatin-ineligible patients.

METHODS

EV-201 is a multicentre, single-arm, phase 2 study of enfortumab vedotin in patients with locally advanced or metastatic urothelial carcinoma previously treated with PD-1 or PD-L1 inhibitors. Cohort 2 included adults (aged ≥18 years) with an Eastern Cooperative Oncology Group performance status score of 2 or less who were considered ineligible for cisplatin at enrolment and who had not received platinum-containing chemotherapy in the locally advanced or metastatic setting. Enfortumab vedotin was given intravenously at a dose of 1·25 mg/kg on days 1, 8, and 15 of every 28-day cycle. The primary endpoint was confirmed objective response rate per Response Evaluation Criteria in Solid Tumours version 1.1 assessed by blinded independent central review. Efficacy and safety were analysed in all patients who received at least one dose of enfortumab vedotin. EV-201 is an ongoing study and the primary analysis is complete. This study is registered with Clinicaltrials.gov, NCT03219333.

FINDINGS

Between Oct 8, 2017, and Feb 11, 2020, 91 patients were enrolled at 40 sites globally, of whom 89 received treatment. Median follow-up was 13·4 months (IQR 11·3-18·9). At data cutoff (Sept 8, 2020), the confirmed objective response rate was 52% (46 of 89 patients; 95% CI 41-62), with 18 (20%) of 89 patients achieving a complete response and 28 (31%) achieving a partial response. 49 (55%) of 89 patients had grade 3 or worse treatment-related adverse events. The most common grade 3 or 4 treatment-related adverse events were neutropenia (eight [9%] patients), maculopapular rash (seven [8%] patients), and fatigue (six [7%] patients). Treatment-related serious adverse events occurred in 15 (17%) patients. Three (3%) patients died due to acute kidney injury, metabolic acidosis, and multiple organ dysfunction syndrome (one [1%] each) within 30 days of first dose and these deaths were considered by the investigator to be related to treatment; a fourth death from pneumonitis occurred more than 30 days after the last dose and was also considered to be related to treatment.

INTERPRETATION

Treatment with enfortumab vedotin was tolerable and confirmed responses were seen in 52% of cisplatin-ineligible patients with locally advanced or metastatic urothelial carcinoma who were previously treated with PD-1 or PD-L1 inhibitors. These patients have few treatment options, and enfortumab vedotin could be a promising new therapy for a patient population with a high unmet need.

FUNDING

Astellas Pharma Global Development and Seagen.

Personalized medicine for Hodgkin lymphoma: Mitigating toxicity while preserving cure

The treatment of classical Hodgkin lymphoma in young patients is one of the success stories of modern medicine. The use of risk- and response-adapted approaches to guide treatment decisions has led to impressive cure rates while reducing the long-term toxicity associated with more intensive therapies. Tissue biomarkers have not yet proven more effective than clinical characteristics for risk stratification of patients at presentation, but functional imaging features such as metabolic tumor volume may be used to predict response, if early observations can be validated. The success of treatment in younger patients has unfortunately not been mirrored in those over 60, where complex decision-making is often required, with a paucity of data from clinical trials. The use of PD1 blocking antibodies and brentuximab vedotin in this cohort, either alone or in combination with chemotherapy, may provide attractive options. The incorporation of frailty assessment, quality-of-life outcomes, and specialist geriatric input is also important to ensure the best outcomes for this diverse group.

Tumor Extracellular Matrix Stiffness Promptly Modulates the Phenotype and Gene Expression of Infiltrating T Lymphocytes

The immune system is a fine modulator of the tumor biology supporting or inhibiting its progression, growth, invasion and conveys the pharmacological treatment effect. Tumors, on their side, have developed escaping mechanisms from the immune system action ranging from the direct secretion of biochemical signals to an indirect reaction, in which the cellular actors of the tumor microenvironment (TME) collaborate to mechanically condition the extracellular matrix (ECM) making it inhospitable to immune cells. TME is composed of several cell lines besides cancer cells, including tumor-associated macrophages, cancer-associated fibroblasts, CD4+ and CD8+ lymphocytes, and innate immunity cells. These populations interface with each other to prepare a conservative response, capable of evading the defense mechanisms implemented by the host's immune system. The presence or absence, in particular, of cytotoxic CD8+ cells in the vicinity of the main tumor mass, is able to predict, respectively, the success or failure of drug therapy. Among various mechanisms of immunescaping, in this study, we characterized the modulation of the phenotypic profile of CD4+ and CD8+ cells in resting and activated states, in response to the mechanical pressure exerted by a three-dimensional in vitro system, able to recapitulate the rheological and stiffness properties of the tumor ECM.

PD-1 Coexpression Gene Analysis and the Regulatory Network in Endometrial Cancer Based on Bioinformatics Analysis

Gynecological malignancies are tumors of the female reproductive system, mainly cervical cancer, endometrial cancer, and ovarian cancer. Endometrial cancer (EC) is the most common gynecological malignant tumor in developed countries. The aim of this study was to construct a network of programmed cell death protein 1 (PD-1) coexpressed genes through bioinformatics analysis and screen the potential biomarkers of PD-1 in endometrial cancer. In addition, genes and pathways involved in PD-1 and modulating tumor immune status were identified. We select the EC transcriptomic dataset in TCGA to retrieve gene sets on the cBioPortal platform, and the PD-1 coexpressed genes were obtained on the platform. GO and KEGG enrichment analysis of coexpressed genes was performed using the DAVID database. The target protein-protein interaction (PPI) network was constructed using Cytoscape 3.7.1 software, and the hub genes were then screened. A total of 976 coexpression genes were obtained. The enrichment analysis showed that PD-1 coexpressed genes were significantly enriched in overall components of the cell structure, the interaction of cytokines with cytokine receptors, chemokine signaling pathways, and cell adhesion molecules (CAMs). Ten hub genes were obtained by node degree analysis. CD3E gene is involved in the prognosis and immune process of EC, and the expression level is related to PD-1 (Pearson correlation coefficient is 0.82, P < 0.01). Patients with low CD3E gene expression in EC have a poor prognosis. The coexpression hub genes of PD-1 are related to immunity, in which CD3E is a prognostic marker that is involved in the PD-1/PD-L1-induced tumor immune escape. This study provides a new area to study the mechanism of PD-1/PD-L1 in EC and the precise treatment with targeted drugs.

Programmed cell death-1 single-nucleotide polymorphism rs10204525 is associated with human immunodeficiency virus type 1 RNA viral load in HIV-1-infected Moroccan subjects

Human Immunodeficiency Virus (HIV-1) infections are characterized by dysfunctional cellular and humoral antiviral immune responses. The progressive loss of effector functions in chronic viral infection has been associated with the up-regulation of programmed death-1 (PD-1), a negative regulator of activated T cells and Natural Killer cells. In HIV-1 infection, increased levels of PD-1 expression correlate with CD8 + T-cell exhaustion. In vitro, PD-1 blockade using PD-1 antibodies led to an increase in HIV-1 specific CD8 + T and memory B cell proliferation. We aimed to investigate the impact of PDCD1 rs10204525 polymorphism on HIV-1 susceptibility, AIDS development, and treatment response outcomes in HIV-1 infection in a Moroccan population. A total of 214 HIV-1 seropositive and 250 seronegative subjects were enrolled to investigate the association between the between the single-nucleotide polymorphism (SNP) rs10204525 of PDCD1 gene and HIV-1 pathogenesis using a predesigned TaqMan SNP genotyping assay. No significant association was found between rs10204525 and susceptibility to HIV-1 infection and AIDS development (p > 0.05). Genotype frequencies were significantly associated with the viral load before ART (p = 0.0105). HIV-1 viral load was significantly higher among subjects with the CC compared to TT genotype (p = 0.0043). In treated subjects, the median of viral load levels was significantly higher in CC and CT groups than TT subjects (p < 0.005). However, analysis of the correlation between CD4 + T-cell levels and PDCD1 polymorphism before and after ART showed no significant difference (p > 0.05). Our results demonstrated that rs10204525 polymorphism does not affect HIV-1 infection. However, this polymorphism may affect the response to treatment as measured by RNA viral load levels.

Molecular Mechanisms of PD-1 and PD-L1 Activity on a Pan-Cancer Basis: A Bioinformatic Exploratory Study

Immune checkpoint blockade targeting PD-1 (PDCD1)/PD-L1 (CD274) is increasingly used for multiple cancers. However, efficacy and adverse-related events vary significantly. This bioinformatic study interrogated molecular differences pertaining to PDCD1/CD274 and their correlated genes on a pan-cancer basis to identify differences between cancer types. Patient RNA-seq data from fifteen cancer types were accessed on cBioPortal to determine the role of PDCD1/CD274 in patient survival and to identify positively and negatively correlated genes, which were also assessed for clinical relevance. Genes correlating with PDCD1/CD274 across multiple cancers were taken forward for drug repurposing via DRUGSURV and microRNA analysis using miRDB and miRabel. MicroRNAs were also screened for clinical relevance using OncomiR. Forty genes were consistently correlated with PDCD1/CD274 across multiple cancers, with the cancers themselves exhibiting a differential role for the correlated genes in terms of patient survival. Esophageal and renal cancers in particular stood out in this regard as having a unique survival profile. Forty-nine putative microRNAs were identified as being linked to the PDCD1/CD274 network, which were taken forward and further assessed for clinical relevance using OncomiR and previously published literature. One hundred and thirty significant survival associations for 46 microRNAs across fourteen groups of cancers were identified. Finally, a total of 23 putative repurposed drugs targeting multiple components of the PDCD1/CD274 network were identified, which may represent immunotherapeutic adjuvants. Taken together, these results shed light on the varying PDCD1/CD274 networks between individual cancers and signpost a need for more cancer-specific investigations and treatments.

Polyphenols Modulating Effects of PD-L1/PD-1 Checkpoint and EMT-Mediated PD-L1 Overexpression in Breast Cancer

Investigating dietary polyphenolic compounds as antitumor agents are rising due to the growing evidence of the close association between immunity and cancer. Cancer cells elude immune surveillance for enhancing their progression and metastasis utilizing various mechanisms. These mechanisms include the upregulation of programmed death-ligand 1 (PD-L1) expression and Epithelial-to-Mesenchymal Transition (EMT) cell phenotype activation. In addition to its role in stimulating normal embryonic development, EMT has been identified as a critical driver in various aspects of cancer pathology, including carcinogenesis, metastasis, and drug resistance. Furthermore, EMT conversion to another phenotype, Mesenchymal-to-Epithelial Transition (MET), is crucial in developing cancer metastasis. A central mechanism in the upregulation of PD-L1 expression in various cancer types is EMT signaling activation. In breast cancer (BC) cells, the upregulated level of PD-L1 has become a critical target in cancer therapy. Various signal transduction pathways are involved in EMT-mediated PD-L1 checkpoint overexpression. Three main groups are considered potential targets in EMT development; the effectors (E-cadherin and Vimentin), the regulators (Zeb, Twist, and Snail), and the inducers that include members of the transforming growth factor-beta (TGF-β). Meanwhile, the correlation between consuming flavonoid-rich food and the lower risk of cancers has been demonstrated. In BC, polyphenols were found to downregulate PD-L1 expression. This review highlights the effects of polyphenols on the EMT process by inhibiting mesenchymal proteins and upregulating the epithelial phenotype. This multifunctional mechanism could hold promises in the prevention and treating breast cancer.

Single-cell sequencing links multiregional immune landscapes and tissue-resident T cells in ccRCC to tumor topology and therapy efficacy

Clear cell renal cell carcinomas (ccRCCs) are highly immune infiltrated, but the effect of immune heterogeneity on clinical outcome in ccRCC has not been fully characterized. Here we perform paired single-cell RNA (scRNA) and T cell receptor (TCR) sequencing of 167,283 cells from multiple tumor regions, lymph node, normal kidney, and peripheral blood of two immune checkpoint blockade (ICB)-naïve and four ICB-treated patients to map the ccRCC immune landscape. We detect extensive heterogeneity within and between patients, with enrichment of CD8A+ tissue-resident T cells in a patient responsive to ICB and tumor-associated macrophages (TAMs) in a resistant patient. A TCR trajectory framework suggests distinct T cell differentiation pathways between patients responding and resistant to ICB. Finally, scRNA-derived signatures of tissue-resident T cells and TAMs are associated with response to ICB and targeted therapies across multiple independent cohorts. Our study establishes a multimodal interrogation of the cellular programs underlying therapeutic efficacy in ccRCC.

ShRNA-mediated silencing of PD-1 augments the efficacy of chimeric antigen receptor T cells on subcutaneous prostate and leukemia xenograft

Chimeric antigen receptor T cells (CAR-T) immunotherapy has shown promising clinical results in the treatment of leukemia and lymphoma, but the effectiveness is limited for solid tumors. The PD-1/PD-L1 pathway is a key immunosuppressive mechanism for cancer cells to avoid eradication by CAR-T cells. In this study, the shRNA (short hair RNA) gene-silencing technique was used to construct the third-generation of CAR-T cells with PD-1 silencing which targeted CD19 antigen (CD19/△PD-1 CAR-T) and prostate stem cell antigen (PSCA/△PD-1 CAR-T), thereby blocking the PD-1/PD-L1 pathway in treatment of lymphoma and prostate subcutaneous xenograft and enhancing the anti-tumor effect of CAR-T cells. The cell experiments showed that PD-1 silencing in CAR-T cells effectively blocked the PD-1 / PD-L1 pathway. When the ratio of effector to target cell is 8:1, △PD-1 CAR-T cells exhibited higher killing ability and cytokine releasing ability than normal CAR-T cells did. The subcutaneous tumor models were constructed using human chronic myelogenous leukemia cells expressing CD19 (K562-CD19) and human prostate cancer cells expressing PSCA (PC3-PSCA), and treated with CD19/△PD-1 CAR-T and PSCA/△PD-1 CAR-T cells, respectively. The tumor volumes significantly reduced within one week, indicating the good tumor growth inhibitory effect of △PD-1 CAR-T cells. Mice injected with △PD-1 CAR-T cells showed a significantly prolonged survival time compared to those with normal CAR-T cells. This study proved that shRNA-mediated PD-1 silencing technology is an effective strategy for blocking the PD-1/PD-L1 immunosuppression pathway and enhancing the therapeutic effect of CAR-T cells on subcutaneous xenograft. SUMMARY: The effect of CAR-T in treating solid tumors has not been as successful as that in hematological malignancies. The key immunosuppressive mechanism is the expression of PD-1/PD-L1. We used gene silencing technique mediated by shRNA (short hair RNA) to block the PD-1/PD-L1 pathway in lymphoma and prostate tumors, thus enhancing the anti-tumor effect of CAR-T cells on subcutaneous xenograft.

Programmed cell death 1 (PD-1) receptor and programmed death ligand 1 (PD-L1) gene expression in primary breast cancer

PURPOSE

The interaction of the programmed cell death 1 (PD-1) receptor on tumor-infiltrating lymphocytes with programmed death ligand 1 (PD-L1) on tumor cells downregulates anti-tumor immunity. This study evaluated associations between PD-1 and PD-L1 expression in primary breast cancer, clinical characteristics, and patient outcomes.

METHODS

Microarray data from the Investigation of Serial Studies to predict your therapeutic response with imaging and molecular analysis (I-SPY 1) study (n = 149) was used to evaluate PD-1 and PD-L1 expression. Associations with clinical features and chemotherapy response were determined using Kruskal-Wallis and Wilcoxon rank sum tests, respectively. Recurrence-free survival (RFS) associations were determined with the Cox proportional hazard model. Associations of PD-1 and PD-L1 and selected genes associated with breast cancer, as well as a predictor of olaparib response (PARPi-7), were determined in I-SPY 1 and 2 other datasets: METABRIC (n = 1992) and TCGA (n = 817), using Pearson correlations.

RESULTS

In I-SPY 1, PD-1 expression was higher in triple-negative breast cancer (TNBC) and HER2 + breast cancer (p = 0.003), and grade 2/3 tumors (p = 0.043), and was associated with pathologic complete response (p = 0.006). PD-L1 expression in the lowest quintile was associated with worse RFS, even after subtype adjustment (HR 2.33, p = 0.01). PD-1 and PD-L1 gene expression correlated with the expression of immune-related genes and PARPi-7.

CONCLUSIONS

PD-1 expression is higher in breast cancers with aggressive features such as TNBC. Low PD-L1 expression may be an adverse prognostic factor. PD-1 and PD-L1 gene expression correlates with the expression of immune-related and DNA damage repair genes.

Stem Cell-Derived Viral Antigen-Specific T Cells Suppress HIV Replication and PD-1 Expression on CD4+ T Cells

The viral antigen (Ag)-specific CD8+ cytotoxic T lymphocytes (CTLs) derived from pluripotent stem cells (PSCs), i.e., PSC-CTLs, have the ability to suppress the human immunodeficiency virus (HIV) infection. After adoptive transfer, PSC-CTLs can infiltrate into the local tissues to suppress HIV replication. Nevertheless, the mechanisms by which the viral Ag-specific PSC-CTLs elicit the antiviral response remain to be fully elucidated. In this study, we generated the functional HIV-1 Gag epitope SL9-specific CTLs from the induced PSC (iPSCs), i.e., iPSC-CTLs, and investigated the suppression of SL9-specific iPSC-CTLs on viral replication and the protection of CD4+ T cells. A chimeric HIV-1, i.e., EcoHIV, was used to produce HIV replication in mice. We show that adoptive transfer of SL9-specific iPSC-CTLs greatly suppressed EcoHIV replication in the peritoneal macrophages and spleen in the animal model. Furthermore, we demonstrate that the adoptive transfer significantly reduced expression of PD-1 on CD4+ T cells in the spleen and generated persistent anti-HIV memory T cells. These results indicate that stem cell-derived viral Ag-specific CTLs can robustly accumulate in the local tissues to suppress HIV replication and prevent CD4+ T cell exhaustion through reduction of PD-1 expression.

Immune Checkpoint Profiles in Luminal B Breast Cancer (Alliance)

BACKGROUND

Unlike estrogen receptor (ER)-negative breast cancer, ER-positive breast cancer outcome is less influenced by lymphocyte content, indicating the presence of immune tolerance mechanisms that may be specific to this disease subset.

METHODS

A supervised analysis of microarray data from the ACOSOG Z1031 (Alliance) neoadjuvant aromatase inhibitor (AI) trial identified upregulated genes in Luminal (Lum) B breast cancers that correlated with AI-resistant tumor proliferation (percentage of Ki67-positive cancer nuclei, Pearson r > 0.4) (33 cases Ki67 > 10% on AI) vs LumB breast cancers that were more AI sensitive (33 cases Ki67 < 10% on AI). Overrepresentation analysis was performed using WebGestalt. All statistical tests were two-sided.

RESULTS

Thirty candidate genes positively correlated (r ≥ 0.4) with AI-resistant proliferation in LumB and were upregulated greater than twofold. Gene ontologies identified that the targetable immune checkpoint (IC) components IDO1, LAG3, and PD1 were overrepresented resistance candidates (P ≤ .001). High IDO1 mRNA was associated with poor prognosis in LumB disease (Molecular Taxonomy of Breast Cancer International Consortium, hazard ratio = 1.43, 95% confidence interval = 1.04 to 1.98, P = .03). IDO1 also statistically significantly correlated with STAT1 at protein level in LumB disease (Pearson r = 0.74). As a composite immune tolerance signature, expression of IFN-γ/STAT1 pathway components was associated with higher baseline Ki67, lower estrogen, and progesterone receptor mRNA levels and worse disease-specific survival (P = .002). In a tissue microarray analysis, IDO1 was observed in stromal cells and tumor-associated macrophages, with a higher incidence in LumB cases. Furthermore, IDO1 expression was associated with a macrophage mRNA signature (M1 by CIBERSORT Pearson r = 0.62 ) and by tissue microarray analysis.

CONCLUSIONS

Targetable IC components are upregulated in the majority of endocrine therapy-resistant LumB cases. Our findings provide rationale for IC inhibition in poor-outcome ER-positive breast cancer.

IDO1 Expression in Ovarian Cancer Induces PD-1 in T Cells via Aryl Hydrocarbon Receptor Activation

The immunoregulatory enzyme, indoleamine 2,3-dioxygenase (IDO1) and the PD-1/PD-L1 axis are potent mechanisms that impede effective anti-tumor immunity in ovarian cancer. However, whether the IDO pathway regulates PD-1 expression in T cells is currently unknown. Here we show that tumoral IDO1 expression led to profound changes in tryptophan, nicotinate/nicotinamide, and purine metabolic pathways in the ovarian tumor microenvironment, and to an increased frequency of PD-1+CD8+ tumor infiltrating T cells. We determined that activation of the aryl hydrocarbon receptor (AHR) by kynurenine induced PD-1 expression, and this effect was significantly abrogated by the AHR antagonist CH223191. Mechanistically, kynurenine alters chromatin accessibility in regulatory regions of T cell inhibitory receptors, allowing AHR to bind to consensus XRE motifs in the promoter region of PD-1. These results enable the design of strategies to target the IDO1 and AHR pathways for enhancing anti-tumor immunity in ovarian cancer.

Inhibiting the MNK1/2-eIF4E axis impairs melanoma phenotype switching and potentiates antitumor immune responses

Melanomas commonly undergo a phenotype switch, from a proliferative to an invasive state. Such tumor cell plasticity contributes to immunotherapy resistance; however, the mechanisms are not completely understood and thus are therapeutically unexploited. Using melanoma mouse models, we demonstrated that blocking the MNK1/2-eIF4E axis inhibited melanoma phenotype switching and sensitized melanoma to anti-PD-1 immunotherapy. We showed that phospho-eIF4E-deficient murine melanomas expressed high levels of melanocytic antigens, with similar results verified in patient melanomas. Mechanistically, we identified phospho-eIF4E-mediated translational control of NGFR, a critical effector of phenotype switching. Genetic ablation of phospho-eIF4E reprogrammed the immunosuppressive microenvironment, exemplified by lowered production of inflammatory factors, decreased PD-L1 expression on dendritic cells and myeloid-derived suppressor cells, and increased CD8+ T cell infiltrates. Finally, dual blockade of the MNK1/2-eIF4E axis and the PD-1/PD-L1 immune checkpoint demonstrated efficacy in multiple melanoma models regardless of their genomic classification. An increase in the presence of intratumoral stem-like TCF1+PD-1+CD8+ T cells, a characteristic essential for durable antitumor immunity, was detected in mice given a MNK1/2 inhibitor and anti-PD-1 therapy. Using MNK1/2 inhibitors to repress phospho-eIF4E thus offers a strategy to inhibit melanoma plasticity and improve response to anti-PD-1 immunotherapy.

The Future of Cancer Diagnosis, Treatment and Surveillance: A Systemic Review on Immunotherapy and Immuno-PET Radiotracers

Immunotherapy is an effective therapeutic option for several cancers. In the last years, the introduction of checkpoint inhibitors (ICIs) has shifted the therapeutic landscape in oncology and improved patient prognosis in a variety of neoplastic diseases. However, to date, the selection of the best patients eligible for these therapies, as well as the response assessment is still challenging. Patients are mainly stratified using an immunohistochemical analysis of the expression of antigens on biopsy specimens, such as PD-L1 and PD-1, on tumor cells, on peritumoral immune cells and/or in the tumor microenvironment (TME). Recently, the use and development of imaging biomarkers able to assess in-vivo cancer-related processes are becoming more important. Today, positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is used routinely to evaluate tumor metabolism, and also to predict and monitor response to immunotherapy. Although highly sensitive, FDG-PET in general is rather unspecific. Novel radiopharmaceuticals (immuno-PET radiotracers), able to identify specific immune system targets, are under investigation in pre-clinical and clinical settings to better highlight all the mechanisms involved in immunotherapy. In this review, we will provide an overview of the main new immuno-PET radiotracers in development. We will also review the main players (immune cells, tumor cells and molecular targets) involved in immunotherapy. Furthermore, we report current applications and the evidence of using [18F]FDG PET in immunotherapy, including the use of artificial intelligence (AI).

Transcriptional and epigenetic regulation of PD-1 expression

Programmed cell death-1 (PD-1) is a co-inhibitory receptor that plays important roles in regulating T cell immunity and peripheral tolerance. PD-1 signaling prevents T cells from overactivation during acute infections, but it maintains T cell exhaustion during chronic infections. Tumor cells can exploit the PD-1 signaling pathway to evade antitumor immune responses. The PD-1 signaling pathway is also essential for maintaining peripheral tolerance and prevention of autoimmunity. PD-1 expression is strictly and differentially regulated by diverse mechanisms in immune cells. It is activated and repressed by distinct transcription factors in different circumstances. Moreover, epigenetic mechanisms are also involved in regulating PD-1 expression. In this review, we summarize the knowledge of the transcriptional and epigenetic regulation of PD-1 expression during different immune responses.

Blocking of the PD-1/PD-L1 interaction by a novel cyclic peptide inhibitor for cancer immunotherapy

The interaction of PD-1/PD-L1 allows tumor cells to escape from immune surveillance. Clinical success of the antibody drugs has proven that blockade of PD-1/PD-L1 pathway is a promising strategy for cancer immunotherapy. Here, we developed a cyclic peptide C8 by using Ph.D.-C7C phage display technology. C8 showed high binding affinity with hPD-1 and could effectively interfere the interaction of PD-1/PD-L1. Furthermore, C8 could stimulate CD8+ T cell activation in human peripheral blood mononuclear cells (PBMCs). We also observed that C8 could suppress tumor growth in CT26 and B16-OVA, as well as anti-PD-1 antibody resistant B16 mouse model. CD8 T cells infiltration significantly increased in tumor microenvironment, and IFN-γ secretion by CD8+ T cells in draining lymph nodes also increased. Simultaneously, we exploited T cells depletion models and confirmed that C8 exerted anti-tumor effects via activating CD8+ T cells dependent manner. The interaction model of C8 with hPD-1 was simulated and confirmed by alanine scanning. In conclusion, C8 shows anti-tumor capability by blockade of PD-1/PD-L1 interaction, and C8 may provide an alternative candidate for cancer immunotherapy.