The signaling adaptor TRAF1 negatively regulates Toll-like receptor signaling and this underlies its role in rheumatic disease.

TRAF1 is a signaling adaptor known for its role in tumor necrosis factor receptor-induced cell survival. Here we show that monocytes from healthy human subjects with a rheumatoid arthritis-associated single-nucleotide polymorphism (SNP) in the TRAF1 gene express less TRAF1 protein but greater amounts of inflammatory cytokines in response to lipopolysaccharide (LPS). The TRAF1 MATH domain binds directly to three components of the linear ubiquitination (LUBAC) complex, SHARPIN, HOIP and HOIL-1, to interfere with the recruitment and linear ubiquitination of NEMO. This results in decreased NF-κB activation and cytokine production, independently of tumor necrosis factor. Consistent with this, Traf1-/- mice show increased susceptibility to LPS-induced septic shock. These findings reveal an unexpected role for TRAF1 in negatively regulating Toll-like receptor signaling, providing a mechanistic explanation for the increased inflammation seen with a disease-associated TRAF1 SNP.

Dichotomous Expression of TNF Superfamily Ligands on Antigen-Presenting Cells Controls Post-priming Anti-viral CD4+ T Cell Immunity.

T cell antigen-presenting cell (APC) interactions early during chronic viral infection are crucial for determining viral set point and disease outcome, but how and when different APC subtypes contribute to these outcomes is unclear. The TNF receptor superfamily (TNFRSF) member GITR is important for CD4+ T cell accumulation and control of chronic lymphocytic choriomeningitis virus (LCMV). We found that type I interferon (IFN-I) induced TNFSF ligands GITRL, 4-1BBL, OX40L, and CD70 predominantly on monocyte-derived APCs and CD80 and CD86 predominantly on classical dendritic cells (cDCs). Mice with hypofunctional GITRL in Lyz2+ cells had decreased LCMV-specific CD4+ T cell accumulation and increased viral load. GITR signals in CD4+ T cells occurred after priming to upregulate OX40, CD25, and chemokine receptor CX3CR1. Thus IFN-I (signal 3) induced a post-priming checkpoint (signal 4) for CD4+ T cell accumulation, revealing a division of labor between cDCs and monocyte-derived APCs in regulating T cell expansion.

TNFRs and Control of Chronic LCMV Infection: Implications for Therapy.

The control of persistent viral infections requires the immune system to limit the spread of the virus while avoiding immunopathology. Recent studies have revealed that members of the tumor necrosis factor receptor (TNFR) superfamily play unique and pivotal roles in control of chronic lymphocytic choriomeningitis virus (LCMV) infection and in some settings can tip the balance between immune control and immune pathology. We review these findings and discuss how our understanding of the role of TNFRs in the immune response to chronic LCMV infection may shed light on what happens during HIV infection in humans. We discuss preclinical models of TNF/TNFR family-targeted immunotherapy of chronic LCMV infection and evaluate which TNFRs present the most promising targets for immune intervention.

GITR intrinsically sustains early type 1 and late follicular helper CD4 T cell accumulation to control a chronic viral infection.

CD4 T cells are critical for control of persistent infections; however, the key signals that regulate CD4 T help during chronic infection remain incompletely defined. While several studies have addressed the role of inhibitory receptors and soluble factors such as PD-1 and IL-10, significantly less work has addressed the role of T cell co-stimulatory molecules during chronic viral infection. Here we show that during a persistent infection with lymphocytic choriomeningitis virus (LCMV) clone 13, mice lacking the glucocorticoid-induced tumor necrosis factor receptor related protein (GITR) exhibit defective CD8 T cell accumulation, increased T cell exhaustion and impaired viral control. Differences in CD8 T cells and viral control between GITR+/+ and GITR-/- mice were lost when CD4 T cells were depleted. Moreover, mixed bone marrow chimeric mice, as well as transfer of LCMV epitope-specific CD4 or CD8 T cells, demonstrated that these effects of GITR are largely CD4 T cell-intrinsic. GITR is dispensable for initial CD4 T cell proliferation and differentiation, but supports the post-priming accumulation of IFNγ+IL-2+ Th1 cells, facilitating CD8 T cell expansion and early viral control. GITR-dependent phosphorylation of the p65 subunit of NF-κB as well as phosphorylation of the downstream mTORC1 target, S6 ribosomal protein, were detected at day three post-infection (p.i.), and defects in CD4 T cell accumulation in GITR-deficient T cells were apparent starting at day five p.i. Consistently, we pinpoint IL-2-dependent CD4 T cell help for CD8 T cells to between days four and eight p.i. GITR also increases the ratio of T follicular helper to T follicular regulatory cells and thereby enhances LCMV-specific IgG production. Together, these findings identify a CD4 T cell-intrinsic role for GITR in sustaining early CD8 and late humoral responses to collectively promote control of chronic LCMV clone 13 infection.

The contextual role of TNFR family members in CD8(+) T-cell control of viral infections.

Immunity to viruses must be tightly controlled to avoid pathology. Receptors and ligands of the tumor necrosis factor (TNF) family play important roles in controlling lymphocyte activation and survival during an immune response. The role of specific TNF receptor (TNFR) family members in antiviral immunity depends on the stage of the immune response and can vary with the virus type and its virulence. Here, we focus on five members of the TNFR family that are prominently expressed on CD8(+) T cells during viral infections, namely, 4-1BB (CD137), CD27, OX40 (CD134), GITR, and TNFR2. 4-1BB, CD27, OX40, and GITR have primarily prosurvival roles for CD8(+) T cells during viral infection, although under some circumstances 4-1BB, GITR, or CD27 signals can limit immunity. Although TNFR2 can be costimulatory under some circumstances, its main role in CD8(+) T-cell responses during viral infection appears to be in contraction of the response. Several TNF family ligands are being explored as adjuvants for viral vaccines, and agonistic antibodies to TNFR family members are being investigated for immunotherapy of chronic viral infection alone and in combination with checkpoint blockade. Such therapies will require thorough and specific optimization to avoid pathology induced by hyperstimulation of these pathways.

Anti-GITR agonist therapy intrinsically enhances CD8 T cell responses to chronic lymphocytic choriomeningitis virus (LCMV), thereby circumventing LCMV-induced downregulation of costimulatory GITR ligand on APC.

The costimulatory TNFR family member GITR can provide important survival signals for CD8 T cells. However, little is known about the regulation of this pathway during a chronic infection. In this study, we show that GITR ligand (GITRL) is maximally induced on APCs at day 2 post-lymphocytic choriomeningitis virus (LCMV) clone 13 infection, but is downregulated to below baseline levels by day 8 postinfection (p.i.), and remains so at the chronic stage of infection. At its peak, GITRL expression is highest on macrophages, with lower expression on conventional and plasmacytoid dendritic cells. GITR expression was highest on T regulatory cells but was also detected on Th1 and LCMV-specific CD8 T cells at day 8 p.i. and was maintained at low, but above baseline levels at the chronic stage of LCMV infection. As GITRL was limiting at the chronic stage of infection, we investigated the potential of therapeutic stimulation of GITR at this stage using agonistic anti-GITR Ab. Anti-GITR treatment at day 21 p.i. increased the frequency and number of LCMV-specific CD8 T cells, resulting in increased in vivo CTL activity and a concomitant decrease in viral load, despite the persistence of PD-1 expression. These effects of anti-GITR were CD8 T cell intrinsic, with no detectable effects on Th1 or T regulatory cells. In contrast to other TNFR agonists, such as anti-4-1BB, which can cause immune pathology, a single therapeutic dose of anti-GITR did not induce splenomegaly or increase serum alanine transaminase. These studies identify GITR as a promising therapeutic target for chronic infection.

GITR-dependent regulation of 4-1BB expression: implications for T cell memory and anti-4-1BB-induced pathology.

The TNFR family member 4-1BB plays a key role in the survival of activated and memory CD8 T cells. However, the mechanisms that regulate 4-1BB re-expression on memory CD8 T cells after Ag clearance are unknown. In unimmunized mice, ∼10% of CD8 CD44(hi) memory T cells in the bone marrow (BM) and liver express 4-1BB, with minimal 4-1BB expression in spleen and lymph node. IL-2, IL-15, and IL-7 are collectively dispensable for 4-1BB expression on the memory CD8 T cells. Rather, T cell-intrinsic glucocorticoid-induced TNFR-related protein (GITR) contributes to 4-1BB expression on CD8 T cells upon their entry into the BM or liver. Consistent with its role in regulation of 4-1BB, GITR is required on memory CD8 T cells for their persistence in vivo. These findings reveal site-specific effects of the BM and liver microenvironment on CD8 memory T cells. Previous work has demonstrated that 4-1BB agonists given to unimmunized mice induce splenomegaly, hepatitis, and other immune system anomalies. Moreover, severe liver pathology has been observed in a subset of anti-4-1BB-treated melanoma patients. Remarkably, the absence of GITR in mice almost completely abrogates cellular expansions, splenomegaly, and liver inflammation associated with anti-4-1BB agonist treatment of unimmunized mice. In contrast, lack of CD8 T cells selectively improves liver pathology, but not splenomegaly in the mice. Thus, the regulation of 4-1BB expression by GITR on CD8 T cells, as well as on other cells, contributes to the pathological effects of anti-4-1BB in unimmunized mice.

Tumor reactive γδ T cells contribute to a complete response to PD-1 blockade in a Merkel cell carcinoma patient.

Immunotherapies targeting PD-1/PD-L1 are now widely used in the clinic to treat a variety of malignancies. While most of the research on T cell exhaustion and PD-1 blockade has been focused on conventional αß T cells, the contribution of innate-like T cells such as γδ T cells to anti-PD-1/PD-L1 mediated therapy is limited. Here we show that tumor reactive γδ T cells respond to PD-1 blockade in a Merkel cell carcinoma (MCC) patient experiencing a complete response to therapy. We find clonally expanded γδ T cells in the blood and tumor after pembrolizumab treatment, and this Vγ2Vδ1 clonotype recognizes Merkel cancer cells in a TCR-dependent manner. Notably, the intra-tumoral γδ T cells in the MCC patient are characterized by higher expression of PD-1 and TIGIT, relative to conventional CD4 and CD8 T cells. Our results demonstrate that innate-like T cells could also contribute to an anti-tumor response after PD-1 blockade.

Real-world treatment patterns and survival outcomes for treated biliary tract cancer patients using administrative databases in Ontario.

Background: There are limited data available on treatment patterns and outcomes of biliary tract cancers (BTCs) in Canada. The aim of this study was to understand treatment patterns, survival outcomes and healthcare resource use of BTC patients in Ontario, Canada. Methods: We conducted a retrospective population-level study using administrative data of patients diagnosed with advanced or metastatic BTC between January 1, 2010 and December 31, 2019. Results: A total of 2,142 BTC patients were identified; 702 (32.8%) with intrahepatic cholangiocarcinoma, 688 (32.1%) with extrahepatic cholangiocarcinoma, 363 (16.9%) with gallbladder cancer, 174 (8.1%) with ampulla of Vater cancer, and 215 (10.0%) with other types of BTC. In total, 1,314 patients (61.3%) were recurrent cases, and 828 (38.7%) were diagnosed with de novo advanced disease. A total of 1,727 patients (80.6%) received first-line systemic treatment of cisplatin plus gemcitabine (75.2%), FOLFOX [5-fluorouracil (5-FU), folinic acid (FA), and oxaliplatin] or FOLFIRI (5-FU, FA, and irinotecan) (11.5%), carboplatin plus gemcitabine (7.6%), or gemcitabine plus taxane (5.7%). Five hundred and twelve patients (29.6%) went on to receive a second-line treatment. Mean and median overall survival from diagnosis was 20.6 and 11.0 months, respectively. Mean and median overall survival from diagnosis was much higher among patients who received a systemic treatment at 23.8 and 14.1 months, respectively compared to 7.0 and 3.3 months, respectively for untreated patients (P<0.0001). Conclusions: Platinum and gemcitabine combinations are the most common first-line treatments. However, only a small proportion of patients go on to receive subsequent treatments. Survival in treated patients is higher than that in untreated patients. Our findings highlight the unmet need for effective systemic therapies for BTC.

A real-world retrospective analysis of the management of metastatic castrate-resistant prostate cancer in Ontario, Canada from 2010 - 2018.

PURPOSE: We sought to quantify mCRPC patient treatment patterns and survival across multiple lines of therapy after prior androgen-receptor-axis-targeted therapy (ARAT) failure. METHODS: Individuals diagnosed with prostate cancer between 2010 and 2018 were identified in the Ontario Cancer Registry (OCR). An algorithm was created to identify patients with mCRPC that was aligned to Prostate Cancer Clinical Trials Working Group 3 criteria (PCWG3) and validated with Canadian clinical experts. In the mCRPC setting, treatment patterns were assessed by line of therapy, and survival was calculated from treatment initiation until death or lost to follow-up. RESULTS: 64,484 men were diagnosed withprostate cancer in Ontario between 2010 and 2018with 5,588 men assessed to have mCRPC and 2,970 (53%) of those received first-line systemic treatment. Across the first-, second- and third-line of therapy, ARATs (abiraterone and enzalutamide) were the most used therapies. Survival for mCRPC patients treated with ARATs in first-, second- and third-line were 13.0 (95% CI, 11.6 - 14.5), 11.5 (95% CI, 10.1 - 13.4) and 8.9 (95% CI, 7.4 - 10.2) months, respectively. Survival for mCRPC patients treated with taxanes in first, second- and third-line were 16.7 (95% CI, 14.8 - 18.0), 11.3 (95% CI, 10.1 - 12.5) and 7.8 (95% CI, 6.5 - 10.6) months, respectively. No statistical difference in overall survival was found between taxanes and ARATs. CONCLUSION: In this analysis of a large retrospective cohort of Canadian men with mCRPC, we found that survival in patients treated with ARATs and taxanes was fairly similar across all lines of therapy. Importantly, this trend was maintained in ARAT-exposed patients, where sequential ARAT and taxanes offered similar survival. These data may help inform optimal sequencing of therapies in mCRPC.

Real-world treatment patterns, clinical outcomes, and health care resource utilization in advanced unresectable hepatocellular carcinoma.

BACKGROUND: The incidence of advanced unresectable hepatocellular carcinoma (HCC) is increasing in developed countries and the prognosis of advanced HCC remains poor. Real-world evidence of treatment patterns and outcomes can highlight the unmet clinical need. METHODS: We conducted a retrospective population-based cohort study of patients with advanced unresectable HCC diagnosed in Alberta, Canada (2008-2018) using electronic medical records and administrative claims data. A chart review was conducted on patients treated with systemic therapy to capture additional information related to treatment. RESULTS: A total of 1,297 advanced HCC patients were included of whom 555 (42.8%) were recurrent cases and the remainder were unresectable at diagnosis. Median age at diagnosis was 64 (range 21-94) years and 82.1% were men. Only 274 patients (21.1%) received first-line systemic therapy and, of those, 32 patients (11.7%) initiated second-line therapy. Nearly all of the patients received sorafenib (>96.4%) in first-line, and these patients had considerably higher median survival (12.23 months; 95% CI 10.72-14.10) compared with patients not treated with systemic therapy (2.66 months; 95% CI 2.33-3.12; log-rank p <0.001). Among patients treated with systemic therapy, overall survival was higher for recurrent cases, patients with Child-Pugh A functional status, and patients with HCV or multiple known HCC risk factors (p <0.05). CONCLUSIONS: In a Canadian real-world setting, patients who received systemic therapy had greater survival than those who did not, but outcomes were universally poor. These results underscore the need for effective front-line therapeutic options.

Pan-cancer analysis of longitudinal metastatic tumors reveals genomic alterations and immune landscape dynamics associated with pembrolizumab sensitivity.

Serial circulating tumor DNA (ctDNA) monitoring is emerging as a non-invasive strategy to predict and monitor immune checkpoint blockade (ICB) therapeutic efficacy across cancer types. Yet, limited data exist to show the relationship between ctDNA dynamics and tumor genome and immune microenvironment in patients receiving ICB. Here, we present an in-depth analysis of clinical, whole-exome, transcriptome, and ctDNA profiles of 73 patients with advanced solid tumors, across 30 cancer types, from a phase II basket clinical trial of pembrolizumab (NCT02644369) and report changes in genomic and immune landscapes (primary outcomes). Patients stratified by ctDNA and tumor burden dynamics correspond with survival and clinical benefit. High mutation burden, high expression of immune signatures, and mutations in BRCA2 are associated with pembrolizumab molecular sensitivity, while abundant copy-number alterations and B2M loss-of-heterozygosity corresponded with resistance. Upon treatment, induction of genes expressed by T cell, B cell, and myeloid cell populations are consistent with sensitivity and resistance. We identified the upregulated expression of PLA2G2D, an immune-regulating phospholipase, as a potential biomarker of adaptive resistance to ICB. Together, these findings provide insights into the diversity of immunogenomic mechanisms that underpin pembrolizumab outcomes.

Personalized circulating tumor DNA analysis as a predictive biomarker in solid tumor patients treated with pembrolizumab.

Immune checkpoint blockade (ICB) provides clinical benefit to a subset of patients with cancer. However, existing biomarkers do not reliably predict treatment response across diverse cancer types. Limited data exist to show how serial circulating tumor DNA (ctDNA) testing may perform as a predictive biomarker in patients receiving ICB. We conducted a prospective phase II clinical trial to assess ctDNA in five distinct cohorts of patients with advanced solid tumors treated with pembrolizumab (NCT02644369). We applied bespoke ctDNA assays to 316 serial plasma samples obtained at baseline and every three cycles from 94 patients. Baseline ctDNA concentration correlated with progression-free survival, overall survival, clinical response and clinical benefit. This association became stronger when considering ctDNA kinetics during treatment. All 12 patients with ctDNA clearance during treatment were alive with median 25 months follow up. This study demonstrates the potential for broad clinical utility of ctDNA-based surveillance in patients treated with ICB.

An interim report on the investigator-initiated phase 2 study of pembrolizumab immunological response evaluation (INSPIRE).

BACKGROUND: Immune checkpoint inhibitors (ICIs) demonstrate unprecedented efficacy in multiple malignancies; however, the mechanisms of sensitivity and resistance are poorly understood and predictive biomarkers are scarce. INSPIRE is a phase 2 basket study to evaluate the genomic and immune landscapes of peripheral blood and tumors following pembrolizumab treatment. METHODS: Patients with incurable, locally advanced or metastatic solid tumors that have progressed on standard therapy, or for whom no standard therapy exists or standard therapy was not deemed appropriate, received 200 mg pembrolizumab intravenously every three weeks. Blood and tissue samples were collected at baseline, during treatment, and at progression. One core biopsy was used for immunohistochemistry and the remaining cores were pooled and divided for genomic and immune analyses. Univariable analysis of clinical, genomic, and immunophenotyping parameters was conducted to evaluate associations with treatment response in this exploratory analysis. RESULTS: Eighty patients were enrolled from March 21, 2016 to June 1, 2017, and 129 tumor and 382 blood samples were collected. Immune biomarkers were significantly different between the blood and tissue. T cell PD-1 was blocked (≥98%) in the blood of all patients by the third week of treatment. In the tumor, 5/11 (45%) and 11/14 (79%) patients had T cell surface PD-1 occupance at weeks six and nine, respectively. The proportion of genome copy number alterations and abundance of intratumoral 4-1BB+ PD-1+ CD8 T cells at baseline (P < 0.05), and fold-expansion of intratumoral CD8 T cells from baseline to cycle 2-3 (P < 0.05) were associated with treatment response. CONCLUSION: This study provides technical feasibility data for correlative studies. Tissue biopsies provide distinct data from the blood and may predict response to pembrolizumab.

Landscape of genomic alterations in high-grade serous ovarian cancer from exceptional long- and short-term survivors.

BACKGROUND: Patients diagnosed with high-grade serous ovarian cancer (HGSOC) who received initial debulking surgery followed by platinum-based chemotherapy can experience highly variable clinical responses. A small percentage of women experience exceptional long-term survival (long term (LT), 10+ years), while others develop primary resistance to therapy and succumb to disease in less than 2 years (short term (ST)). To improve clinical management of HGSOC, there is a need to better characterize clinical and molecular profiles to identify factors that underpin these disparate survival responses. METHODS: To identify clinical and tumor molecular biomarkers associated with exceptional clinical response or resistance, we conducted an integrated clinical, exome, and transcriptome analysis of 41 primary tumors from LT (n = 20) and ST (n = 21) HGSOC patients. RESULTS: Younger age at diagnosis, no residual disease post debulking surgery and low CA125 levels following surgery and chemotherapy were clinical characteristics of LT. Tumors from LT survivors had increased somatic mutation burden (median 1.62 vs. 1.22 non-synonymous mutations/Mbp), frequent BRCA1/2 biallelic inactivation through mutation and loss of heterozygosity, and enrichment of activated CD4+, CD8+ T cells, and effector memory CD4+ T cells. Characteristics of ST survival included focal copy number gain of CCNE1, lack of BRCA mutation signature, low homologous recombination deficiency scores, and the presence of ESR1-CCDC170 gene fusion. CONCLUSIONS: Our findings suggest that exceptional long- or short-term survival is determined by a concert of clinical, molecular, and microenvironment factors.

Requisite role for Nck adaptors in cardiovascular development, endothelial-to-mesenchymal transition, and directed cell migration.

Development of the cardiovascular system is critically dependent on the ability of endothelial cells (ECs) to reorganize their intracellular actin architecture to facilitate migration, adhesion, and morphogenesis. Nck family cytoskeletal adaptors function as key mediators of actin dynamics in numerous cell types, though their role in EC biology remains largely unexplored. Here, we demonstrate an essential requirement for Nck within ECs. Mouse embryos lacking endothelial Nck1/2 expression develop extensive angiogenic defects that result in lethality at about embryonic day 10. Mutant embryos show immature vascular networks, with decreased vessel branching, aberrant perivascular cell recruitment, and reduced cardiac trabeculation. Strikingly, embryos deficient in endothelial Nck also fail to undergo the endothelial-to-mesenchymal transition (EnMT) required for cardiac valve morphogenesis, with loss of Nck disrupting expression of major EnMT markers, as well as suppressing mesenchymal outgrowth. Furthermore, we show that Nck-null ECs are unable to migrate downstream of vascular endothelial growth factor and angiopoietin-1, and they exhibit profound perturbations in cytoskeletal patterning, with disorganized cellular projections, impaired focal adhesion turnover, and disrupted actin-based signaling. Our collective findings thereby reveal a crucial role for Nck as a master regulator within the endothelium to control actin cytoskeleton organization, vascular network remodeling, and EnMT during cardiovascular development.

Cell-specific and context-dependent effects of GITR in cancer, autoimmunity, and infection.

A breadth of studies have demonstrated the importance of GITR-GITRL in diverse immune processes. However, only a limited number of studies to date have attributed the effects of GITR/GITRL to specific cell types. Moreover, the context-dependent role of GITR/GITRL in different models makes the consequences of GITR ligation difficult to generalize. There is a significant interest in the therapeutic application of GITR agonists and antagonists in human disease. Thus, the field must come to a consensus regarding the cell type-specific and physiological effects of GITR in different disease states. Here we attempt to summarize the extensive literature on GITR, to synthesize a more cohesive picture of the role of GITR/GITRL in immunity, and to identify areas that require clarification.