Allergy History and Immunotherapy Response in Patients With Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma

OBJECTIVE

This study examines the association between patient-reported allergy history and immune checkpoint inhibition (ICI) response in patients with recurrent or metastatic head and neck squamous cell carcinoma (RMHNSCC).

STUDY DESIGN

Retrospective cohort study.

SETTING

Academic tertiary care hospital.

METHODS

Data were collected from the electronic medical records on baseline age, sex, allergy history, human papillomavirus status, T-stage, N-stage, smoking status, and survival for patients with and without an allergy history. The primary outcome was ICI response defined as complete or partial response by the RECIST criteria. Chi-square and logistic regression analyses were conducted to compare rates and odds of ICI response. Kaplan-Meier analyses were used to compare survival between groups.

RESULTS

Our study included 52 patients with an allergy history and 36 patients without an allergy history. The groups were similar in age, sex, HPV status, smoking status, and T- and N-stage. Patients with an allergy history (17/52, 32.1%) had a greater ICI response rate than patients without allergy history (4/36, 11.1%) (P = .02). After adjusting for HPV, patients with allergies had 3.93 (1.19-13.00) times increased odds of ICI response compared to patients without allergies. The median progression-free survival was 6.0 and 4.2 months for patients with and without an allergy history respectively (log-rank, P = .04). The median overall survival was 25.0 and 11.1 months for patients with and without an allergy history respectively (log-rank, P = .002).

CONCLUSION

Patient-reported allergy history was associated with ICI response in patients with RMHNSCC, underscoring the potential clinical utility of allergy history in estimating ICI response.

Impact of comorbidities on outcomes in patients with advanced head and neck cancer undergoing immunotherapy

OBJECTIVES

To explore the impact of pre-existing comorbidities on immunotherapy response, overall and progression-free survival, and immune-related adverse events (irAEs) of patients with advanced head and neck cancer (HNC) treated with immunotherapy.

PATIENTS AND METHODS

Ninety-three patients treated with immunotherapy were identified and stratified into comorbidity absent or present (CCI < 1 and CCI ≥ 1, respectively) cohorts, and clinical outcomes were compared between these two groups.

RESULTS

Patients with no comorbidities had longer overall survival (aHR = 2.74, 95% CI [1.18, 6.40], p = 0.02) and progression-free survival (aHR = 2.07, 95% CI [1.03, 4.16], p = 0.04) and a higher tumor response rate (32% in CCI < 1 vs. 14% in CC ≥ 1, p = 0.05). Risk for irAEs was higher in the comorbidity absent group (p = 0.05).

CONCLUSION

Comorbidity should be considered as a significant prognostic factor in clinical decision-making for patients with advanced HNC undergoing immunotherapy.

Distinct Myeloid Derived Suppressor Cell Populations Promote Tumor Aggression in Glioblastoma

The diversity of genetic programs and cellular plasticity of glioma-associated myeloid cells, and thus their contribution to tumor growth and immune evasion, is poorly understood. We performed single cell RNA-sequencing of immune and tumor cells from 33 glioma patients of varying tumor grades. We identified two populations characteristic of myeloid derived suppressor cells (MDSC), unique to glioblastoma (GBM) and absent in grades II and III tumors: i) an early progenitor population (E-MDSC) characterized by strong upregulation of multiple catabolic, anabolic, oxidative stress, and hypoxia pathways typically observed within tumor cells themselves, and ii) a monocytic MDSC (M-MDSC) population. The E-MDSCs geographically co-localize with a subset of highly metabolic glioma stem-like tumor cells with a mesenchymal program in the pseudopalisading region, a pathognomonic feature of GBMs associated with poor prognosis. Ligand-receptor interaction analysis revealed symbiotic cross-talk between the stemlike tumor cells and E-MDSCs in GBM, whereby glioma stem cells produce chemokines attracting E-MDSCs, which in turn produce growth and survival factors for the tumor cells. Our large-scale single-cell analysis elucidated unique MDSC populations as key facilitators of GBM progression and mediators of tumor immunosuppression, suggesting that targeting these specific myeloid compartments, including their metabolic programs, may be a promising therapeutic intervention in this deadly cancer.

One-Sentence Summary

Aggressive glioblastoma harbors two unique myeloid populations capable of promoting stem-like properties of tumor cells and suppressing T cell function in the tumor microenvironment.

Interrogation of T Cell-Enriched Tumors Reveals Prognostic and Immunotherapeutic Implications of Polyamine Metabolism

Metabolic features of the tumor microenvironment (TME) antagonize anti-tumor immunity. We hypothesized that T cell infiltrated tumors with a known antigen should exhibit superior clinical outcomes, though some fare worse given unfavorable metabolic features leveraging T cell-infiltrated (Thi), human papillomavirus-related (HPV+) head and neck squamous cell carcinomas (HNSC) to test this hypothesis. Expression of 2,520 metabolic genes were analyzed among Thi HPV+ HNSCs stratified by high-risk molecular subtype. RNAseq data from The Cancer Genome Atlas (TCGA; 10 cancer types), single cell RNAseq data, and an immunotherapy-treated melanoma cohort were used to test the association between metabolic gene expression and clinical outcomes and contribution of tumor versus stromal cells to metabolic gene expression. Polyamine (PA) metabolism genes were overexpressed in high-risk, Thi HPV+ HNSCs. Genes involved in PA biosynthesis and transport were associated with T cell infiltration, recurrent or persistent cancer, overall survival status, primary site, molecular subtype, and MYC genomic alterations. PA biogenesis gene sets were associated with tumor intrinsic features while myeloid cells in HPV+ HNSCs were enriched in PA catabolism, regulatory, transport, putrescine, and spermidine gene set expression. PA gene set expression also correlated with IFNγ or cytotoxic T cell ssGSEA scores across TCGA tumor types. PA transport ssGSEA scores were associated with poor survival whereas putrescine ssGSEA scores portended better survival for several tumor types. Thi melanomas enriched in PA synthesis or combined gene set expression exhibited worse anti-PD-1 responses. These data address hurdles to anti-tumor immunity warranting further investigation of divergent polyamine metabolism in the TME.

Tumor-induced double positive T cells display distinct lineage commitment mechanisms and functions

Transcription factors ThPOK and Runx3 regulate the differentiation of "helper" CD4+ and "cytotoxic" CD8+ T cell lineages respectively, inducing single positive (SP) T cells that enter the periphery with the expression of either the CD4 or CD8 co-receptor. Despite the expectation that these cell fates are mutually exclusive and that mature CD4+CD8+ double positive (DP) T cells are present in healthy individuals and augmented in the context of disease, yet their molecular features and pathophysiologic role are disputed. Here, we show DP T cells in murine and human tumors as a heterogenous population originating from SP T cells which re-express the opposite co-receptor and acquire features of the opposite cell type's phenotype and function following TCR stimulation. We identified distinct clonally expanded DP T cells in human melanoma and lung cancer by scRNA sequencing and demonstrated their tumor reactivity in cytotoxicity assays. Our findings indicate that antigen stimulation induces SP T cells to differentiate into DP T cell subsets gaining in polyfunctional characteristics.

Tumor Histological Grade and Immunotherapy Response in Patients With Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Importance

Tumor histological factors that predict immunotherapy response in patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) are not well defined.

Objective

To investigate the association between tumor grade and immunotherapy response in patients with recurrent or metastatic mucosal HNSCC.

Design, Setting, and Participants

In this retrospective cohort study, the medical records of 60 patients with recurrent or metastatic mucosal HNSCC treated with immune checkpoint inhibitors at Johns Hopkins Hospital between July 1, 2015, and January 22, 2020, were reviewed.

Exposures

High-grade tumors (HGTs) vs low-grade tumors (LGTs) in recurrent or metastatic HNSCC.

Main Outcomes and Measures

Patients were divided into 2 groups: those with LGTs (well differentiated and moderately differentiated) and those with HGTs (poorly differentiated). The main outcome was a clinically beneficial immunotherapy response, defined as complete response or partial response. Univariable and multivariable logistic regressions were conducted to calculate odds ratios for each variable's association with immunotherapy response. Survival differences were evaluated using Kaplan-Meier survival curves with multivariable Cox proportional hazards regression models.

Results

The 60 patients (35 with HGTs and 25 with LGTs) had a mean (SD) age of 64.6 (8.88) years; 51 were male (85%); and 38 were current or former smokers (63%). The oropharynx was the most common primary tumor site both in patients with HGTs (22 of 35; 63%) and those with LGTs (12 of 25; 48%). Bivariate analysis showed the proportion of patients having a beneficial response to immunotherapy was greater for patients with HGTs (12 of 35; 34.3%) than those with LGTs (2 of 25, 8.0%) (difference, 26.3%; 95% CI, 7.3%-45.3%). Upon multivariable analysis, patients with HGTs had 5.35-fold increased odds (95% CI, 1.04-27.37) of having a clinically beneficial response to immunotherapy. Among patients with available tumor genomic profiling data, the mean tumor mutational burden was greater for patients with HGTs (mean [SD], 8.6 [5.4] mut/Mb; n = 8) than patients with LGTs (mean [SD], 3.6 [1.1] mut/Mb; n = 4) (difference = 5.0 mut/Mb; 95% CI -1.4 to 11.4 mut/Mb; Cohen d = 1.2).

Conclusions and Relevance

In this cohort study, tumor grade was independently associated with immunotherapy response in patients with recurrent or metastatic mucosal HNSCC. These findings highlight the potential role of tumor grade in predicting immunotherapy response in mucosal HNSCC.

The role of ionotropic AMPA receptors in T cell tolerance

The ability of T cells to mount effective immune responses to pathogens and cancer while remaining tolerant to self-tissue is critical for maintaining immune homeostasis. Previously, our group identified neuritin, a neuronal protein, as a highly differentially expressed gene in anergic and regulatory T cells. Furthermore, our results indicate neuritin deficient mice exhibit enhanced autoimmunity due, in part, to dysfunctional regulatory T cells. Neuritin was recently identified as an accessory component of the ionotropic AMPA receptor (AMPAR) complex in neurons. AMPAR complexes are typically found on the post-synaptic neuronal cell and mediate glutamate dependent cation flux. Given our previous findings involving neuritin in autoimmunity and this newly identified interaction between neuritin and AMPAR, we sought to evaluate whether there is a role for the AMPAR in T cell tolerance. Here, we show that the AMPAR is expressed in CD4+ T cells and that the specific deletion of the AMPAR in T cells (AMPAR KO) leads to significantly reduced disease pathogenesis in an experimental autoimmune encephalomyelitis (EAE) model. The spinal cord inflammatory immune infiltrates from AMPAR KO mice are markedly reduced in cell number, proliferative state, and expression of proinflammatory cytokines compared to wild type (WT) mice. In addition, we have observed an increase in the CD4+FoxP3+ regulatory cell population among spinal cord infiltrates from AMPAR KO EAE mice. Consistent with the EAE model, AMPAR KO T cells also exhibit increased induced regulatory T cell development during in vitro differentiation. Taken together our results support a previously unappreciated role for ionotropic AMPA receptors in regulating T cell tolerance.

Target the activin receptor 1c on CD4+ T cells to achieve anti-tumor therapeutic effects

Activin signaling molecules and their receptors have not been substantially studied in the context of the immune system and cancer. We show here that tumor-bearing mice had elevated Activins levels, which correlated directly with tumor burden. Likewise, cancer patients had elevated plasma Activins compared to healthy controls. Importantly, our in vitro studies suggested that Activins promoted differentiation of naive wild type CD4+ cells into induced FoxP3-expressing Tregs. Database and qRT-PCR analysis of sorted major immune cell subsets in mice revealed that Activin Receptor 1C (ActR1c) was uniquely expressed on Tregs. ActR2b, as paired to ActR1c, was found to be highly upregulated during iTreg differentiation. In humans, these receptors were expressed on CD4+ Foxp3− cells. Thus, while Activins may have many cellular targets, signaling through these receptors on CD4+ cells likely promotes Treg-mediated immunosuppression. In vivo B16 melanoma and MC38 colon tumor studies have demonstrated that mice lacking ActR1c were more resistant to cancer progression compared to wild type mice. This phenotype correlated with reduced expression of the FoxP3 transcription factor in CD4+ cells. The anti-tumor effect was T-cell dependent, as T cell-deficient mice reconstituted with naïve ActR1c knock out CD4+ cells had delayed tumor progression. In vitro, naïve CD4+ cells lacking ActR1c had a defect in their ability to gain FoxP3 expression when Activin A was present and when TGF-β was limited. Thus, blocking Activins signaling through this receptor is a promising and disease-specific strategy for preventing the accumulation of immunosuppressive iTregs in cancer.

Supported by grants from NIH (R01AI137046)

The neurotrophic factor Neuritin regulates T cell anergy and T regulatory cell function

T cell activation and tolerance are tightly regulated to ensure effective elimination of foreign antigen while maintaining immune tolerance to self-antigens. Development of T cell anergy and regulatory T cell (Treg) mediated suppression both contribute to the establishment of immune tolerance. Here, we show that neuritin (Nrn1), a conserved GPI-anchored surface molecule important for the development, survival and function of neurons, is highly expressed in anergic and Treg cells. Nrn1 deficient CD4 cells are resistant to Treg cell mediated suppression, display defective anergy induction, and have reduced peripheral Treg generation. Nrn1 deficient Foxp3+ Treg cells exhibit reduced control of inflammatory colitis. Moreover, upon induction of experimental autoimmune encephalomyelitis (EAE), Nrn1 deficient mice develop non-remitting disease and have increased spinal cord inflammatory infiltrates. These in vivo findings underscore the importance of Nrn1 in immune tolerance. Recently, Nrn1 was identified as an accessory component of the ionotropic AMPA receptor (AMPAR) complex in neurons. AMPARs mediate glutamate dependent cation flux and regulate cell membrane potential. Cell membrane potential can impact nutrient uptake, calcium influx, cell size, proliferation and survival. In vitro analysis reveals that Nrn1 deficient Treg cells exhibit reduced proliferation and survival, associated with higher membrane potential, reduced nutrient sensitivity, reduced glycolysis and mTOR activation. AMPAR blockade can correct proliferation defect in Nrn1 deficient Treg cells. These findings reveal Nrn1 as an important regulator of immune tolerance functioning through the modulation of glutamate activated AMPAR.

Neoadjuvant immunotherapy prior to surgery for mucosal head and neck squamous cell carcinoma: Systematic review

Given the recent successes of anti-PD-1 immunotherapy, many clinical trials have sought to assess the safety and efficacy of this treatment modality in the neoadjuvant setting. This systematic review provides a comprehensive summary of findings from neoadjuvant head and neck cancer immunotherapy clinical trials with a focus on PD-1/PD-L1 axis blockade. Pubmed, Embase, Cochrane Library, Web of Science, Google Scholar, and clinicaltrials.gov were systematically searched for all eligible neoadjuvant head and neck cancer immunotherapy clinical trials. Eight clinical trials met the inclusion criteria comprising a total of 260 patients. Study drugs included nivolumab, pembrolizumab, ipilimumab, durvalumab, and tremelimumab. The overall mean objective response rate (ORR) was 45.9 ± 5.7% with a 41.5 ± 5.6% single agent mean ORR. There were no deaths due to immune-related toxicities. Neoadjuvant immunotherapy for mucosal head and neck squamous cell cancer has demonstrated favorable response rates with no unexpected immune-related toxicities in phase I/II clinical trials.

836 Murine fecal microbiota transfer models colonize human microbes selectively and reveal transcriptional pathways associated with response to neoadjuvant checkpoint inhibitors

Background

Human gut microbial species found to associate with clinical responses to immune checkpoint inhibitors (ICIs) are often tested in murine models using fecal microbiota transfer (FMT), wherein tumor responses in recipient mice may recapitulate human responses to ICI treatment. However, many FMT studies have reported only limited methodological description, including identification of colonizing species associated with murine outcomes, details of murine cohorts, and statistical methods. Thus, the reproducibility and robustness of ICI murine models remain uncertain.

Methods

To investigate gut microbial species that impact ICI responses, we performed human to germ-free (GF) mouse FMT using pre-treatment stools from a pathologic lung cancer responder (R) and a pathologic lung cancer non-responder (NR) after neoadjuvant anti-PD-1 and anti-CTLA4 treatment, followed by implantation of the mice with syngeneic tumors and anti-PD-L1 treatment. Cohorts of GF mice varied by sex, age and syngeneic cell line implanted. To identify relevant microbes, murine tumor progressors (MT-P) and non-progressors (MT-NP) to anti-PD-L1 were classified based on tumor growth curves, 16S rRNA sequencing of human and mouse stools was performed, and data was statistically corrected for mouse characteristics using a generalized linear model. RNA sequencing was performed to assess transcriptional changes in murine tumors.

Results

R-FMT mice yielded a greater anti-tumor response in combination with anti-PD-L1 treatment compared to NR-FMT, although the magnitude varied depending on the mouse cell line, sex, and individual experiment. Microbiota analysis revealed a shared presence of the most highly abundant taxa between the human inocula and mice, however low abundance human taxa colonized mice more variably after FMT. Multiple Clostridium species correlated with tumor outcome in individual anti-PD-L1-treated R-FMT mice. RNAseq analysis revealed differential expression of T cell and NK cell-related pathways in responding tumors, irrespective of FMT source, and enrichment of these cell types were confirmed by immunohistochemistry.

Conclusions

This study identifies several human intestinal microbial species that may play a role in clinical responses to ICIs and suggests attention to biological variables is needed to improve reproducibility and limit variability across experimental murine models.

Ethics Approval

All studies in this abstract have been approved by Johns Hopkins University Animal Care and Use and Johns Hopkins Medicine Institutional Review Board.

IMMU-27. SINGLE CELL RNA-SEQUENCING IDENTIFIES NOVEL BONE MARROW DERIVED MYELOID CELLS IN GLIOBLASTOMA ASSOCIATED WITH TUMOR AGGRESSION

BACKGROUND

Glioma associated myeloid cells (GAMs) can be induced to adopt an immunosuppressive phenotype that can lead to inhibition of anti-tumor responses in glioblastoma (GBM). Understanding the composition and phenotypes of GAMs is essential to modulating the myeloid compartment as a therapeutic adjunct to improve anti-tumor immune response.

METHODS

We performed single-cell RNA-sequencing (sc-RNAseq) of 435,400 myeloid and tumor cells to identify transcriptomic and phenotypic differences in GAMs across glioma grades. We further correlated the heterogeneity of the GAM landscape with tumor cell transcriptomics to investigate interactions between GAMs and tumor cells.

RESULTS

sc-RNAseq revealed a diverse landscape of myeloid-lineage cells in gliomas with an increase in preponderance of bone marrow derived myeloid cells (BMDMs) with increasing tumor grade. We identified two populations of BMDMs unique to GBMs; Mac-1and Mac-2. Mac-1 demonstrates upregulation of immature myeloid gene signature and altered metabolic pathways. Mac-2 is characterized by expression of scavenger receptor MARCO. Pseudotime and RNA velocity analysis revealed the ability of Mac-1 to transition and differentiate to Mac-2 and other GAM subtypes. We further found that the presence of these two populations of BMDMs are associated with the presence of tumor cells with stem cell and mesenchymal features. Bulk RNA-sequencing data demonstrates that gene signatures of these populations are associated with worse survival in GBM.

CONCLUSION

We used sc-RNAseq to identify a novel population of immature BMDMs that is associated with higher glioma grades. This population exhibited altered metabolic pathways and stem-like potentials to differentiate into other GAM populations including GAMs with upregulation of immunosuppressive pathways. Our results elucidate unique interactions between BMDMs and GBM tumor cells that potentially drives GBM progression and the more aggressive mesenchymal subtype. Our discovery of these novel BMDMs have implications in new therapeutic targets in improving the efficacy of immune-based therapies in GBM.

Abstract 2410: Supraphysiological androgens induce ferroptotic cell death in prostate cancer cells

Castration resistant prostate cancer (CRPC) first manifests as a sustained rise in the androgen-responsive gene, PSA, consistent with reactivation of a functioning androgen receptor (AR) axis. This observation led to the development of “second-line” therapies aimed at further blocking androgen/AR signaling. Unfortunately, resistance to these agents can also develop quickly. Paradoxically, several studies have suggested that the growth of AR-positive human CRPC cell lines may be inhibited by supraphysiologic levels of testosterone (SupT). These studies suggested that the adaptive reliance on AR signaling by CRPC cells becomes a therapeutic liability that can be exploited through the administration of SupT, which we termed as bipolar androgen therapy (BAT). Understanding how BAT works at the molecular and cellular levels might help in rationally combining BAT with other agents to achieve increased efficacy and tumor responses. Our data indicates that SupT induces autophagy mediated degradation of ferritin in prostate cancer (PCa) cells. Degradation of ferritin results in increase in labile iron pool increasing lipid peroxidation. Our data further indicates that SupT distinctly induces ferroptosis, a nonapoptotic regulated form of cell death induced by the accumulation of labile iron. Ferroptosis is thought to have tumor suppressing capabilities by clearing tumor cells via immune system activation. BAT has been discussed as a potential therapy for prostate cancer, but further research is needed to understand its full potential. Future combination of BAT with existing immunotherapeutics including immune checkpoint blockade may prove beneficial for treatment of CRPC.

Citation Format: Rajendra Kumar, Kavya Boyapati, Naiju Thomas, Deven Topiwala, Suthicha Kanacharoen, Olutosin Owoyemi, Max Coffey, Michael Carducci, Mark C. Markowski, Emmanuel S. Antonarakis, Drew Pardoll, Samuel Denmeade, Sushant K. Kachhap. Supraphysiological androgens induce ferroptotic cell death in prostate cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2410.

Risk factors for human papillomavirus-positive nonoropharyngeal squamous cell carcinoma

BACKGROUND

Human papillomavirus (HPV)-positive oropharyngeal cancer (HPV-OPC) is distinct from HPV-unassociated head and neck cancer. However, whether risk factors for HPV-positive oropharyngeal and nonoropharyngeal squamous cell cancer are the same is unclear.

METHODS

Incident cases of HPV-positive head and neck cell cancer and matched non-cancer controls were enrolled in a multi-institutional, prospective study examining risk factors, biomarkers, and survival.

RESULTS

HPV-nonOPC (n = 20) were more likely to be ever smokers than controls (n = 80, OR 3.49, 95%CI 1.11-10.9) and HPV-OPC (n = 185, OR 3.28, 95%CI 1.10-10.2). Compared with HPV-OPC, HPV-nonOPC were less likely to have had over 3 oral sexual partners (OR 0.29, 95%CI 0.06-0.9), more likely to have multimorbidity (OR 3.30, 95%CI 1.04-10.5), and less likely to have antibodies to HPV16 E6 (90% vs 28%, OR 0.05, 95%CI 0.02-0.2). HPV-nonOPC had worse 4-year OS (77% vs 96%, P = .001) and RFS (69% vs 94%, P < .001) than HPV-OPC.

CONCLUSIONS

HPV-positive nonoropharyngeal are distinct from HPV-positive oropharyngeal cancers.

RTHP-43 (LTBK-02). MULTI-TIME POINT EVALUATION OF PERIPHERAL BLOOD MYELOID-DERIVED SUPPRESSOR CELL AND LYMPHOCYTE POPULATIONS IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA RECEIVING ADJUVANT THERAPY

Alterations in peripheral blood cell populations, including myeloid cell subsets and lymphocytes, have been associated with poor prognostic outcomes in patients with glioblastoma (GBM). To date, evaluation of these populations has largely been on freeze-thawed samples at a limited number of time points. The purpose of our study is to identify the frequency and activation status of tumor-supportive myeloid and lymphocyte subsets during the course of standard adjuvant therapy in patients with GBM in fresh peripheral blood samples. We hypothesize that dysfunctional myeloid and lymphocyte populations expand during standard care temozolomide (TMZ)/radiation therapy (RT). We prospectively enrolled 16 patients with a new diagnosis of GBM that underwent maximal safe surgical resection. Twelve received standard adjuvant therapy consisting of six weeks of TMZ/RT. Four received alternative therapies: one experimental chemotherapeutic/three alternative radiation schemes. Peripheral blood was obtained seven times over the course of adjuvant therapy: prior to starting adjuvant therapy, five during treatment, and once one month after completion of therapy. Eleven patients completed all seven time points. Peripheral blood samples were analyzed by flow cytometry, focusing on immune checkpoints and critical markers of activation of systemic immunity. Available preliminary data demonstrate a median increase of 2.1% (-21.2–27.4%) in the frequency (%fx) of myeloid-derived suppressor cells (MDSC) after commencement of adjuvant therapy at time point 2 (TP2), compared to baseline. To date, 7/16 patients are alive and without evidence of recurrent disease on imaging. The majority of these patients had a decrease in %fx of MDSC at TP2, after starting adjuvant therapy, compared to baseline. The %fx of CD8+ T cells was greatest at TP7 (range: 21.7%-67.0%), one month after TMZ/RT, for most patients. PD-1 and FOXP3 expression by lymphocytes was variable across time points, suggesting the importance of additional factors which will be explored through future analyses. These early findings suggest that the immune response changes throughout the course of TMZ/RT. An understanding of these changes in the peripheral blood, termed immunodynamics in the context of our studies, may be valuable future tool to aid in optimizing immunity in patients with GBM.

IMMU-18. IMMUNOGENOMIC RESPONDER PHENOTYPE FROM A PHASE I TRIAL OF ANTI-LAG3 OR ANTI-CD137 ALONE AND IN COMBINATION WITH ANTI-PD-1 IN PATIENTS WITH RECURRENT GBM

BACKGROUND

Immune checkpoint inhibitors (ICIs) are not uniformly effective in glioblastoma treatment. Immunogenomic determinants may identify patients who are most likely to benefit from these therapies. Therefore, we compared the immunogenomic phenotype of a responder to combination anti-LAG-3 and anti-PD-1 therapy to non-responders.

METHODS

We performed T cell receptor (TCR) sequencing and gene expression analysis on pre-treatment, post-chemoradiation, and post-immunotherapy tumor specimens of glioblastoma patients treated with anti-LAG3 in combination with anti-PD-1 after first recurrence (NCT02658981, ongoing). We evaluated T cell clonotypes and immunophenotype of serially collected peripheral blood mononuclear cells (PBMCs) during treatment using multi-parametric flow cytometry.

RESULTS

To date, six patients have been enrolled in the initial anti-LAG-3 and anti-PD-1 cohort. One patient demonstrated complete response, one had stable disease, and four had progressive disease by radiographic evaluation. The responder demonstrated substantially higher TCR clonality in the resected tumor at initial diagnosis compared to non-responders (mean 0.028 vs. 0.005). Shared tumor infiltrating clonotypes with pre-immunotherapy PBMCs exhibited an increase in frequency from initial resection (6.8%) to resection at recurrence (20%). The responder’s tumor at initial resection exhibited increased gene signatures of PD1low CD8+ T cells, chemokine signaling, and interferon gamma pathways. On PBMC phenotypic analysis, the responder demonstrated significantly higher percentages of CD137+ CD8+T cells (median 8.38% vs 3.24%, p=0.02) and lower percentages of Foxp3+CD137+ CD4+T cells compared to non-responders (median 18.5% vs. 38.5%, p=0.006). Interestingly, dynamic analysis of PBMCs showed that the responder demonstrated a lower percentage of PD1+ CD8+ T cells pre-immunotherapy (median 2.5% vs.12.4%, p=0.002), with persistent decrease over the course of treatment while non-responders showed no consistent pattern.

CONCLUSION

Our preliminary results demonstrate significant differences in tumor and peripheral blood immunogenomic characteristics between responder and non-responders to anti-LAG3 and anti-PD-1 therapy. These immunogenomic characteristics may help stratify patients’ response to combination ICIs.

2845. Oral Antibiotic Use and Risk of Colorectal Cancer in the UK, 1989–2012: A Matched Case–Control Study

Background

Microbiome dysbiosis predisposes to colorectal cancer (CRC), but a population-based study of oral antibiotic exposure and CRC risk is lacking.

Methods

A matched case–control study (incident CRC cases and up to 5 matched controls) was conducted in the Clinical Practice Research Datalink (CPRD; 1989–2012). The CRPD is validated as 92% and 99% sensitive and specific for CRC detection (98% PPV). Antibiotic exposure [categorical and continuous terms (spline)] was investigated for risk pattern, stratified by tumor location, using conditional logistic regression and adjusting for known confounders.

Results

In total, 28,980 CRC cases and 137,077 controls were identified. Oral antibiotic use increased risk of colon cancer in a dose-dependent fashion (P_trend < 0.001), but effects differed by anatomic location. Colon cancer risk was greatest in the proximal colon and with antibiotics with anti-anaerobic activity (Figure 1). In contrast, an inverse association was detected between antibiotic use and rectal cancers (P_trend = 0.003), particularly with length of antibiotic exposure >60 days (adjusted odds ratio [AOR], 0.85, 95% CI 0.79–0.93) when compared with no antibiotic exposure. Nonlinearity models showed significantly increased colon cancer risk after minimal antibiotic use, but decreased rectum cancer risk with cumulative use of over 30 days (Figure 2). Penicillins, particularly ampicillin/amoxicillin, increased risk of colon cancer (AOR,1.09, [1.05–1.13]) whereas tetracyclines reduced risk for rectal cancer (AOR, 0.90, [0.84–0.97]). Significant interactions were detected between antibiotic use and tumor location (colon vs. rectum, P_interaction < 0.001). The antibiotic-cancer association was found for antibiotic exposure occurring >10 years before diagnosis (AOR, 1.17, [1.06–1.31]).

Conclusion

We conclude that oral antibiotic use associates with increased colon cancer risk, particularly in the right colon, but a reduced risk for rectal cancer. This effect heterogeneity suggests unabsorbed antibiotics impact gut microbiota in the right colon to enhance carcinogenesis whereas antibiotic anti-inflammatory or anti-proliferative actions may yield an inverse effect on carcinogenesis in the rectum.

Disclosures

Sara E. Cosgrove, MD, MS, Basilea: Consultant; Theravance: Consultant.

Abstract 517: Supraphysiological androgens activate innate immune signaling in prostate cancer

Castration resistance prostate cancer (CRPC) first manifests as a sustained rise in the androgen-responsive gene, PSA, consistent with reactivation of a functioning androgen receptor (AR) axis. This observation led to the development of “second-line” therapies aimed at further blocking androgen/AR signaling. Unfortunately, resistance to these agents can also develop quickly. Paradoxically, several studies have suggested that the growth of AR-positive human CRPC cell lines may be inhibited by supraphysiologic levels of testosterone (SupT). These studies suggested that the adaptive reliance on AR signaling by CRPC cells becomes a therapeutic liability that can be exploited through the administration of SupT, which we termed as bipolar androgen therapy (BAT). Understanding how BAT works at the molecular and cellular levels might help in rationally combining BAT with other agents to achieve increased efficacy and tumor responses. Our data indicates that SupT induces DNA double strand breaks (DSBs) in prostate cancer (PCa) cells. Unrepaired DSBs induced by SupT are routed for specialized autophagic degradation, termed nucleophagy. We further show that SupT-induced autophagosomal DNA can activate cytoplasmic DNA sensing pathways and downstream innate immune signaling. Based on our findings, we propose that BAT engages the immune system to inhibit tumor growth. Future combination of BAT with existing immunotherapeutics including immune checkpoint blockade may prove beneficial for treatment of CRPC.

Citation Format: Janet Mendonca, Olutosin Owoyemi, Marc Rosen, Michael Carducci, Mark Markowski, Emmanuel Antonarakis, Drew Pardoll, Samuel Denmeade, Sushant K. Kachhap. Supraphysiological androgens activate innate immune signaling in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 517.

Mouse PVRIG Has CD8+ T Cell-Specific Coinhibitory Functions and Dampens Antitumor Immunity

A limitation to antitumor immunity is the dysfunction of T cells in the tumor microenvironment, in part due to upregulation of coinhibitory receptors such as PD-1. Here, we describe that poliovirus receptor-related immunoglobulin domain protein (PVRIG) acts as a coinhibitory receptor in mice. Murine PVRIG interacted weakly with poliovirus receptor (PVR) but bound poliovirus receptor-like 2 (PVRL2) strongly, making the latter its principal ligand. As in humans, murine NK and NKT cells constitutively expressed PVRIG. However, when compared with humans, less PVRIG transcript and surface protein was detected in murine CD8⁺ T cells ex vivo However, activated CD8⁺ T cells upregulated PVRIG expression. In the mouse tumor microenvironment, infiltrating CD8⁺ T cells expressed PVRIG whereas its ligand, PVRL2, was detected predominantly on myeloid cells and tumor cells, mirroring the expression pattern in human tumors. PVRIG-deficient mouse CD8⁺ T cells mounted a stronger antigen-specific effector response compared with wild-type CD8⁺ T cells during acute Listeria monocytogenes infection. Furthermore, enhanced CD8⁺ T-cell effector function inhibited tumor growth in PVRIG^-/- mice compared with wild-type mice and PD-L1 blockade conferred a synergistic antitumor response in PVRIG^-/- mice. Therapeutic intervention with antagonistic anti-PVRIG in combination with anti-PD-L1 reduced tumor growth. Taken together, our results suggest PVRIG is an inducible checkpoint receptor and that targeting PVRIG-PVRL2 interactions results in increased CD8⁺ T-cell function and reduced tumor growth.See related article on p. 257.

Abstract LB-293: IL-2 diphtheria toxin fusion protein with anti-PD1: in mouse B16-F10 melanoma model

In tumor immunotherapy, regulatory T lymphocytes (Tregs) play an important role in the suppression of beneficial anti-tumor responses. In the non-immunogenic B16-F10 mouse melanoma model, tumors are found to be highly infiltrated by Tregs. DAB389IL-2 (Ontak, denileukin diftitox) is an IL-2 diphtheria toxin-related fusion protein that has been showed to deplete Tregs in both humans and mice. We treated mice with established B16F10 tumors with s-DAB389IL-2 (produced as a secreted protein from C. diphtheria) and observed a significant decrease in tumor growth rate in C57BL/6 mice. Also, s-DAB389IL-2 treatment increased the frequency of CD8+IFNγ+ T cells (TILs) in tumors and spleens. S-DAB389IL-2 treatment followed by PD-1 blockade resulted in greater tumor growth inhibition than either monotherapy alone. These data suggest that s-DAB389IL-2 plus anti-PD1 treatment can improve anti-tumor responses in non-immunogenic B16F10 melanoma and inhibit tumor growth. Additionally, we mutated a vascular leak inducing motif to construct s-DAB389IL-2 (V6A), which cause less vascular leak in vitro. S-DAB389IL-2 (V6A) inhibited tumor growth with similar efficacy to the original fusion toxin. As vascular leak is the major adverse effect caused by Ontak, DAB389IL-2 (V6A) shows promise as a better tolerated drug for further studies as a cancer immunotherapy.

Citation Format: Juan Fu, Drew Pardoll, Laurene Cheung. IL-2 diphtheria toxin fusion protein with anti-PD1: in mouse B16-F10 melanoma model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-293.

Abstract 1736: The combination of CXCR4 and checkpoint receptor inhibition improves survival in an orthotopic murine glioma model

Introduction: Angiogenesis plays an important role in the malignancy of glioblastoma (GBM) as well as in cancer immunotherapy. In addition, PD-1 checkpoint receptors are upregulated in GBM. We investigate the treatment effects of combination immunotherapy with checkpoint inhibitor anti-PD-1 and anti-CXCR4, an antagonist of a chemokine receptor involved in immune cell homing as well as vasculature development, in a murine glioma model.

Methods: C57Bl/6 mice were implanted with GL261-Luc+ glioma cells and randomized into 4 treatment arms: 1) control, 2) anti-PD-1 monotherapy, 3) anti-CXCR4 monotherapy, and 4) combination anti-PD-1 and anti-CXCR4 therapy. Overall survival and median survival were assessed. Brain samples from untreated mice were stained for CXCR4 expression on plasma membrane, and immunohistochemistry studies were conducted on human glioblastoma specimens as well. Immune cell activation and cell population changes were assessed through flow cytometry analysis.

Results: Both murine and human glioma specimens demonstrated robust positive expression of CXCR4 on tumor-infiltrating immune cells and endothelial cells of vasculature specific to the tumor bed. Combination therapy with anti-PD-1 and anti-CXCR4 conferred survival benefit compared to control and both monotherapy arms. Long-term survivors that had received combination therapy demonstrate immune memory and decreased populations of immunosuppressive, tumor-promoting immune cells. For instance, the monocytic myeloid-derived suppressor cell population was decreased in the brain in mice treated with combination therapy. The pattern of change in microglia was similar in the brain compartment for the combination treatment group as well.

Conclusion: Anti-CXCR4 and anti-PD-1 synergistic immunotherapy not only modulates the immune cell make-up of the glioma microenvironment but also affects vasculature within the tumor region. Dual therapy targeting both checkpoint and chemokine receptors results in improved survival rates.

Citation Format: Adela Wu, Pina Cardarelli, Miho Oyasu, Daniel Menezes, Paul Ponath, John Cogswell, Russell Maxwell, Andrew Luksik, Alice Hung, Eileen Kim, Zineb Belcaid, Henry Brem, Drew Pardoll, Michael Lim. The combination of CXCR4 and checkpoint receptor inhibition improves survival in an orthotopic murine glioma model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1736.

YAP Is Essential for Treg-Mediated Suppression of Antitumor Immunity

Regulatory T cells (Treg) are critical for maintaining self-tolerance and immune homeostasis, but their suppressive function can impede effective antitumor immune responses. FOXP3 is a transcription factor expressed in Tregs that is required for their function. However, the pathways and microenvironmental cues governing FOXP3 expression and Treg function are not completely understood. Herein, we report that YAP, a coactivator of the Hippo pathway, is highly expressed in Tregs and bolsters FOXP3 expression and Treg function in vitro and in vivo. This potentiation stemmed from YAP-dependent upregulation of activin signaling, which amplifies TGFβ/SMAD activation in Tregs. YAP deficiency resulted in dysfunctional Tregs unable to suppress antitumor immunity or promote tumor growth in mice. Chemical YAP antagonism and knockout or blockade of the YAP-regulated activin receptor similarly improved antitumor immunity. Thus, we identify YAP as an unexpected amplifier of a Treg-reinforcing pathway with significant potential as an anticancer immunotherapeutic target.Significance: Tregs suppress antitumor immunity, and pathways supporting their function can be novel immunotherapy targets. Here, the selective expression of YAP by Tregs, its importance for their function, and its unexpected enhancement of pro-Treg Activin/SMAD signaling are reported, as are validations of potential cancer-fighting antagonists of YAP and its regulatory targets. Cancer Discov; 8(8); 1026-43. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 899.

Caspase-1 from Human Myeloid-Derived Suppressor Cells Can Promote T Cell-Independent Tumor Proliferation

Immunosuppressive myeloid-derived suppressive cells (MDSCs) are characterized by their phenotypic and functional heterogeneity. To better define their T cell-independent functions within the tumor, sorted monocytic CD14⁺CD11b⁺HLA-DR^low/- MDSCs (mMDSC) from squamous cell carcinoma patients showed upregulated caspase-1 activity, which was associated with increased IL1β and IL18 expression. In vitro studies demonstrated that mMDSCs promoted caspase-1-dependent proliferation of multiple squamous carcinoma cell lines in both human and murine systems. In vivo, growth rates of B16, MOC1, and Panc02 were significantly blunted in chimeric mice adoptively transferred with caspase-1 null bone marrow cells under T cell-depleted conditions. Adoptive transfer of wild-type Gr-1⁺CD11b⁺ MDSCs from tumor-bearing mice reversed this antitumor response, whereas caspase-1 inhibiting thalidomide-treated MDSCs phenocopied the antitumor response found in caspase-1 null mice. We further hypothesized that MDSC caspase-1 activity could promote tumor-intrinsic MyD88-dependent carcinogenesis. In mice with wild-type caspase-1, MyD88-silenced tumors displayed reduced growth rate, but in chimeric mice with caspase-1 null bone marrow cells, MyD88-silenced tumors did not display differential tumor growth rate. When we queried the TCGA database, we found that caspase-1 expression is correlated with overall survival in squamous cell carcinoma patients. Taken together, our findings demonstrated that caspase-1 in MDSCs is a direct T cell-independent mediator of tumor proliferation. Cancer Immunol Res; 6(5); 566-77. ©2018 AACR.

Abstract 3843: Autologous resconstitution of human cancer and immune system in vivo

Correlative studies from checkpoint inhibitor trials have indcated that better understanding of human leukocytic trafficking into the human tumor microenvironment can expedite the translation of future immune-oncologic agents. In order to directly characterize signaling pathways that can regulate human leukocytic trafficking into the tumor, we have developed a completely autologous xenotransplanation method to reconstitute the human tumor immune microenvironment in vivo. When we analyzed the TCGA database of human head and neck squamous cell carcinoma(HNSCC), we found that STAT3 signaling was associated with worse prognostic mesenchymal subtye. We silenced STAT3 signaling in the tumor compartment in these autologously reconstituted humanized mice, and we noted increased tumor infiltrating lymphocytes and slower tumor growth rate. We also used this novel agents that can alter endogenous leukocytic infiltration into the tumor. Taken together, we present a valuable method to study individialized human tumor microenvironments in vivo without confound allgeneic responses.

Citation Format: Juan Fu, Rupashree Sen, David L Masica, Rachel Karchin, Drew Pardoll, Young Kim. Autologous resconstitution of human cancer and immune system in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3843. doi:10.1158/1538-7445.AM2017-3843

Micromanaging lupus nephritis: miR17-92 modulates TFH development and regulatory T cell activity

T follicular helper (TFH) cell provide crucial growth signals to germinal center (GC) B cells supporting antibody production. Tight control of TFH numbers maintains self-tolerance. Regulatory T (Treg) cells play a critical role in maintaining self-tolerance and controlling the magnitude of physiologic immune response. The Treg transcription factor forkhead box P3 (Foxp3) works in concert with other co-regulator molecules to determine suppressive phenotype of Treg. Compiling evidence show that aberrant TFH, GC responses and deficiencies of Treg are associated with systemic lupus erythematous and autoantibody production. We induce pristane nephropathy on T cell specific miR-17–92 knockout (miR-17–92−/−) mice. Mir17-92 T cell specific deficiency mitigates pristane induced-lupus nephropathy in mice. The mice showed less TFH cells, less GC B cells and lower autoantibody formation. Consistent with the reduction in autoantibody production, histological analysis revealed a lower mean renal histopathology score and less compliment deposition. We demonstrate that the miR17-92 cluster regulates TFH development by targeting Akt pathway. Moreover, miR17-92 mitigate the suppression function of Tregs by targeting Foxp3 co-regulators. Ectopic expression of miR17-92 downmodulates the suppression functions of Tregs and provides Tregs with partial effector activity via de-repression of cytokine genes. Our studies suggest that miR17-92 modulates lupus activity through critical regulation in TFH and Treg, unveiling the future therapeutic potential of microRNA manipulation in lupus nephritis.

Autologous reconstitution of human cancer and immune system in vivo

Correlative studies from checkpoint inhibitor trials have indicated that better understanding of human leukocytic trafficking into the human tumor microenvironment can expedite the translation of future immune-oncologic agents. In order to directly characterize signaling pathways that can regulate human leukocytic trafficking into the tumor, we have developed a completely autologous xenotransplantation method to reconstitute the human tumor immune microenvironment in vivo. We were able to genetically mark the engrafted CD34+ bone marrow cells as well as the tumor cells, and follow the endogenous leukocytic infiltration into the autologous tumor. To investigate human tumor intrinsic factors that can potentially regulate the immune cells in our system, we silenced STAT3 signaling in the tumor compartment. As expected, STAT3 signaling suppression in the tumor compartment in these autologously reconstituted humanized mice showed increased tumor infiltrating lymphocytes and reduction of arginase-1 in the stroma, which were associated with slower tumor growth rate. We also used this novel system to characterize human myeloid suppressor cells as well as to screen novel agents that can alter endogenous leukocytic infiltration into the tumor. Taken together, we present a valuable method to study individualized human tumor microenvironments in vivo without confounding allogeneic responses.

The Neurotrophic Factor Neuritin Maintains and Promotes the Function of Regulatory T cells in Autoimmunity and Cancer

Regulatory T cells (Tregs) enforce immune homeostasis and self-tolerance and inhibit both natural and induced anti-tumor immunity. Consequently, there is considerable interest in therapeutic Treg enhancement or blockade to treat inflammatory/autoimmune diseases and cancer, respectively. Targeting Tregs requires a comprehensive understanding of the factors important for their maintenance, differentiation and function. Here we report that neuritin, a conserved, gpi-anchored molecule important for the development, survival and function of neurons, is highly expressed by induced and natural Tregs. Furthermore, neuritin expression was found to promote the maintenance of the Treg pool by stabilizing Foxp3 expression and promoting the persistence of these cells. Knockout of the neuritin gene in Tregs or anti-neuritin antibody treatment mitigated both Treg-dependent inhibition of colitis and resolution of experimental autoimmune encephalitis. Also, tumors grew poorly in Nrn1−/− mice, which mobilized more robust anti-tumor immunity than their wild type litter mates evidenced by elevated IFNgamma production and reduced PD1 expression. Importantly, we also found that in Tregs, neuritin expression was closely linked to the functional differentiation of Tregs into an activated, peripheral tissue-homing phenotype. As such, neuritin deficiency resulted in an imbalance between “central”- and “effector”-like Treg populations and functions. These findings characterize this neurotrophin as a hitherto unappreciated immunoregulatory molecule and a potential target for therapies aimed at the fine-tuning of Treg function in cancer and inflammatory/autoimmune diseases.

Micromanging lupus nephritis: miR17-92 modulates regulatory T cell activity by targeting foxp3 co-regulators

Regulatory T (Treg) cells play a critical role in maintaining self-tolerance and controlling the magnitude of physiologic immune response. The Treg transcription factor forkhead box P3 (Foxp3) works in concert with other co-regulator molecules including Eos to determine suppressive phenotype of Treg. A strong correlation between systemic lupus erythematous and deficiencies of Treg has been reported. We induce pristane nephropathy on T cell specific miR-17-92 knockout mice. Mir17-92 T cell specific deficiency mitigates pristane induced-lupus nephropathy in mice. The mice showed less Th17 cells and lower autoantibody formation. Consistent with the reduction in autoantibody production, histological analysis revealed a lower mean renal histopathology score and less compliment deposition. We showed for the first time that one microRNA of the miR17-92 cluster, miR-17, regulates the suppression function of Tregs. We identify a gene target of miR-17, Eos, which regulates Tregs through Foxp3-mediated gene suppression. Ectopic expression of miR-17 downmodulates the suppression functions of Tregs and provides Tregs with partial effector activity via de-repression of cytokine genes. Our studies suggest that miR17-92 modulates Treg cell function by targeting Eos, unveiling the future therapeutic potential of microRNA manipulation in lupus nephritis.

Adoptive transfer of activated marrow-infiltrating lymphocytes induces measurable antitumor immunity in the bone marrow in multiple myeloma

Successful adoptive T cell therapy (ACT) requires the ability to activate tumor-specific T cells with the ability to traffic to the tumor site and effectively kill their target as well as persist over time. We hypothesized that ACT using marrow-infiltrating lymphocytes (MILs) in multiple myeloma (MM) could impart greater antitumor immunity in that they were obtained from the tumor microenvironment. We describe the results from the first clinical trial using MILs in MM. Twenty-five patients with either newly diagnosed or relapsed disease had their MILs harvested, activated and expanded, and subsequently infused on the third day after myeloablative therapy. Cells were obtained and adequately expanded in all patients with anti-CD3/CD28 beads plus interleukin-2, and a median of 9.5 × 10(8) MILs were infused. Factors indicative of response to MIL ACT included (i) the presence of measurable myeloma-specific activity of the ex vivo expanded product, (ii) low endogenous bone marrow T cell interferon-γ production at baseline, (iii) a CD8(+) central memory phenotype at baseline, and (iv) the generation and persistence of myeloma-specific immunity in the bone marrow at 1 year after ACT. Achieving at least a 90% reduction in disease burden significantly increased the progression-free survival (25.1 months versus 11.8 months; P = 0.01). This study demonstrates the feasibility and efficacy of MILs as a form of ACT with applicability across many hematologic malignancies and possibly solid tumors infiltrating the bone marrow.

Tissue matrix arrays for high-throughput screening and systems analysis of cell function

Cell and protein arrays have demonstrated remarkable utility in the high-throughput evaluation of biological responses; however, they lack the complexity of native tissue and organs. Here, we describe tissue extracellular matrix (ECM) arrays for screening biological outputs and systems analysis. We spotted processed tissue ECM particles as two-dimensional arrays or incorporated them with cells to generate three-dimensional cell-matrix microtissue arrays. We then investigated the response of human stem, cancer, and immune cells to tissue ECM arrays originating from 11 different tissues, and validated the 2D and 3D arrays as representative of the in vivo microenvironment through quantitative analysis of tissue-specific cellular responses, including matrix production, adhesion and proliferation, and morphological changes following culture. The biological outputs correlated with tissue proteomics, and network analysis identified several proteins linked to cell function. Our methodology enables broad screening of ECMs to connect tissue-specific composition with biological activity, providing a new resource for biomaterials research and translation.

Abstract B42: Cyclic dinucleotides (CDNs) activated DC and NK cells in antitumor immunotherapy

Abstract Our laboratory developed cell based cancer vaccines (STINGVAX) that was formulated with cyclic dinucleotides that and sensed by STING to phosphorylate interferon regulatory factor3 (IRF3) and nuclear factor kappa-light-chain-enhancer (NF-κB) to induce B cells and myeloid cells to secrete IFN-β. IFN-β can active NK cells through Tyk2-STAT1 signaling pathway, and we found increased number of activated NK cells in tumor bearing mice treated with STINGVAX. In the context of formulation with GM-CSF secreting cellular vaccines, the anti-tumor effect of CDN was dependent on IFNα/β receptors. We found that CDN activated NK cells both in vitro and in vivo, and at the molecular level, CDN increased TYK2-STAT1 signaling. When we tested STINGVAX's anti-tumor efficacy with NK depletion, its anti-tumor effect was abrogated.

Citation Format: Juan Fu, Qi Zhen, Drew Pardoll, Tom Dubensky, Young Kim. Cyclic dinucleotides (CDNs) activated DC and NK cells in antitumor immunotherapy. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B42.

Abstract 5033: Azacitidine pretreatment sensitizes NSCLC cells to interferon-γ

Epigenetic treatment and immune checkpoint blockade are novel therapeutic approaches being investigated in NSCLC. Our previous studies showed that DNA methyltransferase inhibitor azacitidine (AZA) treatment in NSCLC cell lines led to up-regulation of genes related to the response to interferon and adaptive immune attack. We hypothesize that Interferon-γ(IFN-γ), an immune effecter made primarily by activated T cells and NK cells, has a direct tumor suppression effect in NSCLC cells, which can be enhanced by the DNA hypomethylation agent.

To test this hypothesis, NSCLC cells (H838 and/or H1299) were first treated with or without 500nM AZA for 3 days, and then received IFN-γ. The samples were subsequently tested for cell viability, apoptosis, cell cycle, and gene expression assays. This preclinical study is part of the collective efforts to investigate the efficacy of combined epigenetic and immune therapy in NSCLC.

IFN-γ causes moderate direct growth inhibition in H838 and H1299 cells, which was enhanced, using cell viability assays as a readout, by pretreatment with AZA. The AZA sensitizing effect lasted at least 3 weeks and was not detectable 8 weeks after stopping treatment. This timing is consistent with initial reprogramming of the cells and eventual waning of this effect. Flow cytometry studies showed that AZA enhances lung cell apoptosis induced by IFN-γ. However, no significant change in cell cycle was observed. To examine the mechanisms behind these effects on cell growth, we further determined how AZA altered IFN-γ induced gene expression in H1299 cells, first using Agilent expression arrays, and then validating specific changes in key IFN and cell death pathway genes with RT-PCR based methods. IFN-γ significantly up-regulated a group of known IFN targeted genes, including IFI27, IFITM1, ISG20, ICAM1, CCL5, CXCL10, MX1 and others, and this upregulation was further enhanced by AZA pretreatment. AZA also enhanced IFN-γ induced expression of CASP1, CASP4, TNFSF 10, and BCL2A. These AZA enhanced IFN-γ induced genes are important in tumor immune response and evasion, cell death, cytokine response and other critical cellular process.

Our studies demonstrated that AZA enhanced lung cancer cell response to the immune effecter IFN-γ. This supports the clinical exploration of epigenetic “priming” and its combination with subsequent immune therapy in NSCLC treatment. It may also provide mechanistically derived biomarkers that can be used to monitor and predict epigenetic and immune response in NSCLC.

Citation Format: Kai He, Xin Zhang, Ludmila Danilova, Xiaoyu Pan, Julie Brahmer, Drew Pardoll, Malcolm Brock, Stephen Baylin, James Herman, John Wrangle. Azacitidine pretreatment sensitizes NSCLC cells to interferon-γ. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5033. doi:10.1158/1538-7445.AM2015-5033

Abstract 1312: Transcriptional signatures associated with lack of response to anti-PD-1 therapy in patients with renal cell carcinoma

Background: The PD-1/PD-L1 immune checkpoint pathway limits host immune responses to cancer in the local tumor microenvironment. Monoclonal antibodies blocking PD-1 or PD-L1 have shown promising clinical results in a variety of advanced human cancers including renal cell carcinoma (RCC). We previously reported that response to anti-PD-1 therapy correlates with PD-L1 expression by tumor cells in pre-treatment biopsies. Although 20-30% of patients with metastatic RCC respond to anti-PD-1 therapy, many patients with PD-L1+ tumors still do not respond. The current study was undertaken to understand mechanisms underlying the failure of anti-PD-1 targeted therapies in patients with PD-L1+ RCC.

Methods: The specimen cohort included formalin-fixed, paraffin-embedded (FFPE) pre-treatment tumor biopsies expressing PD-L1, derived from 13 RCC patients treated with nivolumab (anti-PD-1) at a single institution [4 responders (R), 9 non-responders (NR); RECIST]. PD-L1+ specimens were defined as those having ≥5% of tumor cells with cell surface PD-L1 expression by immunohistochemistry (IHC). RNA was isolated from PD-L1+ regions on FFPE slides. Whole genome microarray profiling with cDNA-mediated Annealing, Selection, extension and Ligation (DASL) was performed. Global gene expression analysis was profiled using BRBArrayTools. Multiplex quantitative (q)RT-PCR was used to validate differential expression of genes of interest, and IHC was used to validate protein expression from select genes, in R vs. NR.

Results: Whole genome analysis revealed 234 transcripts that were differentially expressed in R vs. NR (p value ≤ 0.01, fold change ≥1.5). Ingenuity Pathway Analysis (IPA) of these transcripts showed the involvement of metabolic and immune pathways as well as genes encoding oxidation stress response molecules. Multiplex qRT-PCR for a subset of 60 differentially expressed genes validated significant over-expression of genes with metabolic functions, such as drug glucuronidation (UGT1A6/A1/A3), glucose transport (SLC23A1), and mitochondrial oxidation (AKR1C3) in NR vs. R. Conversely, R were found to overexpress immune markers such as BMP1, which has been shown to positively regulate PD-L1 expression, and CCL3 involved in leukocyte migration.

Conclusions: Although tumor PD-L1 expression is associated with an increased likelihood of response to anti-PD-1/PD-L1 therapy, tumor cell-intrinsic metabolism may contribute to treatment resistance in PD-L1+ patients. Our data suggest that overexpression of certain metabolic factors may contribute to the failure of PD-L1+ RCC to respond to PD-1 pathway blockade, while immune factors in the tumor immune microenvironment may contribute to success. Treatment strategies that co-target these factors may be needed to enhance responses to anti-PD-1 immunotherapy in RCC.

Supported by grants from Bristol-Myers Squibb and Stand Up to Cancer

Citation Format: Maria Libera Ascierto, Tracee McMiller, Alan Berger, Robert A. Anders, Chris Cheadle, Haiying Hu, Charles Drake, Drew Pardoll, Janis Taube, Suzanne L. Topalian. Transcriptional signatures associated with lack of response to anti-PD-1 therapy in patients with renal cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1312. doi:10.1158/1538-7445.AM2015-1312

Cancer and the Immune System: Basic Concepts and Targets for Intervention

A number of consensuses regarding cancer immunology have recently emerged from both preclinical immunotherapy models and analysis of cancer patients. First and foremost, the natural state of endogenous tumor reactive T cells is characterized by general hyporesponsiveness or anergy. This is likely due to a number of mechanisms that tumors use to induce tolerance as they develop. While many of the newer generation vaccines can effectively transfer antigen to and activate dendritic cells, T-cell tolerance remains a major barrier that is difficult to overcome by vaccination alone. Preclinical models demonstrate that for poorly immunogenic tumors, once tolerance has been established, therapeutic vaccines alone are ineffective at curing animals with a significant established tumor burden. However, combination strategies of vaccination together with inhibitors of immunologic checkpoints and agonists for co-stimulatory pathways are proving capable of overcoming tolerance and generating significant anti-tumor responses even in cases of established metastatic cancer.

Infectious tolerance of LAG-3+ regulatory T cells with attenuated T-bet induction (IRC11P.433)

Infectious tolerance describes the maintenance of tolerance by a small number of antigen-specific regulatory T (Treg) cells through converting naïve T cells into further cohorts of Treg cells in vivo. Thus a very small number of antigen-specific Treg cells can be so efficient in exerting long-term suppressive effect with self-perpetuating immune homeostasis in vivo. We have previously shown LAG-3+ CD4+ Treg cells are engaged in dominant immune regulation in vivo. Here we revealed that LAG-3+ CD4+ Treg cells pass on the suppressive activity to the naïve CD4+ T cells they suppress and enable them to become the next generation of Treg cells. The effector function of suppressed CD4+ T cells is modulated with diminished T-bet induction and interferon-γ production. However, they still expand, acquire LAG-3 expression and in turn suppress the activation of another batch of naïve CD4+ T cells in vivo. The suppressed cells express elevated level of active TGF-β but not IL-10. Suppressed cells with Foxp-3 expression acquire LAG-3, although the overall Foxp-3 expression is not increased. Our results imply activation with attenuated effector function as the major mechanism by which LAG+ CD4+ Treg cells propagates their suppressive abilities and the infectious tolerance.

Enterotoxigenic Bacteroides fragilis induces oncogenic regulatory T cells (TUM9P.1000)

Enterotoxigenic Bacteroides fragilis (ETBF) is an occasional inducer of inflammatory diarrhea and acute colitis, and preliminary studies have recently demonstrated an association with inflammatory bowel disease and colorectal cancer in humans. The pathogenesis of ETBF can largely be attributed to the secretion of a toxin, BFT (B. fragilis toxin), which has a profound effect on the colonic microenvironment. BFT promotes cleavage of E-cadherin, activates NF-kB and Wnt/b-catenin signaling, and stimulates the secretion of pro-inflammatory cytokines, such as IL-6, IL-8, and TNF-a. The inflammation associated with ETBF is characterized by robust IL-17 cytokine secretion, and in MinAPC/+ mice, ETBF induces IL-17-dependent distal colon tumorigenesis. In an attempt to elucidate the immunologic differences between the distal and proximal colon, we found ETBF induced a greater density of Foxp3+ Tregs in the distal colon. Furthermore, those Tregs initiate the oncogenic IL-17 response to ETBF. While investigating the Treg and IL-17 responses to ETBF, we found that depletion of Tregs in ETBF-colonized C57BL/6 Foxp3DTR-GFP MinAPC/+ mice mitigated intestinal IL-17 production as well as colonic neoplasia. Antibody blockade of IL-2, but not genetic ablation of IFN-γ, restored ETBF-induced microadenoma formation. These findings unveil a new mechanism of cancer-induced inflammation whereby an overt Treg response to intestinal bacteria promotes colon tumorigenesis.