Combined IL6 and CCR2 blockade potentiates antitumor activity of NK cells in HPV-negative head and neck cancer

BACKGROUND

While T cell-activating immunotherapies against recurrent head and neck squamous cell carcinoma (HNSCC) have shown impressive results in clinical trials, they are often ineffective in the majority of patients. NK cells are potential targets for immunotherapeutic intervention; however, the setback in monalizumab-based therapy in HNSCC highlights the need for an alternative treatment to enhance their antitumor activity.

METHODS

Single-cell RNA sequencing (scRNA-seq) and TCGA HNSCC datasets were used to identify key molecular alterations in NK cells. Representative HPV-positive ( +) and HPV-negative ( -) HNSCC cell lines and orthotopic mouse models were used to validate the bioinformatic findings. Changes in immune cells were examined by flow cytometry and immunofluorescence.

RESULTS

Through integration of scRNA-seq data with TCGA data, we found that the impact of IL6/IL6R and CCL2/CCR2 signaling pathways on evasion of immune attack by NK cells is more pronounced in the HPV - HNSCC cohort compared to the HPV + HNSCC cohort. In orthotopic mouse models, blocking IL6 with a neutralizing antibody suppressed HPV - but not HPV + tumors, which was accompanied by increased tumor infiltration and proliferation of CD161+ NK cells. Notably, combining the CCR2 chemokine receptor antagonist RS504393 with IL6 blockade resulted in a more pronounced antitumor effect that was associated with more activated intratumoral NK cells in HPV - HNSCC compared to either agent alone.

CONCLUSIONS

These findings demonstrate that dual blockade of IL6 and CCR2 pathways effectively enhances the antitumor activity of NK cells in HPV-negative HNSCC, providing a novel strategy for treating this type of cancer.

Radiation and anti-PD-L1 synergize by stimulating a stem-like T cell population in the tumor-draining lymph node

Radiotherapy (RT) and anti-PD-L1 synergize to enhance local and distant (abscopal) tumor control. However, clinical results in humans have been variable. With the goal of improving clinical outcomes, we investigated the underlying synergistic mechanism focusing on a CD8+ PD-1+ Tcf-1+ stem-like T cell subset in the tumor-draining lymph node (TdLN). Using murine melanoma models, we found that RT + anti-PD-L1 induces a novel differentiation program in the TdLN stem-like population which leads to their expansion and differentiation into effector cells within the tumor. Our data indicate that optimal synergy between RT + anti-PD-L1 is dependent on the TdLN stem-like T cell population as either blockade of TdLN egress or specific stem-like T cell depletion reduced tumor control. Together, these data demonstrate a multistep stimulation of stem-like T cells following combination therapy which is initiated in the TdLN and completed in the tumor.

Clinically relevant orthotopic pancreatic cancer models for adoptive T cell transfer therapy

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive tumor. Prognosis is poor and survival is low in patients diagnosed with this disease, with a survival rate of ~12% at 5 years. Immunotherapy, including adoptive T cell transfer therapy, has not impacted the outcomes in patients with PDAC, due in part to the hostile tumor microenvironment (TME) which limits T cell trafficking and persistence. We posit that murine models serve as useful tools to study the fate of T cell therapy. Currently, genetically engineered mouse models (GEMMs) for PDAC are considered a "gold-standard" as they recapitulate many aspects of human disease. However, these models have limitations, including marked tumor variability across individual mice and the cost of colony maintenance.

METHODS

Using flow cytometry and immunohistochemistry, we characterized the immunological features and trafficking patterns of adoptively transferred T cells in orthotopic PDAC (C57BL/6) models using two mouse cell lines, KPC-Luc and MT-5, isolated from C57BL/6 KPC-GEMM (KrasLSL-G12D/+p53-/- and KrasLSL-G12D/+p53LSL-R172H/+, respectively).

RESULTS

The MT-5 orthotopic model best recapitulates the cellular and stromal features of the TME in the PDAC GEMM. In contrast, far more host immune cells infiltrate the KPC-Luc tumors, which have less stroma, although CD4+ and CD8+ T cells were similarly detected in the MT-5 tumors compared with KPC-GEMM in mice. Interestingly, we found that chimeric antigen receptor (CAR) T cells redirected to recognize mesothelin on these tumors that signal via CD3ζ and 41BB (Meso-41BBζ-CAR T cells) infiltrated the tumors of mice bearing stroma-devoid KPC-Luc orthotopic tumors, but not MT-5 tumors.

CONCLUSIONS

Our data establish for the first time a reproducible and realistic clinical system useful for modeling stroma-rich and stroma-devoid PDAC tumors. These models shall serve an indepth study of how to overcome barriers that limit antitumor activity of adoptively transferred T cells.

Progressively Enhancing Stemness of Adoptively Transferred T Cells with PI3Kδ Blockade Improves Metabolism and Antitumor Immunity

Generating stem-like memory T cells (TSCM) is a potential strategy to improve adoptive immunotherapy. Elucidating optimal ways to modulate signaling pathways that enrich TSCM properties could identify approaches to achieve this goal. We discovered herein that blocking the PI3Kδ pathway pharmaceutically to varying degrees can generate T cells with increasingly heightened stemness properties, based on the progressive enrichment of the transcription factors Tcf1 and Lef1. T cells with enhanced stemness features exhibited metabolic plasticity, marked by improved mitochondrial function and glucose uptake after tumor recognition. Conversely, T cells with low or medium stemness were less metabolically dynamic, vulnerable to antigen-induced cell death, and expressed more inhibitory checkpoint receptors. Only T-cell receptor-specific or chimeric antigen receptor (CAR)-specific T cells with high stemness persisted in vivo and mounted protective immunity to tumors. Likewise, the strongest level of PI3Kδ blockade in vitro generated human tumor-infiltrating lymphocytes and CAR T cells with elevated stemness properties, in turn bolstering their capacity to regress human solid tumors. The stemness level of T cells in vitro was important, ultimately impacting their efficacy in mice bearing three distinct solid tumors. Lef1 and Tcf1 sustained antitumor protection by donor high CD8+ TSCM or CD4+ Th17SCM, as deletion of either one compromised the therapeutic efficacy. Collectively, these findings highlight the importance of strategic modulation of PI3Kδ signaling in T cells to induce stemness and lasting protective responses to solid tumors.

SIGNIFICANCE

Elevating T-cell stemness by progressively blocking PI3Kδ signaling during ex vivo manufacturing of adoptive cell therapies alters metabolic and functional properties to enhance antitumor immunity dependent on Tcf1 and Lef1.

Distinct host preconditioning regimens differentially impact the antitumor potency of adoptively transferred Th17 cells

Background

Mechanisms by which distinct methods of host preconditioning impact the efficacy of adoptively transferred antitumor T helper cells is unknown.

Methods

CD4 + T cells with a transgenic TCR that recognize TRP-1 melanoma antigen were polarized to the T helper 17 (Th17) phenotype and then transferred into melanoma-bearing mice preconditioned with either total body irradiation or chemotherapy.

Results

We found that preconditioning mice with a non-myeloablative dose of total body irradiation (TBI of 5 Gy) was more effective than using an equivalently dosed non-myeloablative chemotherapy (CTX at 200 mg/kg) at augmenting therapeutic activity of anti-tumor TRP-1 Th17 cells. Anti-tumor Th17 cells engrafted better following preconditioning with TBI and regressed large established melanoma in all animals. Conversely, only half of mice survived long-term when preconditioned with CTX and infused with anti-melanoma Th17 cells. IL-17 and IFN-g produced by the infused Th17 cells, were detected in animals given either TBI or CTX preconditioning. Interestingly, inflammatory cytokines (G-CSF, IL-6, MCP-1, IL-5, and KC) were significantly elevated in the serum of mice preconditioned with TBI versus CTX after Th17 therapy.

Conclusions

Our results indicate, for the first time, that the antitumor response, persistence, and cytokine profiles resulting from Th17 therapy are impacted by the specific regimen of host preconditioning. This work is important for understanding mechanisms that promote long-lived responses by ACT, particularly as CD4 + based T cell therapies are now emerging in the clinic.

Top advances of the year: Pancreatic cancer

This commentary highlights the key recent advances made in the field of pancreatic cancer. Although there has yet to be a major breakthrough in clinical care for the majority of patients, significant strides have been made in understanding the complex biology of this malignancy and identifying new therapeutic targets.

Trans-vaccenic acid reprograms CD8+ T cells and anti-tumour immunity

Diet-derived nutrients are inextricably linked to human physiology by providing energy and biosynthetic building blocks and by functioning as regulatory molecules. However, the mechanisms by which circulating nutrients in the human body influence specific physiological processes remain largely unknown. Here we use a blood nutrient compound library-based screening approach to demonstrate that dietary trans-vaccenic acid (TVA) directly promotes effector CD8+ T cell function and anti-tumour immunity in vivo. TVA is the predominant form of trans-fatty acids enriched in human milk, but the human body cannot produce TVA endogenously1. Circulating TVA in humans is mainly from ruminant-derived foods including beef, lamb and dairy products such as milk and butter2,3, but only around 19% or 12% of dietary TVA is converted to rumenic acid by humans or mice, respectively4,5. Mechanistically, TVA inactivates the cell-surface receptor GPR43, an immunomodulatory G protein-coupled receptor activated by its short-chain fatty acid ligands6-8. TVA thus antagonizes the short-chain fatty acid agonists of GPR43, leading to activation of the cAMP-PKA-CREB axis for enhanced CD8+ T cell function. These findings reveal that diet-derived TVA represents a mechanism for host-extrinsic reprogramming of CD8+ T cells as opposed to the intrahost gut microbiota-derived short-chain fatty acids. TVA thus has translational potential for the treatment of tumours.

Phase II trial of nivolumab and metformin in patients with treatment-refractory microsatellite stable metastatic colorectal cancer

BACKGROUND

Preclinical studies showed metformin reduces exhaustion of tumor-infiltrating lymphocytes and potentiates programmed cell death protein-1 (PD-1) blockade. We hypothesized that metformin with nivolumab would elicit potent antitumor and immune modulatory activity in metastatic microsatellite stable (MSS) colorectal cancer (CRC). We evaluated this hypothesis in a phase II study.

METHODS

Nivolumab (480 mg) was administered intravenously every 4 weeks while metformin (1000 mg) was given orally, two times per day following a 14-day metformin only lead-in phase. Patients ≥18 years of age, with previously treated, stage IV MSS CRC, and Eastern Cooperative Oncology Group 0-1, having received no prior anti-PD-1 agent were eligible. The primary endpoint was overall response rate with secondary endpoints of overall survival (OS) and progression-free survival (PFS). Correlative studies using paired pretreatment/on-treatment biopsies and peripheral blood evaluated a series of immune biomarkers in the tumor microenvironment and systemic circulation using ChipCytometry and flow cytometry.

RESULTS

A total of 24 patients were enrolled, 6 patients were replaced per protocol, 18 patients had evaluable disease. Of the 18 evaluable patients, 11/18 (61%) were women and the median age was 58 (IQR 50-67). Two patients had stable disease, but no patients had objective response, hence the study was stopped for futility. Median OS and PFS was 5.2 months (95% CI (3.2 to 11.7)) and 2.3 months (95% CI (1.7 to 2.3)). Most common grade 3/4 toxicities: Anemia (n=2), diarrhea (n=2), and fever (n=2). Metformin alone failed to increase the infiltration of T-cell subsets in the tumor, but combined metformin and nivolumab increased percentages of tumor-infiltrating leukocytes (p=0.031). Dual treatment also increased Tim3+ levels in patient tissues and decreased naïve CD8+T cells (p=0.0475).

CONCLUSIONS

Nivolumab and metformin were well tolerated in patients with MSS CRC but had no evidence of efficacy. Correlative studies did not reveal an appreciable degree of immune modulation from metformin alone, but showed trends in tumorous T-cell infiltration as a result of dual metformin and PD-1 blockade despite progression in a majority of patients.

Impact of nodal status in determining multimodal treatment strategies in non-cardia gastric cancer

BACKGROUND

Patients with resectable noncardia gastric cancer may be subjected to perioperative chemotherapy (PEC), postoperative chemoradiation (POCR), or postoperative chemotherapy (POC). We analyzed these treatment strategies to determine optimal therapy based on nodal status.

METHOD

The National Cancer Database was used to identify patients with resected noncardia gastric cancer (2004-2016). Patients were stratified based on clinical nodal status-negative (cLN-), positive (cLN+) and pathological nodal status (pLN-, pLN+). In cLN- patients who underwent upfront resection and were upstaged to pLN+, POC, and POCR were compared. Overall survival (OS) with PEC, POCR, and POC were compared in cLN- and cLN+.

RESULTS

We identified 6142 patients (cLN-: 3831; cLN+: 2311). In cLN- patients who underwent upfront resection (N = 3423), 69% were upstaged to pLN+ disease (N = 2499; POCR = 1796, POC = 703). On MVA, POCR was associated with significantly improved OS when compared to POC (hazard ratio [HR]: 0.75; p < 0.001). In patients with cLN- disease (PEC = 408; POCR = 2439; POC = 984), PEC(HR: 0.77; p = 0.01) and POCR(HR: 0.81; p < 0.001) were associated with improved OS compared with POC. In cLN+ group (PEC = 452; POCR = 1284; POC = 575), POCR was associated with improved OS compared with POC (HR: 0.81; p < 0.01), and trend towards improved OS was noted when PEC(HR: 0.83; p = 0.055) was compared with POC.

CONCLUSION

Postoperative chemoradiation may be the preferred treatment strategy over postoperative chemotherapy in non-cardia gastric cancer patients who receive upfront resection and are upstaged from clinically node negative to pathologically node positive disease.

Perspectives in Immunotherapy: meeting report from Immunotherapy Bridge (Naples, November 30th-December 1st, 2022)

The discovery and development of novel treatments that harness the patient's immune system and prevent immune escape has dramatically improved outcomes for patients across cancer types. However, not all patients respond to immunotherapy, acquired resistance remains a challenge, and responses are poor in certain tumors which are considered to be immunologically cold. This has led to the need for new immunotherapy-based approaches, including adoptive cell transfer (ACT), therapeutic vaccines, and novel immune checkpoint inhibitors. These new approaches are focused on patients with an inadequate response to current treatments, with emerging evidence of improved responses in various cancers with new immunotherapy agents, often in combinations with existing agents. The use of cell therapies, drivers of immune response, and trends in immunotherapy were the focus of the Immunotherapy Bridge (November 30th-December 1st, 2022), organized by the Fondazione Melanoma Onlus, Naples, Italy, in collaboration with the Society for Immunotherapy of Cancer.

Augmenting TCR signal strength and ICOS costimulation results in metabolically fit and therapeutically potent human CAR Th17 cells

IL-17-producing antigen-specific human T cells elicit potent antitumor activity in mice. Yet, refinement of this approach is needed to position it for clinical use. While activation signal strength regulates IL-17 production by CD4+ T cells, the degree to which T cell antigen receptor (TCR) and costimulation signal strength influences Th17 immunity remains unknown. We discovered that decreasing TCR/costimulation signal strength by incremental reduction of αCD3/costimulation beads progressively altered Th17 phenotype. Moreover, Th17 cells stimulated with αCD3/inducible costimulator (ICOS) beads produced more IL-17A, IFNγ, IL-2, and IL-22 than those stimulated with αCD3/CD28 beads. Compared with Th17 cells stimulated with the standard, strong signal strength (three beads per T cell), Th17 cells propagated with 30-fold fewer αCD3/ICOS beads were less reliant on glucose and favored the central carbon pathway for bioenergetics, marked by abundant intracellular phosphoenolpyruvate (PEP). Importantly, Th17 cells stimulated with weak αCD3/ICOS beads and redirected with a chimeric antigen receptor that recognizes mesothelin were more effective at clearing human mesothelioma. Less effective CAR Th17 cells generated with high αCD3/ICOS beads were rescued by overexpressing phosphoenolpyruvate carboxykinase 1 (PCK1), a PEP regulator. Thus, Th17 therapy can be improved by using fewer activation beads during manufacturing, a finding that is cost effective and directly translatable to patients.

Short-Term Soy Bread Intervention Leads to a Dose-Response Increase in Urinary Isoflavone Metabolites and Satiety in Chronic Pancreatitis

Patients with chronic pancreatitis (CP) are particularly vulnerable to nutrient malabsorption and undernutrition caused by the underlying pathology of their disease. Dietary intervention trials involving soy isoflavones in patients with CP are limited and isoflavone metabolites have not yet been reported. We hypothesized soy bread containing plant-based protein, dietary fiber, and isoflavones would be well-tolerated and restore gut functional capacity which would lead to isoflavone metabolites profiles like those of healthy populations. Participants (n = 9) received 1 week of soy bread in a dose-escalation design (1 to 3 slices/day) or a 4-week maximally tolerated dose (n = 1). Dietary adherence, satiety, and palatability were measured. Isoflavone metabolites from 24 h urine collections were quantified using high-performance liquid chromatography. A maximum dose of three slices (99 mg of isoflavones) of soy bread per day was achieved. Short-term exposure to soy bread showed a significant dose-response increase (p = 0.007) of total isoflavones and their metabolites in urine. With increasing slices of soy bread, dietary animal protein intake (p = 0.009) and perceived thirst (p < 0.001) significantly decreased with prolonged satiety (p < 0.001). In this study, adherence to short-term intervention with soy bread in CP patients was excellent. Soy isoflavones were reliably delivered. These findings provide the foundation for evaluating a well-characterized soy bread in supporting healthy nutrition and gut function in CP.

Data from Melanoma Cells Exhibit Variable Signal Transducer and Activator of Transcription 1 Phosphorylation and a Reduced Response to IFN-α Compared with Immune Effector Cells.. [DOI: 10.1158/1078-0432.c.6517377.v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

<div>Abstract<p><b>Purpose:</b> IFN-α is administered to melanoma patients and its endogenous production is essential for immune-mediated tumor recognition. We hypothesized that a reduced capacity for signal transducer and activator of transcription (STAT) 1 activation allows melanoma cells to evade the direct actions of IFN-α.</p><p><b>Experimental Design:</b> Tyr⁷⁰¹-phosphorylated STAT1 (P-STAT1) was measured by flow cytometry in IFN-α–stimulated human melanoma cell lines, melanoma cells derived from patient tumors, and peripheral blood mononuclear cells (PBMC). Expression of other Janus-activated kinase (Jak)-STAT intermediates (STAT1, STAT2, Jak1, tyrosine kinase 2, IFN-α receptor, STAT3, and STAT5) was evaluated by flow cytometry, immunoblot, or immunohistochemistry.</p><p><b>Results:</b> Significant variability in P-STAT1 was observed in human melanoma cell lines following IFN-α treatment (<i>P</i> < 0.05) and IFN-α–induced P-STAT1 correlated with the antiproliferative effects of IFN-α (<i>P</i> = 0.042). Reduced formation of P-STAT1 was not explained by loss of Jak-STAT proteins or enhanced STAT5 signaling as reported previously. Basal levels of P-STAT3 were inversely correlated with IFN-α–induced P-STAT1 in cell lines (<i>P</i> = 0.013). IFN-α–induced formation of P-STAT1 was also variable in melanoma cells derived from patient tumors; however, no relationship between P-STAT3 and IFN-α–induced P-STAT1 was evident. Because IFN-α acts on both tumor and immune cells, we examined the ability of IFN-α to induce P-STAT1 in patient-derived melanoma cells and PBMCs. IFN-α induced significantly lower levels of P-STAT1 in melanoma cells compared with matched PBMCs (<i>P</i> = 0.046). Melanoma cells and human melanocytes required 10-fold higher IFN-α doses to exert P-STAT1 levels comparable with PBMCs.</p><p><b>Conclusions:</b> Melanoma cells are variable in their IFN-α responsiveness, and cells of the melanocytic lineage exhibit a lower capacity for IFN-α–induced Jak-STAT signaling compared with immune cells.</p></div>

Supplementary Data from Melanoma Cells Exhibit Variable Signal Transducer and Activator of Transcription 1 Phosphorylation and a Reduced Response to IFN-α Compared with Immune Effector Cells.. [DOI: 10.1158/1078-0432.22439997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Supplementary Data from Melanoma Cells Exhibit Variable Signal Transducer and Activator of Transcription 1 Phosphorylation and a Reduced Response to IFN-α Compared with Immune Effector Cells

Data from Melanoma Cells Exhibit Variable Signal Transducer and Activator of Transcription 1 Phosphorylation and a Reduced Response to IFN-α Compared with Immune Effector Cells.. [DOI: 10.1158/1078-0432.c.6517377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

<div>Abstract<p><b>Purpose:</b> IFN-α is administered to melanoma patients and its endogenous production is essential for immune-mediated tumor recognition. We hypothesized that a reduced capacity for signal transducer and activator of transcription (STAT) 1 activation allows melanoma cells to evade the direct actions of IFN-α.</p><p><b>Experimental Design:</b> Tyr⁷⁰¹-phosphorylated STAT1 (P-STAT1) was measured by flow cytometry in IFN-α–stimulated human melanoma cell lines, melanoma cells derived from patient tumors, and peripheral blood mononuclear cells (PBMC). Expression of other Janus-activated kinase (Jak)-STAT intermediates (STAT1, STAT2, Jak1, tyrosine kinase 2, IFN-α receptor, STAT3, and STAT5) was evaluated by flow cytometry, immunoblot, or immunohistochemistry.</p><p><b>Results:</b> Significant variability in P-STAT1 was observed in human melanoma cell lines following IFN-α treatment (<i>P</i> < 0.05) and IFN-α–induced P-STAT1 correlated with the antiproliferative effects of IFN-α (<i>P</i> = 0.042). Reduced formation of P-STAT1 was not explained by loss of Jak-STAT proteins or enhanced STAT5 signaling as reported previously. Basal levels of P-STAT3 were inversely correlated with IFN-α–induced P-STAT1 in cell lines (<i>P</i> = 0.013). IFN-α–induced formation of P-STAT1 was also variable in melanoma cells derived from patient tumors; however, no relationship between P-STAT3 and IFN-α–induced P-STAT1 was evident. Because IFN-α acts on both tumor and immune cells, we examined the ability of IFN-α to induce P-STAT1 in patient-derived melanoma cells and PBMCs. IFN-α induced significantly lower levels of P-STAT1 in melanoma cells compared with matched PBMCs (<i>P</i> = 0.046). Melanoma cells and human melanocytes required 10-fold higher IFN-α doses to exert P-STAT1 levels comparable with PBMCs.</p><p><b>Conclusions:</b> Melanoma cells are variable in their IFN-α responsiveness, and cells of the melanocytic lineage exhibit a lower capacity for IFN-α–induced Jak-STAT signaling compared with immune cells.</p></div>

Supplementary Data from Melanoma Cells Exhibit Variable Signal Transducer and Activator of Transcription 1 Phosphorylation and a Reduced Response to IFN-α Compared with Immune Effector Cells.. [DOI: 10.1158/1078-0432.22439997.v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Supplementary Data from Melanoma Cells Exhibit Variable Signal Transducer and Activator of Transcription 1 Phosphorylation and a Reduced Response to IFN-α Compared with Immune Effector Cells

The degree of T cell stemness differentially impacts the potency of adoptive cancer immunotherapy in a Lef-1 and Tcf-1 dependent manner

Generating stem memory T cells (T _SCM ) is a key goal for improving cancer immunotherapy. Yet, the optimal way to modulate signaling pathways that enrich T _SCM properties remains elusive. Here, we discovered that the degree to which the PI3Kδ pathway is blocked pharmaceutically can generate T cells with differential levels of stemness properties. This observation was based on the progressive enrichment of transcriptional factors of stemness (Tcf-1 and Lef-1). Additional investigation revealed that T cells with high stemness features had enhanced metabolic plasticity, marked by heightened mitochondrial function and glucose uptake. Conversely, T cells with low or medium features of stemness expressed more inhibitory checkpoint receptors (Tim-3, CD39) and were vulnerable to antigen-induced cell death. Only TCR-antigen specific T cells with high stemness persisted following adoptive transfer in vivo and mounted protective immunity to melanoma tumors. Likewise, the strongest level of PI3Kδ blockade in vitro generated human tumor infiltrating lymphocytes (TILs) and CAR T cells with heightened stemness properties, in turn bolstering their capacity to regress human mesothelioma tumors. We find that the level of stemness T cells possess in vitro differentially impacts their potency upon transfer in three tumor models. Mechanistically, both Lef-1 and Tcf-1 sustain anti-tumor protection by high T _SCM , as deletion of either one compromised cellular therapy. Collectively, these findings highlight the therapeutic potential of carefully modulating PI3Kδ signaling in T cells to confer high stemness and mediate protective responses to solid tumors.

Dual IL-6 and CTLA-4 blockade regresses pancreatic tumors in a T cell and CXCR3-dependent manner

This study aimed to enhance anti-tumor immune responses to pancreatic cancer via antibody-based blockade of IL-6 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). Mice bearing subcutaneous or orthotopic pancreatic tumors were treated with blocking antibodies to IL 6 and/or CTLA-4. In both tumor models, dual IL-6 and CTLA-4 blockade significantly inhibited tumor growth. Additional investigations revealed that dual therapy induced an overwhelming infiltration of T cells into the tumor as well as changes in CD4+ T cell subsets. Dual blockade therapy elicited CD4+ T cells to secrete increased IFN-γ in vitro. Likewise, in vitro stimulation of pancreatic tumor cells with IFN-γ profoundly increased tumor cell production of CXCR3 specific chemokines, even in the presence of IL-6. In vivo blockade of CXCR3 prevented orthotopic tumor regression in the presence of the combination treatment, demonstrating a dependence on the CXCR3 axis for anti-tumor efficacy. Both CD4+ and CD8+ T cells were required for the anti-tumor activity of this combination therapy, as their in vivo depletion via antibodies impaired outcomes. These data represent the first report of IL-6 and CTLA 4 blockade as a means to regress pancreatic tumors with defined operative mechanisms of efficacy. Given these results, this therapeutic combination has potential for immediate clinical translation.

ETCTN 10476: A randomized phase 2 study of combination atezolizumab and varlilumab (CDX-1127) with or without addition of cobimetinib in previously treated unresectable biliary tract cancer

TPS639

Background: The combination of the MEK inhibitor, Cobimetinib, with the PD-L1 antagonist, Atezolizumab, significantly improved progression-free survival (PFS) compared to Atezolizumab monotherapy in patients with advanced biliary tract cancer (BTC) following first-line chemotherapy (NCT03201458). Interrogation of biospecimens from this trial and parallel pre-clinical work showed that the addition of MEK inhibition enhanced tumor immunogenicity but simultaneously had detrimental effects on host T-cell activation and priming. The addition of immune co-stimulants rescues T-cell function in the setting of systemic MEK inhibition in vivo. Unlike other immune co-stimulatory markers, CD27 is one of the most positively differentially expressed receptors in the TME post-treatment with combined MEK inhibition and PD-L1 blockade. We hypothesize that addition of CD27 immune agonism to the combination of PD-L1 and MEK inhibition can improve immunotherapy outcomes in patients with BTC. Methods: We are conducting an open-label, randomized ph 2 trial evaluating a PD-L1 inhibitor (atezolizumab) in combination with a CD27 immune agonist (CDX-1127 [Varlilumab]) with or without addition of a MEK inhibitor (Cobimetinib) in patients with unresectable, previously treated, BTC. Key inclusion criteria include: adults with pathologically-confirmed BTC, s/p 1-2 lines of systemic therapy (including any FDA-approved targeted therapies) in the metastatic setting, measurable disease, ECOG performance status ≤1, adequate baseline organ and marrow function. Patients who have received gem-cis-durvalumab, and/or prior FGFR2/IDH1 targeted therapy are eligible for enrollment. The study is planned for 64 evaluable subjects (32 subjects per treatment arm) randomized in a 1:1 ratio, stratified by site of BTC location, to either Atezolizumab + CDX-1127 or Atezolizumab + CDX-1127 + Cobimetinib. During the 28-day treatment cycles, all patients receive Atezolizumab (840mg flat dose) and CDX-1127 (3mg/kg) infusions on D1 and D15. For those randomized to the triplet regimen arm, the additional Cobimetinib will be dosed orally at 60mg daily on days 1-21. Overall response rate and PFS are co-primary endpoints. A clinically meaningful improvement in ORR warranting further study is 20%. The primary correlative outcome is treatment-related changes in CD8+ infiltrating T cells. After an initial safety lead-in, a planned interim efficacy analysis will take place following enrollment of the first 18 patients in each treatment arm. Currently, 14 participants (n=6 [triplet arm], n=8 [doublet arm]), have been enrolled & treated on protocol. This study is sponsored by the NCI Cancer Therapy Evaluation Program and is open nationally at designated NCI Experimental Therapeutics Clinical Trials Network sites. Clinical trial information: NCT04941287 .

Statin drugs enhance responses to immune checkpoint blockade in head and neck cancer models

BACKGROUND

Anti-PD-1 immune checkpoint blockade is approved for first-line treatment of recurrent/metastatic head and neck squamous cell carcinoma (HNSCC), but few patients respond. Statin drugs (HMG-CoA reductase inhibitors) are associated with superior survival in several cancer types, including HNSCC. Emerging data suggest that manipulation of cholesterol may enhance some aspects of antitumor immunity.

METHODS

We used syngeneic murine models (mouse oral cancer, MOC1 and TC-1) to investigate our hypothesis that a subset of statin drugs would enhance antitumor immunity and delay tumor growth.

RESULTS

Using an ex vivo coculture assay of murine cancer cells and tumor infiltrating lymphocytes, we discovered that all seven statin drugs inhibited tumor cell proliferation. Simvastatin and lovastatin also enhanced T-cell killing of tumor cells. In mice, daily oral simvastatin or lovastatin enhanced tumor control and extended survival when combined with PD-1 blockade, with rejection of MOC1 tumors in 30% of mice treated with lovastatin plus anti-PD-1. Results from flow cytometry of tumors and tumor-draining lymph nodes suggested T cell activation and shifts from M2 to M1 macrophage predominance as potential mechanisms of combination therapy.

CONCLUSIONS

These results suggest that statins deserve further study as well-tolerated, inexpensive drugs that may enhance responses to PD-1 checkpoint blockade and other immunotherapies for HNSCC.

The phase 1/2 trial of indomethacin in chronic pancreatitis (The PAIR trial): Protocol for a parallel multi-center randomized controlled trial

BACKGROUND/OBJECTIVES

Current treatments for chronic pancreatitis focus on symptom management and therapeutics targeting disease reversal are lacking. Given the role of the cyclooxygenase-2 (COX-2) enzyme in producing prostaglandin E2 (PGE2), a key component in the inflammatory pathway of chronic pancreatitis, this study evaluates the physiologic effect of oral indomethacin, a COX-2 inhibitor, on PGE2 levels in pancreatic fluid.

METHODS

This pilot two-center randomized controlled trial seeks to examine 32 subjects with chronic pancreatitis who have no contraindications to indomethacin. Subjects will be randomized to either oral indomethacin 50 mg twice a day or placebo twice a day for a total of 28 days. Baseline (pre-treatment) assessment of pain and quality of life will be performed using the Brief Pain Inventory and the PROMIS-10 questionnaires, respectively. Biological specimens including blood, urine, and saliva will be collected at pre-treatment and post-treatment(day 28). Endoscopic pancreatic function testing with concomitant pancreatic fluid collection will also be performed pre- and post-treatment to assess the change in pancreatic fluid PGE2 levels. The relationship between pancreatic fluid PGE2 levels with blood and saliva PGE2 levels will be examined.

CONCLUSIONS

This study will elucidate the effect of oral indomethacin on PGE2 levels in the pancreas to assess its role in the inflammatory pathway of chronic pancreatitis. Should indomethacin significantly reduce PGE2 levels, this may represent a potential disease-altering treatment for chronic pancreatitis.

Bring on the brequinar: an approach to enforce the differentiation of myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSCs) hinder antitumor immunity in multiple cancer types. While brequinar (BRQ), an inhibitor of dihydroorotate dehydrogenase, shows cytotoxicity in hematological malignancy, it has not yet been adapted to attenuate MDSCs by augmenting bone marrow progenitors in breast cancer. In this issue of the JCI, Colligan et al. demonstrate that BRQ restored terminal differentiation of MDSCs. Using in vivo models of immunotherapy-resistant breast cancer, the authors uncovered a mechanism by which BRQ promoted myeloid cell differentiation by limiting their suppressive function and enhancing the efficacy of immune checkpoint blockade therapy. The findings offer insight into the biogenesis of MDSCs, provide an alternative avenue for cancers that remain unresponsive to conventional therapies, and may be extended to future translational studies in patients.

Abstract C007: Targeting vasoactive intestinal peptide receptor signaling enhances T-cell mediated anti-tumor response to immune checkpoint therapy in pancreatic ductal adenocarcinoma

Current immune checkpoint therapies including anti-CTLA-4 and anti-PD1 have limited efficacy in the treatment of pancreatic ductal adenocarcinoma (PDAC), largely due to a paucity of effector T cells within the tumor microenvironment (TME). In our study, we show that vasoactive intestinal peptide (VIP), an immunosuppressive neuropeptide, is over-expressed in human PDAC tumors. Thus, we hypothesized that paracrine production of VIP by tumor cells within the PDAC TME constitutes an immune checkpoint pathway that limits the antitumor activity of VIP-receptor (VIP-R) expressing T cells. We first evaluated whether inhibiting VIP-R signaling by peptide-based VIP-R antagonist affects the growth of PDAC cells in vitro. Treatment of PDAC cells with increasing concentrations of VIP-R antagonist did not affect the viability of PDAC cell lines in vitro, except for a transient effect in MT5 albeit not significant. Furthermore, depletion of VIP receptor 2 (VPAC2) in a PDAC cell line, Panc02, by CRISPR-Cas9 KO had similar growth rates in vitro with a slight growth delay in vivo compared to the parental cell line. These data suggest that the expression of VPAC2 on PDAC cells may not confer a significant autocrine effect on tumor growth impacted by VIP signaling. On the contrary, human T cells cultured with VIP-R antagonists had enhanced activation, decreased proportions of Tregs, and exhausted T cells co-expressing PD-1, Tim-3, and Lag-3. Next, we performed pharmacological inhibition with VIP-R antagonists in tumor-bearing mice to model T cell homing, activation, and antitumor responses in preclinical murine models of PDAC. Daily subcutaneous injections of VIP-R antagonists had synergistic antitumor activity when combined with anti-PD-1 therapy with decreased tumor burden and improved survival. In contrast to the limited single-agent activity of anti-PD1 or VIP-R antagonists, combination therapy eliminated tumors in up to 40% of animals. Anti-tumor responses were T cell-dependent, as the combination therapy failed to improve survival in CD4 or CD8 deficient mice using knock-out strains and antibody depletion. In addition, tumor-free mice were resistant to tumor re-challenge, indicating the generation of anti-cancer immunological memory. In correspondent to these data, combination therapy led to enhanced T cell activation in vivo with increased antigen-specific T cells, decreased frequencies of Tregs as well as enhanced T cell infiltration to the tumor site as observed by infiltration of adoptively transferred GFP+ T cells into PDAC tumors. Taken together, our findings show that VIP-VIPR signaling is a targetable mechanism of immune escape in PDAC. Inhibiting VIP-R signaling improves T cell effector properties and enhances the responsiveness of PDAC to immune checkpoint therapy. Further pharmacokinetic and toxicology studies are underway.

Citation Format: Tenzin Passang, Sruthi Ravindranathan, Jian-Ming Li, Shuhua Wang, Michael Brandon Ware, Hanwen Zhang, Gregory B. Lesinski, Edmund K. Waller. Targeting vasoactive intestinal peptide receptor signaling enhances T-cell mediated anti-tumor response to immune checkpoint therapy in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C007.

STAT3 in tumor fibroblasts promotes an immunosuppressive microenvironment in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is associated with an incredibly dense stroma, which contributes to its recalcitrance to therapy. Cancer-associated fibroblasts (CAFs) are one of the most abundant cell types within the PDAC stroma and have context-dependent regulation of tumor progression in the tumor microenvironment (TME). Therefore, understanding tumor-promoting pathways in CAFs is essential for developing better stromal targeting therapies. Here, we show that disruption of the STAT3 signaling axis via genetic ablation of Stat3 in stromal fibroblasts in a Kras G12D PDAC mouse model not only slows tumor progression and increases survival, but re-shapes the characteristic immune-suppressive TME by decreasing M2 macrophages (F480+CD206+) and increasing CD8+ T cells. Mechanistically, we show that loss of the tumor suppressor PTEN in pancreatic CAFs leads to an increase in STAT3 phosphorylation. In addition, increased STAT3 phosphorylation in pancreatic CAFs promotes secretion of CXCL1. Inhibition of CXCL1 signaling inhibits M2 polarization in vitro. The results provide a potential mechanism by which CAFs promote an immune-suppressive TME and promote tumor progression in a spontaneous model of PDAC.

Targeting vasoactive intestinal peptide-mediated signaling enhances response to immune checkpoint therapy in pancreatic ductal adenocarcinoma

A paucity of effector T cells within tumors renders pancreatic ductal adenocarcinoma (PDAC) resistant to immune checkpoint therapies. While several under-development approaches target immune-suppressive cells in the tumor microenvironment, there is less focus on improving T cell function. Here we show that inhibiting vasoactive intestinal peptide receptor (VIP-R) signaling enhances anti-tumor immunity in murine PDAC models. In silico data mining and immunohistochemistry analysis of primary tumors indicate overexpression of the neuropeptide vasoactive intestinal peptide (VIP) in human PDAC tumors. Elevated VIP levels are also present in PDAC patient plasma and supernatants of cultured PDAC cells. Furthermore, T cells up-regulate VIP receptors after activation, identifying the VIP signaling pathway as a potential target to enhance T cell function. In mouse PDAC models, VIP-R antagonist peptides synergize with anti-PD-1 antibody treatment in improving T cell recruitment into the tumors, activation of tumor-antigen-specific T cells, and inhibition of T cell exhaustion. In contrast to the limited single-agent activity of anti-PD1 antibodies or VIP-R antagonist peptides, combining both therapies eliminate tumors in up to 40% of animals. Furthermore, tumor-free mice resist tumor re-challenge, indicating anti-cancer immunological memory generation. VIP-R signaling thus represents a tumor-protective immune-modulatory pathway that is targetable in PDAC.

Combined MEK/PD-L1 Inhibition Alters Peripheral Cytokines and Lymphocyte Populations Correlating with Improved Clinical Outcomes in Advanced Biliary Tract Cancer

PURPOSE

Biliary tract cancers (BTC) are aggressive malignancies refractory to chemotherapy and immunotherapy. MEK inhibition (MEKi)-based regimens may have utility in this disease when combined with PD-L1 blockade. We hypothesize that dual MEK/PD-L1 inhibition alters circulating soluble and cellular immune mediators to improve clinical outcomes in patients with advanced BTC.

EXPERIMENTAL DESIGN

We examined immune features in peripheral blood from 77 patients with advanced BTC enrolled in a phase II clinical trial investigating atezolizumab with or without cobimetinib. Plasma and peripheral blood mononuclear cells (PBMC) were isolated from whole blood to evaluate soluble factors and immune cell populations. Baseline blood samples were additionally compared with healthy donors to identify immune signatures unique to BTC.

RESULTS

At baseline, the soluble factors platelet-derived growth factor B (PDGF)-BB, placental growth factor (PlGF)-1, IL5, and IL17A were elevated in patients with BTC compared with healthy adult donors, and higher baseline frequencies of CD8+BTLA+ T cells correlated with better overall survival (OS) in this trial. There were also significant treatment-related alterations in several factors, including decreased PDGF-BB following combination treatment, that correlated with improved OS and progression-free survival (PFS). Higher baseline levels of IL23 and RANTES corresponded to improved clinical outcomes following combination treatment. Dual MEK/PD-L1 inhibition increased populations of CD4+TIM3+ and decreased CD8+VISTA+ T cells, correlating with worse OS and better PFS, respectively.

CONCLUSIONS

This work represents a comprehensive analysis of peripheral immune features in patients with BTC and systemic responses to dual MEK/PD-L1 inhibition. These data support further investigation to understand how MEKi combines with immunotherapeutic approaches to improve clinical outcomes for patients with advanced BTC.

GM-CSF drives myelopoiesis, recruitment and polarisation of tumour-associated macrophages in cholangiocarcinoma and systemic blockade facilitates antitumour immunity

OBJECTIVE

Intrahepatic cholangiocarcinoma (iCCA) is rising in incidence, and at present, there are limited effective systemic therapies. iCCA tumours are infiltrated by stromal cells, with high prevalence of suppressive myeloid populations including tumour-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs). Here, we show that tumour-derived granulocyte-macrophage colony-stimulating factor (GM-CSF) and the host bone marrow is central for monopoiesis and potentiation of TAMs, and abrogation of this signalling axis facilitates antitumour immunity in a novel model of iCCA.

METHODS

Blood and tumours were analysed from iCCA patients and controls. Treatment and correlative studies were performed in mice with autochthonous and established orthotopic iCCA tumours treated with anti-GM-CSF monoclonal antibody.

RESULTS

Systemic elevation in circulating myeloid cells correlates with poor prognosis in patients with iCCA, and patients who undergo resection have a worse overall survival if tumours are more infiltrated with CD68+ TAMs. Mice with spontaneous iCCA demonstrate significant elevation of monocytic myeloid cells in the tumour microenvironment and immune compartments, and tumours overexpress GM-CSF. Blockade of GM-CSF with a monoclonal antibody decreased tumour growth and spread. Mice bearing orthotopic tumours treated with anti-GM-CSF demonstrate repolarisation of immunosuppressive TAMs and MDSCs, facilitating T cell response and tumour regression. GM-CSF blockade dampened inflammatory gene networks in tumours and TAMs. Human tumours with decreased GM-CSF expression exhibit improved overall survival after resection.

CONCLUSIONS

iCCA uses the GM-CSF-bone marrow axis to establish an immunosuppressive tumour microenvironment. Blockade of the GM-CSF axis promotes antitumour T cell immunity.

Abstract 1059: Paricalcitol, hydroxychloroquine and gemcitabine promote antitumor effects and modulate immune profile in pancreatic ductal adenocarcinoma

Background Pancreatic ductal adenocarcinoma (PDAC) has low (&lt;5%) five-year survival. We hypothesized combined Vitamin D3 (Paricalcitol; Par) and hydroxychloroquine (HCQ) impacts stroma, anti-tumor immunity, and autophagy, thereby sensitizing PDAC to gemcitabine (Gem).

Methods For subcutaneous efficacy, 5-6-week-old female nude mice (n=5/group) were injected with KPC-Luc cells and randomized to: 1) vehicle (PBS), 2) Gem plus HCQ, 3) Gem plus Par, and 4) Gem, HCQ, and Par once tumors were palpable. Gem and Par (twice weekly) were administered via intraperitoneal injection. HCQ was given orally (daily). For orthotropic efficacy and single cell analysis, female C57BL/6J mice (n=6/group) were injected with 2×105 KPC-Luc cells into the pancreas tail. On day 5, animals were randomized to 1) PBS and 2) combined Gem/HCQ/Par as above. Tumors were analyzed via bioluminescent imaging. After 15 days, animals were euthanized, tumors were weighed and dissociated into single cells. High viability samples were used to generate scRNA-Seq libraries using 10X genomics droplet approach.

Results Gem, HCQ, and Par significantly (p&lt;0.001) reduced tumor growth/weight versus controls in both models. Single cell transcriptome profiles of 11,188 cells (controls) and 7,624 cells (Gem/HCQ/Par) were obtained. Split UMAP plots of samples were generated with cell clusters annotated from established gene markers. Eight clusters expressing PDAC-associated genes were designated as PDAC cells. The tumor microenvironment (TME) showed dramatic post-treatment changes with significant decreases in PDAC cells (p=0.007) and increases in B cells, monocytes/macrophages (p=0.0006, 0.03 respectively), and increased T/NK cells in treated versus control mice. Supervised analysis among T cells showed more activation (Cd44, Tnfrsf4/9) and exhaustion (Ctla4, Lag3, Pdcd1) associated gene expression post-treatment, indicating robust T cell response. ssGSEA analysis showed significant (p&lt;.001) activation of Th1/Th2/Th17 pathways. Monocyte/macrophages clusters analysis revealed greater expression of M1 genes and M2 genes in treated and control samples, respectively. Modified EMT was observed in stromal cells with enhanced MHC1 expression.

Conclusion HCQ and Par enhance the efficacy of Gem in two mice PDAC models. Single cell transcriptome analyses revealed the combination treatment promoted immune shifts in the PDAC TME. Effects of Par and HCQ and standard chemotherapy drugs, Gem and nab-paclitaxel are being studied in an ongoing clinical trial (NCT04524702).

Citation Format: Purnachandra Nagaraju Ganji, Beena Elizabeth Thomas, Maggie Phillips, Cameron Herting, Amanda Ruggieri, Jessica Millian Keilson, Michael Kim Turgeon, Sisira Saraswatula, William Pilcher, Gregory B. Lesinski, Manoj Bhasin, Bassel F. El-Rayes. Paricalcitol, hydroxychloroquine and gemcitabine promote antitumor effects and modulate immune profile in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1059.

Abstract 3482: Correlative analysis of metformin and nivolumab combination in treatment-refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC)

Background: Preclinical results indicate that metformin can modulate immune cell populations in the tumor microenvironment of solid tumors by diminishing exhaustion of CD8+ tumor infiltrating cells and improving T cell responses. Studies also suggest that metformin could complement PD-1 blockade and potentiate its antitumor activity. Previously we reported the results of a phase II trial with metformin and nivolumab and here we report the findings of correlative analysis of the prospectively collected research samples of 18 patients.

Methods: We conducted a phase II trial with nivolumab and metformin in treatment-refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC). Nivolumab 480 mg IV every 4 weeks and metformin 1000 mg orally twice daily was administered in 28-day cycles following a 14-day metformin only lead-in phase. The primary endpoint was overall response rate (ORR). Secondary endpoints were overall survival (OS) and progression free survival (PFS). Pre-treatment and on-treatment research biopsies and correlative peripheral blood specimens were collected. Paired biopsies obtained at baseline and following treatment with metformin only (n=9) or metformin and nivolumab (n=9) and were stained with a panel of 13 markers using ChipCytometry technology by Canopy Biosciences. Sample was assessed prior to establishing the multiplex assay. 30 out of 36 samples were imaged and analyzed up to 30 Fields of View. Single cell recognition and quantitative biomarker analysis were performed to compare immune cell numbers and population distribution in pre- versus post-treatment samples.

Results: As previously reported, no patients had objective response based on RECIST version 1.1 and the study was stopped after the first stage for futility. Median OS and PFS was 5.1 months [95% CI (2-11.7)] and 2.3 months [95% CI (1.7-2.4)], respectively. Multiplex analysis of tissues from patients receiving lead in with metformin alone revealed fewer effector CD4 T cells and effector and effector memory CD8 T cells after treatment vs. baseline biopsy. Biopsy tissue from patients treated with metformin and nivolumab had lower pAMPK and decreased PDL-1 expression vs. baseline. The combination also increased percentages of leukocytes, effector CD4 T cells, effector and effector memory CD8 T cells as well as levels of PDL1-Tim3+ cells.

Conclusion: In the setting of MSS mCRC, metformin as a single agent did not enhance effector CD4 and CD8 T cell percentages in clinical samples in our patient cohort. Metformin in combination with nivolumab was associated with increased percentages of effector CD4 and CD8 T cells in biopsy specimens, although these improvements did not translate into enhanced clinical endpoints. Analysis of peripheral blood samples are currently underway to corroborate the findings in the tissue samples.

Citation Format: Batoul Farran, Jeffrey M. Switchenko, Lana Khalil, Walid L. Shaib, Brian Olson, Amanda Ruggieri, Christina Wu, Olatunji B. Alese, Maria Diab, Gregory B. Lesinski, Bassel El-Rayes, Mehmet Akce. Correlative analysis of metformin and nivolumab combination in treatment-refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3482.

Abstract 104: Targeting NAD(P)H:quinone oxidoreductase 1 (NQO1) in pancreatic ductal adenocarcinoma: An in silco, in vitro and in vivo approach

NAD(P)H: quinone oxidoreductase 1 (NQO1) is a ubiquitous flavoenzyme. NQO1 is important for catalyzation, detoxification, and reduction of organic compounds including quinone. Elevated NQO1 expression is associated with increased pancreatic ductal adenocarcinoma (PDAC) growth, and metastasis as well as poor prognosis. BBI 608 is a small molecule that exhibits potential therapeutic properties for PDAC due to its powerful anti-inflammatory and antioxidant properties and ability to regulate multiple signaling pathways. The current study explores the binding capacity and ligand efficacy of BBI608 against NQO1 in PDAC. To observe the molecular properties of BBI608 and to analyze the exact mechanism of NQO1 on PDAC, computational approaches were applied, including molecular docking. This investigation provides a detailed understanding of the interaction between NQO1 and BBI608 and its implication in PDAC therapy. To support this computational analysis, we performed in vitro and in vivo studies. The combination of BBI608 with gemcitabine plus irradiation creates higher cytotoxicity (decreased proliferation, clonogenicity and increased Annexin V positive cells; p&lt;0.001) in PDAC cell lines and the mice bearing subcutaneous PANC-02 and MIA PaCa-2 model. Collectively, this investigation offers mechanistic insight into the cytotoxicity initiated by BBI608 and suggests further investigation of its utility for PDAC therapy is warranted.

Citation Format: Purnachandra N. Ganji, Gregory B. Lesinski, Bassel F. El-Rayes. Targeting NAD(P)H:quinone oxidoreductase 1 (NQO1) in pancreatic ductal adenocarcinoma: An in silco, in vitro and in vivo approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 104.

Abstract 5595: Statin drugs have anti-tumor activity and enhance responses to anti-PD-1 therapy in preclinical models of head and neck cancer

Background/Rationale: Head and neck squamous cell carcinoma (HNSCC) is a common malignancy with significant morbidity and mortality. Approximately half of patients with HNSCC develop recurrent or metastatic disease. Recently, anti-PD-1 immune checkpoint blockade was FDA-approved for first-line treatment of recurrent or metastatic disease, and although relatively well tolerated, only a minority of patients respond. There is an unmet clinical need for agents that enhance responses to anti-PD-1 therapy without excessive toxicity. HMG-CoA reductase inhibitors, also known as statin drugs, are in wide clinical use for hyperlipidemia and are inexpensive and well tolerated. Statin drugs are associated with superior survival outcomes in retrospective population studies of several cancers, including HNSCC. Moreover, statins may reduce multiple treatment-related toxicities, such as radiation-induced skin fibrosis and cisplatin chemotherapy-induced hearing loss. Emerging data suggest that statins may also enhance some aspects of anti-tumor immunity, but this has not been studied in HNSCC. Further, the pleiotropic effects of different statin drugs are highly variable. We hypothesized that a subset of statin drugs would enhance anti-tumor immunity and delay tumor growth in preclinical models of HNSCC.

Methods: Two immunocompetent, syngeneic murine models of oral cancer (MOC1 and MOC22) were used. To identify which of the seven FDA-approved statin drugs are capable of antitumor activity and enhancing T-cell induced killing, we used a high-throughput ex vivo co-culture assay of murine oral cancer cells and tumor infiltrating CD8+ T lymphocytes. Tumor-bearing mice were then treated with anti-PD-1 antibody (twice weekly IP) and/or statin drug (daily by oral gavage) for up to three weeks, and tumor kinetics and survival were tracked.

Results: When added at or near physiologic drug concentrations, all 7 statins strongly inhibited proliferation of MOC1 and MOC22 cell lines. Moreover, the combination of CD8+ T cells and a subset of statins mediated nearly two-fold tumor cell killing effect versus either treatment used alone. In mice, tumor growth delay did not reach statistical significance with statins or anti-PD-1 alone. However, combination therapy induced a significant tumor growth delay versus control mice (p&lt;0.05).

Conclusions: Our results have significant implications for both biologic mechanisms and therapeutic applications of statin drugs in HNSCC. Additional experiments to investigate the mechanisms by which statins inhibit tumor cell proliferation and enhance anti-tumor immunity are currently underway.

Funding: supported by Winship Cancer Institute and the Morningside Center for Innovative and Affordable Medicine.

Citation Format: Andre J. Burnham, Vikash Kansal, Brendan L. Kinney, Chrystal M. Paulos, Gregory B. Lesinski, Nabil F. Saba, Nicole C. Schmitt. Statin drugs have anti-tumor activity and enhance responses to anti-PD-1 therapy in preclinical models of head and neck cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5595.

Clinical, Genomic, and Transcriptomic Data Profiling of Biliary Tract Cancer Reveals Subtype-Specific Immune Signatures

PURPOSE

Biliary tract cancers (BTCs) are aggressive cancers that carry a poor prognosis. An enhanced understanding of the immune landscape of anatomically and molecularly defined subsets of BTC may improve patient selection for immunotherapy and inform immune-based combination treatment strategies.

METHODS

We analyzed deidentified clinical, genomic, and transcriptomic data from the Tempus database to determine the mutational frequency and mutational clustering across the three major BTC subtypes (intrahepatic cholangiocarcinoma [IHC], extrahepatic cholangiocarcinoma, and gallbladder cancer). We subsequently determined the relationship between specific molecular alterations and anatomical subsets and features of the BTC immune microenvironment.

RESULTS

We analyzed 454 samples of BTC, of which the most commonly detected alterations were TP53 (42.5%), CDKN2A (23.4%), ARID1A (19.6%), BAP1 (15.5%), KRAS (15%), CDKN2B (14.2%), PBRM1 (11.7%), IDH1 (11.7%), TERT (8.4%), KMT2C (10.4%) and LRP1B (8.4%), and FGFR2 fusions (8.7%). Potentially actionable molecular alterations were identified in 30.5% of BTCs including 39.1% of IHC. Integrative cluster analysis revealed four distinct molecular clusters, with cluster 4 predominately associated with FGFR2 rearrangements and BAP1 mutations in IHC. Immune-related biomarkers indicative of an inflamed tumor-immune microenvironment were elevated in gallbladder cancers and in cluster 1, which was enriched for TP53, KRAS, and ATM mutations. Multiple common driver genes, including TP53, FGFR2, IDH1, TERT, BRAF, and BAP1, were individually associated with unique BTC immune microenvironments.

CONCLUSION

BTC subtypes exhibit diverse DNA alterations, RNA inflammatory signatures, and immune biomarkers. The association between specific BTC anatomical subsets, molecular alterations, and immunophenotypes highlights new opportunities for therapeutic development.

Modulation of the tumor microenvironment by armed vesicular stomatitis virus in a syngeneic pancreatic cancer model

Background

The immunosuppressive microenvironment in pancreatic ductal adenocarcinoma is a major factor that limits the benefits of immunotherapy, especially immune checkpoint blockade. One viable strategy for reverting the immunosuppressive conditions is the use of an oncolytic virus (OV) in combination with other immunotherapy approaches. Infection of PDAC cells with a robust OV can change the tumor microenvironment and increase tumor antigen release by its lytic activities. These changes in the tumor may improve responses to immunotherapy, including immune checkpoint blockade. However, a more potent OV may be required for efficiently infecting pancreatic tumors that may be resistant to OV.

Methods

Vesicular stomatitis virus, a rapid replicating OV, was armed to express the Smac protein during virus infection (VSV-S). Adaptation by limited dilution largely increased the selective infection of pancreatic cancer cells by VSV-S. The engineered OV was propagated to a large quantity and evaluated for their antitumor activities in an animal model.

Results

In a syngeneic KPC model, intratumoral injection of VSV-S inhibited tumor growth, and induced increasing tumor infiltration of neutrophils and elimination of myeloid derived suppressor cells and macrophages in the tumor. More importantly, M2-like macrophages were eliminated preferentially over those with an M1 phenotype. Reduced levels of arginase 1, TGF-β and IL-10 in the tumor also provided evidence for reversion of the immunosuppressive conditions by VSV-S infection. In several cases, tumors were completely cleared by VSV-S treatment, especially when combined with anti-PD-1 therapy. A long-term survival of 44% was achieved.

Conclusions

The improved OV, VSV-S, was shown to drastically alter the immune suppressive tumor microenvironment when intratumorally injected. Our results suggest that the combination of potent OV treatment with immune checkpoint blockade may be a promising strategy to treat pancreatic cancer more effectively.

Galectin-9 expression and decreased survival in advanced biliary tract cancers

465

Background: Biliary tract cancers (BTCs) are a group of rare and aggressive malignancies often refractory to chemotherapeutic or targeted therapies, carrying an overall poor prognosis and high mortality. Identifying prognostic biomarkers and effective therapeutic targets for this disease therefore remains a high priority. T-cell immunoglobulin mucin domain-containing protein 3 (TIM-3), a negative regulatory immune checkpoint receptor, is known to induce immune tolerance and inhibit T-cell antitumor immunity. Its ligand, galectin-9 (Gal-9), has been shown to play a paradoxical role in tumorigenesis in a number of disease states. However, the role of Gal-9 in the setting of BTCs is not completely understood. Methods: We examined expression patterns of total cellular Gal-9 and TIM-3 in a panel of human BTC cell lines with diverse molecular profiles via immunoblot. Soluble Gal-9 (sGal-9) was measured by enzyme-linked immunoassay (ELISA). Tetrazolium-based MTT assay was utilized to evaluate cell viability following Ab-mediated Gal-9 neutralization. Pre-treatment peripheral blood was obtained from patients with metastatic BTCs enrolled in a randomized phase II clinical trial (NCI10139) and sGal-9 levels were measured. ROC curve analysis was employed to identify an optimal concentration cut-point value. Kaplan-Meier models were used to assess the association between sGal-9 levels and overall survival. Results: Human BTC cells demonstrate detectable and differential expression levels of total Gal-9 and TIM-3 proteins in vitro, with greater expression among intrahepatic cell lines (HUCCT-1, HUH28, SNU478). TIM-3 expression was not detected among extrahepatic (MzChA-1) and gallbladder cancer (WITT) cell lines. sGal-9 is secreted at variable levels between cell lines and its neutralization does not affect viability. Pre-treatment peripheral blood was obtained from 73 patients with metastatic BTCs (53% (n = 39) intrahepatic cholangiocarcinoma, 22% (n = 16) extrahepatic cholangiocarcinoma, 25% (n = 18) gallbladder cancer). There was no significant difference in sGal-9 levels between disease sites (p = 0.08). Patients were dichotomized by low and high sGal-9 levels. High baseline plasma levels of sGal-9 were associated with worse overall survival among patients with advanced BTCs (p = 0.03). Conclusions: Biliary tract cancer cells differentially express galectin-9 and its ligand, TIM-3, in vitro. Higher plasma levels of soluble galectin-9 are associated with worse overall survival, suggesting galectin-9 expression may be related to a more aggressive disease state. Additional work is needed to better inform the mechanistic role of the galectin-9/TIM-3 axis on disease progression and how best to leverage this pathway as a therapeutic target in the management of biliary tract cancers.

High-risk gene expression in colorectal liver metastasis: Potential for novel therapies

147

Background: Over half of patients with colorectal cancer (CRC) develop liver metastases. While immunotherapy is an emerging treatment of solid tumors, its use among CRC patients is limited. Furthermore, gene expression patterns of liver-specific CRC metastases remain unclear. The purpose of this study was to identify a high-risk gene expression profile for patients with colorectal liver metastasis (CRLM) to better inform prognosis and development of novel targeted therapies. Methods: Fifty-three FFPE CRLM samples from patients who underwent complete metastatectomy from 2009-2017 were examined. Expression profiling of extracted RNA was performed using NanoString Immuno-Oncology (IO360) 750-gene panel. Statistical analyses using cutoffs of absolute log 2-fold change≥1.5 and p-value≤0.05 were performed. Patients were analyzed by extremes of outcomes: survival time in the lowest quartile compared to those still alive at last follow-up. Results: Eight differentially expressed genes were associated with poor survival. Overexpressed genes included IL6R, CXCL2, C7, MGMT, PCK2, CSF1 and LILRB4 (Table). PLA2G2A was under-expressed. Conclusions: This study demonstrates differential gene expression associated with poor survival among patients with CRLM. Specific genes of interest include IL6R, MGMT, CSF1 and LILRB4. IL6R is a known effector in tumor proliferation via IL-6 signaling from tumor-associated macrophages, myeloid-derived suppressor cells (MDSCs) and T-cells. MGMT repairs alkylating DNA damage and is implicated in carcinogenesis and response to chemotherapy. CSF1 promotes macrophage differentiation to M2 phenotype, suppressing inflammation and anti-tumor defense mechanisms. LILRB4 activation via MDSCs leads to T-cell inhibition. These overall suggest a myeloid-dominant tumor immune microenvironment and represent important potential therapeutic targets. Next steps include performing immunohistochemistry to validate findings at the protein level and investigate the tumor intrinsic role using human cell lines.[Table: see text]

Phase Ib/II trial of siltuximab and spartalizumab in patients in metastatic pancreatic cancer

TPS626

Background: Interleukin-6 (IL-6) is associated with carcinogenesis, immune suppression, and poor prognosis in pancreatic adenocarcinoma (PDAC). Preclinical data demonstrated dual inhibition of IL-6 and (programmed death ligand-1) PD-L1 facilitates CD8+ T cell migration into pancreatic tumors and was effective in controlling tumor growth in syngeneic and genetically engineered PDAC mouse models. Siltuximab is a chimeric monoclonal antibody which targets the IL-6 molecule specifically and spartalizumab is a high-affinity ligand-blocking humanized IgG4 antibody against the PD-1 receptor. Based on this preclinical rationale, we developed a phase Ib/II trial to determine the recommended phase II dose (RP2D), evaluate the safety, toxicity profile, preliminary antitumor activity, and immunogenicity of the siltuximab and spartalizumab in patients with previously treated metastatic PDAC. Methods: The phase Ib trial design is standard 3+3. Primary endpoint is to determine RP2D. Siltuximab is administered intravenously (IV) in three dose levels of 6 mg/kg (DL1), 11 mg/kg (DL2), 9 mg/kg (only if 2 DLTs observed on DL2) every 3 weeks with spartalizumab at 300 mg IV every 3 weeks. Eligible patients must have stage IV PDAC who have failed at least one prior therapy age ≥18 years, ECOG PS 0-1, no prior anti PD-1 or anti-PD-L1 agent. After RP2D is established, an expansion phase will enroll 24 patients with PDAC. Pre and on-treatment biopsy will be performed in 24 patients in the expansion cohort for correlative analysis. Pre-treatment and on-treatment peripheral blood samples will be collected from all patients. In the expansion phase patients will receive initial cycle (every 3 weeks) treatment with either spartalizumab or spartalizumab plus siltuximab and then starting cycle 2 all patients receive the combination following the on-treatment research biopsy. This design will enable us to evaluate the immunological effects of spartalizumab alone versus the combination in the tumor microenvironment and peripheral blood. This study was activated in January 2020 and to date 12 patients were enrolled in dose escalation phase. The dose expansion phase has recently started accrual. Clinical trial information: NCT04191421.

Multicenter randomized phase II trial of atezolizumab with or without cobimetinib in biliary tract cancers

BACKGROUNDMEK inhibitors have limited activity in biliary tract cancers (BTCs) as monotherapy but are hypothesized to enhance responses to programmed death ligand 1 (PD-L1) inhibition.METHODSThis open-label phase II study randomized patients with BTC to atezolizumab (anti-PD-L1) as monotherapy or in combination with cobimetinib (MEK inhibitor). Eligible patients had unresectable BTC with 1 to 2 lines of prior therapy in the metastatic setting, measurable disease, and Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 1. The primary endpoint was progression-free survival (PFS).RESULTSSeventy-seven patients were randomized and received study therapy. The trial met its primary endpoint, with a median PFS of 3.65 months in the combination arm versus 1.87 months in the monotherapy arm (HR 0.58, 90% CI 0.35-0.93, 1-tail P = 0.027). One patient in the combination arm (3.3%) and 1 patient in the monotherapy arm (2.8%) had a partial response. Combination therapy was associated with more rash, gastrointestinal events, CPK elevations, and thrombocytopenia. Exploratory analysis of tumor biopsies revealed enhanced expression of antigen processing and presentation genes and an increase in CD8/FoxP3 ratios with combination treatment. Patients with higher baseline or lower fold changes in expression of certain inhibitory ligands (LAG3, BTLA, VISTA) on circulating T cells had evidence of greater clinical benefit from the combination.CONCLUSIONThe combination of atezolizumab plus cobimetinib prolonged PFS as compared with atezolizumab monotherapy, but the low response rate in both arms highlights the immune-resistant nature of BTCs.TRIAL REGISTRATIONClinicalTrials.gov NCT03201458.FUNDINGNational Cancer Institute (NCI) Experimental Therapeutics Clinical Trials Network (ETCTN); F. Hoffmann-La Roche, Ltd.; NCI, NIH (R01 CA228414-01 and UM1CA186691); NCI's Specialized Program of Research Excellence (SPORE) in Gastrointestinal Cancers (P50 CA062924); NIH Center Core Grant (P30 CA006973); and the Passano Foundation.

Mirage or long-awaited oasis: reinvigorating T-cell responses in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is plagued by a dismal 5-year survival rate, early onset of metastasis and limited efficacy of systemic therapies. This scenario highlights the need to fervently pursue novel therapeutic strategies to treat this disease. Recent research has uncovered complicated dynamics within the tumor microenvironment (TME) of PDAC. An abundant stroma provides a framework for interactions between cancer-associated fibroblasts, suppressive myeloid cells and regulatory lymphocytes, which together create an inhospitable environment for adaptive immune responses. This accounts for the poor infiltration and exhausted phenotypes of effector T cells within pancreatic tumors. Innovative studies in genetically engineered mouse models have established that with appropriate pharmacological modulation of suppressive elements in the TME, T cells can be prompted to regress pancreatic tumors. In light of this knowledge, innovative combinatorial strategies involving immunotherapy and targeted therapies working in concert are rapidly emerging. This review will highlight recent advances in the field related to immune suppression in PDAC, emerging preclinical data and rationale for ongoing immunotherapy clinical trials. In particular, we draw attention to foundational findings involving T-cell activity in PDAC and encourage development of novel therapeutics to improve T-cell responses in this challenging disease.

Context-Dependent Immunomodulatory Effects of MEK Inhibition are Enhanced with T-cell Agonist Therapy

MEK inhibition (MEKi) is proposed to enhance antitumor immunity but has demonstrated mixed results as an immunomodulatory strategy in human clinical trials. MEKi exerts direct immunomodulatory effects on tumor cells and tumor-infiltrating lymphocytes, but these effects have not been independently investigated. Here we modeled tumor-specific MEKi through CRISPR/Cas-mediated genome editing of tumor cells (MEK1 KO) and pharmacologic MEKi with cobimetinib in a RAS-driven model of colorectal cancer. This approach allowed us to distinguish tumor-mediated and tumor-independent mechanisms of MEKi immunomodulation. MEK1 KO tumors demonstrated upregulation of JAK/STAT signaling; enhanced MHCI expression, CD8+ T-cell infiltration and T-cell activation; and impaired tumor growth that is immune-dependent. Pharmacologic MEKi recapitulated tumor-intrinsic effects but simultaneously impaired T-cell activation in the tumor microenvironment. We confirmed a reduction in human peripheral lymphocyte activation from a clinical trial of anti-PD-L1 (atezolizumab) with or without cobimetinib in biliary tract cancers. Impaired activation of tumor-infiltrating lymphocytes treated with pharmacologic MEKi was reversible and was rescued with the addition of a 41BB agonist. Collectively, these data underscore the ability of MEKi to induce context-dependent immunomodulatory effects and suggest that T cell-agonist therapy maximizes the beneficial effects of MEKi on the antitumor immune response.

Mismatch Repair (MMR) Gene Alteration and BRAF V600E Mutation Are Potential Predictive Biomarkers of Immune Checkpoint Inhibitors in MMR-Deficient Colorectal Cancer

BACKGROUND

Immune checkpoint inhibitor (ICI) therapy is highly effective in metastatic mismatch repair-deficient (MMR-D) colorectal cancer (CRC). In this study, we evaluated molecular and clinical predictors of ICI response in MMR-D CRC.

MATERIALS AND METHODS

Patient databases at four cancer institutions were queried. The Fisher exact test was performed to test the association of clinical and molecular markers. The Kaplan-Meier method was used to estimate progression-free survival (PFS) and compared by the log-rank test. Twelve- and 24-month PFS rates were compared by the Z test.

RESULTS

A total of 60 patients with CRC with MMR-D/microsatellite instability-high who previously received ICIs were identified. Patients with liver metastasis had a lower overall response rate as compared with other sites of metastasis (36.4% vs. 68.7%; p = .081). Patients with MLH1/PMS2 loss had worse 1-year and 2-year PFS rates compared with patients with MSH2/MSH6 loss (84.2% vs. 57.8% and 78.2% vs. 54.2%, respectively; p < .001). There were improved 1-year and 2-year PFS rates in patients with wild-type BRAF when compared with patients with BRAF V600E mutation (73.3% vs. 40%, and 73.3% vs. 26.7%; respectively; p < .001). Patients aged >65 had significantly worse PFS rates as compared with patients aged ≤65 (p < .001).

CONCLUSION

BRAF V600E mutation, MLH1 and/or PMS2 loss, as well as age >65 years and liver metastasis, may be predictive of duration of ICI response in patients with MMR-D CRC. Larger cohorts are needed to confirm our findings.

IMPLICATIONS FOR PRACTICE

The results of this study reveal clinically important biomarkers that potentially predict immune checkpoint inhibitor response in patients with mismatch repair-deficient colorectal cancer.

A multi-center, single-arm, phase Ib study of pembrolizumab (MK-3475) in combination with chemotherapy for patients with advanced colorectal cancer: HCRN GI14-186

Modified FOLFOX6 is an established therapy for patients with metastatic colorectal cancer (mCRC). We conducted a single-arm phase Ib study to address the hypothesis that addition of pembrolizumab to this regimen could safely and effectively improve patient outcomes (NCT02375672). The relationship between immune biomarkers and clinical response were assessed in an exploratory manner. Patients with mCRC received concurrent pembrolizumab and modified FOLFOX6. The study included safety run-in for the first six patients. The primary objective was median progression-free survival (mPFS), with secondary objectives including median overall survival, safety, and exploratory assessment of immune changes. To assess immunological impact, peripheral blood was collected at baseline and during treatment. The levels of soluble factors were measured via bioplex, while a panel of checkpoint molecules and phenotypically defined cell populations were assessed with flow cytometry and correlated with RECIST and mPFS. Due to incidences of grade 3 and grade 4 neutropenia in the safety lead-in, the dose of mFOLFOX6 was reduced in the expansion cohort. Median PFS was 8.8 months and median OS was not reached at data cutoff. Best responses of stable disease, partial response, and complete response were observed in 43.3%, 50.0%, and 6.7% of patients, respectively. Several soluble and cellular immune biomarkers were associated with improved RECIST and mPFS. Immunosuppressive myeloid and T cell subsets that were analyzed were not associated with response. Primary endpoint was not superior to historic control. Biomarkers that were associated with improved response may be informative for future regimens combining chemotherapy with immune checkpoint inhibitors.

Multimodal profiling of biliary tract cancers to detect potentially actionable biomarkers and differences in immune signatures between subtypes

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Background: Biliary tract cancers (BTC) are increasingly subtyped by molecular alterations, but little is known about the relationship between gain-of-function mutations and the RNA transcript expression of immune-related pathways. Methods: A sample of retrospective, clinicogenomic and transcriptomic data from de-identified records of patients with BTC in the Tempus database was selected. We then investigated the relationship between the mutational landscape and immune-related RNA signatures of different anatomic and genomic BTC subtypes. Results: The cohort included 455 samples of intrahepatic bile duct (IH) (n=267), gallbladder (GB) (n=153), and extrahepatic bile duct (EH) (n=35) cancer subtypes. Across all subtypes, we detected alterations in TP53 (43.8%), ARID1A (19.8%), KMT2C (18.2%), BAP1 (14.6%), KRAS (12.7%), TERT (12.0%), IDH1 (11.4%), KMT2D (11.0%), LRP1B (11.0%), and PBRM1 (10.7%), along with FGFR2 fusions (2.6%). Potentially actionable biomarkers ( FGFR2 and NTRK1-3 fusions, IDH1 and BRAFV600E mutations, tumor mutational burden [TMB]>10, HER2 expression, and/or microsatellite instability) were identified in 21.1% of all BTC and 28.6% of IH samples. Mutually exclusive alterations observed between subtypes were TP53 & BAP1, KRAS & BAP1, TP53 & IDH1, KRAS & IDH1, and SMAD4 & BAP1 ( P < 0.001 for all). GB was more inflamed based on RNA signatures and classical immune biomarkers, including PD-L1 and TMB. RNA signature analyses revealed a higher expression of immune-related pathways in GB than IH ( P = 0.001) with no differences in comparison with EH. PD-L1 expression and continuous TMB were elevated in GB versus the other anatomical subtypes. Significant associations were noted between particular genetic mutations and immune profiling features (table). Conclusions: BTC subtypes are diverse in DNA alterations, RNA inflammatory signatures, and immune markers. Notably, potentially actionable biomarkers were identified in a sizable portion of the cohort and varied significantly between subtypes. These results provide guidance for targeted therapy development and support the use of multimodal immune profiling for BTC. For example, GB-specific clinical trials may be considered due to the relative increase in immune-related biomarkers observed in GB and the historically limited success of BTC trials.[Table: see text]

Phase II trial of nivolumab and metformin in patients with treatment refractory microsatellite stable metastatic colorectal cancer

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Background: Preclinical data suggests metformin can improve immune exhaustion of tumor infiltrating lymphocytes and potentiate the effects of PD-1 blockade. By normalizing the hypoxic TME, metformin was shown to improve cytotoxic T cell function and efficacy of anti-PD-1 antibody in highly aggressive B16 melanoma and MC38 colon adenocarcinoma tumor models. Based on this preclinical rationale we conducted a phase II study with nivolumab and metformin combination in treatment refractory MSS metastatic colorectal cancer (mCRC). Methods: Nivolumab 480 mg IV every 4 weeks and Metformin 1000 mg po twice daily was administered in 28-day cycles following a 14-day metformin only lead-in phase.Eligible patients included stage IV metastatic treatment refractory MSS mCRC (patients must have received oxaliplatin, irinotecan, and fluoropyrimidine), age ≥18 years, ECOG PS 0-1, adequate organ function, no prior anti PD-1 agent. The primary endpoint was overall response rate (ORR). Secondary endpoints included overall survival (OS) and progression free survival (PFS). Simon’s two-stage Minimax design was employed (H0: ORR =4%; H1: ORR=15%; alpha = 0.1; power =80%). If ≥1 objective response was observed in the first evaluable 18 patients, 10 additional patients would be included in the cohort. ≥3 objective responders in 28 patients would be required to be considered positive study. Pre-treatment and on-treatment research biopsies and correlative peripheral blood specimens were collected. Results: A total of 24 patients were enrolled, 6 patients were replaced per protocol, and 18 patients had evaluable disease. Of the 18 evaluable patients 11/18 (61%) were female, median age 58 [IQR 50-67]. 2 patients had prolonged stable disease (4 and 10 cycles). No patients had objective response based on RECIST 1.1. Median OS and PFS was 5.1 months [95% CI (2-11.7)] and 2.3 months [95% CI (1.7-2.4)], respectively. Most common grade 3 and 4 toxicities were anemia (n=2) and diarrhea (n=2). Conclusions: In treatment refractory MSS mCRCnivolumab and metformin combination was well tolerated. Two patients achieved stable disease, but no objective response was seen; therefore, the study did not proceed with the second stage of enrollment. Immunologic correlative analysis of this study is ongoing. Clinical trial information: NCT03800602.

Delayed Processing of Secretin-Induced Pancreas Fluid Influences the Quality and Integrity of Proteins and Nucleic Acids

OBJECTIVES

Endoscopic pancreatic function tests are used to diagnose pancreatic diseases and are a viable source for the discovery of biomarkers to better characterize pancreatic disorders. However, pancreatic fluid (PF) contains active enzymes that degrade biomolecules. Therefore, we tested how preservation methods and time to storage influence the integrity and quality of proteins and nucleic acids.

METHODS

We obtained PF from 9 subjects who underwent an endoscopic pancreatic function test. Samples were snap frozen at the time of collection; after 1, 2, and 4 hours on ice; or after storage overnight at 4°C with or without RNase or protease inhibitors (PIs). Electrophoresis and mass spectrometry analysis determined protein abundance and quality, whereas nucleic acid integrity values determined DNA and RNA degradation.

RESULTS

Protein degradation increased after 4 hours on ice and DNA degradation after 2 hours on ice. Adding PIs delayed degradation. RNA was significantly degraded under all conditions compared with the snap frozen samples. Isolated RNA from PF-derived exosomes exhibited similar poor quality as RNA isolated from matched PF samples.

CONCLUSIONS

Adding PIs immediately after collecting PF and processing the fluid within 4 hours of collection maintains the protein and nucleic acid integrity for use in downstream molecular analyses.

Heat Shock Protein-90 Inhibition Alters Activation of Pancreatic Stellate Cells and Enhances the Efficacy of PD-1 Blockade in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has a prominent fibrotic stroma, which is a result of interactions between tumor, immune and pancreatic stellate cells (PSC), or cancer-associated fibroblasts (CAF). Targeting inflammatory pathways present within the stroma may improve access of effector immune cells to PDAC and response to immunotherapy. Heat shock protein-90 (Hsp90) is a chaperone protein and a versatile target in pancreatic cancer. Hsp90 regulates a diverse array of cellular processes of relevance to both the tumor and the immune system. However, to date the role of Hsp90 in PSC/CAF has not been explored in detail. We hypothesized that Hsp90 inhibition would limit inflammatory signals, thereby reprogramming the PDAC tumor microenvironment to enhance sensitivity to PD-1 blockade. Treatment of immortalized and primary patient PSC/CAF with the Hsp90 inhibitor XL888 decreased IL6, a key cytokine that orchestrates immune changes in PDAC at the transcript and protein level in vitro XL888 directly limited PSC/CAF growth and reduced Jak/STAT and MAPK signaling intermediates and alpha-SMA expression as determined via immunoblot. Combined therapy with XL888 and anti-PD-1 was efficacious in C57BL/6 mice bearing syngeneic subcutaneous (Panc02) or orthotopic (KPC-Luc) tumors. Tumors from mice treated with both XL888 and anti-PD-1 had a significantly increased CD8+ and CD4+ T-cell infiltrate and a unique transcriptional profile characterized by upregulation of genes associated with immune response and chemotaxis. These data demonstrate that Hsp90 inhibition directly affects PSC/CAF in vitro and enhances the efficacy of anti-PD-1 blockade in vivo.

Abstract 5571: Turning up the heat on pancreatic ductal adenocarcinoma via inhibiting vasoactive intestinal peptide signaling

Pancreatic ductal adenocarcinoma (PDAC) constitutes more than 90% of all pancreatic cancers and has a 5-year survival rate of only 5-7%. A dense stroma, an immunosuppressive tumor microenvironment (TME) and scarce tumor infiltrating T cells, contribute toward the poor responsiveness of PDAC to conventional and FDA-approved checkpoint therapies. In this study, we show that vasoactive intestinal peptide (VIP) signaling is a novel immune checkpoint pathway in PDAC, which when inhibited in combination with anti-PD1 checkpoint inhibitor, significantly decreases tumor burden and enhances T cell infiltration in mouse models of PDAC.

VIP is a 28-amino acid neuropeptide secreted at the nerve terminals, pancreas and the GI tract, and is commonly associated with regulating gut motility and blood pressure. Interestingly, VIP is also secreted by immune cells and is known to have immunosuppressive properties such as decreasing T cell proliferation and polarizing T cells towards Th2 phenotype. Intriguingly, according to the cancer genome atlas (TCGA), human exocrine pancreatic cancers expresses the highest level of VIP mRNA expression when compared to other solid malignancies. Similarly, we have generated preliminary data that shows enhanced VIP levels both systemically and locally in mouse models of PDAC and in human PDAC patients. Thus, taking all this into consideration, we hypothesized that enhanced VIP signaling is a potential mechanism of immune escape in PDAC and that inhibiting VIP signaling either alone or in combination with checkpoint inhibitors would significantly enhance treatment response in mouse models of PDAC.

We tested the effect of inhibiting VIP signaling by using a VIP receptor antagonist (VIPR antagonist) in orthotopic mouse models of PDAC, where luciferase transfected KPC cells (mouse PDAC cell line), were implanted in the tail of the pancreas. Mice were then treated with VIPR antagonist and/or anti-PD1 seven days after tumor implantation. Our results showed that the combination treatment significantly reduced tumor burden and growth rate, as well as, enhanced the infiltration of both CD4+ and CD8+ T cells into the tumor microenvironment (as per immunohistochemistry of tumor tissues). Furthermore, analysis of tumor infiltrating T cells via Nanostring analysis showed that the combination treatment also significantly enhanced levels of IFN gamma and TNF alpha secreting T cells and costimulatory and effector molecules, including CD27 and FasL.

In summary, we have identified that VIP signaling is a novel and targetable immune checkpoint pathway in PDAC, which when inhibited in combination with checkpoint inhibitors, significantly improves treatment response in mouse PDAC models. As the VIP sequence is conserved across different species including mouse and human, and since we have observed VIPR antagonists stimulate proliferation of human T cells, there is an increased potential for clinical translation of VIPR antagonists in the treatment of human PDAC.

Citation Format: Sruthi Ravindranathan, Brandon Ware, Mohammad Zaidi, Jingru Zhu, Rohan K. Dhamsania, Shuhua Wang, Yiwen Li, Ishani H. Rao, Susan N. Thomas, Gregory B. Lesinski, Bassel El-Rayes, Edmund K. Waller. Turning up the heat on pancreatic ductal adenocarcinoma via inhibiting vasoactive intestinal peptide signaling [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 5571.

Abstract 2980: Effects of cetuximab and CD-3379 on cytokine/chemokine balance in the tumor micro-environment (TME) of squamous cell carcinoma of the head and neck (SCCHN)

Background: The Anti-EGFR agent cetuximab has shown promising outcomes and remains to be the only FDA-approved non-immunotherapeutic targeted agent for the treatment of squamous cell carcinoma of the head and neck (SCCHN). There is evidence that immune modulation represents a mechanism by which cetuximab elicits its clinical activity in SCCHN. As resistance inevitably occurs to cetuximab, there is a need to further elucidate the biological mechanisms by which cetuximab affects immune effectors in the tumor microenvironment (TME). We aimed to explore the effect of EGFR inhibition on the cytokine/chemokine balance in the TME.

Methods: Three SCCHN cancer cell lines UM-SCC47 (HPV positive), JHU022 (HPV negative), and SCC-1C (HPV negative and resistant to cetuximab) were treated with cetuximab, CD-3379 (a HER3 inhibitor), and their combination. After 48 and/or 72 hours, the supernatants of the treated and untreated cells were collected and subjected to multiplexed immunoassay [Meso Scale Discovery (MSD) U-PLEX Assays] to study the cytokine/chemokine alteration. Changes in immune suppressive chemokines were confirmed by ELISA. A potential effect of a chemokine neutralizing antibody on apoptosis was further evaluated using patient-derived organotypic cancer spheroids (PDOCSs).

Results: Our results identified 10 down regulated cytokines/chemokines, including IL6, IL-8, IL-2, IL-12, IL-27, IL-4, IL-5, TGF-β, GM-CSF, and IFN-γ in at least one SCCHN cell line. Three cytokines/chemokines were up regulated, including IL-15, MCP-3, and MCP-1. MCP-1 (CCL2) is a modulator of myeloid-derived suppressor cells (MDSCs). Enhancing MCP-1 by cetuximab and/or CD-3379 in the SCCHN cell lines was confirmed by ELISA. Treating multiple PDOCSs with the same combination along with MCP-1 neutralizing antibody enhanced apoptosis in comparison to cetuximab, CD-3379, or the cetuximab/CD-3379 combination.

Conclusions: Our findings suggest that cetuximab in combination with HER3 inhibition affects secretion of cytokines/chemokines which are both immune stimulatory and suppressive in the TME of SCCHN. Alteration of the selected cytokines/chemokines may enhance the clinical activity of EGFR targeting in SCCHN.

Citation Format: Dongsheng Wang, Sreenivas Nannapaneni, Gregory B. Lesinski, Dong M. Shin, Nabil F. Saba, Georgia Z. Chen. Effects of cetuximab and CD-3379 on cytokine/chemokine balance in the tumor micro-environment (TME) of squamous cell carcinoma of the head and neck (SCCHN) [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 2980.