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Supplementary Tables 1-7 and Figures 1-17

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in the United States. Pancreatic tumors are minimally infiltrated by T cells and are largely refractory to immunotherapy. Accordingly, the role of T-cell immunity in pancreatic cancer has been somewhat overlooked. Here, we hypothesized that immune resistance in pancreatic cancer was induced in response to antitumor T-cell immune responses and that understanding how pancreatic tumors respond to immune attack may facilitate the development of more effective therapeutic strategies. We now provide evidence that T-cell–dependent host immune responses induce a PDAC-derived myeloid mimicry phenomenon and stimulate immune resistance. Three KPC mouse models of pancreatic cancer were used: the mT3-2D (Kras+/LSL-G12D; Trp53+/LSL-R172H; Pdx1-Cre) subcutaneous and orthotopic models, as well as the KP1 (p48-CRE/LSL-Kras/Trp53flox/flox) subcutaneous model. KPC cancer cells were grown in immunocompetent and immunodeficient C57BL/6 mice and analyzed to determine the impact of adaptive immunity on malignant epithelial cells, as well as on whole tumors. We found that induced T-cell antitumor immunity, via signal transducer and activator of transcription 1 (STAT1), stimulated malignant epithelial pancreatic cells to induce the expression of genes typically expressed by myeloid cells and altered intratumoral immunosuppressive myeloid cell profiles. Targeting the Janus Kinase (JAK)/STAT signaling pathway using the FDA-approved drug ruxolitinib overcame these tumor-protective responses and improved anti–PD-1 therapeutic efficacy. These findings provide future directions for treatments that specifically disable this mechanism of resistance in PDAC.

Supplementary Table 1. Gene symbol and target sequences for two pooled siRNAs used in primary screens. Supplementary Table 2. Gene symbols and target sequences for four individual siRNAs utilized in secondary screens. Supplementary Table 3. Gene symbols and QuantiTect Primer Assays (Qiagen) used for quantitative reverse-transcription PCR (Q-RT-PCR) assessments.

Inhibition of c-Abl kinase activity by imatinib and sensitivity of HNSCC cell lines to ADCC.

Gene list used to construct IL-4 focused siRNA library.

Characterization of a real-time cell assay (RTCA) for assessment of ADCC.

Differential cytotoxicity from primary screens and specific lysis and differential cytotoxicity from secondary screens.

Tumor-targeted antibody therapy has had a major impact on reducing morbidity and mortality in a wide range of cancers. Antibodies mediate their antitumor activity in part by activating immune effector cells; however, the tumor microenvironment (TME) is enriched with cellular and soluble mediators that actively suppress generation of antitumor immunity. Here, we investigate the potential of prospectively identifying and neutralizing an immunomodulatory soluble mediator within the TME to enhance therapeutic efficacy of the HER2-directed antibody trastuzumab. Using the D5-HER2 cell line and an immunocompetent human HER2 transgenic animal (hmHER2Tg) in which human HER2 is a self-antigen, we determined that IL4 was present in the TME and produced by both tumor and stromal cells. A siRNA-based screening approach identified STAT5A as a novel negative regulator of IL4 production by D5-HER2 tumor cells. Furthermore, IL4 neutralization using the anti-IL4 antibody 11B11 enhanced the efficacy of trastuzumab and modulated the TME. For example, IL4 neutralization resulted in reduced levels of myeloid chemoattractants CCL2, CCL11, and CXCL5 in the TME. Combination therapy with 11B11 and trastuzumab resulted in a reduction of tumor-infiltrating CD11b+CD206+ myeloid cells compared with monotherapy. These data suggest that IL4 neutralization enhances the efficacy of trastuzumab by influencing the phenotype of myeloid cells within the TME and provide further rationale for combining tumor-targeted antibody therapy with agents that neutralize factors in the TME that suppress generation of productive antitumor immune responses. Cancer Immunol Res; 2(11); 1103–12. ©2014 AACR.

Supplementary Figure Legend

EGFR surface expression after knockdown of ABL1 or imatinib treatment in A431 cells.

Development of a screening assay for modulators of ADCC.

IL-4 neutralization alters the composition of the tumor microenvironment.

Effect of various c-Abl tyrosine kinase inhibitors on ADCC.

Monoclonal antibodies (mAb) can modulate cancer cell signal transduction and recruit antitumor immune effector mechanisms—including antibody-dependent cellular cytotoxicity (ADCC). Although several clinically effective antibodies can promote ADCC, therapeutic resistance is common. We hypothesized that oncogenic signaling networks within tumor cells affect their sensitivity to ADCC. We developed a screening platform and targeted 60 genes derived from an EGFR gene network using RNAi in an in vitro ADCC model system. Knockdown of GRB7, PRKCE, and ABL1 enhanced ADCC by primary and secondary screens. ABL1 knockdown also reduced cell proliferation, independent of its ADCC enhancement effects. c-Abl overexpression decreased ADCC sensitivity and rescued the effects of ABL1 knockdown. Imatinib inhibition of c-Abl kinase activity also enhanced ADCC—phenocopying ABL1 knockdown—against several EGFR-expressing head-and-neck squamous cell carcinoma cell lines by ex vivo primary natural killer cells. Our findings suggest that combining c-Abl inhibition with ADCC-promoting antibodies, such as cetuximab, could translate into increased therapeutic efficacy of mAbs. Cancer Immunol Res; 2(12); 1186–98. ©2014 AACR.

The impact of host-derived IL-4 on expression of soluble mediators in the tumor microenvironment.

Background Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Despite the decrease in both incidence and mortality rates in the last few years, Hepatitis B virus (HBV) and Hepatitis C virus (HCV) infection account for 70% of global liver cancer deaths. However, few researches have explored the prognostic similarities and differences between HBV-related HCC (HBV-HCC) and HCV-related HCC (HCV-HCC) at transcript level. Therefore, we aim to identify genes that may play an important role in regulating prognosis for HBV-HCC and HCV-HCC respectively and potentially lead to the prognostic difference between HBV-HCC and HCV-HCC. Methods Weighted correlation network analysis (WGCNA) was first conducted to identify gene modules related with prognosis using The Cancer Genome Atlas Liver Hepatocellular Carcinoma (TCGA-LIHC) cohort. The K-means clustering algorithm, Univariate and Multivariate Cox regression were, in turn, used to identify hub gene related to prognosis. The hub genes were then validated using ICGC-LIRI-JP cohort from The International Cancer Genome Consortium(ICGC) database by Multivariate Cox regression. Lastly, the validated genes in each group were alternately validated in other group. Results Midnightblue and paleturquoise modules in HBV group, greenyellow and white modules in HCV group were selected during WGCNA. Later, CALCRL, TMEM204, APLNR, MED8, HSPB11, TRAPPC3, ADPRS and BTF3L4 in HBV group, NEU1, DHX16, EDEM3, GLRX2 and CYB5R1 in HCV group were screened as our hub genes. Eventually, during validation phase, TMEM204 remained significant in both groups, and CYB5R1 was only significant in HCV group. Conclusions Our study suggested that there may be substantial prognostic differences between HBV-HCC and HCV-HCC in terms of mechanism. CYB5R1 may be partially related to prognostic difference between HBV-HCC and HCV-HCC.

Growth of pancreatic cancer is stimulated by gastrin in both a paracrine and an autocrine fashion. Traditional therapies have not significantly improved survival, and recently pancreatic cancer has been deemed a “cold” tumor due to its poor response to immunotherapy. Strategies to improve survival of pancreatic cancer are desperately needed. In the current investigation, we studied the effects of an anti-gastrin cancer vaccine, polyclonal antibody stimulator (PAS; formerly called G17DT and Gastrimmune), used alone or in combination with a programmed cell death receptor (PD)-1 immune checkpoint antibody on pancreatic cancer growth, metastases, and the tumor microenvironment (TME). Immune-competent female C57BL/6 mice bearing syngeneic orthotopic murine pancreatic cancer treated with PAS had significantly smaller tumors and fewer metastases. Examination of the TME demonstrated decreased fibrosis with fewer M2 and more M1 tumor-associated macrophages. Expression of the E-cadherin gene was significantly increased and expression of the TGFβR2 gene was decreased compared with controls. Mice treated with PAS or the combination of PAS and PD-1 antibody exhibited significantly less tumor expression of phospho-paxillin, the focal adhesion protein β-catenin, and matrix metalloproteinase-7. This study suggests that inhibition of the cancer-promoting effects of gastrin in pancreatic cancer can decrease metastases by altering the TME and decreasing pathways that activate the epithelial mesenchymal transition. The PAS vaccine appears to change the TME, making it more susceptible to therapy with an immune checkpoint antibody. This novel combination of two immunotherapies may improve survival of pancreatic cancer by decreasing both tumor growth and metastasis formation.NEW & NOTEWORTHY Survival from advanced pancreatic cancer is poor, in part due to dense fibrosis of the tumor microenvironment, increased number of M2-polarized macrophages that promote angiogenesis and invasion, and lack of “target-specific” therapy. Herein, we report that a tumor vaccine that selectively targets gastrin decreases pancreatic cancer growth and metastases. Furthermore, the gastrin vaccine polyclonal antibody stimulator alters the tumor microenvironment rendering it more responsive to immunotherapy with a programmed cell death receptor-1 immune checkpoint antibody.

We identified a rare missense germline mutation in BARD1 (c.403G>A or p.Asp135Asn) as pathogenic using integrated genomics and transcriptomics profiling of germline and tumor samples from an early-onset triple-negative breast cancer patient who later was administrated with a PARP inhibitor for 2 months. We demonstrated in cell and mouse models that, compared to the wild-type, (1) c.403G>A mutant cell lines were more sensitive to irradiation, a DNA damage agent, and a PARP inhibitor; (2) c.403G>A mutation inhibited interaction between BARD1 and RAD51 (but not BRCA1); and (3) c.403G>A mutant mice were hypersensitive to ionizing radiation. Our study shed lights on the clinical interpretation of rare germline mutations of BARD1. Supplementary Information The online version contains supplementary material available at 10.1186/s13058-021-01428-5.

BackgroundPancreatic ductal adenocarcinoma (PDAC) is projected to be the second leading cause of cancer death in the USA by 2030. Immune checkpoint inhibitors fail to control most PDAC tumors because of PDAC’s extensive immunosuppressive microenvironment and poor immune infiltration, a phenotype also seen in other non-inflamed (ie, ‘cold’) tumors. Identifying novel ways to enhance immunotherapy efficacy in PDAC is critical. Dipeptidyl peptidase (DPP) inhibition can enhance immunotherapy efficacy in other cancer types; however, the impact of DPP inhibition on PDAC tumors remains unexplored.MethodsWe examined the effects of an oral small molecule DPP inhibitor (BXCL701) on PDAC tumor growth using mT3-2D and Pan02 subcutaneous syngeneic murine models in C57BL/6 mice. We explored the effects of DPP inhibition on the tumor immune landscape using RNAseq, immunohistochemistry, cytokine evaluation and flow cytometry. We then tested if BXCL701 enhanced anti-programmed cell death protein 1 (anti-PD1) efficacy and performed immune cell depletion and rechallenged studies to explore the relevance of cytotoxic immune cells to combination treatment efficacy.ResultsIn both murine models of PDAC, DPP inhibition enhanced NK and T cell immune infiltration and reduced tumor growth. DPP inhibition also enhanced the efficacy of anti-PD1. The efficacy of dual anti-PD1 and BXCL701 therapy was dependent on both CD8+ T cells and NK cells. Mice treated with this combination therapy developed antitumor immune memory that cleared some tumors after re-exposure. Lastly, we used The Cancer Genome Atlas (TCGA) to demonstrate that increased NK cell content, but not T cell content, in human PDAC tumors is correlated with longer overall survival. We propose that broad DPP inhibition enhances antitumor immune response via two mechanisms: (1) DPP4 inhibition increases tumor content of CXCL9/10, which recruits CXCR3+ NK and T cells, and (2) DPP8/9 inhibition activates the inflammasome, resulting in proinflammatory cytokine release and Th1 response, further enhancing the CXCL9/10-CXCR3 axis.ConclusionsThese findings show that DPP inhibition with BXCL701 represents a pharmacologic strategy to increase the tumor microenvironment immune cell content to improve anti-PD1 efficacy in PDAC, suggesting BXCL701 can enhance immunotherapy efficacy in ‘cold’ tumor types. These findings also highlight the potential importance of NK cells along with T cells in regulating PDAC tumor growth.

PDAC is typically resistant to chemotherapy and immunotherapy; therefore, novel strategies are needed to enhance therapeutic response. BXCL701 is a well-studied inhibitor of dipeptidyl peptidases 4, 8, 9, and Fibroblast Activation Protein, and has been postulated to work through cytokine induction and macrophage pyroptosis. We examined the effects of BXCL701 and/or PD1 therapy in murine models of PDAC. In the mT3-2D PDAC model, combination therapy of established (~75mm3) sc tumors reduced tumor growth to a greater extent (PBS: 1349±230 mm3 on day 42 vs B + PD1: 355±161mm3, p Citation Format: Shangzi Wang, Allison Fitzgerald, Reham Ajina, Sandra A. Jablonsk, Louis M. Weiner, John MacDougall, Veena Agarwal, Vince J. O'Neill. Therapy with BXCL701 (B), a DPP8, DPP9, DPPIV and FAP inhibitor, in combination with anti-PD1 antibody (PD1) in a syngeneic murine pancreatic ductal adenocarcinoma (PDAC) model improves treatment outcomes and induces intratumoral NK cell infiltrates and a marked reduction in tumor stromal fibrosis [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 6636.

Tumor-targeted antibody therapy has had a major impact on reducing morbidity and mortality in a wide range of cancers. Antibodies mediate their anti-tumor activity in part by activating immune effector cells; however, the tumor microenvironment is enriched with cellular and soluble mediators that actively suppress generation of anti-tumor immunity. Here, we investigate the potential of prospectively identifying and neutralizing an immunomodulatory soluble mediator within the tumor microenvironment to enhance therapeutic efficacy of the HER2-directed antibody trastuzumab. Using the D5-HER2 cell line and an immunocompetent human HER2 transgenic animal (hmHER2Tg) in which human HER2 is seen as a self-antigen, we determined that IL-4 was present in the tumor microenvironment and produced by both tumor and stromal cells. A siRNA-based screening approach identified Stat5a as a novel negative regulator of IL-4 production by D5-HER2 tumor cells. Furthermore, IL-4 neutralization using the anti-IL-4 antibody 11B11 enhanced the efficacy of trastuzumab and modulated the tumor microenvironment. For example, IL-4 neutralization resulted in reduced levels of myeloid chemoattractants CCL2, CCL11, and CXCL5 in the tumor microenvironment. Combination therapy with 11B11 and trastuzumab resulted in a reduction of tumor-infiltrating CD11b+CD206+ myeloid cells compared to monotherapy. These data suggest that IL-4 neutralization enhances the efficacy of trastuzumab by influencing the phenotype of myeloid cells within the tumor microenvironment and provides further rationale for combining tumor-targeted antibody therapy with agents that neutralize factors in the tumor microenvironment that suppress generation of productive anti-tumor immune responses.

Advanced pancreatic ductal adenocarcinoma (PDAC) has typically been resistant to chemotherapy and immunotherapy; therefore, novel strategies are needed to enhance therapeutic response. Cholecystokinin (CCK) has been shown to stimulate growth of pancreatic cancer. CCK receptors (CCKRs) are present on pancreatic cancer cells, fibroblasts, and lymphocytes. We hypothesized that CCKR blockade would improve response to immune checkpoint antibodies by promoting influx of tumor-infiltrating lymphocytes (TILs) and reducing fibrosis. We examined the effects of CCKR antagonists or immune checkpoint blockade antibodies alone or in combination in murine models of PDAC. Monotherapy with CCKR blockade significantly decreased tumor size and metastases in SCID mice with orthotopic PDAC, and in C57BL/6 mice, it reduced fibrosis and induced the influx of TILs. Immune-competent mice bearing syngeneic pancreatic cancer (Panc02 and mT3-2D) that were treated with the combination of CCK receptor antagonists and immune checkpoint blockade antibodies survived significantly longer with smaller tumors. Tumor immunohistochemical staining and flow cytometry demonstrated that the tumors of mice treated with the combination regimen had a significant reduction in Foxp3+ T-regulatory cells and an increase in CD4+ and CD8+ lymphocytes. Masson’s trichrome stain analysis revealed 50% less fibrosis in the tumors of mice treated with CCKR antagonist compared to controls and compared to checkpoint antibody therapy. CCKR antagonists given with immune checkpoint antibody therapy represent a novel approach for improving survival of PDAC. The mechanism by which this combination therapy improves the survival of PDAC may be related to the decreased fibrosis and immune cells of the tumor microenvironment.

Met is a receptor tyrosine kinase that promotes cancer progression. In addition, Met has been implicated in resistance of tumors to various targeted therapies such as epidermal growth factor receptor inhibitors in lung cancers, and has been prioritized as a key molecular target for cancer therapy. However, the underlying mechanism of resistance to Met-targeting drugs is poorly understood. Here, we describe screening of 1310 genes to search for key regulators related to drug resistance to an anti-Met therapeutic antibody (SAIT301) by using a small interfering RNA-based synthetic lethal screening method. We found that knockdown of 69 genes in Met-amplified MKN45 cells sensitized the antitumor activity of SAIT301. Pathway analysis of these 69 genes implicated fibroblast growth factor receptor (FGFR) as a key regulator for antiproliferative effects of Met-targeting drugs. Inhibition of FGFR3 increased target cell apoptosis through the suppression of Bcl-xL expression, followed by reduced cancer cell growth in the presence of Met-targeting drugs. Treatment of cells with the FGFR inhibitors substantially restored the efficacy of SAIT301 in SAIT301-resistant cells and enhanced the efficacy in SAIT301-sensitive cells. In addition to FGFR3, integrin β3 is another potential target for combination treatment with SAIT301. Suppression of integrin β3 decreased AKT phosphorylation in SAIT301-resistant cells and restored SAIT301 responsiveness in HCC1954 cells, which are resistant to SAIT301. Gene expression analysis using CCLE database shows that cancer cells with high levels of FGFR and integrin β3 are resistant to crizotinib treatment, suggesting that FGFR and integrin β3 could be used as predictive markers for Met-targeted therapy and provide a potential therapeutic option to overcome acquired and innate resistance for the Met-targeting drugs.

Cancer stem-like cells (CSCs) have been implicated in recurrence and treatment resistance in many human cancers. Thus, a CSC-targeted drug delivery strategy to eliminate CSCs is a desirable approach for developing a more effective anticancer therapy. We have developed a tumor-targeting nanodelivery platform (scL) for systemic administration of molecular medicines. Following treatment with the scL nanocomplex carrying various payloads, we have observed exquisite tumor-targeting specificity and significant antitumor response with long-term survival benefit in numerous animal models. We hypothesized that this observed efficacy might be attributed, at least in part, to elimination of CSCs. Here, we demonstrate the ability of scL to target both CSCs and differentiated nonstem cancer cells (non-CSCs) in various mouse models including subcutaneous and intracranial xenografts, syngeneic, and chemically induced tumors. We also show that systemic administration of scL carrying the wtp53 gene was able to induce tumor growth inhibition and the death of both CSCs and non-CSCs in subcutaneous colorectal cancer xenografts suggesting that this could be an effective method to reduce cancer recurrence and treatment resistance. This scL nanocomplex is being evaluated in a number of clinical trials where it has been shown to be well tolerated with indications of anticancer activity.

O1 IL-15 primes an mTOR-regulated gene-expression program to prolong anti-tumor capacity of human natural killer cells #### Andreas Lundqvist1, Vincent van Hoef1, Xiaonan Zhang1, Erik Wennerberg2, Julie Lorent1, Kristina Witt1, Laia Masvidal Sanz1, Shuo Liang1, Shannon Murray3, Ola Larsson1

Fibroblast activation protein (FAP) is a type II transmembrane serine protease that functions as both a dipeptidyl peptidase and an endopeptidase. FAP is minimally expressed in normal pancreas but overexpressed in 90% of pancreatic ductal adenocarcinoma (PDAC) specimens. A meta-analysis of PDAC studies demonstrated elevated tumor FAP expression is associated with worse clinical outcomes. While immunotherapy offers remarkable results for certain cancer types, it has been largely ineffective in PDAC. This lack of efficacy may be attributed to the dense stromal fibrosis, comprised largely of pancreatic stellate cells (PSCs), that is characteristic of PDAC lesions. Here we demonstrate that human NK cell line (NK92) is activated by and kill PSCs. Upon direct contact with PSCs, NK92 cells upregulate FAP. FAP expression by NK92 cells is associated with an inactivation phenotype. Talabostat, a non-specific inhibitor of FAP, enhances NK92 killing of PSCs in vitro and enhances PDAC tumor clearance in vivo. This suggests that FAP may be a novel NK cell immune checkpoint that can be pharmacologically modulated to enhance NK cell antitumor activity. Citation Format: Allison O'Connell, Shangzi Wang, Louis M. Weiner. The potential role of fibroblast activation protein as a natural killer cell immune checkpoint [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A096.

Background: Animal models to study cancer progression and therapeutics are essential but these animal models are most useful when they resemble human cancers, particularly with respect to inflammation and the immune system in carcinogenesis and therapy. Hence, athymic nude mice bearing human cancer explants are being replaced by genetically modified animal models with intact immune systems. Panc02 cancer cells have been used to create a syngeneic immune competent murine model of pancreatic cancer. However, unlike human pancreatic cancer, Panc02 cells express wild-type KRAS and CCK-A type receptors (rather than CCK-B type receptors). We previously showed that the Pdx1-Cre / LSL-KrasG12D transgenic mice develop de novo CCK-B receptors with PanIN progression. Aim: The goal of this investigation was to examine cell cultures derived from the KrasG12D mice to determine if they are indeed similar to human cancers in regard to in vivo growth properties and expression of gastrin and CCK-B receptors. Methods: Five different pancreatic cell lines were obtained that had been derived from the KPC mice (KPC1, KPC2) or organoids (MT3-2D, MT4-2D, and MT5-2D) of the KPC mice. RNA was extracted from the cell lines and evaluated for CCK-A and CCK-B receptors and the ligand gastrin. Growth studies were characterized in syngeneic C57BL/6 mice. The effects of CCK receptor blockade with proglumide was evaluated on tumor growth in vivo. Histologic sections were stained with H&E, Trichrome, and a PD-L1 Ab.Results: RT-PCR revealed that the KPC and MT-2D cells no longer express the CCK-A receptor found in normal mouse pancreas but all expressed the CCK-B receptor, characteristic of human pancreatic cancers. Gastrin expression was also detected by RT-PCR in all cells. Subcutaneous tumors grew rapidly to 1000mm3 within 21 days after inoculation of 105 cells. Tumor growth in MT3-2D tumors was significantly inhibited and survival of mice prolonged with the CCK-receptor antagonist proglumide compared to PBS controls (p=0.0048). Tumors showed extensive fibrosis characteristic of the human PDAC microenvironment and all tumors had PD-L1 expression. Conclusion: These studies show that cell lines developed from PanIN lesions in KRAS mice exhibit phenotypic and genetic characteristics comparable to human pancreatic cancers and therefore are promising models to study the relationship of CCK receptor-mediated biology to the development and therapy of pancreatic cancer. De novo expression of the CCK-B receptor and gastrin from mouse pancreas suggests a possible relationship between CCK receptor signaling and mutant KRAS expression.Supported by NCI CA50633, CA51008, and CA194745 Citation Format: Jill P. Smith, Shangzi Wang, Louis Weiner, Sandeep Nadella. De novo expression of gastrin and CCK-B receptors in cell lines derived from KPC mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-133. doi:10.1158/1538-7445.AM2017-LB-133

Introduction: Advanced pancreatic ductal adenocarcinoma (PDAC) has typically been resistant to chemotherapy and immune therapy; therefore, novel strategies are needed to enhance therapeutic response. Cholecystokinin receptors (CCKRs) are present on pancreatic cancer epithelial cells, fibroblasts of the microenvironment, and lymphocytes. We hypothesized that CCK receptor blockade would improve response to immune checkpoint blockade and survival by promoting influx of tumor infiltrating lymphocytes (TILs) and reducing fibrosis. Methods: Subcutaneous tumors were established using Panc02 murine pancreatic cancer cells (1.0- or 2.0 x10E6) in a syngeneic immune competent mouse model. Three separate experiments were performed with 40 mice each. Mice (C57BL/6) were divided into 4 groups (N = 10 mice each) and treated with PBS (control), a CCKR antagonist (L364,718 or proglumide), an immune checkpoint blockade antibody (PD-1 or CTLA-4; Im-Ab), or the combination of CCKR antagonist and immune checkpoint blockade antibody (combination). Tumor growth and animal survival were evaluated. Tumors were subjected to immunohistochemical staining for TILs, trichrome staining, and flow cytometry. Results: On day 50 after inoculation of 10E6 cells all control mice had died while 42%, 42% and 71% of L364,718, CTLA-4 mice, or combination-treated mice, respectively were alive (p = 0.02). By day 90 all mice died except one in the combination-treated group. In the experiment where mice were injected with 2×10E6 Panc02 cells, survival was also increased in mice receiving a proglumide and PD-1 antibody combination (p = 0.0009). CD8+TILs increased by 3-,6.3-,and 7.5-fold in CCKR antagonist, Im-Ab, and combination therapy, respectively compared to controls (p Conclusions: The combination of CCKR antagonism and immune checkpoint blockade antibodies significantly improve survival in a murine model of PDAC. The mechanism is associated with decreased fibrosis in the microenvironment and an accompanying influx of CD8+ and CD4+ TILs. Supported by NCI CA50633, CA51008, and CA194745 Citation Format: Jill P. Smith, Shangzi Wang, Ajina Reham, Sandra A. Jablonski, Louis M. Weiner. Combination therapy with immune checkpoint inhibitor and CCK-receptor blockade increases survival of pancreatic cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4023.

Antibodies against cancer-relevant targets can recruit Fc receptor-bearing myeloid and natural killer cells to mediate antibody dependent cellular cytotoxicity (ADCC). Toll-like receptors are potent activators of the innate immune system and generate signals leading to the initiation of an adaptive immune response that can be utilized for therapeutic purposes. We tested the efficacy of E6020, a TLR4 agonist, administered in combination with the clinically approved anti-HER2 antibody trastuzumab. A four-week course of therapy with trastuzumab and E6020 protected against the outgrowth of syngeneic D5 melanoma cells transfected with the human tumor antigen HER2 in immunodeficient C57BL/6 SCID mice, in immunocompetent wild-type C57BL/6 mice as well as in human HER2-tolerant C57BL/6 hmHER2 transgenic mice. In each tested strain of mice, the addition of E6020 to trastuzumab significantly increased the proportion of animals that survived initial tumor challenge compared to trastuzumab treatment alone (83% vs. 33% in C57BL/6 hmHER2 transgenic mice; p < 0.05). To determine if apparently cured mice had been effectively immunized against human HER2, the transgenic mice were inoculated subcutaneously with 103 D5-HER2 cells and then received a 4-week course of trastuzumab+E6020, or trastuzumab alone. Animals that survived the primary tumor challenge were followed for at least 120 days and then rechallenged with 5 × 103 D5-HER2 or unmodified D5 cells and followed for a minimum of 60 additional days. Mice that had been initially treated with the combination of trastuzumab and E6020 demonstrated superior protection (22/30; 73%) to those treated with trastuzumab alone (16/36; 44%; p < 0.05) against rechallenge with D5-HER2, but no protection was seen against D5 challenge. Both CD4 and CD8 T-cells were required for full protection against rechallenge. These findings suggest that trastuzumab therapy can induce a host-protective adaptive immune response. Moreover, combined treatment with trastuzumab and a TLR4 agonist enhances both the direct anti-tumor effects of trastuzumab and a host-protective human HER2-directed adaptive immune response. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-324.

We have previously described the critical structural determinants of anti-tumor antibodies that promote in vivo tumor targeting and antibody-dependent cellular cytotoxicity (ADCC). We now describe treatment strategies in murine models that 1) improve in vitro and in vivo ADCC, 2) dissect the relative contributions of tumor signaling perturbation and ADCC for in vivo therapeutic efficacy, and 3) identify therapy conditions that promote the induction of host-protective adaptive immunity. We also have identified tumor-intrinsic factors that sensitize tumor cells to EGFR-directed antibody therapy, using a siRNA library focused on genes functionally linked to the EGFR signaling pathway. We predict that these findings will be important for the improved efficacy of EGFR family-directed antibody therapies. Supported by CA50633, CA121033. Citation Information: Clin Cancer Res 2010;16(7 Suppl):PL6-2