Project description:Immunotherapeutics represent highly promising agents with the potential to improve patient outcomes in a variety of cancer types. Unfortunately, single-agent immunotherapy has achieved limited clinical benefit to date in patients suffering from pancreatic ductal adenocarcinoma (PDAC). This may be due to the presence of a uniquely immunosuppressive tumor microenvironment (TME) present in PDACs, which creates a barrier to effective immune surveillance. Critical obstacles to immunotherapy in PDAC tumors include the dense desmoplastic stroma that acts as a barrier to T-cell infiltration and the high numbers of tumor-associated immunosuppressive cells. We have identified hyperactivated focal adhesion kinase (FAK) activity in neoplastic PDAC cells as a significant regulator of the fibrotic and immunosuppressive TME. We found that FAK activity was elevated in human PDAC tissues and correlates with high levels of fibrosis and poor CD8+ cytotoxic T-cell infiltration. Single-agent FAK inhibition (VS-4718) dramatically limited tumor progression, resulting in a doubling of survival in the p48-Cre/LSL-KrasG12D/p53Flox/+ (KPC) mouse model of human PDAC. This alteration in tumor progression was associated with dramatically reduced tumor fibrosis, decreased numbers of tumor-infiltrating immature myeloid cells and immunosuppressive macrophages. We postulated that these desirable effects of FAK inhibition on the TME might render PDAC tumors more sensitive to immunotherapy. Accordingly, we found that VS-4718 rendered the previously unresponsive KPC mouse model responsive to anti-PD1 and anti-CTLA4 antagonists leading to a nearly tripling of survival times. These data suggest that FAK inhibition increases immune surveillance by overcoming the fibrotic and immunosuppressive PDAC TME thus rendering tumors more responsive to immunotherapy. We treated KP orthotopic tumor-bearing mice with vehicle and FAK inhibitor (FAKi) for 14 days, then extracted total RNA from tumor tissues.

Project description:Purpose: Chemotherapy is pivotal in the multimodal treatment of pancreatic cancer patients. In recent years, technical advances have developed experimental methods that unveiled a high degree of inter- and intratumoral heterogeneity in pancreatic cancer. We hypothesized that intratumoral heterogeneity (ITH) impacts response to gemcitabine treatment and demands specific targeting of resistant subclones. Experimental Design: We addressed the effect of ITH on response to gemcitabine treatment using single cell-derived cell lines (SCDCL) from the classical-like cell line BxPC3 and the basal-like cell line Panc-1 which were analyzed by mRNA-seq and mass spectrometry. Results: Individual SCDCLs of the parental tumor cell populations of BxPC3 and Panc-1 showed considerable heterogeneity in response to gemcitabine. Unsupervised principal component analysis (PCA) including the 1,000 most variably expressed genes showed a clustering of the SCDCLs according to their respective sensitivity to gemcitabine treatment for BxPC3, while this clustering was less clear for Panc-1. In BxPC3 SCDCLs, enriched signaling pathways EMT, TNF signaling via NfKB, and IL2STAT5 signaling correlated with more resistant behavior to gemcitabine. In Panc-1 SCDCLs MYC targets V1 and V2 as well as E2F targets were associated with stronger resistance to gemcitabine. Feature extraction of proteomes again identified less proteins whose expression was associated with the response of individual SCDCLs in Panc-1 compared to BxPC3. Based on molecular profiles, we could show that the gemcitabine-resistant SCDCLs of both BxPC3 and Panc-1 are more sensitive to the BET inhibitor JQ1 compared to the respective gemcitabine-sensitive SCDCLs. Conclusions: Our model system of SCDCLs identified gemcitabine-resistant subclones within a parental tumor population and provides evidence for the critical role of ITH for treatment response in pancreatic cancer. Through molecular profiling, we identified specific signaling pathways and protein signatures that might help to explain the differential response to treatment among clones. We exploited these molecular differences for an improved and more targeted therapy of resistant subclones of a heterogeneous tumor.

Project description:Immunotherapy provides an alternative approach for cancer treatment. However, in-depth analyses of the effects of immunotherapy on the tumor microenvironment (TME) have not been conducted in non-melanoma tumors. Here we describe changes in the pancreatic ductal adenocarcinoma (PDAC) TME following immunotherapy treatment, and show for the first time that vaccine-based immunotherapy directly alters the TME, inducing neogenesis of tertiary lymphoid structures that convert immunologically quiescent tumors into immunologically active tumors. Alterations in five pathways important for immune modulation and lymphoid structure development (TH17/Treg, NFkB, Ubiquitin-proteasome, Chemokines/chemokine receptors, and Integrins/adhesion molecules) in vaccine-induced intratumoral lymphoid aggregates were associated with improved post-vaccination responses. Additional studies in other cancers and patients treated with other forms of immunotherapy are warranted to further develop signatures defined in intratumoral lymphoid structures into biomarkers that predict effective anti-tumor immune responses. These signatures may also expose therapeutic targets for promoting more robust antitumor immune responses in the TME. Between July 2008 and September 2012, 59 patients were enrolled into an ongoing study of an irradiated, allogeneic GM-CSF-secreting pancreatic tumor vaccine (GVAX) administered intradermally either alone or in combination with immune modulatory doses of cyclophophamide (Cy) as neoadjuvant and adjuvant treatment for patients with resectable pancreatic ductal adenocarcinoma (PDAC). Patients were randomized 1:1:1 to 3 treatment arms. In Arm A, patients received GVAX alone; in Arm B, patients received GVAX plus a single intravenous dose of Cy at 200 mg/m2 1 day prior to each vaccination; in Arm C, patients received GVAX plus oral Cy at 100 mg once daily for 1 week on and 1 week off. Up to 6 GVAX treatments were administered and all of the patients remained in their initial treatment arms throughout the duration of the study. All 59 of the patients received the 1st GVAX treatment 2 weeks +/-4 days prior to surgery. Formalin-fixed paraffin-embedded (FFPE) tissue blocks of surgically resected PDAC were obtained from the pathology archive. FFPE tissue blocks from each subject were stained by H&E immediately before the vaccine therapy-induced lymphoid aggregates were microdissected . To better understand the functional status of these vaccine therapy induced lymphoid aggregate structures, gene microarray analysis on RNA isolated from microdissected lymphoid aggregates was performed. Gene expression was compared among samples grouped according to patient overall survival, post-vaccination induction of enhanced mesothelin-specific T cell responses in peripheral blood lymphocytes (PBL), and the intratumoral CD8+ T effector to FoxP3+ Treg ratio. Post-vaccination induction of enhanced mesothelin-specific T cell responses has been reported to correlate with longer survival in patients treated with Panc GVAX.

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Transcriptional profiling of parental and immunotherapy-resistant mouse pancreatic tumor cells

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