Investigations of the tumor microenvironment of resectable transgenic hepatobiliary tumors after neoadjuvant therapy with gemcitabine and oncolytic virus

• Applicant: Professor Dr. Florian Kühnel, since 11/2015
• Subject Area: Gastroenterology ; General and Visceral Surgery ; Immunology
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 259353827

Advances in liver surgery frequently facilitate complete resection (R0) of intrahepatic cholangiocarcinoma (ICC). However, novel therapies are urgently needed due to the high rate of disease recurrence and dismal prognosis. The aim of this project is the analysis of the tumor microenvironment and investigations of tumor specific immune responses in a novel resectable tumor model after neoadjuvant treatment. Therefore, a novel neoadjuvant approach with gemcitabine and oncolytic viral inflammation will be developed.Suitable animal models for preclinical investigations of neoadjuvant systemic therapies do not exist. For this purpose, we established a novel R0-resectable transgenic mouse model of ICC. We used local liver electroporation of a transposon vector for oncogenic Kras-G12V expression on the background of Cre-inducible p53-knockout. This transgenic local ICC model reproduces autochthonous tumor development as well as the most abundant clinical manifestations observable in the majority of the patients, including local and systemic tumor progression and disease recurrence after potential curative R0-resection. Consequently, this novel ICC model is well suited for direct comparison of innovative preclinical neoadjuvant and palliative treatments. In previous works, we could show that survival of animals after palliative gemcitabine treatment was not significantly affected. Though this treatment induced a downregulation of myeloid suppressor cells (MDSC), we observed a strong increase of regulatory T cells (Treg) in the primary tumors that could be interpreted as a counteraction in order to maintain the tumor specific immune tolerance. In contrast to systemic chemotherapy, acute viral infection induced a significant reduction of Tregs in the tumor microenvironment. These studies suggest a promising new approach of neoadjuvant immune therapy by combining Gemcitabine-related downregulation of MDSCs and additional repression of Tregs by oncolytic virotherapy.The high recurrence rate after R0-resection of the primary tumor in our new transgenic ICC model reflects one of the most important challenges in the majority of patients with a solid tumor. This transgenic ICC model facilitates for the first time preclinical investigations of innovative neoadjuvant therapies and analyses of tumor specific immune responses in a reliable experimental setting. Initially, we want to characterize immune cells and cytokines in primary tumors, metastases and local recurrence at different stages of tumor development. Additionally, immunomodulation of the tumor microenvironment after therapeutic interventions by Gemcitabine and oncolytic virotherapy will be determined. By investigating the influence of therapy-related immunomodulation on tumorspecific immune responses and on survival we want to establish an optimized neoadjuvant therapeutic strategy for metastatic ICC. Results of these investigations will be translated into a clinical trial.

• DFG Programme: Research Grants
• Participating Persons: Professor Dr. Diego Calvisi; Professorin Dr. Christine Falk; Professor Dr. Stefan Kubicka; Dr. Norman Woller
• Ehemaliger Antragsteller: Dr. Engin Gürlevik, until 10/2015