Dr. Greten is a physician-scientist who uses his medical expertise in Gastroenterology, Hepatology and Medical Oncology along with his research expertise in tumor immunology to develop novel treatments for patients with cancer. He heads a research team to study the tumor microenvironment in the liver in the context of Hepatocellular Carcinoma, Cholangiocarcinoma, and liver metastasis and studies how exogenous factors such as diet and the gut microbiome may affect immune responses in the liver. He also directs the GI Medical Oncology clinical team, that conducts clinical trials in patients with GI cancers. He and his team cover the entire research spectrum from basic tumor immunology and use of complex murine cancer models to the development and evaluation of new immunotherapies (including CAR T cells) for patients with gastrointestinal cancers. He conducts investigator-initiated first-in-human trials, phase I and II trials and has been one of the first investigators to test immune checkpoint inhibitors in patients with Hepatocellular carcinoma and Cholangiocarcinoma either alone or in combination with locoregional therapies.