Broadening the Impact of Immunotherapy to Pancreatic Cancer: Challenges and Opportunities.

Pancreatic ductal adenocarcinoma (PDAC) is projected to become the second deadliest cancer in the United States by 2025, with 5-year survival at less than 10%. In other recalcitrant cancers, immunotherapy has shown unprecedented response rates, including durable remissions after drug discontinuation. However, responses to immunotherapy in PDAC are rare. Accumulating evidence in mice and humans suggests that this remarkable resistance is linked to the complex, dueling role of the immune system in simultaneously promoting and restraining PDAC. In this review, we highlight the rationale that supports pursuing immunotherapy in PDAC, outline the key barriers that limit immunotherapy efficacy, and summarize the primary preclinical and clinical efforts to sensitize PDAC to immunotherapy.