Immunotherapy in Colorectal Cancer

Individuals with colorectal cancer who have high levels of deficiency in DNA mismatch repair (MMR) have a higher production of neo-antigens and are potential candidates for immunotherapy, states Dirk Arnold, MD, PhD. The phase II trial found that MMR status predicts the clinical benefit of immune checkpoint blockade with pembrolizumab. In patients with MMR deficiencies the objective response rate was 62% compared with 0% in patients with MMR-proficient tumors.

There may be other subsets of patients who would benefit from immunotherapy, says Fortunato Ciardiello, MD, PhD. Investigators will soon be able to explore the appropriate time to intervene with immunotherapy and how to optimally use these drugs MMR-high population, Ciardiello adds.

Data suggest that immune infiltrate is a strong prognostic predictor in primary colon cancers. An assay to measure infiltrate is currently in development and can function as another means to help identify patients who may benefit from immunotherapy.