Immunotherapy in Colorectal Cancer.

Colorectal cancer (CRC) is the third leading cause of cancer deaths, with only 15% of patients surviving 5 years in the metastatic setting. Recent exciting developments in cancer immunotherapy, which involves priming the host's natural immune defenses to recognize, target, and destroy cancer cells effectively, have brought some glimpse of hope in fighting this deadly disease. Although CRC has been shown to evade immune detection like many other cancers do, immunotherapy has been noted to produce some very impressive results in a select group of patients. Patients with mismatch repair-deficient and microsatellite instability-high type CRC have benefited most from recent immunotherapy approaches, leading to US Food and Drug Administration approval of new immunotherapeutic agents in recurrent refractory metastatic disease. Research continues to explore and hopefully define the role of immunotherapy in CRC as single-agent therapy or in combination with other agents in neoadjuvant, adjuvant, and first-line metastatic setting, and to find the optimal combination and sequencing of this new therapeutic approach. One of the most challenging tasks is to find ways to expand the use of immunotherapy to not only a select group of CRC patients but also to all patients with this disease. This article will provide a practical concise overview of the current landscape of immunotherapy in CRC for the practicing oncologist along with a representative case presentation from our community oncology practice.