Title:The Current and Evolving Role of Immunotherapy in Metastatic Colorectal
Cancer
Volume: 22
Issue: 8
Author(s): Virgilio S. Silva, Rachel P. Riechelmann*, Celso A. Mello, Tiago Felismino and Rodrigo Taboada
Affiliation:
- Department of Clinical Oncology, AC Camargo Cancer Center, Sao Paulo, Brazil
Keywords:
Colorectal cancer, immune checkpoint inhibitors, immunotherapy, microsatellite stability, microsatellite instability, monoclonal antibody.
Abstract: Immunotherapy can be considered a therapeutic revolution in oncology, with great impact
on many tumor types, such as melanoma and non-small cell lung cancer. However, in metastatic colorectal
cancer, the benefits in terms of prolonged tumor control and high response rate are limited to the
rare subgroup of tumors with high mutation burden - mostly tumors that harbor microsatellite instability
(MSI) or a deficient mismatch repair system (dMMR), or tumor microsatellite stability and damaging
mutations in the exonuclease domains of POLE or POLD. The KEYNOTE-028 uncontrolled phase
II trial demonstrated an impressive antitumor activity of pembrolizumab in patients with treatmentrefractory
Lynch-associated tumors, including colorectal cancer. Nivolumab with or without ipilimumab
confirmed the efficacy of immune checkpoint inhibitors in patients with previously treated
dMMR / MSI metastatic colorectal cancer. The recent KEYNOTE-177 phase III trial demonstrated
that pembrolizumab significantly reduced the relative risk of disease progression or death and improved
progression-free survival in patients with treatment-naive dMMR / MSI metastatic colorectal
cancer in comparison with first-line chemotherapy with or without biologics. Unfortunately, current
pharmacological strategies with immunotherapy have not been successful for most patients with microsatellite
stable metastatic colorectal cancer. In this review, we critically appraise the applicability of
immune checkpoint inhibitors in dMMR/MSI metastatic colorectal cancer. We also discuss the recent
negative trials of immunotherapy combinations in microsatellite stable tumors and more mature immunotherapy
ongoing studies in the field of advanced colorectal cancer.