Checkpoint blockade immunotherapy may benefit patients with microsatellite stable colorectal cancer whose disease has not spread to the liver, according to research published Aug. 9 in JAMA Network Open.
Prior to the finding, immunotherapy has been largely considered ineffective against microsatellite stable colorectal cancer — the most common type of metastatic colorectal cancer.
Researchers from Duarte, Calif.-based City of Hope conducted a retrospective study involving 95 patients with the advanced form of colorectal cancer. Once their disease became chemotherapy-resistant, all patients in the study received immune checkpoint inhibitor PD-1/PD-L1 targeted therapy.
None of the patients whose cancer spread to the liver responded to the immunotherapy, while some of those without liver metastasis did, findings showed.
"When we stratified the patients by the presence of absence of liver metastases, we noted that about 20 percent of patients without liver metastases had a major response to anti-PD-1 or anti-PD-L1 therapy, while none of the patients with liver metastases experienced a positive response," said Marwan Fakih, MD, study author and co-director of the gastrointestinal cancer program and clinical research director at City of Hope. "Colorectal cancer patients without liver metastases could benefit from immunotherapy considerably more than patients with liver metastases."