Impact of liver metastasis on efficacy of anti-PD-(L)1 therapy for microsatellite stable mCRC

Microsatellite stable (MSS) metastatic colorectal cancer (mCRC) has been historically characterized as resistant to immunotherapy. A retrospective study at City of Hope (Duarte, CA) evaluated anti-PD-(L)1 therapy for previously treated MSS mCRC. Among the patients with liver metastases the overall response rate was 0 and the disease control rate was 1.9%. Among the patients with nonliver metastases the ORR was 19.5% and the DCR was 58.5%. The median progression-free survival was 4.0 months in the group of patients with nonliver metastases versus 1.5 months in the group with liver metastases. The authors conclude that PD-(L)1 therapy should be reinvestigated in prospective trials in patients with MSS mCRC without liver involvement.