Third- or Further-Line Treatment in Patients with MSS Type Metastatic Colorectal Cancer

The survival benefit from later-line treatment for patients with metastatic colorectal cancer (mCRC) remains disappointing. Here, in a real-world study, we were aimed to evaluate which choice will affect the survival of mCRC patients after standard treatment in Chinese patients.

A total of 129 patients with refractory mCRC were involved in the study. They received targeted monotherapy or combined with chemo-agents or PD-1 inhibitor before death. Overall survival (OS) and progression-free survival (PFS) were reviewed and evaluated from clinical features and treatment options.

Among the 129 patients, the median age was 56 years (25–81). The mOS from third-line was 12.5 months. OS of patients who treated with chemo plus targeted therapy group in third-line was shown to be superior to pd-1 inhibitor in combination with antiangiogenic agents or antiangiogenic monotherapy group (15.6 m vs. 10.5 m vs. 8.4 m, p < 0.05). Patients had received triplet-drugs (bevacizumab plus low-dose irinotecan and oxaliplatin) and had prolonged survival compared to those had not (21.3 m vs 10.3 m, p = 0.004). OS between patients who had immunotherapy history or not was not significantly different (p > 0.05). The mPFS was 3.5 months in patients who had administered with antiangiogenic targeted agents plus anti-pd-1 and 4.7 months in chemo plus targeted therapy group and 2.2 months in the other group. In the triplet drugs group, preliminary results showed that ORR was 13.3% and DCR was 80%. The median PFS was 5.1 m, and the median OS was 10.6 m.

Triplet drugs resulted in significantly longer overall survival, and immunotherapy may have limited benefit in MSS type CRC patients.