This is a multicenter observational study aimed to describe the efficacy and safety of regorafenib plus programmed cell death-1 (PD-1) inhibitors in Chinese patients with advanced colorectal cancer in routine clinical practice. The primary end point is overall survival. The secondary endpoints include progression-free survival, objective response rate, disease control rate and the incidence of treatment-related adverse events.

The investigators retrospectively identify patients with advanced colorectal adenocarcinoma who received at least one dose of PD-1 inhibitors plus regorafenib from 5/2019 to 2/2021 in 14 Chinese medical centers. Patients received the study treatment as part of routine medical care based on the consensus of clinicians and patients. In addition to the primary and secondary outcomes, other patient and treatment characteristics including baseline microsatellite instability status, metastatic sites, previous treatment regimens, post-treatment regimens, are collected in order to describe the real-world treatment patterns.

Inclusion Criteria:

1. 18 years of age and older
2. Histologically or cytologically confirmed advanced or metastatic colorectal adenocarcinoma
3. Disease progression on standard of care therapy
4. Patients must have received at least one dose of PD-1 inhibitors in combination with regorafenib
5. At least one available laboratory or vital sign measurement obtained subsequent to at least one dose of study treatment for safety analysis
6. Confirmed treatment discontinuation/disease progression/available radiological evaluation or at least eight weeks of follow-up subsequent to the first dose of study treatment for efficacy analysis
7. Prior exposure to regorafenib monotherapy or a PD-1 inhibitor monotherapy was allowed

Exclusion Criteria:

1. Other malignancies within the past 5 years except for adequately treated carcinoma of the cervix or basal or squamous cell carcinoma of the skin
2. Participation in other interventional studies while receiving regorafenib plus a PD-1 inhibitor

The investigators performed a retrospective review of medical records to identify patients with advanced colorectal cancer who received at least one dose of PD-1 inhibitors in combination with regorafenib as routine medical care in 14 Chinese medical centers.