What does this research mean for the field?

The combination of tislelizumab, bevacizumab, and chemotherapy demonstrates promising efficacy and manageable safety as a second-line therapy for patients with PD-L1-positive, RAS-mutant metastatic colorectal cancer. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To evaluate the efficacy and safety of tislelizumab, bevacizumab, and chemotherapy in RAS-mutant, PD-L1-positive metastatic colorectal cancer after first-line therapy.

May 30, 2026

Tislelizumab, bevacizumab, and chemotherapy as second-line therapy in PD-L1-positive, RAS-mutant metastatic colorectal cancer: A single-arm, phase II clinical trial.

Key Points

To evaluate the efficacy and safety of tislelizumab, bevacizumab, and chemotherapy in RAS-mutant, PD-L1-positive metastatic colorectal cancer after first-line therapy.
Single-arm phase II trial enrolled 42 RAS-mutant PD-L1-positive mCRC patients who progressed after first-line therapy.
Patients received tislelizumab, bevacizumab, and switched chemotherapy with a focus on 6-month progression-free survival rate.
Conducted from April 2023 to March 2025 with screening of 50 patients.
Primary endpoint met with a 6-month progression-free survival rate of 66.67% (95% CI: 53.83-82.56%).
Confirmed objective response rate (ORR) was 16.67% (95% CI: 6.97-31.36%) and disease control rate (DCR) was 88.10% (95% CI: 74.37-96.02%).
Median overall survival (OS) was 16.3 months (95% CI: 13.2-NA months) with 76.7% experiencing treatment-related adverse events.

Abstract

e15540 Background: The therapeutic options for RAS-mutant metastatic colorectal cancer (mCRC) post first-line therapy are limited, with suboptimal efficacy of standard second-line regimens. Preclinical and clinical data support the synergistic antitumor effect of anti-PD-1 and anti-VEGF agents. Methods: This single-arm phase II study enrolled 42 eligible RAS-mutant, PD-L1-positive mCRC patients who progressed after first-line fluoropyrimidine-based chemotherapy. Patients received tislelizumab, bevacizumab, and switched chemotherapy. The primary endpoint was 6-month progression-free survival (PFS) rate. Results: Between April 2023 and March 2025, 50 patients were screened and 42 patients were eligible. The primary endpoint was met, with a 6-month PFS rate was 66.67% (95% CI:53.83-82.56%). The confirmed ORR was 16.67% (95% CI: 6.97-31.36%), and DCR was 88.10% (95% CI: 74.37-96.02%). The median OS was 16.3 months (95% CI: 13.2-NA months). Treatment-related adverse events occurred in 76.7% of patients, with 4.76% being grade 3–4. Immune-related adverse events were grade 1-2 in 21.43% of patients. No treatment-related deaths occurred. Conclusions: This combination regimen showed promising efficacy and manageable safety, providing a potential therapeutic option for this patient population (ChiCTR2200066728). Clinical trial information: ChiCTR2200066728 .

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