Study summary

Tislelizumab plus chemotherapy as first treatment extended survival

RATIONALE-306 · Worldwide phase 3 · FDA approval March 2025

What was tested

Tislelizumab, a PD-1 immunotherapy, or placebo, added to platinum chemotherapy as the first treatment for advanced disease.

What they found

• In PD-L1 positive tumors, typical survival was 16.8 months with tislelizumab and 9.6 months without (hazard ratio 0.66).
• After almost four years of follow-up, a later look at higher PD-L1 tumors found 19.1 vs 10.0 months.

What it means

One of three PD-1 drugs approved in the US as part of the first treatment, for tumors that test positive for PD-L1.