- In a phase 3 trial, pembrolizumab led to better PFS than chemotherapy in first-line treatment of microsatellite-instability-high mismatch-repair deficiency advanced colorectal cancer (CRC).
Why this matters
- Pembrolizumab is FDA approved in this group after progression following chemotherapy.
- Interim analysis of a phase 3, open-label trial (KEYNOTE-177; n=307).
- Patients were randomly assigned to 200 mg pembrolizumab every 3 weeks or chemotherapy (5-fluorouracil-based therapy with or without bevacizumab or cetuximab) every 2 weeks.
- Funding: Merck Sharp and Dohme; Stand Up to Cancer.
- Median PFS was higher in the pembrolizumab group:
- 16.5 vs 8.2 months.
- HR, 0.60 (P=.0002).
- More patients were free of progression in the pembrolizumab group at 12 months (55.3% vs 37.3%) and 24 months (48.3% vs 18.6%).
- After 24 months of follow-up, the mean period of PFS was higher in the pembrolizumab group (13.7 vs 10.8 months).
- Among patients with a complete or partial response, at 24 months 83% in the pembrolizumab were ongoing vs 35% in the chemotherapy group.
- Adverse events grade ≥3 were less common in the pembrolizumab group (56% vs 78%).
- Open label.