- Add-on pembrolizumab to chemotherapy bests placebo for pathological complete response (pCR) in patients with early triple-negative breast cancer (TNBC) enrolled in the KEYNOTE-522 phase 3 trial.
Why this matters
- This is the first phase 3 trial of an immune checkpoint inhibitor in early breast cancer.
- Findings are likely to lead to regulatory approvals.
- Previously untreated patients with stage II or III TNBC were randomly assigned to:
- 4 cycles of 200 mg pembrolizumab every 3 weeks plus paclitaxel and carboplatin; or
- 4 cycles of placebo plus paclitaxel and carboplatin.
- Both groups then received 4 cycles of pembrolizumab or placebo and anthracycline-based chemo.
- After definitive surgery, patients received pembrolizumab or placebo every 3 weeks for up to 9 cycles.
- Funding: Merck Sharp & Dohme.
- The pembrolizumab-chemo group was more likely to achieve pCR:
- 64.8% vs 51.2% in the placebo-chemo group;
- Difference: 13.6% (P<.001>
- Fewer pembrolizumab-chemo patients had disease progression after a median of 15.5 months:
- 7.4% vs 11.8%;
- HR, 0.63 (95% CI, 0.43-0.93).
- Pembrolizumab-chemo patients had a higher rate of grade ≥3 treatment-related adverse events:
- 76.8% vs 72.2%;
- Death: 0.4% vs 0.3%.
- Short duration of follow-up.
- PFS and OS not yet available.