KEYNOTE-522 Regimen for Early-Stage Triple-Negative Breast Cancer
According to the KEYNOTE-522 trial, the regimen consists of 4 cycles of carboplatin plus paclitaxel with pembrolizumab, followed by 4 cycles of epirubicin (or doxorubicin) plus cyclophosphamide with pembrolizumab in the neoadjuvant phase, then up to 9 cycles of adjuvant pembrolizumab after surgery. 1, 2, 3
Detailed Treatment Schedule
Neoadjuvant Phase (Before Surgery)
First 4 cycles:
- Pembrolizumab 200 mg IV every 3 weeks
- Paclitaxel + Carboplatin every 3 weeks
- Duration: 12 weeks total
Next 4 cycles:
- Pembrolizumab 200 mg IV every 3 weeks
- Epirubicin-Cyclophosphamide (EC) OR Doxorubicin-Cyclophosphamide (AC) every 3 weeks
- Duration: 12 weeks total
Surgical Intervention
Definitive surgery performed after completion of neoadjuvant therapy
Adjuvant Phase (After Surgery)
Up to 9 cycles:
- Pembrolizumab 200 mg IV every 3 weeks (or 400 mg every 6 weeks)
- Continue until completion of 9 cycles, disease recurrence, or unacceptable toxicity
- Maximum total treatment duration: approximately 24 months from start 2, 3
Clinical Context
This regimen is the Category 1 recommendation for stage II-III triple-negative breast cancer according to NCCN 2025 guidelines 1. The KEYNOTE-522 trial demonstrated:
- Pathologic complete response (pCR): 64.8% with pembrolizumab-chemotherapy vs 51.2% with chemotherapy alone (P<0.001) 3
- Event-free survival benefit: Hazard ratio 0.63 (95% CI 0.43-0.93) 3
- Overall survival at 60 months: 86.6% with pembrolizumab vs 81.7% with placebo (P=0.002) 2
Important Caveats
- The sequence can be reversed (taxane-carboplatin first, then anthracycline), though the standard sequence as described above is most commonly used 1
- Dose-dense schedules with G-CSF support are preferred when using this regimen 4
- For patients ineligible for pembrolizumab or anthracyclines, alternative regimens exist, including the anthracycline-free docetaxel/carboplatin/pembrolizumab for 6 cycles (NeoPACT regimen), though this is considered "useful in certain circumstances" rather than preferred 1