SABCS 2019 – Pembrolizumab boosts response in TNBC with lymph node involvement


  • Emily Willingham, PhD
  • Univadis
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Takeaway

  • Pembrolizumab with neoadjuvant chemotherapy and then as adjuvant yields good pathologic complete response (pCR) in patients with triple-negative breast cancer (TNBC) with lymph node (LN) involvement.
  • Study author said the trend for event-free survival is “favorable” but does not yet meet predefined boundaries for statistical significance.

Why this matters

  • These findings from KEYNOTE-522 add to results that showed the benefit of pembrolizumab in metastatic TNBC.

Key results

  • At a median follow-up of 15.5 months, event rate was 7.4% with pembrolizumab+chemo + pembrolizumab vs 11.8% with placebo+chemo + placebo (HR, 0.63; 95% CI, 0.43-0.93).
  • With no LN involvement, pCR rates were:
    • 64.9% with pembrolizumab vs 58.6% placebo.
    • Difference: 6.3% (95% CI, −5.3% to 18.2%).
  • With LN involvement, pCR rates were:
    • 64.8% with pembrolizumab vs 44.1% with placebo.
    • Difference: 20.6% (95% CI, 8.8%-31.9%).
  • pCR was also higher with pembrolizumab in stage III disease.

Study design

  • Randomized, placebo-controlled trial of 1174 participants with untreated early TNBC (age ≥18 years) from 21 countries.
  • All patients underwent chemotherapy with pembrolizumab or placebo (saline), followed by pembrolizumab or placebo as postoperative adjuvant.
  • Study is ongoing.
  • Primary endpoint: pCR, event-free survival.
  • Presentation included analyses of data for LN-involvement group.
  • Funding: MSD.

Limitations

  • Event-free survival data are preliminary in the ongoing study.
  • Results presented without peer review at a conference.