Metastatic TNBC: phase 2 points to benefit with niraparib + pembrolizumab

  • Vinayak S & al.
  • JAMA Oncol
  • 13 Jun 2019

  • curated by Emily Willingham, PhD
  • Univadis Clinical Summaries
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Takeaway

  • For triple-negative breast cancer (TNBC), niraparib + pembrolizumab shows antitumor activity and durability in responsive cases but did not meet the statistical objective in this open-label phase 2 trial . 

Why this matters

  • Editorial: although the study did not meet the prespecified criterion (null ≤15%), the results point to benefits that could best current standard-of-care or monotherapy with either drug.

Key results

  • Of 55 women, 5 had complete response, 5 partial response, 13 stable disease, 24 progression. 
  • Objective response rate (ORR; n=47), 21% (90% CI, 12%-33%); disease control rate (DCR), 49% (90% CI, 36%-62%).
    • Median PFS,  2.3 months.
    • Median duration of response not reached (range, 4.6 to ≥15.9 months).
  • BRCA+ (n=15): ORR, 47% (90% CI, 24%-70%), DCR, 80% (90% CI, 56%-94%); median PFS, 8.3 months (95% CI, 2.1 months to not estimable).
  • BRCA wild-type (n=27): ORR, 11% (90% CI, 3%-26%), DCR, 33% (90% CI, 19%-51%); median PFS, 2.1 months (95% CI, 1.4-2.5 months). 
  • Most frequent treatment-related grade ≥3 adverse events: anemia, thrombocytopenia, fatigue.
  • No new safety signals.

Study design

  • Open-label, single-arm, phase 2 trial (n=55) of advanced/metastatic TNBC at 34 US centers.
  • Funding: TESARO: A GSK Company; Merck & Co., Inc., Kenilworth, NJ, USA.

Limitations

  • Unblinded, no comparator group, small population.