ASCO-SITC 2019—Adding nelipepimut-S to trastuzumab boosts DFS in TNBC


  • Melissa Pandika
  • Univadis
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Takeaway

  • Adding nelipepimut-S (NPS) to trastuzumab significantly extended disease-free survival (DFS) in a phase 2b study of patients with triple-negative breast cancer (TNBC).

Why this matters

  • No targeted therapies approved for TNBC.
  • Warrants confirmatory phase 3 trial in TNBC.

Study design

  • Final analysis of multicenter, single-blinded phase 2b trial in 275 patients with HER2 low-expressing tumors, randomly assigned to granulocyte macrophage-colony stimulating factor (GM-CSF) with placebo or NPS; all received trastuzumab every 3 weeks for 1 year.
    • GM-CSF or NPS+GM-CSF was given every 3 weeks for 6 cycles, starting with the third trastuzumab dose, and boosters every 6 months x 4.
  • Primary endpoint: DFS at 24 months.
  • Funding: George E. Peoples.

Key results

  • Recurrences
    • Median follow-up: 24.7 months.
    • Intention-to-treat (ITT)-All patients: No significant difference between arms.
    • ITT-TNBC patients:
      • NPS+trastuzumab (n=53): 7.5%.
      • Trastuzumab (n=44): 26.7%.
      • P=.01.
  • DFS
    • ITT-All patients: No significant difference in 24-, 36-month DFS between arms.
    • ITT-TNBC patients:
      • NPS+trastuzumab (n=53)
        • 24 months: 92.6%.
        • 36 months: 82.3%.
      • Trastuzumab (n=44)
        • 24 months: 70.2%.
        • 36 months: 70.2%.
      • P=.013, HR 0.26.
  • NPS+trastuzumab safe; no notable differences between arms.

Limitations

  • Unclear if TNBC subgroup analysis planned/post-hoc.
  • Data on memory attributes of NPS-induced T-cells could help clarify whether secondary prevention provided.