ASCO 2020 – Add-on tucatinib improves survival in HER2+ breast cancer with brain metastasis


  • Deepa Koli
  • Oncology Conference reports
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Takeaway

  • In patients with HER2-positive (HER2+) breast cancer with brain metastases treated with trastuzumab and capecitabine, add-on tucatinib is associated with significantly improved survival and response.

Why this matters

  • The authors say that add-on tucatinib has the potential to become the new standard of care for these patients.

Study design

  • Substudy of double-blind, phase 2 HER2CLIMB trial.
  • 291 patients with HER2+ breast cancer (median age, 52 years) and with brain metastases were randomly assigned 2:1 to tucatinib (n=198) or placebo (n=93) in combination with trastuzumab+capecitabine.
  • Funding: Seattle Genetics.

Key results

  • Tucatinib vs placebo was linked to significant improvement in:
    • Median central nervous system (CNS) PFS:
      • 9.9 vs 4.2 months.
      • HR, 0.32 (P<.0001>
    • Median OS:
      • 18.1 vs 12.0 months.
      • HR, 0.58 (P=.005).
    • Intracranial objective response rate:
      • 47.3% vs 20.0% (P=.03).
    • Median intracranial-duration of response:
      • 6.8 vs 3.0 months.
  • In 117 patients with stable brain metastasis:
    • Estimated 1-year CNS-PFS:
      • 53.3% in the tucatinib group vs 0% in the control group.
      • HR, 0.31 (P=.002).
  • In 30 patients with isolated brain progression who continued study therapy after local treatment, there was a 67% reduction in risk for second progression or death (HR, 0.33; 95% CI, 0.11-1.02; not statistically significant).
  • The median time from the first CNS progression to a second progression/death was 7.6 months with tucatinib vs 3.1 months with placebo (P=.02).