The Absolute Effect / Evidence index
Advanced / Metastatic · Randomized clinical trial; N=551; ERBB2-low advanced breast cancer. Trastuzumab rezetecan 6.4 mg/kg q3w vs physician-choice chemotherapy. Primary endpoint BICR PFS in chemotherapy-naive and overall populations. · Overall median PFS 16.4 vs 6.8 months
HORIZON-Breast06
Clinical question: Does trastuzumab rezetecan improve PFS over physician-choice chemotherapy in ERBB2-low advanced breast cancer?
Overall median PFS 16.4 vs 6.8 months; HR 0.27 (95% CI 0.21–0.34; P<0.001). Chemotherapy-naive PFS 16.6 vs 6.8 months; HR 0.25. · Registry:
Design, population and treatment
Randomized clinical trial; N=551; ERBB2-low advanced breast cancer. Trastuzumab rezetecan 6.4 mg/kg q3w vs physician-choice chemotherapy. Primary endpoint BICR PFS in chemotherapy-naive and overall populations.
Key efficacy outcome
Grade ≥3 treatment-related AEs 84.1% vs 67.9%, chiefly neutrophil-count decrease.
Safety and absolute effect
Median PFS (months)
https://jamanetwork.com/journals/jama/article-abstract/2855791
Interpretation and limitations
Current-practice context · 14 November 2026: Primary publication/abstract and trial identifier checked. Guideline-level current-practice mapping was not established in this publication-led batch; no NCCN citation provenance is claimed. Where detailed QoL, follow-up or toxicity data were not present in the retrieved abstract, they are not inferred.