Neratinib as extended adjuvant therapy in patients with copositive early breast cancer: German health technology assessment–driven analyses from the ExteNET study

Abstract

BackgroundNeratinib is approved in the European Union for extended adjuvant treatment of human epidermal growth factor receptor 2–positive/hormone receptor–positive (copositive) early breast cancer ≤1 year of completion of prior trastuzumab-based therapy. Here, we report analyses of the hormone receptor–positive subgroup (N = 1631) from the ExteNET trial performed for the German health technology assessment (HTA). ResultsWith 2 years of median follow-up, HTA analyses revealed a significant advantage in disease-free survival (DFS) for neratinib vs. placebo (absolute/relative risk reduction: 4.1/48.2%; hazard ratio [HR] [95% confidence interval {CI}]: 0.45 [0.29; 0.69]; p = 0.0002), consistent with distant DFS (absolute/relative risk reduction: 3.1/46.3%; HR [95% CI]: 0.52 [0.32; 0.84]; p = 0.0082). The 5-year follow-up confirmed this outcome.Quality of life analyses did not show clinically relevant differences over all time points. Only at month 1, the Functional Assessment of Cancer Therapy – General total score revealed a statistically relevant difference to the disadvantage of neratinib classified as clinically relevant. The tolerability profile of neratinib was dominated by gastrointestinal events, mainly diarrhoea (all grades: 94.4%; grade III: 39.4%; no systematic antidiarrhoeal prophylaxis), nausea (all grades/grade III: 43.9/1.6%), vomiting (26.6/3.2%), abdominal pain (23.8/1.9%), fatigue (28.1/1.9%) and rash (14.3/0.4%). No cumulative or irreversible toxicities were observed. As shown in the CONTROL study and instituted via a risk management plan, diarrhoea management can reduce frequency, cumulative duration and severity of diarrhoea. ConclusionExtended adjuvant neratinib provides a clinically relevant benefit with further incremental reduction of relapse risk in the curative setting. Accordingly, the German HTA authority has granted an added benefit for this new treatment option.