Breast Cancer Drug Neratanib Meets Trial Goal
Treatment extends disease-free survival versus placebo
Positive results have been reported from a phase III clinical study of the investigational drug neratinib (PB272, Puma Biotechnology, Inc.), a pan-ErbB tyrosine kinase inhibitor, for the extended adjuvant treatment of breast cancer.
The ExteNET trial was a double-blind, placebo-controlled study of neratinib in 2,821 women with early-stage human epidermal growth factor receptor 2 (HER2)-positive breast cancer who had undergone surgery and adjuvant treatment with trastuzumab (Herceptin, Genentech).
After completing trastuzumab therapy, the patients were randomly assigned to receive extended adjuvant treatment with either neratinib or placebo for 1 year. The patients were then followed for recurrent disease, ductal carcinoma in situ (DCIS), or death for 2 years after enrollment into the trial.
The study’s primary endpoint was disease-free survival (DFS). Treatment with neratinib resulted in a 33% improvement in DFS compared with placebo. The hazard ratio was 0.67, which was statistically significant (P = 0.0046).The trial’s secondary endpoint was DFS including DCIS. Treatment with neratinib resulted in a 37% improvement in DFS-DCIS compared with placebo. The hazard ratio was 0.63, which was statistically significant (P = 0.0009).
Based on these results, regulatory approval will be sought for neratinib in the extended adjuvant setting in the first half of 2015.
Neratinib has had toxicity problems in the clinic. Most notably, patients have experienced diarrhea, which has been so severe in some cases that it has limited the doses used in clinical trials.