The Clinical Efficacy and Safety of Neratinib in Combination with Capecitabine for the Treatment of Adult Patients with Advanced or Metastatic HER2-Positive Breast Cancer

Human epidermal growth factor receptor 2 (HER2) positive cancers account for 15–20% of all breast tumors. Several drugs have been approved in the metastatic setting, including monoclonal antibodies, tyrosine kinase inhibitors (TKI) and, more recently, antibody-drug conjugates. Neratinib is a pan-HER, irreversible TKI with potent preclinical activity against trastuzumab-resistant breast cancer models. Based on Phase I and II clinical trials, the combination of neratinib plus capecitabine was compared to lapatinib and capecitabine, an established regimen for trastuzumab-resistant disease, in the randomized, Phase III NALA trial. In this trial, neratinib yielded increased progression-free survival, response duration and a benefit in time to intervention for CNS progression. However, there was no overall survival benefit, no increase in overall response rate and no improvement in QoL. The most frequent adverse event in the neratinib arm was diarrhea, which was manageable with prophylactic treatment with loperamide. Conclusion: Neratinib is a valuable addition to the therapeutic armamentarium to treat metastatic, HER2-positive breast cancer. The current positioning of the combination of neratinib and capecitabine based on the results of the NALA trial needs to consider the rapidly evolving scenario due to the recent introduction of new drugs, like the pure-HER2 TKI tucatinib and the antibody drug-conjugate trastuzumab-deruxtecan.