tRFs were also found to be upregulated in trastuzumab-resistant breast cancer cell lines compared to trastuzumab-sensitive breast cancer and higher levels of tRF expression were correlated with worse progression-free survival in human epidermal growth factor receptor 2 (HER2) positive patients, indicating that tRFs are involved in patient response to trastuzumab-targeted therapy in HER2 positive breast cancer [7]. This evidence concerns the gene ERBB2 and breast cancer.