Evaluation of PIK3CA Gene Mutations in Breast Cancer Patients Treated by Trastuzumab

Abstract

Background: The phosphatidylinositol 3-kinases are known as a family of lipid kinases, playing a role in various cellular processes. A member of this family is PIK3CA which is frequently mutated in breast cancer. In this study, the association between H1047R, E542K and E545K mutations, and therapy resistance was investigated in Iranian breast cancer patients treated by Trastuzumab. Methods: Resistance and sensitive groups were chosen from Iranian patients treated by Trastuzumab. A PCR-RFLP approach was designed for detecting the H1047R mutation. Mutations in positions of codons E542K and E545K were detected using PCR-based DNA Sanger sequencing assay. The overall survival and disease-free survival were assessed. Results: A significant relationship was observed between the presence and absence of H1047R mutation and the overall survival (P = 0.025). In addition, there was a significant relationship between the response to Trastuzumab and some clinicopathological features, including the age and the status of ER/PR receptors (P-value<0.05). E542K and E545K mutations were not observed in the patients. Conclusion: It can be said that probably H1047R mutation is a prognostic marker in the Trastuzumab-based therapy resistant breast cancer. Further studies can be performed to evaluate this mutation before using Trastuzumab to predict the effectiveness of this treatment.