Detection of PIK3/AKT pathway in Moroccan population with triple negative breast cancer

Background: Triple Negative Breast Cancer (TNBC) is an aggressive form of breast cancer, that represents 10-20% of all breast carcinomas and characterized by the lack of a specific cell surface marker compared to other breast cancer subtypes. Due to the absence of molecular markers for TNBC his treatment options remains limited, without proven targeted therapies, which emphasize the need for discovering molecular markers that could be targeted for patient treatment, An important number of TNBC cases harbor aberrations in the phosphoinositide 3-kinase (PI3K) pathway, leading to constitutive activation of the downstream signaling pathway. Among mechanisms of PI3K enhancement, PIK3CA mutations are most frequently (~ 30%) observed, along with protein loss of PTEN and AKT activation by phosphorylation (pAkt). Therefore, we propose to analyze clinocopathologic and molecular characteristics of PI3K/AKT/PTEN pathway in Moroccan triple negative breast cancer patients.

Methods: We conducted a retrospective study of 39 patients diagnosed with triple negative breast cancer between early 2013 and 2016. In this study, we used the Ion Personal Genome Machine (PGM) and Ion Torrent Ampliseq Cancer panel to sequence hotspot regions from PIK3CA, AKT and PTEN genes to identify genetic mutations in 39 samples of TNBC subtype from Moroccan patients and to correlate the results with clinical-pathologic data.

Results: All patients were female with a median age of 46 years from (34-65). Most patients have had invasive ductal carcinoma (84.6%) and 69.2% of them were grade III SBR. Among the 39, 9 were right sided tumor patients and the remaining 30 were left-sided. Mutational analysis of PIK3CA gene was achieved in all TNBC patients. PIK3CA hotspot mutations were detected in 5/39 of TNBC (13%), in detail, among these 5 TNBC patients, one harbored mutation in exons 9 and four in exon 20.

Conclusion: The PI3KCA gene is highly activated and plays a crucial role in the pathogenesis of TNBC more, therefore, may be a potential therapeutic target to improve outcomes in patients.