TEST:

cobas® PIK3CA Mutation Test

The commercially available Oncolipsy PIK3CA CE-IVD kit is highly sensitive and specific for the detection of four PIK3CA hotspot mutations in primary tumors and plasma-cfDNA.

Our results support the PIK3CA determination in tissue as the diagnostic method of choice, although further studies could better define the role of liquid biopsy in the detection of PIK3CAm. In our population, the presence of PIK3CAm confers poorer prognosis in luminal BC, being significantly worse in mutation carriers in exon 9 regardless visceral involvement and plasma mutation detection. Table.

The developed assay is cost-effective and can reliably and simultaneously detect ten hotspot PIK3CA mutations in plasma cfDNA. The clinical performance of the assay will be further evaluated in liquid biopsy samples.

Statistically significant increase in the frequency of exon 9 mutations of the PIK3CA gene is specific for the group of patients with Her2-low BC. Our results supported the concept of Her2-low BCs as the unique entity and pointed out the need of their further study.

Table: 439P PIK3CA mutation results of HeSMO's program Conclusions In our series, 40.94% of the patients tested, were detected with mutations in PIK3CA gene, in accordance with published data. Apart from the significant implications for treatment possibilities in a substantial patients' population, these results provide valuable epidemiological data and strengthen our efforts for reimbursement of PIK3CA mutation testing in Greece.

Table: 495P Conclusions Our results support the determination of PIK3CA in tissue as the diagnostic method of choice, although further studies are needed to assess the role of liquid biopsy in the detection of PIK3CAm. In our population, the presence of PIK3CAm confers worse prognosis in luminal BC, being significantly worse in mutation carriers in exon 9 regardless visceral involvement.

We observed worse prognosis and resistance to endocrine therapy in PIK3CAm luminal BC. We need larger studies to evaluate the role of liquid biopsy in the detection of PIK3CAm.

Assessment of PIK3CA mutational status is required to identify patients eligible for treatment with PI3Kα inhibitors, with alpelisib currently the only approved tyrosine kinase inhibitor in this setting...The analysis of molecular reports revealed the need to implement the use of appropriate sequence variant nomenclature with the identification of reference sequences (HGVS-nomenclature) and to state the tumor cell content in each sample. The concordance rates between the method used by each tester center and NGS validate the use of the PIK3CA mutational status test performed at these centers in clinical practice in patients with advanced ER+/HER2- BC.

P3; Completed --> Terminated; The Sponsor discontinued the manufacturing and development of taselisib due to modest clinical benefit and limited tolerability.