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Updated: Jul 6, 2026
Detection and Monitoring of Tumor Associated Circulating DNA in Patient Biofluids
Published on: June 8, 2019
Multiplexed assays for detection of mutations in PIK3CA
Ruth E Board1, Nicola J Thelwell, Paul F Ravetto
1Discovery Medicine, AstraZeneca Pharmaceuticals, Macclesfield, UK. ruth.board@astrazeneca.com
Background:
Mutations in the PIK3CA gene (phosphoinositide-3-kinase, catalytic, alpha polypeptide) have recently been described in a number of cancers, and their detection is currently limited because of the low sensitivity of conventional sequencing techniques.
Methods:
We combined Amplification Refractory Mutation System (ARMS; AstraZeneca) allele-specific PCR and Scorpions (DxS) to develop assays for tumor-borne PIK3CA mutations and used real-time PCR to develop high-throughput multiplexed assays for the most commonly reported PIK3CA mutants (H1047L, H1047R, E542K, E545K).
Results:
These assays were more sensitive than sequencing and could detect 5 copies of mutant DNA in proportions as low as 0.1% of the total DNA. We assayed DNA extracted from human tumors and detected PIK3CA mutation frequencies of 10.2% in colorectal cancer, 38.7% in breast cancer, 1.9% in lung cancer, and 2.9% in melanoma. In contrast, sequencing detected only 53% of the mutations detected by our assay.
Conclusions:
Multiplexed assays, which can easily be applied to clinical samples, have been developed for the detection of PIK3CA mutations.
