# PIK3CA mutation

Source: https://onco.cc/biomarkers/pik3ca-hotspot-mutation/  
OnCo record `pik3ca-hotspot-mutation` (Biomarker). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

PIK3CA mutations in the helical and kinase domains are found in about 40 percent of hormone-receptor-positive breast cancers. Alpelisib, inavolisib and capivasertib are approved for tumours that carry them.

## Summary

Hotspots E542K and E545K (helical domain, exon 9) and H1047R (kinase domain, exon 20) are detected in tissue or plasma; the therascreen PIK3CA RGQ PCR Kit covers 11 mutations and FoundationOne CDx and Liquid CDx report the gene. Alpelisib (Piqray) is labelled with fulvestrant for HR-positive HER2-negative PIK3CA-mutated advanced breast cancer after endocrine therapy; inavolisib (Itovebi) with palbociclib and fulvestrant for endocrine-resistant PIK3CA-mutated disease recurring during or after adjuvant endocrine therapy; capivasertib (Truqap) with fulvestrant for tumours with PIK3CA, AKT1 or PTEN alterations. All three name an FDA-approved test. Hyperglycaemia and rash are the class effects that the PIK3CA result buys into.

## Fields

- Kind: Biomarker
- Last checked: 2026-09-23
- Also known as: PIK3CA mutation; PIK3CA-mutated; PIK3CA H1047R; PIK3CA E545K; PIK3CA E542K; PIK3CA hotspot; PI3K mutation breast cancer
- Tags: biomarker; pi3k

## Sources

- PIQRAY prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b20b4e18-7a4b-4500-a08f-06c6dab0ee5b
- Itovebi prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5de59f5b-e5db-410f-b692-658686ef4107
- TRUQAP prescribing information (DailyMed): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d698c106-2322-401e-b738-cbd83c843ecf

## Connected records

- biomarkers: [AKT1 E17K mutation](https://onco.cc/biomarkers/akt1-e17k/), [ESR1 mutation (ligand-binding domain, usually in ctDNA)](https://onco.cc/biomarkers/esr1-mutation-ctdna/), [PTEN alteration (sequencing) and PTEN loss (IHC)](https://onco.cc/biomarkers/pten-alteration/)
- cancers: [Endometrial cancer](https://onco.cc/cancers/endometrial/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [HR-positive metastatic breast cancer after CDK4/6 inhibitors](https://onco.cc/cancers/hr-positive-metastatic-post-cdk46/)
- drugs: [Alpelisib](https://onco.cc/drugs/alpelisib/), [Capivasertib](https://onco.cc/drugs/capivasertib/), [FoundationOne CDx / Liquid CDx](https://onco.cc/drugs/foundationone-cdx/), [Inavolisib](https://onco.cc/drugs/inavolisib/), [therascreen companion diagnostic kits (KRAS, EGFR, PIK3CA, FGFR, BRAF)](https://onco.cc/drugs/therascreen-cdx/)
- terms: [Hyperglycaemia (PI3K/AKT inhibitor class effect)](https://onco.cc/terms/hyperglycaemia/), [Next-generation sequencing (NGS)](https://onco.cc/terms/ngs/)
- targets: [PIK3CA / PI3K-alpha](https://onco.cc/targets/pik3ca/)

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