# PTEN alteration (sequencing) and PTEN loss (IHC)

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

## TL;DR

PTEN can be lost by mutation or deletion (read by sequencing) or as absent protein on a stain. Both readouts select capivasertib: alterations in breast cancer, and protein deficiency in metastatic hormone-sensitive prostate cancer.

## Summary

PTEN loss removes the brake on PI3K signalling. In breast cancer capivasertib with fulvestrant is labelled for tumours with PIK3CA, AKT1 or PTEN alterations by FoundationOne CDx (CAPItello-291); in prostate cancer, following CAPItello-281, the 2026 label adds capivasertib with abiraterone for metastatic androgen pathway modulation-naive or -sensitive prostate cancer selected on PTEN deficiency in tumour tissue by the VENTANA PTEN (SP218) RxDx Assay (P250031, 12 June 2026). The IHC rule is loss of PTEN staining in tumour cells with retained stromal staining; the sequencing rule is a deleterious mutation or homozygous deletion.

## Fields

- Kind: Biomarker
- Last checked: 2026-09-23
- Also known as: PTEN loss; PTEN deficiency; PTEN-deficient; PTEN alteration; PTEN deletion; PTEN mutation; PTEN IHC loss; PTEN null
- Tags: biomarker; pi3k

## Sources

- 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/), [PIK3CA mutation](https://onco.cc/biomarkers/pik3ca-hotspot-mutation/)
- cancers: [Endometrial cancer](https://onco.cc/cancers/endometrial/), [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Metastatic hormone-sensitive prostate cancer](https://onco.cc/cancers/prostate-mhspc/), [Prostate cancer](https://onco.cc/cancers/prostate/)
- drugs: [Abiraterone acetate](https://onco.cc/drugs/abiraterone/), [Capivasertib](https://onco.cc/drugs/capivasertib/), [FoundationOne CDx / Liquid CDx](https://onco.cc/drugs/foundationone-cdx/)
- terms: [Immunohistochemistry (IHC)](https://onco.cc/terms/ihc/), [PTEN loss](https://onco.cc/terms/pten-loss/)
- targets: [PTEN](https://onco.cc/targets/pten/)

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JSON: https://onco.cc/api/v1/entities/pten-alteration.json