# Prostatic acid phosphatase (ACP3, PAP)

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

## TL;DR

Prostatic acid phosphatase is an enzyme made almost only by the prostate; the cell vaccine sipuleucel-T trains a patient's immune cells against it.

## Summary

Prostatic acid phosphatase (PAP, gene ACP3) is secreted by prostate epithelium and was the prostate cancer blood marker before PSA. Because it is nearly prostate-specific, it serves as the antigen for sipuleucel-T: the patient's antigen-presenting cells are loaded with a PAP-GM-CSF fusion protein and re-infused to raise an anti-PAP immune response in metastatic castration-resistant prostate cancer.

## Fields

- Kind: Target
- Last checked: 2026-09-04
- Symbol: ACP3
- Class: surface-antigen
- Biology: A prostate-restricted phosphatase found in secreted and transmembrane forms; expression persists in most prostate cancers.
- Where found: Prostate epithelium and prostate cancer (most cases); Low in other tissues

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Prostatic_acid_phosphatase
- UniProt P15309: ACP3: https://www.uniprot.org/uniprotkb/P15309/entry
- HGNC:125 ACP3: https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:125
- ChEMBL target CHEMBL2633: https://www.ebi.ac.uk/chembl/explore/target/CHEMBL2633

## Connected records

- cancers: [Prostate cancer](https://onco.cc/cancers/prostate/)
- drugs: [Sipuleucel-T](https://onco.cc/drugs/sipuleucel-t/)

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JSON: https://onco.cc/api/v1/entities/pap.json