# STEAP1

Source: https://onco.cc/targets/steap1/  
OnCo record `steap1` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

STEAP1 is a protein on the surface of most prostate cancer cells, now the address for a T-cell engager in phase 3.

## Summary

Six-transmembrane epithelial antigen of the prostate 1 is expressed in most prostate cancers including PSMA-low and neuroendocrine-like disease, with limited normal expression. Xaluritamig (STEAP1×CD3 XmAb 2+1) produced PSA50 in ~half of heavily pretreated mCRPC patients at target doses in phase 1 and is in two phase 3 trials (XALute post-taxane; XALience with abiraterone chemo-naive). Also an ADC target historically (vandortuzumab vedotin, discontinued).

## Fields

- Kind: Target
- Last checked: 2026-09-06
- Tags: t-cell-engager-target
- Symbol: STEAP1
- Class: surface-antigen
- Biology: STEAP1 is a metalloreductase at cell junctions, upregulated by androgen receptor signalling; its expression is partly independent of PSMA, making it complementary.
- Where found: Prostate cancer (most cases); Ewing sarcoma; Bladder (subset)

## Notes

- Prevalence not recorded: no peer-reviewed STEAP1 expression series with a stated denominator was found for prostate cancer; the widely repeated '>80%' figure could not be traced to a series with an n, so it has been removed.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/STEAP1
- Wikipedia: https://en.wikipedia.org/wiki/STEAP1

## Connected records

- cancers: [Prostate cancer](https://onco.cc/cancers/prostate/)
- drugs: [Xaluritamig](https://onco.cc/drugs/xaluritamig/)
- trials: [XALute](https://onco.cc/trials/xalute/)
- people: [Owen N. Witte](https://onco.cc/people/owen-witte/)

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JSON: https://onco.cc/api/v1/entities/steap1.json