# MUC16 (CA-125)

Source: https://onco.cc/targets/muc16/  
OnCo record `muc16` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The giant mucin that is shed into blood as the CA-125 ovarian cancer marker; its membrane stalk is being targeted by ADCs and T-cell engagers.

## Summary

MUC16 is a giant transmembrane mucin overexpressed in ovarian (~80%), pancreatic, endometrial and lung cancers; its shed ectodomain is CA-125, used since 1983 for monitoring ovarian cancer. Therapeutics target the membrane-retained stalk: ubamatamab (MUC16×CD3 bispecific, Regeneron) in phase 2 in ovarian cancer, sofituzumab vedotin (ADC) discontinued, MUC16 CAR-T (with IL-12 armouring) in phase 1. Anti-CA-125 vaccines (abagovomab, oregovomab) failed in phase 3, oregovomab most recently in 2024 (FLORA-5).

## Fields

- Kind: Target
- Last checked: 2026-09-21
- Tags: gap-fill
- Symbol: MUC16
- Class: surface-antigen
- Biology: 22,000-amino-acid mucin with tandem repeats, SEA domains cleaved to release CA-125, and a short cytoplasmic tail; mediates immune evasion (binds Siglec-9, mesothelin), adhesion to mesothelium and metastasis.
- Where found: High-grade serous ovarian cancer (~80%); Pancreatic adenocarcinoma (~65%); Endometrial, lung adenocarcinoma, mesothelioma; Serum CA-125 in ovarian cancer monitoring

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/CA-125
- Ubamatamab phase 1/2 study design (JCO 2024, TPS5632): https://doi.org/10.1200/JCO.2024.42.16_suppl.TPS5632
- Ubamatamab translational study (Zhu et al., Clin Transl Sci 2024): https://doi.org/10.1111/cts.70082

## Connected records

- targets: [Folate receptor alpha](https://onco.cc/targets/folr1/), [Mesothelin](https://onco.cc/targets/mesothelin/)
- cancers: [Endometrial cancer](https://onco.cc/cancers/endometrial/), [Ovarian cancer](https://onco.cc/cancers/ovarian/), [Pancreatic ductal adenocarcinoma](https://onco.cc/cancers/pancreatic/)
- technologies: [Antibody-drug conjugate (ADC)](https://onco.cc/technologies/adc/), [CAR-T cell therapy](https://onco.cc/technologies/car-t/), [Serum tumour markers: proper use and misuse](https://onco.cc/technologies/serum-tumour-markers/), [T-cell engagers (bispecific)](https://onco.cc/technologies/t-cell-engager/)
- drugs: [Ubamatamab](https://onco.cc/drugs/ubamatamab/)
- companies: [Regeneron](https://onco.cc/companies/regeneron/)
- terms: [CA-125](https://onco.cc/terms/ca-125/), [Tumour markers (CEA, LDH, chromogranin, thyroglobulin)](https://onco.cc/terms/tumour-markers/)
- trials: [Dual-Targeting CAR-NK Cells for Recurrent Ovarian Cancer (MSLN, FRα, MUC16)](https://onco.cc/trials/nct07480954/)
- key papers: [Translational findings support regimen selection for first-in-human study of ubamatamab (MUC16 × CD3 bispecific antibody) in patients with recurrent ovarian cancer](https://onco.cc/key-papers/paper-zhu-clin-transl-sci/)

---
JSON: https://onco.cc/api/v1/entities/muc16.json