# Miniprotein radioconjugates

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

## TL;DR

A radioactive cancer medicine built on a small engineered protein instead of an antibody or a tiny peptide. It is meant to reach deep into a tumour, stay there, and leave the rest of the body quickly.

## Summary

Radiopharmaceuticals have mostly used small molecules and peptides (PSMA ligands, somatostatin analogues) or whole antibodies. Small binders clear fast but exist for few targets; antibodies bind almost anything but circulate for days and irradiate the bone marrow. Miniprotein radioconjugates use engineered binding proteins of intermediate size to reach targets that small molecules cannot, while still clearing quickly. Aktis Oncology describes its platform as designed to penetrate tumours deeply with long residence time while being rapidly cleared from the rest of the body, and pairs it with the alpha emitter actinium-225.

In November 2026 Aktis listed two clinical programmes, both in phase 1b: AKY-1189 against Nectin-4 (NCT07020117; FDA Fast Track designation in previously treated advanced urothelial cancer) and AKY-2519 against B7-H3 in metastatic castration-resistant prostate cancer (NCT07581184). No efficacy results from a full publication are recorded here.

## Fields

- Kind: Technology
- Status: phase-1
- Last checked: 2026-11-03
- Also known as: miniprotein radiopharmaceuticals; miniprotein radioligands; miniprotein radioconjugate platform
- Principle: A small engineered protein binder against a tumour surface antigen carries a chelated radioisotope, usually an alpha emitter; its size is chosen for tumour penetration and retention with fast renal or hepatic clearance.
- Strengths: Reaches antigens that peptides and small molecules cannot; Faster clearance than antibodies; Pairs with alpha emitters for short-range kill
- Limitations: Only phase 1b data so far; Kidney exposure depends on clearance route; Actinium-225 supply is limited

## Sources

- Aktis Oncology: platform: https://www.aktisoncology.com/platform/
- Aktis Oncology: pipeline and publications: https://www.aktisoncology.com/pipeline/
- ClinicalTrials.gov NCT07020117 (AKY-1189): https://clinicaltrials.gov/study/NCT07020117
- ClinicalTrials.gov NCT07581184 (AKY-2519): https://clinicaltrials.gov/study/NCT07581184

## Connected records

- cancers: [Bladder & urothelial cancer](https://onco.cc/cancers/urothelial/), [Metastatic castration-resistant prostate cancer](https://onco.cc/cancers/prostate-mcrpc/)
- fronts: [Radiopharmaceuticals & Theranostics](https://onco.cc/fronts/radiopharma/)
- technologies: [Radioligand therapy (beta emitters)](https://onco.cc/technologies/radioligand-therapy/), [Targeted alpha therapy](https://onco.cc/technologies/targeted-alpha-therapy/)
- targets: [B7-H3](https://onco.cc/targets/b7h3/), [Nectin-4](https://onco.cc/targets/nectin4/)
- companies: [Aktis Oncology](https://onco.cc/companies/aktis-oncology/)

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