# Bradykinin B1 receptor (B1R)

Source: https://nuclide.cc/targets/bradykinin-b1-receptor/  
Nuclide record `bradykinin-b1-receptor` (Target). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A receptor that healthy tissue barely makes but inflammation and many cancers switch on. Gallium-68 and fluorine-18 peptides built from B1R-blocking drugs give sharp PET images in mice, but no B1R tracer has been given to a patient.

## Summary

The bradykinin B1 receptor, encoded by BDKRB1 (HGNC:1029), is a G-protein-coupled receptor that is overexpressed in a variety of cancers while being essentially absent from healthy tissue, which is what first drew imaging groups to it.

Most of the published radiochemistry comes from BC Cancer in Vancouver. In a 2015 Journal of Nuclear Medicine study, three gallium-68-labelled peptides derived from the B1R antagonists B9858 and B9958 bound the receptor with nanomolar affinity (Ki 1.1 to 16.0 nM), cleared through the kidneys, and at one hour showed only kidneys, bladder and B1R-positive tumours on PET; the best, 68Ga-P04158 and 68Ga-Z02090, reached 19.6 and 14.4% injected dose per gram in tumour. The same group then made 68Ga- and 18F-labelled derivatives of the more peptidase-stable antagonist R954, with tumour uptake around 8.5 to 9.3% injected dose per gram at one hour. Those studies used cells engineered to express human B1R. In 2024 a Showa Pharmaceutical University group showed that an indium-111 R954 derivative also tracks B1R expressed naturally in glioblastoma cells, with uptake that followed B1R levels and was blocked by unlabelled R954.

A search of ClinicalTrials.gov on 24 September 2026 found no registered B1R imaging or therapy trial. The gaps are a first-in-human study and evidence of which human tumours carry enough receptor to image or treat.

## Fields

- Kind: Target
- Last checked: 2026-09-24
- Also known as: B1R; BDKRB1; BKR1; B1BKR
- Tags: GPCR; peptide receptor; preclinical only; unmet need
- Symbol: BDKRB1
- Class: other
- Biology: An inducible G-protein-coupled receptor for des-Arg kinins. It is barely expressed in healthy tissue but upregulated by inflammation and in many tumours, and antagonist peptides such as B9858, B9958 and R954 bind it with nanomolar affinity, which is the basis of the radiolabelled derivatives.
- Where found: A variety of cancers, with limited or no expression in healthy tissue (BC Cancer radiochemistry series); Glioblastoma cell lines: U87MG expresses more than U251MG, and radiotracer uptake follows that difference; Inflamed tissue, where expression is induced

## Sources

- HGNC: BDKRB1 gene record (HGNC:1029): https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:1029
- Lin et al., J Nucl Med 2015: three 68Ga-labelled [des-Arg10]kallidin derivatives for B1R PET (PMID 25745086): https://pubmed.ncbi.nlm.nih.gov/25745086/
- Kuo et al., Mol Pharm 2017: 68Ga- and 18F-labelled R954 derivatives for B1R PET (PMID 28094956): https://pubmed.ncbi.nlm.nih.gov/28094956/
- Shukuri et al., Pharmaceuticals 2024: 111In-R954 derivative detects endogenous B1R in glioblastoma xenografts (PMID 39065752): https://pubmed.ncbi.nlm.nih.gov/39065752/

## Connected records

- isotopes: [Fluorine-18](https://nuclide.cc/isotopes/f-18/), [Gallium-68](https://nuclide.cc/isotopes/ga-68/), [Indium-111](https://nuclide.cc/isotopes/in-111/)
- technologies: [PET (positron emission tomography)](https://nuclide.cc/technologies/pet/)
- indications: [Glioma & glioblastoma](https://nuclide.cc/indications/glioblastoma/)
- targets: [GRPR (gastrin-releasing peptide receptor)](https://nuclide.cc/targets/grpr/)

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