CASR as a Radioligand Therapy Target
CASR, calcium sensing receptor, is a cell-surface protein (membrane receptor). In Human Protein Atlas immunohistochemistry, CASR staining is highest in bladder cancer (8% of samples positive). Published literature reports that CASR internalizes after ligand binding, which helps retain a radionuclide inside tumor cells. Clinical status: Clinical-stage (up to phase 2, any modality).
Is CASR a good radioligand therapy target?
Scored against the six criteria that decide whether a protein can become a radioligand therapy:
- ✅ Cell-surface accessibility: Localized to the cell surface, so a radioligand can reach it from circulation.
- ⚠️ Tumor expression: Low IHC staining in bladder cancer, 8% of samples positive.
- ✅ Internalization: Reported to internalize, which favors radionuclide retention.
- ✅ Clinical precedent: Clinical-stage (up to phase 2, any modality)
- ❔ Shedding: Not yet assessed.
- ❔ Normal-tissue dosimetry: Check kidney, liver, bone marrow and salivary expression in the Human Protein Atlas tissue atlas.
CASR expression in cancer
Protein expression of CASR across 20 cancer types from Human Protein Atlas immunohistochemistry. The score is a weighted staining intensity from 0 to 1; "% positive" is the share of patient samples with detectable staining.
| Cancer type | IHC score | Level | % positive |
|---|---|---|---|
| Bladder Cancer | 0.06 | Low | 8% |
Not detected by IHC in: skin cancer, colorectal cancer, head and neck cancer, ovarian cancer, lymphoma, breast cancer, melanoma, kidney cancer, thyroid cancer, neuroendocrine tumors, cervical cancer, lung cancer, pancreatic cancer, prostate cancer, gastric cancer, testicular cancer, endometrial cancer, glioma, liver cancer.
Is CASR internalized?
Yes. The sentence "we demonstrate that a dileucine endocytic motif is required for directing CaSR to dynamic spatiotemporal pathways" indicates that CASR undergoes internalization.
Sources: PMID 40510119 · PMID 40239638 · PMID 39395101 · PMID 39027195 · PMID 34663830. AI-extracted from abstracts, so verify before citing.
CASR clinical trials
Clinical-stage (up to phase 2, any modality). Nuclens hasn't indexed trials for CASR yet. Search ClinicalTrials.gov for CASR trials.
CASR normal tissue expression
Normal-tissue expression in dose-limiting organs (kidney, liver, bone marrow, salivary glands) drives radioligand dosimetry risk. Nuclens is re-validating its normal-tissue values, so they are not shown here yet. See CASR in the Human Protein Atlas tissue atlas, and read how normal-tissue expression predicts radioligand dosimetry risk.
CASR gene essentiality (DepMap)
CRISPR knockout effect across 1224 cancer cell lines: -0.01 (not essential). Radioligands kill by radiation, not by blocking the target, so essentiality matters less than for inhibitors. A non-essential target can still be an excellent radioligand target.
Related bladder cancer radioligand targets
EGFR · HER3 (ERBB3) · c-MET (MET) · SSTR2 · ITGAV · HER2 (ERBB2) · B7-H3 (CD276) · FAP
See all radioligand therapy targets in bladder cancer.
See how CASR ranks against 15,000 targets for your indication.
Run a free analysisData sources
Subcellular localization: UniProt via Open Targets (CC BY 4.0 / CC0). Tumor immunohistochemistry: Human Protein Atlas (CC BY-SA 4.0). Clinical trials: ClinicalTrials.gov (public domain). Gene essentiality: DepMap (CC BY 4.0). Internalization and shedding: AI-extracted from PubMed abstracts, so verify against the cited papers before relying on them. Nuclens is a first-pass triage layer, not a substitute for wet-lab validation or clinical dosimetry. Derived expression data on this page is shared under CC BY-SA 4.0.