APLNR as a Radioligand Therapy Target
APLNR, apelin receptor, is a cell-surface protein (membrane receptor). In Human Protein Atlas immunohistochemistry, APLNR staining is highest in thyroid cancer (100% of samples positive), liver cancer (50% of samples positive) and testicular cancer (55% of samples positive). Published literature reports that APLNR internalizes after ligand binding, which helps retain a radionuclide inside tumor cells. Clinical status: Clinical-stage (up to phase 2, any modality).
Is APLNR 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: Medium IHC staining in thyroid cancer, 100% 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.
APLNR expression in cancer
Protein expression of APLNR 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 |
|---|---|---|---|
| Thyroid Cancer | 0.42 | Medium | 100% |
| Liver Cancer | 0.22 | Medium | 50% |
| Testicular Cancer | 0.18 | Low | 55% |
| Breast Cancer | 0.12 | Low | 36% |
| Skin Cancer | 0.08 | Low | 25% |
| Colorectal Cancer | 0.08 | Low | 25% |
| Neuroendocrine Tumors | 0.08 | Low | 25% |
| Melanoma | 0.06 | Low | 18% |
| Ovarian Cancer | 0.06 | Low | 17% |
| Endometrial Cancer | 0.06 | Low | 17% |
| Lung Cancer | 0.04 | Low | 11% |
| Glioma | 0.03 | Low | 10% |
| Kidney Cancer | 0.03 | Low | 9% |
| Gastric Cancer | 0.03 | Low | 9% |
Not detected by IHC in: head and neck cancer, lymphoma, bladder cancer, cervical cancer, pancreatic cancer, prostate cancer.
Is APLNR internalized?
Yes. In addition, apelin induces the internalization and desensitization of its receptor in endothelial cells (ECs).
Sources: PMID 39060233 · PMID 36012227 · PMID 35060347 · PMID 33123575 · PMID 29727602. AI-extracted from abstracts, so verify before citing.
APLNR clinical trials
Clinical-stage (up to phase 2, any modality). Nuclens hasn't indexed trials for APLNR yet. Search ClinicalTrials.gov for APLNR trials.
APLNR 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 APLNR in the Human Protein Atlas tissue atlas, and read how normal-tissue expression predicts radioligand dosimetry risk.
APLNR gene essentiality (DepMap)
CRISPR knockout effect across 1236 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.
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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.