SSTR1 as a Radioligand Therapy Target
SSTR1, somatostatin receptor 1, is a cell-surface protein (GPCR). In Human Protein Atlas immunohistochemistry, SSTR1 staining is highest in colorectal cancer (92% of samples positive), pancreatic cancer (78% of samples positive) and testicular cancer (90% of samples positive). Evidence on whether SSTR1 internalizes is mixed. Clinical status: Clinical-stage (up to phase 3, any modality).
Is SSTR1 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: High IHC staining in colorectal cancer, 92% of samples positive.
- ⚠️ Internalization: Mixed evidence.
- ✅ Clinical precedent: Clinical-stage (up to phase 3, any modality)
- ❔ Shedding: Not yet assessed.
- ❔ Normal-tissue dosimetry: Check kidney, liver, bone marrow and salivary expression in the Human Protein Atlas tissue atlas.
SSTR1 expression in cancer
Protein expression of SSTR1 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 |
|---|---|---|---|
| Colorectal Cancer | 0.69 | High | 92% |
| Pancreatic Cancer | 0.52 | High | 78% |
| Testicular Cancer | 0.43 | Medium | 90% |
| Gastric Cancer | 0.43 | Medium | 80% |
| Breast Cancer | 0.42 | Medium | 92% |
| Prostate Cancer | 0.36 | Medium | 64% |
| Head and Neck Cancer | 0.33 | Medium | 75% |
| Bladder Cancer | 0.30 | Medium | 73% |
| Cervical Cancer | 0.28 | Medium | 67% |
| Skin Cancer | 0.26 | Medium | 56% |
| Ovarian Cancer | 0.25 | Medium | 42% |
| Liver Cancer | 0.18 | Low | 36% |
| Neuroendocrine Tumors | 0.11 | Low | 33% |
| Lung Cancer | 0.08 | Low | 25% |
| Melanoma | 0.07 | Low | 20% |
| Endometrial Cancer | 0.06 | Low | 17% |
Not detected by IHC in: lymphoma, kidney cancer, thyroid cancer, glioma.
Is SSTR1 internalized?
Uncertain. The abstract does not provide specific information regarding receptor internalization or endocytosis; it discusses somatostatin receptors' expression in tumors but does not clarify the behavior of SSTR1 upon ligand/antibody binding.
Sources: PMID 41928014 · PMID 36804512 · PMID 30416362 · PMID 27375434 · PMID 24587133. AI-extracted from abstracts, so verify before citing.
SSTR1 clinical trials
Clinical-stage (up to phase 3, any modality). Nuclens hasn't indexed trials for SSTR1 yet. Search ClinicalTrials.gov for SSTR1 trials.
SSTR1 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 SSTR1 in the Human Protein Atlas tissue atlas, and read how normal-tissue expression predicts radioligand dosimetry risk.
SSTR1 gene essentiality (DepMap)
CRISPR knockout effect across 1243 cancer cell lines: -0.04 (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 colorectal cancer radioligand targets
c-MET (MET) · HER3 (ERBB3) · FAP · EGFR · CEA (CEACAM5) · EPCAM · SSTR2 · STEAP2
See all radioligand therapy targets in colorectal cancer.
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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.