DOTA-TOC (DOTA-[Tyr3]-octreotide)

DOTA-TOC (DOTA-[Tyr3]-octreotide) is an octreotide-based peptide carrying a tyrosine substitution at position 3 and a DOTA chelator for radiolabeling. The peptide-chelator complex forms a somatostatin analog ligand that binds strongly to SSTR2 and moderately to SSTR5, which are somatostatin receptors often upregulated in neuroendocrine tumors (NETs). Labeled with radionuclides (e.g., Ga-68, Lu-177, Y-90), DOTA-TOC functions as a radioligand for PET/CT imaging of NETs and peptide receptor radionuclide therapy (PRRT). Due to this dual role in diagnosis and therapy, this peptide is widely applied in oncology.

Produced by JPT Peptide Technologies, a leader in custom peptide synthesis and oncology research reagents.

DOTA-TOC (DOTA-[Tyr3]-octreotide), precursor for radiolabeled DOTA-TOC and ligand for somatostatin receptors. Can be bound to radionuclides for development of cancer treatment and diagnosis. For research use only!

DOTA-TOC (DOTA-[Tyr3]-octreotide) - Specifications

• Peptide sequence: DPhe-Cys-Tyr-DTrp-Lys-Thr-Cys-Thr-ol (cyclic disulfide)
• Amount: 2 mg (40 x50µg)
• Purity: >95% (HPLC-MS)
• Delivery Format: Freeze-dried in glass vial
• CAS: 204318-14-9
• Application(s): Nuclear medicine
• Condition(s)/Topic(s): Cancer
• Standard Delivery Time: approx. 3 weeks

We provide the peptide in a range of aliquot sizes, ensuring flexibility for diverse research applications. For any special requirements, please contact our customer support: peptide@jpt.com

Radiolabeled DOTA-TOC Variants and Their Applications

As a precursor of its radiolabeled forms, DOTA-TOC can be complexed with various radionuclides via its DOTA chelator and generate radioligands that allow the visualization and therapy of neuroendocrine tumors (NETs). For instance:

These applications highlight the significance of radiolabeled DOTA peptides in tumor diagnosis and treatment, underscoring their important role in nuclear oncology.

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Research Applications of DOTA-TOC Peptide

• NET diagnosis and staging research: Highly sensitive PET/CT imaging in detecting primary and metastatic neuroendocrine tumors.
• Receptor expression studies: Quantifying SSTR2 and SSTR5 expression in tumors, supporting patient stratification and personalized therapy.
• PRRT treatment studies: Evaluating which patients are suitable for Lu-177- or Y-90-DOTA-TOC therapy and correlating receptor uptake with treatment response.
• Therapy monitoring development: Tracking disease progression, therapeutic outcomes, and recurrence in radionuclide-based therapies.
• Exploration in other SSTR-positive tumors: Investigated for potential use in thyroid, lung, or breast cancers with SSTR2 expression.
• Theranostic research: Combining diagnostic PET/CT imaging with therapeutic radionuclide delivery.
• Biodistribution and pharmacokinetics research: Studying tracer kinetics, tumor uptake, organ distribution, and clearance in preclinical and early clinical studies.
• Novel radioconjugate development research: Creating new radionuclide-drug conjugates unifying imaging and therapeutic applications.

Benefits of DOTA-TOC Peptide and Its Radiolabeled Variants

• High sensitivity: Detects small or early NET lesions missed by conventional imaging.
• Functional imaging: Provides molecular insight by visualizing SSTR2 activity, complementing anatomical PET/CT data.
• High receptor specificity: High selectivity for SSTR2 and moderate for SSTR5, enabling accurate tumor identification.
• Theranostic versatility: Integrates PET/CT imaging with PRRT therapy, combining diagnosis and treatment.

What are radionuclides and radioligands?

Radionuclides are unstable isotopes that emit radiation during decay, valuable in oncology. Their clinical value depends on the emission type: positron and gamma emitters enable high-resolution diagnostic imaging, while beta and alpha emitters deliver localized radiation capable of destroying tumor cells.

When a radionuclide is attached to a molecule (ligand) that specifically binds to certain receptors or cells, the resulting compound is called a radioligand. Radioligands combine the targeting ability of the ligand with the functional effects of the radionuclide, enabling precise tumor imaging or targeted treatment.

What is Peptide Receptor Radionuclide Therapy?

Peptide Receptor Radionuclide Therapy (PRRT) is a form of targeted molecular treatment mainly used for neuroendocrine tumors (NETs) overexpressing somatostatin receptors. In this approach, somatostatin analogs such as octreotide derivatives are coupled with therapeutic radionuclides (e.g., Lu-177 or Y-90) via the DOTA chelator.

After intravenous delivery, the radiolabeled peptide interacts with tumor receptors and is internalized, emitting localized ionizing radiation within malignant tissue while largely sparing healthy cells. This receptor-directed strategy enables tumor reduction and disease control, making PRRT a valuable therapy for advanced or metastatic NETs.

Impact of Tyr3 Substitution on Receptor Affinity

The tyrosine (Tyr3) substitution replaces the third amino acid of octreotide with a polar aromatic side chain. This enhances receptor interaction, leading to high SSTR2 and moderate SSTR5 affinity. Consequently, this Tyr3-octreotide analog provides strong and selective targeting of SSTR2-positive tumors, forming the basis for its clinical use in imaging and therapy of neuroendocrine tumors.

What is a DOTA chelator?

A DOTA chelator (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) is a macrocyclic compound forming highly stable complexes with metal ions, including radionuclides like Ga-68, Lu-177, and Y-90. Acting as a molecular cage, DOTA keeps the radionuclide securely bound in vivo, preventing premature release and minimizing off-target radiation. This stability is essential for effective tumor targeting and patient safety, allowing the radioligand to reach receptor-expressing tumor sites intact.

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Benefits of JPT's Single Catalogue Peptides
- Synthesis protocols designed to avoid toxic contaminants and side products
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