Gallium (68GA) edotreotide

Table of contents

• What is gallium (68Ga) edotreotide?
• How does gallium (68Ga) edotreotide work?
• Which conditions is gallium (68Ga) edotreotide used or studied for?
• How is gallium (68Ga) edotreotide given?
• What do the clinical trials show?
• What side effects are known?

What is gallium (68Ga) edotreotide?

Gallium (68Ga) edotreotide is a chemically synthesised radioactive substance used as a diagnostic agent. It belongs to a class of medicines called radiopharmaceuticals, which are radioactive compounds given in very small amounts to help doctors see inside the body during imaging scans. The substance is also known as edotreotide gallium Ga-68 or 68Ga-DOTATOC.^[4]

In the European Union, gallium (68Ga) edotreotide is already authorised as a medicine under the trade name SomaKit TOC. It is approved for diagnostic use only, meaning it is used to detect disease, not to treat it.^[3] The product records from the registered trials confirm that the substance has a marketing authorisation, although the specific authorisation number is not listed in these records.^[1]

How does gallium (68Ga) edotreotide work?

Gallium (68Ga) edotreotide works by binding to a specific protein on the surface of certain tumor cells called the somatostatin receptor type 2 (SSTR2). Many neuroendocrine tumors have large numbers of these receptors, while most healthy tissues have fewer. When the radioactive tracer binds to SSTR2, it accumulates in the tumor tissue.^[4]

During a PET scan, the radioactive gallium (68Ga) emits positrons that the scanner detects. This creates a detailed image showing where the tracer has collected in the body, helping doctors locate primary tumors and their metastases.^[3] The substance is classified as a diagnostic radiopharmaceutical for cancer detection under the ATC code V09IX09.^[4]

Which conditions is gallium (68Ga) edotreotide used or studied for?

• Gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs) — gallium (68Ga) edotreotide is already authorised for localizing primary tumors and their metastases in adults with confirmed or suspected well-differentiated GEP-NETs.^[3]
• Nasopharyngeal carcinoma — a Phase 1 trial is testing whether the imaging method can assess SSTR2 expression in patients with EBV-associated nasopharyngeal carcinoma in a non-endemic region.^[2]
• Hepatocellular carcinoma — a Phase 3 trial is evaluating multiplexed PET imaging, including gallium (68Ga) edotreotide, for detection and staging of hepatocellular carcinoma.^[1]

How is gallium (68Ga) edotreotide given?

Gallium (68Ga) edotreotide is given by direct slow intravenous injection into a vein. The product information states that the recommended activity for an adult weighing 70 kg is 100 to 200 MBq (megabecquerels), a unit used to measure radioactivity.^[3]

The substance is prepared by radiolabelling edotreotide with a gallium (68Ga) chloride solution shortly before use. It should only be administered by trained healthcare professionals in a designated nuclear medicine facility.^[3] The registered trials also use intravenous administration.^[1]

What do the clinical trials show?

Two clinical trials involving gallium (68Ga) edotreotide are currently authorised in the EU registry. The substance is being investigated as the study drug (Test role) in one trial, and as part of a multiplexed imaging approach in another.^[1]

The first trial is a Phase 1 proof-of-concept pilot study in nasopharyngeal carcinoma. It aims to include 10 participants and will measure whether [68Ga]Ga-DOTA-TOC PET imaging can visualize and quantify tumor uptake in at least seven out of ten patients, and whether repeat imaging can be completed in at least six patients.^[2]

The second trial is a Phase 3 basket diagnostic performance study in hepatocellular carcinoma and gastro-entero-pancreatic tumors. It plans to enroll 28 participants and will assess the safety of staggered injection of two radiopharmaceuticals, the technical feasibility of image reconstruction after multiplexed PET scanning, and the diagnostic efficacy of multiplexed PET imaging compared to single-radiopharmaceutical PET imaging.^[1]

What side effects are known?

According to the European Medicines Agency's summary of the risk management plan for SomaKit TOC, there are no important potential risks or missing information identified for gallium (68Ga) edotreotide. The document states that important identified risks are outlined together with measures to minimize them, such as specific warnings and precautions in the product information addressed to healthcare professionals.^[3] The Phase 3 trial is also collecting adverse reactions during and shortly after imaging as part of its safety assessment.^[1]