Active substances of peptide radiopharmaceuticals
Radiopharmaceuticals used in the diagnosis and treatment of various diseases, such as cancer tumors, are divided into the following three categories.
- FDG-based radiopharmaceuticals: Due to their glucose structure, these radiopharmaceuticals have a high tendency to bind to cells of the body that have a high glucose consumption. As a result, considering the consumption of high amounts of glucose in cancer cells, FDG-based radiopharmaceuticals have a high tendency to bind to cancer cells. However, due to the fact that other non-cancerous cells in the body also consume glucose, FDG-based radiopharmaceuticals also bind to non-cancerous cells, so FDG-based radiopharmaceuticals have low specificity in their action. As a result, if these types of radiopharmaceuticals are used in photography, the image quality may be low, and if they are used for therapeutic purposes, the possibility of side effects is higher.
- Antibody-based radiopharmaceuticals: Due to their special structure, these radiopharmaceuticals have higher specificity for cancer cells than FDG-based radiopharmaceuticals. Antibody radiopharmaceuticals have a large structure and due to the phenomenon of antigenicity, the risk of allergic reactions due to the use of these radiopharmaceuticals is higher.
- Peptide radiopharmaceuticals: In order to produce these radiopharmaceuticals, according to the specific receptors that exist on the surface of the target cells, specific peptides are made. Then, by connecting them to the intended receptors, the radioelements reach the target tissue. Therefore, peptide radiopharmaceuticals have high specificity and the image resolution and spatial resolution are higher in photography with them. On the other hand, compared to antibody radiopharmaceuticals, they have a smaller structure and the level of antigenicity and the incidence of allergic reactions are lower in them. Also, unlike FDG-based radiopharmaceuticals, which cannot be attached to different radioisotopes, this possibility exists for peptide radiopharmaceuticals, and this advantage will expand their functional range. All these advantages have made peptide radiopharmaceuticals to be used as the most efficient and up-to-date radiopharmaceuticals for cancer treatment and diagnosis. In addition to their use in the field of oncology, their use in cardiology and neurology can also be mentioned.
Peptide radiopharmaceuticals consist of the following three parts.
- Peptide part that is responsible for binding to specific receptors on the surface of target cells.
- A linker that allows the connection of radioelements to the peptide part.
- The attached radio element emits radiation after the person is exposed to the radiation, which helps to detect the exact location and progress of the cancerous tumor.