Al18Ftekniken

Al18Ftekniken, or the Al18F-labelling technique, is a radiochemical approach used to produce fluorine-18 labeled tracers for positron emission tomography (PET). The method centers on forming a complex between the radionuclide fluorine-18 and aluminum to generate [18F]AlF, which then coordinates to a bifunctional chelator such as NOTA or NODA that is attached to a biological vector (peptide, protein, or small molecule).

In practice, the [18F]AlF species is formed in aqueous buffer and subsequently bound by the chelator on the targeting molecule. The labeling is typically performed under relatively mild conditions, often in a way that is compatible with peptides and other biomolecules. The final [18F]AlF-chelate tracer is purified and formulated for injection as a PET radiopharmaceutical.

The technique offers several advantages. It generally allows labeling under milder, more aqueous conditions compared with some traditional fluorination methods, and it has the potential for kit-based production, which can simplify manufacturing of radiopharmaceuticals. This has facilitated the development of a family of Al18F-labeled tracers across different targets.

Applications of Al18Ftekniken include imaging somatostatin receptor-positive neuroendocrine tumors using NOTA-conjugated somatostatin analogs, as well as labeling other peptides and small molecules (for example, integrin- or receptor-targeting motifs). The approach has been explored in preclinical and early clinical studies, with ongoing research aimed at expanding the range of suitable vectors and improving in vivo stability.

Limitations include the need for stringent control of metal contaminants and reaction conditions to maintain stability of the in vivo tracer. Not all chelators or targets label efficiently, and regulatory status remains primarily within research and early clinical research, with some tracers advancing to initial human studies.