Insight into Tumor Hypoxia: Radionuclide-based Biomarker as Diagnostic Tools

Area of Science:

• Nuclear Medicine
• Radiochemistry
• Oncology

Background:

• Tumor hypoxia, a state of low oxygen in solid tumors, is associated with treatment resistance, metastasis, and poor prognosis.
• Hypoxia is a critical factor in cancer treatment planning and patient outcomes.
• Radiolabeled tracers are essential for non-invasively assessing physiological and pathological conditions, including tumor hypoxia.

Approach:

• This review focuses on the development of radiochemistry routes for synthesizing various radiopharmaceuticals for hypoxia imaging.
• It examines the literature on chemical scaffolds labeled with radioisotopes like Fluorine-18 and Copper-64 for Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT).
• The discussion includes versatile radiolabeling strategies, such as nucleophilic and electrophilic substitutions, for incorporating radioisotopes into target molecules.

Key Points:

• Several radiotracers, including [18F]FMISO, [18F]FAZA, [18F]FETNIM, and [64Cu][Cu(ATSM)], are highlighted for their exploration in hypoxia imaging.
• Promising scaffolds like [18F]EF1, [18F]EF5, [18F]EF3, and [18F]HX4 are discussed.
• Efficient and selective radionuclide incorporation, crucial for clinical application, is emphasized, requiring high radiochemical yield, specific activity, purity, and radio-scalability.

Conclusions:

• Significant efforts have been made by chemists and radiochemists to develop effective radiopharmaceuticals for hypoxia imaging.
• The review synthesizes information on chemical synthesis routes and the application of these tracers in clinical and preclinical studies.
• Understanding the synthesis and biological significance of these radio-labeled tracers is vital for advancing cancer diagnostics and treatment planning.