Non invasive imaging of hypoxia with the aid of PET-scans could help to select the patients having a hypoxic tumour who could be treated with specific anti-hypoxic treatments such as bio-reductive drugs or hypoxic radio-sensitizers. Several 2-nitroimidazoles to which the compound to be tested, HX-4, belongs, labelled with Fluor-18 have already been used in patients. However, bad image quality and unpredictable kinetics limit their use. In extensive pre-clinical models, the combination of HX-4 labelled with Fluor-18 is a promising non-toxic new probe to determine hypoxia.

To determine the toxicity of the hypoxia PET-tracer [18F]-HX4 in cancer patients in two dose-steps:

• Step 1 (3-6 patients): a single dose of maximum 6 mCi (222 MBq) dose of [18F]HX4 (which contains a maximum of 15 μg HX-4) via a bolus IV injection.
• Step 2 (3-6 patients): a single dose of maximum 12 mCi (444 MBq) dose of [18F]HX4 (which contains a maximum of 27 μg HX-4) via a bolus IV injection.

Inclusion Criteria:

• Histological or cytological confirmed solid tumour, primary or secondary stage IV and/ or tumours with no curative treatment options.
• Normal white blood cell count and neutrophils
• Normal platelet count
• No anaemia requiring blood transfusion or erythropoietin
• Adequate hepatic function: Total bilirubin ≤ 1.5 x upper limit of normal (ULN) for the institution; ALT, AST, and alkaline phosphatase ≤ 2.5 x ULN for the institution).
• Calculated Creatinin clearance at least 60 ml/min
• No administration of Fluor-18 in the previous 24 hours
• Capable of complying with study procedures