Pilot study of PET imaging of (124)I-iodoazomycin galactopyranoside (IAZGP), a putative hypoxia imaging agent, in patients with colorectal cancer and head and neck cancer

BACKGROUND: Hypoxia within solid tumors confers radiation resistance and a poorer prognosis. (124)I-iodoazomycin galactopyranoside ((124)I-IAZGP) has shown promise as a hypoxia radiotracer in animal models. We performed a clinical study to evaluate the safety, biodistribution, and imaging characteristics of (124)I-IAZGP in patients with advanced colorectal cancer and head and neck cancer using serial positron emission tomography (PET) imaging. METHODS: Ten patients underwent serial whole-torso (head/neck to pelvis) PET imaging together with multiple whole-body counts and blood sampling. These data were used to generate absorbed dose estimates to normal tissues for (124)I-IAZGP. Tumors were scored as either positive or negative for (124)I-IAZGP uptake. RESULTS: There were no clinical toxicities or adverse effects associated with (124)I-IAZGP administration. Clearance from the whole body and blood was rapid, primarily via the urinary tract, with no focal uptake in any parenchymal organ. The tissues receiving the highest absorbed doses were the mucosal walls of the urinary bladder and the intestinal tract, in particular the lower large intestine. All (124)I-IAZGP PET scans were interpreted as negative for tumor uptake. CONCLUSIONS: It is safe to administer (124)I-IAZGP to human subjects. However, there was insufficient tumor uptake to support a clinical role for (124)I-IAZGP PET in colorectal cancer and head and neck cancer patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT00588276