Hypoxia and Perfusion Measurements in Human Tumors&Initial Experience with Pimonidazole and IUdR

Abstract

We describe our preliminary studies on the development of methods to measure hypoxia in standard paraffin sections of human tumors. Three parameters were investigated. First, image analysis of tumor vascularity yielded the parameter diffusion limited fraction (DLF), which is the amount of tumor tissue greater than a fixed distance from the nearest blood vessel. Secondly, the amount of tumor tissue stained with antibodies against bound reduced products of the bioreductive marker pimonidazole was assessed. Finally, the fraction of blood vessels showing no surrounding tumor tissue labeled with lUdR, a cell kinetic marker, was measured. DLF and pimonidazole monitor primarily chronic hypoxia, while it is hypothesized that the IUdR-negative fraction monitors acute hypoxia. Feasibility was demonstrated in a series of 10 esophageal and 10 rectal tumors (no drug administration), 10 cervix tumors (pimonidazole) and 14 head and neck tumors (pimonidazole and lUdR). Significant differences between tumors were found for all parameters. DLF correlated significantly with the pimonidazole fraction when all images of all tumors were included, although mean values per tumor showed no correlation. The IUdR-negative fraction did not correlate with either of the other two parameters. We conclude that it is feasible to measure hypoxia-related, and possibly perfusion-related, parameters on paraffin sections for predictive purposes, although each method needs further validation. Each parameter will be correlated with outcome in a larger study on head and neck tumors treated with surgery with or without postoperative radiotherapy.

Clinical relevance and therapeutic predictive ability of hypoxia biomarkers in head and neck cancer tumour models

“…The high variability in hypoxic fraction between individual tumours of the same model is consistent with our previous findings in large tumours [40] and in other tumour models [18,[69][70][71]. This variability, together with the small range of hypoxic fractions we have observed between different tumour models, here and previously [40], suggests that pimonidazole immunohistochemistry on its own is not sufficient for predicting sensitivity of xenografts to hypoxia-targeting therapies.…”

Acetaminophen hepatotoxicity and HIF-1α induction in acetaminophen toxicity in mice occurs without hypoxia

“…Pimonidazole is reductively activated in hypoxic conditions and is a commonly used marker of cellular hypoxia (Begg et al, 2001; Copple et al, 2003; Raleigh et al, 1998; Varia et al, 1998). In order to examine the possible role of hypoxia in the induction of HIF-1α in APAP toxicity, mice were treated with APAP (200 mg/kg IP) followed by pimonidazole (60 mg/kg IP).…”