This Core Component will evaluate reagents developed in the Projects for acute toxicity and the ability to enhance the radiosensitizing effects of moderate hyperthermia in tumor xenografts heated in vivo in mice. The Core will also determine if the parameters that relate to heat-induced radiosensitization (HIR) and/or its enhancement in vitro (as established in the Projects) also relate to HIR or its enhancement in vivo. A long-range goal of this effort is to develo methods to image these parameters non-invasively. Briefly, this Core will collaborate with the Project researchers to extend their in vitro studies to initial pre-clinical models utilizing human tumors grown as xenografts in nude mice. The establishment of this Core will provide an efficient and cost effective resource for evaluating the in vivo efficacy and toxicity of compounds developed in Projects 3 and 4. In addition, the Core will collaborate with all of the Projects to confirm that the parameters (i.e. molecular alterations) that contribute to increased HIR in vitro are also related to HIR or its enhancement in vivo.