Confocal fluorescence microscopy image of a glioblastoma biopsy from a patient treated with the hypoxia-activated prodrug AQ4N. The activated cytotoxic agent AQ4 (red) is found in the nuclei (blue) of glioblastoma tumor cells (green) undergoing DNA fragmentation as shown by the reconstructed three-dimensional z-stack image. AQ4 was preferentially generated in hypoxic tumor tissues compared with normal tissues, which showed the first successful targeting of hypoxic tumors with a bioreductive cytotoxic agent in this phase I clinical study. For further details, please see Albertella and colleagues on page 1096 of this issue.

[Table of Contents]