Biodistribution of 99mTc‐sunitinib as a potential radiotracer for tumor hypoxia imaging

Tyrosine kinases are groups of enzymes, which are over‐expressed in solid tumor cells, representing good targets for different drugs such as sunitinib (N‐[2‐(diethylamino)ethyl]‐5‐{[(3Z)‐5‐fluoro‐2‐oxo‐2,3‐dihydro‐1H‐indol‐3‐ylidene]methyl}‐2,4‐dimethyl‐1H‐pyrrole‐3‐carboxamide). The aim of this work was to design and synthesize ^99mTc‐sunitinib radiotracer and to study its tumor binding specificity as a novel selective radiopharmaceutical for tumor hypoxia imaging. The in vivo biodistribution of ^99mTc‐sunitinib in tumor bearing mice showed high target/non‐target (T/NT) ratio (T/NT ~ 3 at 60 min post injection). This preclinical high biological accumulation in tumor cells suggests that ^99mTc‐sunitinib is ready to go through the clinical trials as a potential selective radiotracer able to image tumor hypoxia.