Development of avidin-based positive contrast agents to detect tumor apoptosis using MRI
NEVES A, KRISHNAN A, HU D, KETTUNEN M, DE-BACKER M, BRINDLE K
UNIVERSITY OF CAMBRIDGE
We have been developing targeted MRI contrast agents (CAs) that can be used to detect tumor cell apoptosis in vivo, a prognostic indicator for the outcome of therapy. These CAs are based on the C2A domain of synaptotagmin I and avidin conjugated to gadolinium chelates, having the potential for signal amplification and improved sensitivity. Relatively large increases in T1 relaxation were observed in vitro (up to 2.5-fold) and in vivo (up to 1.6-fold) when the complexes bound to apoptotic cells. Ongoing tests in vivo will allow the selection of an avidin-based positive CA with adequate sensitivity, specificity and pharmacokinetic properties.