Counting heads in the war against cancer: Defining the role of annexin A5 imaging in cancer treatment and surveillance

The unveiling of the heterogeneous nature of cell death modes has compromised the long-lived consensus that cancer treatment typically kills cancer cells through apoptosis. Moreover, it implies that measures of apoptosis may be misleading indicators of treatment efficacy. Simultaneously, it has become clear that phosphatidylserine exposition, traditionally considered a hallmark of apoptosis, is also associated with most other cell death programs, rendering phosphatidylserine an attractive target for overall cell death imaging. Annexin A5 binds with strong affinity to phosphatidylserine and hence offers an interesting opportunity for visualization of aggregate cell death, thus providing a fit benchmark for in vivo monitoring of anticancer treatment. This might be of significant value for pharmacologic therapy development as well as clinical monitoring of treatment success.