In a recent paper in the Journal of Nuclear Medicine, Tagworks, in collaboration with Austrialian biotech company Avipep, describes an alternative radioimmunotherapy strategy based on separate administration of the tumor-homing agent and a fast clearing radioactive probe. This way, the unwanted high renal retention of low-molecular weight radiometal tumor-homing agents can be overcome.

The Tagworks and Avipep researchers show that a pretargeting strategy with a small protein may be an attractive approach in radioimmunotherapy to reduce kidney uptake while maintaining high tumor targeting. An effective tumor-targeting agent, a TAG72 diabody that had a high kidney uptake as a directly radiometal-labeled analog, showed complete retention of its properties upon TCO-modification. Administration of a radiometal-labeled tetrazine in a second step, showed efficient tumor uptake and most importantly low kidney uptake. This pretargeting strategy could be an important alternative platform, superseding the use of peptides and small proteins as metal-chelate conjugates for imaging and therapy.

Read the full paper: doi:10.2967/jnumed.115.159145