Influence of DOTA chelators on radiochemical purity and biodistribution in xenografted mice of 177Lu- and 90Y-Rituximab

Document Type: Research article


1 National Centre of Nuclear Research, Radioisotope Centre POLATOM.

2 National Centre for Nuclear Research, Radioisotope Centre POLATOM.


Introduction This work presents a comparative biological evaluation of 90Y- and 177Lu- labelled DOTA-SCN and DOTA-NHS conjugated to Rituximab in tumour-bearing mice.
Materials and methods
Two DOTA derivatives, p-SCN-Bn-DOTA and DOTA-NHS-ester were conjugated to Rituximab and then freeze-dried kit formulations were prepared, as previously described [1]. Tissue distribution was investigated in tumour-bearing (Raji s.c.) male Rj:NMRI-Foxn1nu/Foxn1nu mice at different time points after administration of 177Lu-DOTA-Rituximab or 90Y-DOTA-Rituximab (6 MBq/10 μg per mouse). In addition, tumour images were acquired with a PhotonIMAGERTM after injection of 90Y-DOTA(SCN)-Rituximab.
Results and Conclusion All radioimmunoconjugates were obtained with high radiolabelling yield (RCP > 98%) and specific activity of ca. 0.6 GBq/mg. The conjugates were stable in human serum and in 0.9% NaCl, however, progressive aggregation was observed with time, in particular for DOTA(SCN) conjugates. Both 177Lu- and 90Y-DOTA(SCN)-Rituximab revealed slow blood clearance. The maximum tumour uptake was found 72 h after injection of 177Lu-DOTA(SCN)-Rituximab 9.3 ID/g. A high radioactivity uptake was observed in liver and spleen, confirming the hepatobiliary excretion route. The results obtained by the radioactive optical imaging harmonize with those from the biodistribution study.


Main Subjects