A new and convenient method for purification of 86Y using a Sr(II) selective resin and comparison of biodistribution of 86Y and 111In labeled Herceptin.

A simple and rapid procedure was developed for purification of cyclotron produced 86Y via the 86Sr(p,n) 86Y reaction. A commercially available Sr(II) selective resin was used to separate 86Y from the cyclotron irradiated Sr(II) target with a recovery of the enriched Sr(II) target while yielding a 75-80% recovery of 86Y suitable for radiolabeling either proteins or peptides. To demonstrate the utility of this methodology, the anti-HER2 monoclonal antibody Herceptin was radiolabeled with the purified 86Y and compared to 111In labeled Herceptin. The biodistribution study demonstrated that 111In-Herceptin, while a suitable surrogate for 90Y in the major organs, did not parallel the uptake of 86Y-Herceptin in the bone, and thus may not accurately predict the level of 90Y accumulation in the bone for clinical RIT applications. This result exemplifies the requirement of employing appropriate matched pair isotopes for imaging and therapy to insure that dosimetry considerations may be addressed accurately.