The Importance of Careful Filtration Technique in Obtaining High Recovery Yields of Indium-111 OncoScint CR/OV

Abstract

Objective: Indium-111 OncoScint CR/OV (satumomab pendetide) is the first FDA-approved radiolabeled monoclonal antibody for human diagnostic use. In our experience with preparing OncoScint CR/OV according to the manufacturer’s package insert procedure, we have noted that the recovery of the labeled antibody after the required filtration through a 0.22-μm filter was variable; sometimes filtration yields as low as 60% of the initial activity injected into the reaction vial were observed. In this study we investigated whether or not the filtration yield of the radiolabeled immunoconjugate in the injection syringe could be improved.

Methods: We used either a scrupulous technique in withdrawing the material from the reaction vial into the dose syringe through the 0.22-μm filter or the dilution of the radiolabeled antibody solution with saline before careful with-drawal in our attempts to improve the yield.

Results: Our results indicate that it is possible to obtain a consistent recovery of greater than 80% of the labeled antibody without using any diluent if care is taken to completely remove the liquid from the reaction vial.

Conclusions: In our studies performed according to the manufacturer’s directions, the yield was acceptable. An improvement in recovery less than 5% was achieved with the addition of saline which was statistically significant. Therefore, we do not recommend using saline to dilute ¹¹¹In OncoScint CR/OV before filtration.