Semi-automatic Dispensing System for ¹¹¹In/⁹⁰Y-labeled Monoclonal Antibodies:Potential for RIT & PRIT applications

Objectives The ¹¹¹In and ⁹⁰Y radionuclides are used widely in radioimmunotherapy (RIT) and pre-targeted radioimmunotherapy (PRIT) for relapsed lymphomas and leukemias. However,reducing radiation exposure to the hands of radiochemists while preparing/dispensing the final product is vital. We have designed an inexpensive semi-automated closed system for easy and efficient handling of ¹¹¹In and ⁹⁰Y-labeled radiopharmaceuticals for clinical use under aseptic condition.

Methods Using sterile disposable units and a box made of acrylic sheet, a system was designed for dispensing the radiolabeled product from reaction vial to dose syringe using a remote-controlled peristaltic pump and kept behind a lead shield lined with thick acrylic sheet. Binding of ¹¹¹In(10-15mCi) or ⁹⁰Y(30-200mCi) activity to antibodies (anti-CD20) for RIT or to DOTA-Biotin for PRIT involves 1h incubation at 45⁰/85⁰C, respectively. Finally, the reaction product was transferred to dose syringe through a 0.1μm filter using the dispensing system. Amount of radioactivity transferred or retained in each step was measured in a dose calibrator (CapintecCRC-15R). The skin dose measurements during product handling were performed using thermoluminescence detectors (ring badge & whole body badge).

Results The efficacy of the remote controlled semi-automated dispensing system for 12 radiopahramceutical productions for clinical applications were evaluated.The completeness of the transfer of radiolabeled product from the reaction vial was >99.5% with <1% retention in the 0.1μm filter. Thermoluminescent dosimetry showed that hand dose and whole body dose was reduced 10-fold from the personnel exposure by using the semi-automated transfer system.

Conclusions We demonstrate that the simpler and inexpensive semi-automated system can be efficiently used for production of ¹¹¹In and ⁹⁰Y-radiolabeled compounds combining Good Manufacturing Practice with radiation safety.

Research Support Supported by NIH Grant # P01CA044991