Optimization of ⁹⁰ Y-antiCD20 preparation for radioimmunotherapy

Context: The advent of monoclonal antibodies such as Rituximab, in recent years, has brought about decisive progress in the treatment of aggressive and indolent non-Hodgkin's lymphoma. Aims: A further tried and tested improvement to the unmodified antibody has been its coupling to the beta-emitters Y-90. The optimization of ⁹⁰ Y-antiCD20 radioimmunoconjugate production and quality control methods for future clinical studies in the country was targeted in this work. Materials and Methods: The antibody was labeled with ⁹⁰ Y-yttrium chloride (185 MBq) after conjugation with freshly prepared ccDTPA. Y-90 chloride was obtained by thermal neutron flux (4 × 10 ¹³ n/cm ²/s) of a natural Y ₂ O ₃ sample, dissolved in acidic media. Radiolabeling was completed in 24 h by the addition of DTPA-Rituximab conjugate at room temperature. Statistical Analysis Used: All values were expressed as mean ± standard deviation (mean ± SD), and the data were compared using Student's t-test. Statistical significance was defined as P < 0.05. Results: Radiochemical purity of 96% was obtained by using ITLC method for the final radioimmunoconjugate (specific activity = 440-480 MBq/mg). The final isotonic ⁹⁰ Y-Rituximab complex was checked by gel electrophoresis for protein integrity retention. Biodistribution studies in normal rats were carried out to determine the radioimmunoconjugate distribution up to 72 h. Conclusion: The results showed that ⁹⁰ Y-DTPA-Rituximab could be considered for further evaluation in animals and possibly in humans as a radiopharmaceutical for use in radioimmunotherapy against non-Hodgkin's lymphomas. Because of the importance of developing anti-lymphoma B agents in nuclear medicine for country use, an optimized radiolabeling method has been introduced.