Techniques Of Anti-CD20 Monoclonal Antibody Labeling With ～(131)I And Experimental Study On Treatment For Nude Mice Xenografted With Tumor

Objectives:1. To exploit the techniques which is suitable for labeling Rituximab with 131I isotope.2. To observe the stability of 131I-Rituximab and determine the optimal storage condition.3. To observe the tissue distribution and radioimmunotherapy of 13lI-Rituximab on nude mice bearing xenografed Raji cells tumor.Methods:1. Detecting the labeling efficiency, radiochemical purity and immunoreactive fraction of 13lI-Rituximab at different reaction time (2,4,6,8rninutes) and different specific mass-radioactivity ratio (1:10, 1:15,1:20) respectively.2. Measuring the changes of radiochemical purity of 131I-Rituximab in 0-5 days at different storage conditions (stored as original solution at 4℃ or stored directly at 37℃ in CO2 fermentor with 1% hominine albumin) right after the label process.3. Detecting the tissue distribution of 131I-Rituximab on nude mice accepting different therapeutic methods: introtumor and intraperitoneally injection.4. Treating the nude mice bearing Raji cells tumor or SCG7901 cells tumor with different methods, evaluating the development of xenograted tumor, and studying the efficacy of I3lI-Rituximab.Results:1. The labeling efficiency of 131I and Rituximab at 4 minutes reaction (90.2 ±1.3%) was higher than that at 2 minutes (87.4 ±0.7%, P<0.05), and lower than that at 8 minutes (96.6 ±0.83%, P<0.01), and no statistical significance was found when compared with that at 6 minutes (P>0.05). The immunoreactive fraction of 131I-Rituximab at 4 minutes reaction (33.6 ±1.1%) was higher than those at 6 minutes (29.2 ± 1.2%) and 8 minutes (26.6 ± 0.56%), and statistical significance was found( P<0.01). No statistical significance (P>0.05) was found when comparde with that at 2 minutes (33.4% ± 0.62%).2. The labeling efficiency (99.3±0.66%) and the immunoreactive fraction (34.4±0.98%) were all higher at 1:10 mass-radioactivity ratio than those at 1:15(97.2 ±0.81%, 30.2±1.3%, P<0.05) and 1:20(94.3 ±1.1%, 22.6±2.1%, P<0.01). And the radiochemical purity (92.0 ±0.35%) was significantly higher than that of 1:15(76.3 ±0.57%, P<0.01) after being kept in storage for 24 hours.3. The labeled I31I-Rituximab with high specific radioactivities (15μCi/μl and 5~15μg/μl) can be obtained though Na131I was only 12mCi by our labeling techniqus.4. The datum of T/NT(Tumor/Blood) was 15.8 when 131I-Rituximab was injected introtumor but only 0.92 of intraperitoneally 72 hours after injection.5. Of all the therapeutic methods studied, the best inhabitant of tumor growth was obtained when the labeled 131I-Rituximab was injected intratumor.Conclusions:1. According to our research, the optimal conditions for labeling Rituximabwith Na 131I lied in at least two aspects: 4 minutes of reaction time and 1:10 ratio of mass-radioactivity. The labeling efficiency, radiochemical purity and immunoactivity were all high very much, and 131I-Rituximab with high specific radioactivities (15μCi/μl and 5~15μg/μl) can be obtained for intratumor injection at animal tests.2. For the solution containing 131I- Rituximab, the radiochemical activity stillremained 80% after 5-days-storation at 4℃.3. The highest tumor growth inhibitive rate was obtained when treating nudemice bearing CD20+ Raji tumor with 131I- Rituximab injected intratumor.