Analysis of a blood brain barrier model showed minimal distribution of pritumumab in normal brain tissues and significant binding in tumour areas of brain tissues. This indicated that the monoclonal antibody product crosses the tumour brain barrier  .
A total of 10 patients with malignant gliomas were treated with pritumumab IV once or twice a week for 4 weeks, in a phase I trial. No toxicities were observed  .
In a phase II study, 42 patients with malignant gliomas received pritumumab IV once or twice a week for 24 weeks. Mild adverse reactions were reported in 2/21 evaluable patients  .
A concentration-dependent study of pritumumab-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) showed an EC50 of 39.6 ng/ml. Additional studies of pritumumab showed effective prevention of tumour growth in a xenograft model with nude athymic mice but not in SCID mice  .
Binding specificity evaluated using flow cytometry and immunohistochemical analysis, western blot analysis and ADCC activity confirmed the comparability of a recombinant version of pritumumab, made using the GPEx® system in CHO cells, and the original hybridoma  .
In preclinical immunoreactivity studies using cell lines and human tissue, pritumumab had a marked reaction with malignant glioma cell lines and tissue; however, the compound did not react to normal cell lines, or normal adult or fetal brain tissue or other extraneural tissue  .
in a phase II study, patients with malignant gliomas were treated with pritumumab IV twice a week for 24 weeks. The overall response rate was 27%. The five-year survival rate in a group of 66 patients was 25%  .
In another phase II study, 42 patients with malignant gliomas received pritumumab IV once or twice a week for 24 weeks. The overall response rate for the 21 patients who could be evaluated was 38.1%. The response rates for patients who received pritumumab once or twice a week were 14.2 and 50.0%, respectively  .