Immunogenicity of Rituximab, Trastuzumab, and Bevacizumab Monoclonal Antibodies in Patients with Malignant Diseases

Background: One of the most important limiting factors affecting the efficacy of treatment using monoclonal antibodies (mAbs) is their immunogenicity to the patients that may influence the diagnostic and therapeutic process. Objectives: This study determined the unwanted immunologic response to the presence of antibody against some theraputic agents made following taking mAbs in patients with malignancy. Methods: Blood samples were collected from patients with cancer, including 32 patients with lymphoma or leukemia, 43 patients with breast cancer, and 23 patients with adenocarcinoma (colon or ovarian cancer) while receiving treatment with Rituximab, Trastuzumab, and Bevacizumab, respectively. Serum levels of human antibodies against the mentioned mAbs were determined by the standard sandwich ELISA method designed in the research. Results: The presence of human antibodies against the mentioned mAbs was detected in 4 out of 32 (12.5%) Rituximab-treated patients and 7 out of 43 (16.3%) Trastuzumab-treated patients with a meanSD titer of 2.330.37 AU/mL and 1.20.21 AU/mL, respectively. The probability for the presence of anti-mAb in patients treated with Rituximab alone was significantly higher than patients, who took concomitantly Rituximab and once or more chemotherapeutic agents (26.6% vs. 0.0%; P < 0.02). None of Bevacizumabtreated patients, as was anticipated, developed antibody against the administrated mAb. Conclusions: The results of this study indicates the production of antibody against therapeutic mAbs Rituximab and Trastuzumab in a number of treated patients and this may influence their efficacy of treatment. The production of the human anti-mAb may be suppressed by chemotherapeutic drugs in Rituximab-treated patients and this phenomenon may be considered as a bonus effect during treatment. Bevacizumab did not show immunogenicity in the treated patients.