Radioimmunotherapy with intravenously administered 131I-labeled chimeric monoclonal antibody MOv18 in patients with ovarian cancer

We investigated the safety and pharmacokinetics of I-131-labeled chimeric monoclonal antibody MOv18 (I-131-c-MOv18 IgG) in patients with ovarian cancer and the estimated radiation dose to cancer-free organs and tumor. Methods: Three patients were injected intravenously with 3 GBq I-131-c-MOv18. Toxicity was evaluated according to the World Health Organization toxicity scales. Blood sampling was performed for 12 wk after injection. Whole-body and SPECT imaging was performed frequently. Dose rates were obtained with a portable dose-rate measure. Quantitative activity analysis of several organs was performed with the region-of-interest technique. Absorbed doses were calculated using MIRDOSE3. Results: Transient changes in hematologic profiles were seen in 2 patients. Pancytopenia developed in 1 patient; on analysis, she entered the study probably with exhausted bone marrow reserves. Nonhematologic toxicity was mild. No human antichimeric antibody responses were observed. Mean isolation time was 12 d. The plasma elimination half-life increased almost 3-fold compared with that after tracer doses of c-MOv18. Dosimetry showed mean absorbed doses of 163, 380, 276, 338, 781, and 216 cGy, for whole-body, liver, kidney, spleen, lung, and red marrow, respectively. Tumor-absorbed doses ranged from 600 to 3800 cGy. All patients achieved a stable disease state, as confirmed by CT and carcinoma-associated antigen CA 125, lasting from 2 to >6 mo. Conclusion: I-131-labeled c-MOvl8 can safely be given to patients with noncompromised bone marrow reserves and may have therapeutic potential particularly in patients with minimal residual disease.