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

We investigated the safety and pharmacokinetics of I-131-labeled chimeric m onoclonal antibody MOv18 (I-131-c-MOv18 IgG) in patients with ovarian cance r and the estimated radiation dose to cancer-free organs and tumor. Methods : Three patients were injected intravenously with 3 GBq I-131-c-MOv18. Toxi city was evaluated according to the World Health Organization toxicity scal es. Blood sampling was performed for 12 wk after injection. Whole-body and SPECT imaging was performed frequently. Dose rates were obtained with a por table dose-rate measure. Quantitative activity analysis of several organs w as performed with the region-of-interest technique. Absorbed doses were cal culated 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. Nonhema tologic toxicity was mild. No human antichimeric antibody responses were ob served. Mean isolation time was 12 d. The plasma elimination half-life incr eased almost 3-fold compared with that after tracer doses of c-MOv18. Dosim etry showed mean absorbed doses of 163, 380, 276, 338, 781, and 216 cGy, fo r whole-body, liver, kidney, spleen, lung, and red marrow, respectively. Tu mor-absorbed doses ranged from 600 to 3800 cGy. All patients achieved a sta ble disease state, as confirmed by CT and carcinoma-associated antigen CA 1 25, lasting from 2 to >6 mo. Conclusion: I-131-labeled c-MOvl8 can safely b e given to patients with noncompromised bone marrow reserves and may have t herapeutic potential particularly in patients with minimal residual disease .