Radioimmunodetection of residual, recurrent or metastatic germ cell tumors using technetium-99 anti-(α-fetoprotein) Fab' fragment

The majority of patients with germ cell tumors are cured by multimodality therapy that consists of cisplatin-based chemotherapy and/or surgical resection. Serum tumor markers and conventional radiographs are utilized to stratify patients into treatment categories. Efforts to individualize chemotherapy or minimize surgical interventions without compromising outcome are important. Immunomedics (Morris Plains, New Jersey) developed an anti-(alpha-fetoprotein) (anti-AFP) monoclonal antibody IMMU-30 labeled with 15-20 mCi technetium-99, and the purpose of this study is to determine the sensitivity and specificity of radioimmunoscintigraphy using 99mTc anti-AFP antibody for the diagnosis of active germ cell tumors. A group of patients with germ cell tumors were enrolled in a non-prospective fashion and 48 AFP scans using 99Tc anti-AFP Fab' fragment were obtained. At the time of the AFP scan, serum AFP was elevated in 40 measurements with a median level of 21 ng/ml (1.6-66, 210.0 ng/ml). AFP scans were obtained at the initial staging, during treatment, at relapse or at long-term follow-up and compared with conventional radiographs done within 4 weeks of the AFP scans. An overall diagnostic sensitivity of 89% and specificity of 58% were obtained. AFP scanning appears useful and to be sufficiently sensitive to justify prospective studies comparing the procedure with conventional imaging.