Radioimmunodetection of non‐small cell lung cancer using technetium‐99m‐anticarcinoembryonic antigen immu‐4 fab′ fragment

Abstract

Background. Although computed tomography and magnetic resonance imaging have improved the staging and evaluation of non‐small cell lung cancer (NSCLC), mediastinal staging lacks adequate specificity and sensitivity. Radioimmunodetection may augment computed tomography and magnetic resonance imaging. The authors evaluated the ability of the technetium 99m‐anticarcino‐embryonic antigen IMMU‐4 Fab′ fragment to localize NSCLC in vivo, measured its pharmacokinetics, and estimated its radiation dose. Methods. Seventeen patients with carcinoembryonic antigen‐positive NSCLC received 16–30 mCi of technetium 99m IMMU‐4 Fab′. Planar imaging was performed at 1–7 hours and 20–24 hours. Single‐photon emission computed tomography (SPECT) was performed within 8 hours after injection. In 10 patients, blood sampling, urine collection, and quantitative imaging were performed to determine blood and urine pharmacokinetics and radiation dose estimates. Human anti‐mouse antibody response was measured for as long as 3 months after administration. Results. Planar and/or SPECT imaging detected 72% of 32 known lesions. SPECT was more sensitive than planar imaging. T½ohα averaged 0.18 ± 0.33 hours; T½ohβ averaged 8.02 ± 5.53 hours. The mean concentration versus time value was 1.11 ± 0.56 mg.h. The average whole body dose estimated for administration of 30 mCi was 0.45 ± 0.08 rads. No human anti‐mouse antibody responses were detected. Conclusion. The tumor detection rate was high, but the persistent blood pool at < 8 hours complicated image interpretation. An intermediate imaging time point (12–16 hours) might be preferable. SPECT is an important adjunct to imaging with this radioimmunoconjugate. The acceptable dosimetry estimated for 30 mCi Technetium 99m IMMU‐4 Fab′ and the lack of human anti‐mouse antibody responses suggest this is a promising localizing tool for NSCLC. Cancer 1994; 73:890–5. Copyright © 1994 American Cancer Society