Tumor Localization of Radio-Labeled Antibodies against Carcinoembryonic Antigen in Patients with Carcinoma

TLDR

The study aimed to assess the specificity of 131I‑labeled anti‑CEA antibodies for tumor localization by comparing them with 125I‑labeled normal IgG in patients. Twenty‑seven carcinoma patients received injections of purified 131I‑labeled goat anti‑CEA antibodies, were imaged with a scintillation camera at multiple time points, and had both isotopes quantified in tumors and normal tissues by scintillation counting. Only the anti‑CEA antibodies accumulated in tumors, detectable in 11 of 27 patients 48 h post‑injection, but the tumor uptake was only ~0.001 % of the injected dose, rendering the technique clinically ineffective.

Abstract

Purified, [131I]-labeled goat antibodies against carcinoembryonic antigen, which have been shown to localize in human carcinoma in nude mice, were injected into 27 patients with carcinoma. Patients were scanned with a scintillation camera at various intervals. In 11 patients, radioactivity was detectable in the tumor 48 hours after injection. Computerized subtraction of blood-pool radioactivity provided clearer pictures in positive cases, but in 16 patients the scans remained doubtful or negative. To study the specificity of [131I]-antibody localization, we gave some patients simultaneous injections of [125I]-labeled normal IgG. Both isotopes were measured by means of scintillation counting in tumors and normal tissues recovered after surgery. The results demonstrated that only the anti-CEA antibodies localized in tumors. However, the total antibody-derived radioactivity in the tumor was only about 0.001 of the injected dose. We conclude that, despite the present demonstration of specificity, this method of tumor detection is not yet clinically useful.