Localization and imaging of radiolabelled monoclonal antibody against squamous‐cell carcinoma of the head and neck in tumor‐bearing nude mice

Nude mice carrying human squamous‐cell carcinoma xenografts were given i.v. injections of radiolabelled monoclonal antibodies (MAbs). MAb E 48, which reacts with squamous‐cell carcinomas, was labelled with ¹³¹l,while a second control MAb of similar immunoglobulin subclass was labelled with ¹²⁵l. Both antibodies were injected simultaneously, then the mice were scanned with a gamma camera or their tissues were removed and antibody uptake was calculated as a percentage of the injected dose. Uptake of E 48 reached a peak value of 16%/g on day 3, while uptake of the control antibody was less than 1.8%/g. By 24 hr after injection tumor could be visualized without subtraction techniques. At days 3 and 7, only xenografts were visible on imaging. These findings suggest that E 48 is capable of high specificity in targeting isotopes to squamous‐cell carcinomas in an experimental setting.