Indium 111 antimyosin for the detection of leiomyosarcoma and rhabdomyosarcoma.

111In-antimyosin monoclonal antibody complex passes through damaged myocardial cell membranes and binds to the intracellular myosin. Normal myocardial and other muscle cells show no uptake. Rhabdomyosarcoma and Leiomyosarcoma cells also contain intracellular myosin and the cell membrane permeability is greater than normal. Significant uptake of 111In-antimyosin was observed in patients with Leiomyosarcoma and Rhabdomyosarcoma suggesting that the reagent has a potential for the in vivo detection of these tumour types. Tumour to background ratios of 10:1 were measured in one case and in view of the fact that the site of accumulation is intracellular, antimyosin may have a potential as a carrier for therapeutic agents.