Radiolabelled peanut lectin for the scintigraphic detection of cancer

To investigate the role of intravenously administered, radioiodinated peanut lectin (131I-PNA) in the non-invasive detection of cancer, the pharmacokinetics and scintigraphic distribution of this novel tumor-seeking compound were studied in 8 patients with metastatic cancer of the colon, breast or lung. Scintigraphic localization of 131I-PNA was apparent at certain anatomical sites of known metastases in 2 patients and in a further 2 patients an adjacent malignant pleural effusion was visualized. The rapid clearance of radioactivity from the whole body and plasma with marked renal concentration and rapid urinary excretion of significant amounts of intact 131I-PNA (mol. wt. 107,000, pI 5.95) implied that this molecule was excreted selectively by the renal tubules. PNA or other lectins may find a role in the scintigraphic detection of selected types of cancer.