A chimeric, murine-human monoclonal antibody directed against the tumor-associated antigen (TAA) tenascin (hexabrachion) that may, when conjugated with a radioisotope, be useful in radiotherapy or radioimaging. Tenascin, an extracellular matrix glycoprotein is upregulated in certain pathological conditions such as infection, inflammation and tumor growth, and is highly expressed in the tumor microenvironment in some malignancies.