The toxicity, pharmacokinetics, dosimetry and anti-tumour activity of the murine anti-CEA bispecific antibody F6x734 and the bivalent indium-DTPA hapten labelled with iodine-131 were evaluated in a phase I/II clinical trial in 26 patients with recurrent MTC (Kraeber-Bodéré et al. 2006). Here, CEACAM5 is linked to neoplasm.