Non Invasive Imaging of Cetuximab-Zirconium-89 Uptake With PET: a Phase I Trial in Stage IV Cancer

Non invasive imaging of cetuximab uptake with PET could help to select the patients who could be treated by cetuximab, a registered but expensive monoclonal antibody against EGFR. Other monoclonal antibodies labelled with Zirconium-89 have already been used with success in patients. The combination of cetuximab labelled with Zirconium-89 is a promising new probe to determine cetuximab uptake, which has been tested in various pre-clinical animal models in Maastricht with excellent results.

We propose a two step study design (see figure 1). As our ultimate goal for the future is to determine the uptake of 89Zr-cetuximab in the tumour before and during therapy, we need to investigate the toxicity of two consecutive low doses of 89Zr-cetuximab in the first place. However, as in future studies and in some patients, it is also possible that a single, larger dose of 89Zr-cetuximab is needed to obtain the best image quality, we will also investigate the toxicity of a single larger dose.

Step 1: Determination of the toxicity of two low doses of 89Zr-cetuximab In three patients a standard loading dose of 400 mg/m2 of cetuximab will be administered, partly labelled with 89Zr (60 MBq, 2.5mg) on day 0.

On day 14, a second injection with dose of 250 mg/m2 of cetuximab, partly labelled with 89Zr (60 MBq, 2.5mg), will be given.

Step 2: Determination of the toxicity of one larger dose of 89Zr-cetuximab A standard loading dose of 400 mg/m2 of cetuximab will be administered in 3 patients, a part labelled with 89Zr (120MBq, 5mg).