Phase I trialPET imaging of zirconium-89 labelled cetuximab: A phase I trial in patients with head and neck and lung cancer

Background and purposePET imaging of cetuximab uptake may help selecting cancer patients with the highest chance of benefit. The aim of this phase I trial was to determine the safety of the tracer 89Zr-cetuximab and to assess tumour uptake.MethodsTwo dose schedules were used; two consecutive doses of 60 MBq 89Zr-cetuximab or a single dose of 120 MBq, both preceded by 400 mg/m2 of unlabelled cetuximab. Toxicity (CTCAE 3.0) was scored twice weekly. PET-CT scans were acquired on days 4, 5 and 6 (step 1) or 5, 6, 7 (step 2). Because tumour uptake could not be assessed satisfactorily, a third step was added including EGFR overexpressing tumours.ResultsNine patients were included (6 NSCLC; 3 HNC). No additional toxicity was associated with administration of 89Zr-cetuximab compared to standard cetuximab. A tumour to blood ratio (TBR) > 1 was observed in all but one patient, with a maximum of 4.56. TBR was not different between dose schedules. There was a trend for higher TBR at intervals > 5 days after injection.ConclusionsBoth presented 89Zr-cetuximab administration schedules are safe. The recommended dose for future trials is 60 MBq, with a minimum time interval for scanning of 6 days.