A phase II study of 18F-fluorodeoxyglucose PET–CT in non-small cell lung cancer patients receiving erlotinib (Tarceva®); objective and symptomatic responses at 6 and 12 weeks

Abstract

Background The aim of this study was to assess if 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)–CT scanning could minimise the time non-responding patients were exposed to erlotinib (Tarceva®). Methods Patients were selected for clinical factors that would predict response to erlotinib. A FDG PET–CT and diagnostic contrast-enhanced (traditional) CT scan were carried out at baseline, and then a FDG PET–CT at 6 weeks and a traditional CT at 12 weeks were repeated. The primary end-point was rate of early progression in patients after 6 weeks, of which a minimum 12 out of 35 were required to make the study worthwhile. The responses at 6 (PET–CT) and 12 weeks (traditional CT) were compared and correlated with symptomatic response at both these time points. Results Forty seven patients were recruited with 38 and 33 patients assessable by FDG PET–CT at 6 weeks and traditional CT at 12 weeks, respectively. There was good correlation between Partial response (PR) at both time points and all 10 patients who had a PR at 12 weeks had a PR at 6 weeks. Of the 13 patients with progressive disease (PD) at 12 weeks, seven had PD at 6 weeks and could have had their treatment stopped early. No evaluable patient with stable disease (SD) (8/38) or PD (9/38) on FDG PET–CT at 6 weeks went on to have a later response. Symptomatic response at 6 or 12 weeks did not correlate well with objective response on scanning at either time point. Conclusions The primary end-point of this study was met as >12 (15/38) patients could have stopped treatment early on the basis of the FDG PET–CT scan result. A FDG PET–CT evaluable response of SD or PD at 6 weeks does predict future lack of response. No correlation was found between response and symptomatic response at either 6 or 12 weeks.