Functional imaging by DCE-US as a surrogate for response in phase I/II of different targeted therapies by DCE-US: Which quantitative parameter and which timing

Abstract

14093 Background: The early evaluation of targeted treatments is a major challenge in oncology. Functional approaches based on the measure of tumoral vascularization have been developed using different modalities of imaging (CT, MRI, US). We analyzed the response of tumors in three studies using different targeted treatments with dynamic contrast enhanced-ultrasonography (DCE-US). Seven parameters characterizing tumor perfusion were estimated. The objective of the study was to determine which parameter is the most appropriate and when to use it to confirm earlier the efficacy of treatment. Methods: A total of 157 DCE-US were performed in 30 responding patients (PFS>3 months) selected from 3 following studies (multikinase inhibitor targeting angiogenic-receptor with a cytotoxic, thyrosine-kinase inhibitor targeted angiogenic-receptor and C-kit, VEGF monoclonal antibody). Each DCE-US was performed using contrast agent (Sonovue,Bracco) with perfusion and quantification softwares (Toshiba) from raw linear data. Seven quantitative parameters of perfusion were estimated: peak intensity (PI) and area under the curve (AUC), area under the wash-in (AUWI), area under the wash-out (AUWO), time to PI, mean transit time (MTT), wash-in slope. DCE-US were performed before treatment and after during 5 periods (P) : 1–12 days(P1), 13–22 days(P2), 23–43 days(P3), 44–110 days (P4), > 111 days(P5). Results: 1099 parameters have benefited a statistical analysis. Significant modifications (P<0.05) of 4 parameters (PI, AUC, AUWI, AUWO) were observed for the 3 treatments. The earliest significant modifications were observed during the 3rd period for the first 2 studies and during the 4th period for the 3rd study. Conclusions: DCE-US is a sensitive tool to evaluate early tumor response to targeted drugs. Four functional parameters were significantly modified patients responding to treatment: PI, AUC, AUWI, AUWO. Those modifications appear earlier for the multikinase inhibitor targeting angiogenic receptor and the thyrosine-kinase inhibitor targeted angiogenic receptor and C-kit ( (23–43 d) compared to VEGF monoclonal antibody (44 -110 d). DCE- US represent a key add value to early evaluation of targeted therapies. No significant financial relationships to disclose.