Utility of circulating tumor DNA (ctDNA) versus tumor tissue clinical sequencing for enrolling patients (Pts) with advanced gastrointestinal (GI) cancer to matched clinical trials: SCRUM-Japan GI-SCREEN and GOZILA Combined Analysis.

Abstract

5 Background: Blood-based genomic profiling by ctDNA analysis has a promise to potentially identify actionable genomic alterations. However, utility of clinical sequencing with ctDNA compared with that with tumor tissue for enrolling cancer pts to matched clinical trials remains unclear. Herein we investigated the utility of ctDNA clinical sequencing by the SCRUM-Japan GI-SCREEN and GOZILA Combined Analysis. Methods: In the GI-SCREEN, tumor tissue samples of pts with advanced GI cancer were analyzed by a next generation sequencing (NGS)-based assay, Oncomine Comprehensive Assay since Feb 2015. In the GOZILA, plasma samples of pts with advanced GI cancer were analyzed by an NGS-based ctDNA assay, Guardant360 since Feb 2018. Tests were performed centrally by CLIA-certified and CAP-accredited laboratories. Pts with actionable alterations were enrolled to matched company-sponsored or investigator-initiated clinical trials. Results: As of Apr 2019, test results were generated in 5,029 out of 5,743 pts (88%) in GI-SCREEN and 1,089 out of 1,103 pts (99%) in GOZILA ( P < 0.0001).Median turnaround time (TAT) was 35 days in GI-SCREEN and 12 days in GOZILA ( P < 0.0001). There were no differences in other baseline characteristics between GI-SCREEN and GOZILA. Proportion of enrolling matched clinical trials in GOZILA was significantly higher than that in GI-SCREEN (126 pts [2.2%] in GI-SCREEN vs. 60 pts [5.4%] in GOZILA, P < 0.0001). Median time from GI-SCREEN or GOZILA enrollment to clinical trial enrollment was 5.9 and 1.0 months (mo), respectively ( P < 0.0001). The objective response rate (ORR) and progression-free survival (PFS) were not significantly different (ORR: 17.5 vs. 16.7%, P = 1.00; median PFS: 2.8 vs. 2.0 mo, P = 0.24). Conclusions: Clinical sequencing with ctDNA having the advantage of the shorter TAT enrolled more pts with advanced GI cancer to matched clinical trials than those with tumor tissue, without compromising the efficacy. Clinical trial information: UMIN000029315.