Utility of circulating tumor DNA (ctDNA) versus tumor tissue clinical sequencing for enrolling patients (pts) with advanced non-colorectal (non-CRC) gastrointestinal (GI) cancer to matched clinical trials: SCRUM-Japan GI-SCREEN and GOZILA combined analysis.

Abstract

3516 Background: We recently reported that clinical assessment of genomic biomarkers using ctDNA had advantages over tumor tissue-based sequencing for enrollment into matched clinical trials across a wide range of GI cancers. Herein we investigated the utility of ctDNA in non-CRC cancers in a SCRUM-Japan GI-SCREEN and GOZILA combined analysis. Methods: In GI-SCREEN, tumor tissue samples of pts with non-CRC were analyzed by a next generation sequencing (NGS)-based assay, Oncomine Comprehensive Assay, since Feb 2015. In GOZILA, plasma samples of non-CRC pts were analyzed by an NGS-based ctDNA assay, Guardant360, since Feb 2018. Results: As of Apr 2019, 2,952 pts in GI-SCREEN and 633 pts in GOZILA were enrolled. Baseline characteristics between the groups were well matched except that GOZILA included more pancreatic (P < 0.0001) and liver cancers (P = 0.016) but fewer gastric cancers (P < 0.0001) and GIST (P = 0.020) than GI-SCREEN. The success rates of the tests were 86.6% in GI-SCREEN and 87.3% in GOZILA (P = 0.649). Median turnaround time (TAT) was 37 days in GI-SCREEN and 12 days in GOZILA (P < 0.0001). The proportion of cases with actionable alterations detected (tissue vs blood; 29.8% vs 46.8%, P < 0.0001) and enrolled into matched clinical trials (4.8% vs 6.5%, P = 0.286) for each group by cancer type are shown in the Table. Pts with upper GI cancers, especially those in GOZILA, were more often enrolled into matched trials; trial enrollment for those with hepatobiliary and pancreatic (HBP) or other cancers was similar regardless of testing method. Median time from GI-SCREEN or GOZILA enrollment to clinical trial enrollment was 5.0 and 1.0 months (mo), respectively (P < 0.0001). Objective response rates (ORR) and progression-free survival (PFS) were not significantly different (tissue vs. blood; ORR: 14.6 vs. 26.3%, P = 0.30: median PFS: 3.3 vs. 2.6 mo, P = 0.71). Conclusions: Clinical sequencing of ctDNA, with its shorter TAT, contributed to rapid enrollment of non-CRC pts into matched clinical trials compared to those tested by tumor tissue sequencing, particularly for those with upper GI cancer, without compromising efficacy. Clinical trial information: UMIN000029315 . [Table: see text]