Clinical outcomes and ctDNA correlates for CAPOX BETR: A phase II trial of capecitabine, oxaliplatin, bevacizumab, trastuzumab in previously untreated advanced HER2+ gastroesophageal adenocarcinoma

We performed circulating tumor DNA (ctDNA) analysis on plasma of patients with advanced HER2 positive gastroesophageal adenocarcinomas who were treated on a phase 2 clinical trial testing the addition of bevacizumab to capecitabine, oxaliplatin, and trastuzumab. ctDNA was analyzed using panel based next generation sequencing assay (Predicine CARE), low-pass whole genome sequencing (LP-WGS), and methylation based panel assay (Predicine ALERT). This allowed us to derive tumor mutational profiles, circulating tumor fractions in plasma, and changes in both over time. We show that tumor fraction and the presence of mutations in the MAPK pathway are prognostic in our patient cohort. LP-WGS data from baseline and cycle 2 of treatment is available through dbGaP. Additional data is submitted... (for more see dbGaP study page.)