Liquid Biopsy Analysis Of Fgfr3 And Pik3ca Hotspot Mutations For Disease Surveillance In Bladder Cancer

Background: Disease surveillance in patients with bladder cancer is important for early diagnosis of progression and metastasis and for optimal therapeutic treatment. Experimental procedures: Droplet digital PCR (ddPCR) assays were developed and tumour DNA from two patient cohorts was screened for FGFR3 and PIK3CA hotspot mutations. One cohort (NMIBC cohort) included 363 patients with non-muscle invasive bladder cancer (NMIBC). Another cohort (Cx cohort) included 468 patients with bladder cancer undergoing radical cystectomy. Urine supernatants (NMIBC cohort: n=216, Cx cohort: n=27) and plasma samples (NMIBC cohort: n=39, Cx cohort: n=27) from patients harbouring mutations were subsequently screened using ddPCR assays. Liquid biopsies were collected from 2003-2015 with up to 11.3 years of follow-up for the NMIBC cohort and from 1995-2009 with up to 13.5 years of follow-up for the Cx cohort. Results and limitations: In total, 36% of the patients in the NMIBC cohort (129/363) and 11% of the patients in the Cx cohort (44/403) harboured at least one hotspot mutation in FGFR3 or PIK3CA. Screening of DNA from serial urine supernatants from the NMIBC cohort showed high levels of tumour DNA (tDNA) to be significantly associated with later disease progression (p=0.003). Furthermore, high levels of tDNA in preoperative urine supernatants and plasma samples were associated with recurrence in the Cx cohort (p=0.068 and p=0.016 respectively). A positive correlation between the levels of tDNA in urine and plasma was observed (corr.=0.6). The retrospective study design and the low volumes of plasma available for analysis were limitations of the study. Conclusions: Increased levels of FGFR3 and PIK3CA mutated DNA in urine and plasma is indicative of later progression and metastasis in bladder cancer. Citation Format: Emil Christensen, Karin Birkenkamp-Demtroder, Iver Nordentoft, Soren Hoyer, Kirstin Van Der Keur, Kim Van Kessel, Ellen Zwarthoff, Mads Agerbaek, Torben Falck Orntoft, Jorgen Bjerggaard Jensen, Lars Dyrskjot. Liquid biopsy analysis of FGFR3 and PIK3CA hotspot mutations for disease surveillance in bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2752. doi:10.1158/1538-7445.AM2017-2752