Practice Update | Onology

GENITOURINARY 26

Liquid biopsy analysis of FGFR3 and PIK3CA hotspot mutations for disease surveillance in bladder cancer European Association of Urology Take-home message

in primary tumors from two retrospective cohorts, one consisting of 363 NMIBCs and the other consisting of 468 MIBCs from patients undergoing radical cystectomy. 8 They then used digital droplet PCR to meas- ure the same mutations in urine and plasma from subsets of these patients (25 NMIBCs and 31 MIBCs). Overall, the presence of FGFR3 and/or PIK3CAmutations in the urine (tumor DNA, or tDNA) was associated with the presence of tumor as determined by cystoscopy, tumor size >3 cm, and higher EORTC risk score in patients with NMIBC; however, plasma tDNAwas only detected in patients at the time of progression tomuscle forward in the integration of genomics into the routine clinical management of patients with bladder cancer. and Cox regression analysis were applied. RESULTS AND LIMITATIONS In total, 36% of the NMIBC patients (129/363) and 11% of the Cx patients (44/403) harboured at least one FGFR3 or PIK3CA mutation. Screening of DNA from serial urine supernatants from the NMIBC cohort revealed that high levels of tumour DNA (tDNA) were associated with later disease progression in NMIBC (p=0.003). Furthermore, high levels of tDNA in plasma samples were associated with recurrence in the Cx cohort (p=0.016). A positive correlation between tDNA levels in urine and plasma was observed (correlation coefficient 0.6). The retrospective study design and 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 are indicative of later progression and metastasis in bladder cancer. PATIENT SUMMARY Urine and plasma from patients with bladder cancer may be monitored for diagnosis of progression and metastasis using mutation assays. Liquid biopsy analysis of FGFR3 and PIK3CA hotspot mutations for disease surveillance in bladder cancer. Eur Urol 2017 Jun 01;71(6)961- 969, E Christensen, K Birkenkamp-Demtröder, I Nordentoft, et al. This study represents another important step

• Cell-free tumor DNA in liquid biopsies (urine supernatant and plasma) may have bio- marker potential. In this study, urine was evaluated for the presence of established bladder cancer gene mutations (FGFR3 and PIK3CA) to assess their prognostic ability in patients undergoing disease surveillance. Tumor DNA from two patient cohorts (non-muscle invasive bladder cancer [NMIBC] patients, n = 363; bladder cancer patients undergoing cystectomy, n = 468) was screened using droplet digital PCR assays. High levels of tumor DNA were associated with later disease progression in NMIBC. High levels of tumor DNA in plasma samples were associ- ated with recurrence in the cystectomy cohort. • Urine and plasma from patients with bladder cancer might be used to understand disease biology and predict progression and metastasis using mutation assays.

blood and urine collected from patients with bladder cancer are being devel- oped aggressively to monitor subclinical systemic disease and to identify candi- date targets for therapeutic intervention. Approximately 70% of NMIBCs contain activating mutations in the type-3 recep- tor for fibroblast growth factors (FGFR3), 5 making it an extremely attractive biomarker for cancer surveillance. Indeed, past stud- ies established FGFR3 mutations can be detected in the urine in a majority of cases and that assays designed to measure them may out-perform urine cytology 6 and that adding other prevalent mutations such as PIK3CA5 might increase assay sensitivity. 7 Importantly, mutant FGFR3 and PIK3CA also serve as therapeutic targets, 5 so these same assays could prove to be useful in assigning patients to specific therapies. In a paper recently published in European Urology , Christensen and colleagues iden- tified mutations in FGFR3 and/or PIK3CA PIK3CA hotspot mutations. One cohort included 363 patients with non-muscle-invasive bladder cancer (NMIBC). The other cohort included 468 patients with bladder cancer undergoing radi- cal cystectomy (Cx). Urine supernatants (NMIBC n=216, Cx n=27) and plasma samples (NMIBC n=39, Cx n=27) from patients harbouring muta- tions were subsequently screened using ddPCR assays. OUTCOME MEASUREMENTS AND STATISTICAL ANAL- YSIS Progression-free survival, recurrence-free survival, and overall survival were measured. Fisher’s exact test, the Wilcoxon rank-sum test

COMMENT By David J McConkey PhD N on-muscle invasive bladder cancer (NMIBC) does not usually progress to become muscle-invasive and lethal, but 50% to 70% of tumors recur, necessitating that patients undergo reg- ular lifelong surveillance with cystoscopy complemented with urine cytology and biopsy. As a consequence, clinical man- agement of NMIBC is costlier than it is for any other cancer. Cystoscopy is a relatively inefficient means of detecting cancer, as it has been estimated that only one of seven cystoscopies result in the detec- tion of recurrences. 1 The development of more specific, less costly, and less intrusive monitoring approaches is a major priority for ongoing research. Recent studies have demonstrated that cancer-associated mutations and other DNA alterations can be detected in body fluids. 2–4 Strategies to detect these alter- ations in so-called “liquid biopsies” from Abstract BACKGROUND Disease surveillance in patients with bladder cancer is important for early diag- nosis of progression and metastasis and for optimised treatment. OBJECTIVE To develop urine and plasma assays for disease surveillance for patients with FGFR3 and PIK3CA tumour mutations. DESIGN, SETTING, AND PARTICIPANTS Droplet dig- ital polymerase chain reaction (ddPCR) assays were developed and tumour DNA from two patient cohorts was screened for FGFR3 and

PRACTICEUPDATE ONCOLOGY