Interest of next-generation sequencing in BCG-treated high-risk bladder cancer

There are only few predictive factors for response of non-musculo-invasive bladder cancer (NMIBC) to Bacillus Calmette-Guérin (BCG) therapy. Our study analyzed the results of the sequencing of new generation (NGS) targeted on 50 genes of oncological interest obtained on bladder resection parts in high-risk NMIBC patients treated with BCG, to describe this population from a molecular point of view and try to correlate these results in patients who present or not recurrence after BCG.

We reviewed 63 patients with high grade NMIBC treated between 2014 and 2016 with BCG after endoscopic resection. Each one had NGS analysis. Association tests between mutations detected by NGS and recurrence or progression were realized.

The 45 remaining patients were fully analysed. For 73% of cases a mutation has been found, most frequent one's being FGFR3, TP53 and PIK3CA. With a median follow-up of 24 months (4-40), recurrence was present in 15 patients (33.3%), with 10 NMIBC (22.2%) and 5 progressions to muscular-invasive cancer (11.1%). If some mutations were more frequent in different prognostic groups no significant association has been found. No patient presenting CIS had FGFR3 mutation (P<0.0001).

Next generation sequencing in NMIBC could be a supplementary aid in treatment decision making in the future. In an area where personalized medicine is rapidly growing in importance we need larger studies to define molecular characteristics in tumours to detect genomic associations between clinical phenotypes and recurrence or progression of the disease.

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