Targeted treatment of advanced or metastatic urothelial carcinomas (UCs) requires the identification of druggable mutations. This study describes the development of a 3′ Rapid Amplification of cDNA Ends (3′ RACE)-based targeted RNA sequencing panel which accounts for the status of all genes relevant to UC treatment, namely, FGFR1-4, KRAS, NRAS, BRAF, ERBB2 (HER2), CD274 (PD-L1) and PIK3CA. FGFR2/3-activating point mutations or fusions were found in 54/233 (23.2%) tumors. FGFR3 rearrangements were identified in 11 patients, with eight of them being undetectable by commonly used PCR kits. In addition, one tumor contained a high-copy FGFR2 gene amplification accompanied by strong overexpression of the gene. Mutations in RAS/RAF genes were present in 30/233 (12.9%) UCs and were mutually exclusive with alterations affecting FGFR2/3 genes. On the contrary, activating events in the HER2 oncogene (point mutations and overexpression), as well as PIK3CA mutations, which were relatively common, occurred with similar frequencies in RAS/RAF- or FGFR2/3-positive vs. negative samples. High PD-L1 mRNA expression was associated with advanced disease stage and was not observed in tumors with increased HER2 mRNA expression or in UCs with evidence for FGFR2/3 activation. Three of the studied carcinomas had high-level microsatellite instability (MSI). Overall, more than half of the UCs had potentially druggable genetic alterations. The proposed NGS panel permits comprehensive and cost-efficient analysis of UC-specific molecular targets and may be considered in clinical routine.

Next-generation sequencing (NGS) is currently regarded as a preferable method for detection of actionable alterations in non-small cell lung carcinomas (NSCLCs). RNA-based NGS is particularly efficient in detection of gene fusions and allows for mRNA expression analysis of relevant genes. This study describes a novel library preparation pipeline for targeted RNA sequencing, which is based on the 5′ rapid amplification of the cDNA ends (5′ RACE) and anchored multiplex PCR. The NGS panel was designed for the analysis of 15 genes relevant to NSCLC therapeutic decisions (ALK, BRAF, CD274 (PD-L1), EGFR, ERBB2 (HER2), KRAS, MET, NRAS, NRG1-2, NTRK1-3, RET and ROS1). The validation against PCR was performed for 168 NSCLC samples. The NGS assay successfully detected all 85 mutations previously identified by PCR. It also confirmed the absence of tested mutations in 82 out of 83 PCR-negative samples. The only discordant case was subsequently analyzed by digital droplet PCR and demonstrated low fraction of the mutated allele. The newly designed NGS panel was subsequently used for the analysis of 272 carcinomas from young (≤50 years old) patients with no driver mutations identified by PCR tests or with failed PCR analysis. NGS was successful in 240 (88.2%) cases, including 35 (64.8%) PCR-failed samples. Driver mutations were detected in 55 tumors, including three previously unreported fusions (PAPLN::ALK, CD55::ROS1 and FKBP15::RET). We conclude that 5′ RACE-based RNA sequencing is a viable approach for NSCLC molecular testing.