For qualitative detection of actionable alterations in the FGFR3 gene
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The therascreen FGFR RGQ RT-PCR Kit is a qualitative in vitro diagnostic test for the detection of two point mutations in exon 7 [p.R248C (c.742C>T), p.S249C (c.746C>G)], two point mutations in exon 10 [p.G370C (c.1108G>T) and p.Y373C (c.1118A>G)] and two fusions (FGFR3-TACC3v1 and FGFR3-TACC3v3) in the FGFR3 gene.
The therascreen FGFR RGQ RT-PCR Kit is a companion diagnostic (CDx) test for the identification of patients with cases of urothelial cancer (UC) that harbor these actionable FGFR alterations, and for whom treatment with BALVERSA (erdafitinib) is indicated.
Concordance between the clinical trial assay (CTA) used to identify patients for recruitment to the Phase 2 clinical trial of BALVERSA (42756493-BLC2001) and the therascreen FGFR RGQ RT-PCR Kit (CDx) was evaluated in a bridging study (1).
Samples with valid results for both the therascreen FGFR RGQ RT-PCR Kit and CTA (292 samples) were analyzed to assess the positive percent agreement (PPA), negative percent agreement (NPA) and overall percent agreement (OPA), based on agreement between the two methods for overall FGFR gene alteration status (i.e., FGFR Alteration Detected or Alteration Not Detected). Results are shown in Table 1.
Table 1. therascreen FGFR RGQ RT-PCR Kit versus CTA (with CTA as reference method)
| Measure of agreement | Percent agreement % (N) | Two-sided 95% CI |
| Positive percent agreement (PPA) | 87.2% (82/94) | 79.0, 92.5 |
| Negative percent agreement (NPA) | 97.0% (192/198) | 93.5, 98.6 |
| Overall percent agreement (OPA) | 93.8% (274/292) | 90.5, 96.1 |
The primary objective of the 42756493-BLC2001 study was to evaluate the objective response rate (objective response rate [ORR] = complete response [CR] + partial response [PR]) by RECIST criteria as assessed by investigator assessment. The ORR by Blinded Independent Review Committee (BIRC) was also determined. The observed clinical benefit in the subset of patients that were FGFR Alteration Detected with the therascreen FGFR RGQ RT-PCR Kit (n = 81) was comparable to that observed in the full study population (n = 99).
The therascreen FGFR RGQ RT-PCR Kit is therefore indicated for use as an aid in identifying patients with cases of urothelial cancer that harbor these alterations and are therefore eligible for treatment with BALVERSA (erdafinitib).
The therascreen FGFR RGQ RT-PCR Kit is based on the selective amplification of alterations in the FGFR3 gene using the Rotor-Gene Q MDx 5plex HRM instrument for sensitive and specific analysis. The assay exploits the qPCR oligonucleotide hydrolysis principle using TaqMan probes.
Allele-specific technology allows accurate and highly reproducible detection of alterations, based on the use of specific forward and reverse primers and probes; only a perfect match between the primers and probes with the target cDNA allows extension and amplification in the PCR reaction. Result reporting is fully automated. If both the positive and no template controls are valid and the sample internal controls are valid, the FGFR alteration status will be displayed in the software.
The fast and simple workflow takes ~12 hours from Sample to Insight.
RNA is first prepared from formalin-fixed paraffin-embedded (FFPE) urothelial tumor samples using the RNeasy DSP FFPE Kit. Purified RNA is then reverse transcribed using Reverse Transcriptase to generate cDNA for real-time PCR analysis. Optimized reverse transcription reagents and PCR master mixes provided in the kit enable high-fidelity reverse transcription and sensitive real-time PCR on the Rotor-Gene Q MDx 5plex HRM instrument. Qualitative results are displayed in Rotor-Gene AssayManager software, informing the system operator if one or more of the four point mutations and two fusions in the FGFR3 gene detected by the kit are present in each sample.
The therascreen FGFR RGQ RT-PCR Kit is also designed to identify FGFR2 fusions FGFR2-BICC1 and FGFR2-CASP7 and FGFR3 fusion FGFR3-BAIAP2L1, because patients harboring these FGFR fusions were eligible for the BLC2001 clinical trial. However, the test is not clinically validated to detect these three fusions. Drug safety and efficacy has not been established for cases of UC harboring these fusions and no claims are made for the use of the therascreen FGFR RGQ RT-PCR Kit as an aid in the selection of such patients for treatment with BALVERSA (erdafitinib).
The therascreen FGFR RGQ RT-PCR Kit enables qualitative detection of four point mutations and two fusions of the FGFR3 gene for in vitro diagnostic use. It is the only approved CDx assay for the selection of patients with cases of urothelial cancer (UC) harboring actionable alterations, for whom treatment with BALVERSA (erdafitinib) is indicated.
1. Janssen Biotech, Inc. Data on file.
