Sample‐Related Factors Associated With FGFR Testing Validity in Urothelial Cancer: A Japanese THOR Post Hoc Analysis
6 affiliations
- 1Department of Urology, Graduate School of Medicine Osaka Metropolitan University Osaka Japan
- 2Medical Affairs, Oncology Group Johnson & Johnson Innovative Medicine Tokyo Japan
- 3Medical Affairs Johnson & Johnson Innovative Medicine Tokyo Japan
- 4Oncology Clinical Operation Dept., Global Clinical Operations Johnson & Johnson Innovative Medicine Tokyo Japan
- 5Clinical Development, TA Oncology Johnson & Johnson Innovative Medicine Tokyo Japan
- 6Department of Surgical Pathology Hyogo Medical University Hyogo Japan
Abstract
Timely access to valid fibroblast growth factor receptor (FGFR) testing is essential for treatment selection in metastatic urothelial carcinoma; however, invalid results remain a barrier to timely treatment selection. We conducted a post hoc analysis of the Japanese subgroup of the Phase 3 THOR trial to describe FGFR testing validity across sample‐related factors and explore its predictors. Among 612 patients with FGFR testing records, 563 (92.0%) had valid results, and FGFR alterations were detected in 82 of 563 (14.6%). The proportion of valid results tended to be lower in biopsy‐derived samples than in surgical‐resection samples (76.9%–83.3% vs. 92.3%–97.7%). Samples that provided invalid testing results had smaller median total tissue surface area (16.60 vs. 388.85 mm2) and target tumor surface area (2.00 vs. 85.10 mm2). In contrast, for upper tract urothelial carcinoma biopsies, even valid samples had small median total tissue and target tumor surface areas (22.60 and 7.55 mm2), underscoring that specimen source and collection method must be accounted for when interpreting surface area. In multivariable logistic regression, larger target tumor surface area was associated with higher test validity (adjusted odds ratio 1.10 per 10 mm2 increase; 95% confidence interval 1.05–1.16), whereas neither archival sample age nor any of the defined fixation‐duration categories was associated with validity. Most invalid results reflected insufficient tumor cells rather than RNA quality. Specimen source, collection method, and target tumor surface area should therefore be considered together when selecting samples to improve FGFR testing validity, leading to greater access to targeted therapy.
Trial Registration: ClinicalTrials.gov identifier NCT03390504
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BibTeX
@article{kato2026samplerelated,
title = {{Sample‐Related Factors Associated With FGFR Testing Validity in Urothelial Cancer: A Japanese THOR Post Hoc Analysis}},
author = {Minoru Kato and Masaki Yoshida and Hiroshi Horio and Yohei Furukawa and Tatsuya Ote and Chisato Ohe},
journal = {Cancer Science},
year = {2026},
month = nov,
doi = {10.1111/cas.70588},
url = {https://doi.org/10.1111/cas.70588},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Sample‐Related Factors Associated With FGFR Testing Validity in Urothelial Cancer: A Japanese THOR Post Hoc Analysis
AU - Minoru Kato
AU - Masaki Yoshida
AU - Hiroshi Horio
AU - Yohei Furukawa
AU - Tatsuya Ote
AU - Chisato Ohe
PY - 2026
DA - 2026/11/09
JO - Cancer Science
DO - 10.1111/cas.70588
UR - https://doi.org/10.1111/cas.70588
AB - Timely access to valid fibroblast growth factor receptor (FGFR) testing is essential for treatment selection in metastatic urothelial carcinoma; however, invalid results remain a barrier to timely treatment selection. We conducted a post hoc analysis of the Japanese subgroup of the Phase 3 THOR trial to describe FGFR testing validity across sample‐related factors and explore its predictors. Among 612 patients with FGFR testing records, 563 (92.0%) had valid results, and FGFR alterations were detected in 82 of 563 (14.6%). The proportion of valid results tended to be lower in biopsy‐derived samples than in surgical‐resection samples (76.9%–83.3% vs. 92.3%–97.7%). Samples that provided invalid testing results had smaller median total tissue surface area (16.60 vs. 388.85 mm2) and target tumor surface area (2.00 vs. 85.10 mm2). In contrast, for upper tract urothelial carcinoma biopsies, even valid samples had small median total tissue and target tumor surface areas (22.60 and 7.55 mm2), underscoring that specimen source and collection method must be accounted for when interpreting surface area. In multivariable logistic regression, larger target tumor surface area was associated with higher test validity (adjusted odds ratio 1.10 per 10 mm2 increase; 95% confidence interval 1.05–1.16), whereas neither archival sample age nor any of the defined fixation‐duration categories was associated with validity. Most invalid results reflected insufficient tumor cells rather than RNA quality. Specimen source, collection method, and target tumor surface area should therefore be considered together when selecting samples to improve FGFR testing validity, leading to greater access to targeted therapy. Trial Registration: ClinicalTrials.gov identifier NCT03390504
SN - 1347-9032
SN - 1349-7006
ER -