Dr Sonpavde on the Potential Impact of the THOR Study in FGFR2/3-Altered Urothelial Carcinoma

Guru P. Sonpavde, MD, medical director, Genitourinary (GU) Oncology, assistant director, Clinical Research Unit, Christopher K. Glanz Chair, Bladder Cancer Research, AdventHealth Cancer Institute, discusses the potential impact of the phase 3 THOR study (NCT03390504) evaluating erdafitinib (Balversa) vs chemotherapy in patients with advanced or metastatic urothelial cancer harboring FGFR2/3 alterations.

Data from the randomized, confirmatory, open-label trial presented at the 2023 ASCO Annual Meeting showed that the median overall survival (OS) was 12.1 months with erdafitinib (n = 136) vs 7.8 months for chemotherapy (n = 130; HR, 0.64; 95% CI, 0.47-0.88; P = .005). Notably, erdafitinib elicited a significantly longer progression-free survival (PFS) and greater objective response rate (ORR) vs chemotherapy. The median PFS was 5.6 months vs 2.7 months for treatment with erdafitinib vs chemotherapy, respectively (HR, 0.58; 95% CI, 0.44-0.78; P = .0002). The ORR was 45.6% for erdafitinib vs 11.5% for chemotherapy.

THOR compared treatment with erdafitinib, an FGFR inhibitor, vs historically used salvage chemotherapy agents in patients who progressed following 1 or 2 prior lines of therapy that included an anti–PD-1 or –PD-L1 inhibitor, Sonpavde explains. Erdafitinib previously received FDA accelerated approval in April 2019 for the treatment of adult patients with locally advanced or metastatic bladder cancer with an FGFR3 or FGFR2 alteration that has progressed on platinum-containing chemotherapy. That regulatory decision was based on response rates observed with the FGFR inhibitor in the phase 2 BLC2001 trial (NCT02365597).

THOR served as a confirmatory trial, comparing the agent with physician’s choice of chemotherapy, including docetaxel or vinflunine, he continues. The trial’s results were eagerly anticipated because erdafitinib is already being used in the clinic, and these data validated the improvement in OS on top of the ORR improvements previously observed, Sonpavde concludes.