Arlene O. Siefker-Radtke, MD, on Metastatic Urothelial Carcinoma: New Data on Erdafitinib vs Chemotherapy From the THOR Study

Arlene O. Siefker-Radtke: We now have results from the THOR clinical trial studying erdafitinib in patients who have metastatic surgically unresectable urothelial carcinoma, who've received prior therapy for their tumor. This is the first clinical trial, showing proof of concept benefit from FGF targeted therapy, compared to what's been observed with chemotherapy. The design of the trial takes patients who've had prior treatment, typically chemotherapy with platinum or carboplatinum, and patients may have had an immune checkpoint inhibitor. There are two cohorts to this trial. The cohort being presented is the group of patients who've had a prior immune checkpoint inhibitor. Patients were randomized between either erdafitinib alone or single agent taxane, or vinflunine, which is approved in Europe. And the results of the trial looked quite good indeed, with it hitting on all three endpoints. The primary endpoint of the trial was median overall survival, and erdafitinib came in with a statistically significant improvement in overall survival with a median overall survival of 12 months compared to single agent chemotherapy, which was around 7.8 months. We also saw evidence of benefit in progression-free survival and overall survival. The progression-free survival with erdafitinib was around five and a half months. Single agent chemotherapy was half that amount, and the objective response rate for erdafitinib was around 45%, so that's 45% PRs and CRs, while single agent chemotherapy had a response rate of around 11%. The toxicity reported is similar to what has been observed with other clinical trials of FGF targeted therapy, and as a result of this work, erdafitinib is here to stay as part of the standard armamentarium for the treatment of our urothelial cancer patients.