Dr. Siefker-Radtke on the Phase II Study of Erdafitinib in Patients With Urothelial Carcinoma

Arlene O. Siefker-Radtke, MD, professor, Department of Genitourinary Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, discusses the phase II study of erdafitinib in patients with metastatic or unresectable urothelial carcinoma who have FGFR alterations.

The rationale of the trial was to provide another agent to pretreated patients with metastatic disease, Siefker-Radtke says. Some of the patients enrolled in the trial had received prior immunotherapy and others had received chemotherapy alone. The first part of the trial was randomized, as physicians did not know whether intermittent dosing or continuous dosing was better. As a result of the early part of the trial, continuous dosing was selected, says Siefker-Radtke.

Physicians were then able to increase the dose from 8 mg to 9 mg daily if patients did not achieve a certain target phosphorous level in their serum. The trial data suggests that there is evidence of clinical activity, states Siefker-Radtke. The study met its primary endpoint of objective response rate, partial response, and complete response, which were seen in 40% of patients with FGFR-altered tumors. This was out of a total of 99 patients in the selected phase II cohort.

The therapy was well tolerated, explains Siefker-Radtke, and few patients discontinued treatment due to side effects. The most common reason for discontinuation was due to eventual progression of disease. Progression-free survival was approximately 5.6 months with a median overall survival of 13.8 months.