Conclusions
Dovitinib consistently achieved biologically active concentrations within the urothelium and demonstrated pharmacodynamic pFGFR3 inhibition. These results support systemic administration as a viable approach to clinical trials in patients with NMIUC. Long-term dovitinib administration was not feasible due to frequent toxicity. Absent clinical activity suggests that patient selection by pFGFR3 IHC alone does not enrich for response to FGFR3 kinase inhibitors in urothelial carcinoma. Clin Cancer Res; 23(12); 3003-11. ©2016 AACR.
Purpose
To assess the clinical and pharmacodynamic activity of dovitinib in a treatment-resistant, molecularly enriched non-muscle-invasive urothelial carcinoma of the bladder (NMIUC) population.Experimental Design: A multi-site pilot phase II trial was conducted. Key eligibility criteria included the following: Bacillus Calmette-Guerin (BCG)-unresponsive NMIUC (>2 prior intravesical regimens) with increased phosphorylated FGFR3 (pFGFR3) expression by centrally analyzed immunohistochemistry (IHC+) or FGFR3 mutations (Mut+) assessed in a CLIA-licensed laboratory. Patients received oral dovitinib 500 mg daily (5 days on/2 days off). The primary endpoint was 6-month TURBT-confirmed complete response (CR) rate.
Results
Between 11/2013 and 10/2014, 13 patients enrolled (10 IHC+ Mut-, 3 IHC+ Mut+). Accrual ended prematurely due to cessation of dovitinib clinical development. Demographics included the following: median age 70 years; 85% male; carcinoma in situ (CIS; 3 patients), Ta/T1 (8 patients), and Ta/T1 + CIS (2 patients); median prior regimens 3. Toxicity was frequent with all patients experiencing at least one grade 3-4 event. Six-month CR rate was 8% (0% in IHC+ Mut-; 33% in IHC+ Mut+). The primary endpoint was not met. Pharmacodynamically active (94-5,812 nmol/L) dovitinib concentrations in urothelial tissue were observed in all evaluable patients. Reductions in pFGFR3 IHC staining were observed post-dovitinib treatment.Conclusions: Dovitinib consistently achieved biologically active concentrations within the urothelium and demonstrated pharmacodynamic pFGFR3 inhibition. These results support systemic administration as a viable approach to clinical trials in patients with NMIUC. Long-term dovitinib administration was not feasible due to frequent toxicity. Absent clinical activity suggests that patient selection by pFGFR3 IHC alone does not enrich for response to FGFR3 kinase inhibitors in urothelial carcinoma. Clin Cancer Res; 23(12); 3003-11. ©2016 AACR.