Final results of a multicenter, open-label phase II trial of dovitinib (TKI258) in patients with advanced urothelial carcinoma with either mutated or nonmutated FGFR3

255 Background: Increased signaling through mutational activation of fibroblast growth factor receptor 3 (FGFR3) contributes to tumor development and vascularization of urothelial carcinoma (UC). Dovitinib (TKI258), an oral investigational inhibitor of angiogenic factors including FGFR3, has demonstrated inhibition of tumor growth and proliferation in preclinical UC models with FGFR3-activating mutations or protein overexpression. Methods: Advanced UC patients (pts) with 1-3 prior regimens received dovitinib 500 mg/day on a 5-days-on/2-days-off schedule. Pts were stratified into 2 groups based on presence (mut) or absence (non-mut) of FGFR3 gene mutation in archival tissue (initially analyzed by SNaPshot; later by Sanger sequencing for screening and confirmation). The primary objective was overall response rate (ORR) in each group using a Simon’s 2-stage design (20 pts planned for stage 1 and 20 for stage 2 if ≥ 2 responses seen in stage 1). Results: A total of 44 pts (median age, 67 years) were treated in stage 1: 12 FGFR3 mut, 31 FGFR3 non-mut, and 1 unknown mutation status. Over-recruitment of non-mut pts was due to rapid enrollment of non-mut pts with invasive bladder tumors and some tumors initially classified as mut by SNaPshot but reclassified as non-mut after sequencing. Most pts (77%) had metastases in ≥ 2 organs. ORR (local review) was 0% in the FGFR3 mut group and 3% in the FGFR3 non-mut group (1 partial response). Median progression-free survival was 3 months in the FGFR3 mut group and 1.8 months in the FGFR3 non-mut group. There were insufficient non-mut responders to proceed to stage 2. Since most pts in the mut group did not receive > 6 months of treatment and meeting the response threshold to proceed to stage 2 was highly unlikely, the study was terminated. Common adverse events were diarrhea (73%), nausea (61%), and asthenia (50%) and were similar in both groups. Conclusions: Although there were difficulties in evaluating mutation status, dovitinib had limited single-agent activity in pts with advanced bladder cancer regardless of FGFR3 mutation status. Further studies are needed to understand the role of FGFR3 inhibition in advanced UC treatment. Clinical trial information: NCT00790426.