A phase III study of INCB054828 as adjuvant therapy in patients (pts) with high-risk urothelial carcinoma (UC) harboring fibroblast growth factor receptor 3 (FGFR3) genomic alterations

Background: After neoadjuvant chemotherapy (NAC), about 20% of pts withmuscleinvasiveUC are found to have advanced pT-stage or lymph node involvement and 5-year overall survival (OS) of themis<30%. Tumor samples fromthese pts may provide information about chemotherapy resistance, andmay predict for the activity of new drugs given postoperatively. Alterations of FGFR3 gene represent a therapeutic target in UCand FGFR3mutations/fusions are enriched inUC Luminal-1 subtype. The pan-FGFR inhibitor INCB054828 has shown promising results in chemotherapy-treated patients with genomic alterations of FGFR3 in tumor tissue and is currently being evaluated in an international phase 2 study (fight-201,NCT02872714).Our study aims to assess the safety and efficacy of adjuvant INCB054828 in pts with FGFR3mutations/fusions. Trial design: This is an open-label, single-arm, phase 2 study. Subjects will receive INCB054828 at a once-daily (QD) dose of 13.5 mg on a 2-weeks-on and 1-week-off schedule. Treatment should start within 60 days of surgery and will continue until 12 months, or until the evidence of disease recurrence or unacceptable toxicity onset. Key inclusion criteria are predominant UC histology, FGFR3 mutations/fusions (FoundationOne), bladder or upper tract UC, previous radical cystectomy or nephroureterectomy, previous administration≥3 cycles of CDDP-based NAC, pT3-4 and/ or pN1-3 stage. Relapse-free survival (RFS) is the primary endpoint, assessed every 9 weeks until disease recurrence or death. No interim analyses are planned. It is expected that about 30% of the total screened pts will harbor FGFR3 aberrations. In a singlestage design, with 90% power and one-sided alpha at 0.10, the total enrolled pts will be 56 (H0: 2-y RFS: 30%; H1: 2-y RFS: 45%). Translational research on tissue samples will include associations of immune-inflamed phenotype with next-generation sequencing results and outcome of treatment, and response to any subsequent immunotherapy.