Conclusion
These findings reveal a critical role of FGFR3 in regulating MMP-1 and pro-MMP-10 expression and secretion, and identify urinary MMP-1 and pro-MMP-10 as potential pharmacodynamic biomarkers for R3Mab in patients with bladder cancer.
Purpose
The aim of this study was to identify noninvasive pharmacodynamic biomarkers of FGFR3-targeted therapies in bladder cancer to facilitate the clinical development of experimental agent targeting FGFR3. Experimental design: Potential soluble pharmacodynamic biomarkers of FGFR3 were identified using a combination of transcriptional profiling and biochemical analyses in preclinical models. Two matrix metalloproteinases (MMP), MMP-1 and MMP-10, were selected for further studies in human bladder cancer xenograft models treated with a specific anti-FGFR3 monoclonal antibody, R3Mab. Serum and urinary levels of MMP-1 and MMP-10 were determined in healthy donors and patients with bladder cancer. The modulation of MMP-1 and MMP-10 by R3Mab in patients with bladder cancer was further evaluated in a phase I dose-escalation study.
Results
MMP-1 and MMP-10 mRNA and protein were downmodulated by FGFR3 shRNA and R3Mab in bladder cancer cell lines. FGFR3 signaling promoted the expression and secretion of MMP-1 and pro-MMP-10 in a MEK-dependent fashion. In bladder cancer xenograft models, R3Mab substantially blocked tumor progression and reduced the protein levels of human MMP-1 and pro-MMP-10 in tumor tissues as well as in mouse serum. Furthermore, both MMP-1 and pro-MMP-10 were elevated in the urine of patients with advanced bladder cancer. In a phase I dose-escalation trial, R3Mab administration resulted in an acute reduction of urinary MMP-1 and pro-MMP-10 levels in patients with bladder cancer.