1
|
Zopf D, Fichtner I, Bhargava A, Steinke W, Thierauch KH, Diefenbach K, Wilhelm S, Hafner FT, Gerisch M. Pharmacologic activity and pharmacokinetics of metabolites of regorafenib in preclinical models. Cancer Med 2016; 5:3176-3185. [PMID: 27734608 PMCID: PMC5119973 DOI: 10.1002/cam4.883] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 08/01/2016] [Accepted: 08/02/2016] [Indexed: 12/11/2022] Open
Abstract
Regorafenib is an orally administered inhibitor of protein kinases involved in tumor angiogenesis, oncogenesis, and maintenance of the tumor microenvironment. Phase III studies showed that regorafenib has efficacy in patients with advanced gastrointestinal stromal tumors or treatment‐refractory metastatic colorectal cancer. In clinical studies, steady‐state exposure to the M‐2 and M‐5 metabolites of regorafenib was similar to that of the parent drug; however, the contribution of these metabolites to the overall observed clinical activity of regorafenib cannot be investigated in clinical trials. Therefore, we assessed the pharmacokinetics and pharmacodynamics of regorafenib, M‐2, and M‐5 in vitro and in murine xenograft models. M‐2 and M‐5 showed similar kinase inhibition profiles and comparable potency to regorafenib in a competitive binding assay. Inhibition of key target kinases by all three compounds was confirmed in cell‐based assays. In murine xenograft models, oral regorafenib, M‐2, and M‐5 significantly inhibited tumor growth versus controls. Total peak plasma drug concentrations and exposure to M‐2 and M‐5 in mice after repeated oral dosing with regorafenib 10 mg/kg/day were comparable to those in humans. In vitro studies showed high binding of regorafenib, M‐2, and M‐5 to plasma proteins, with unbound fractions of ~0.6%, ~0.9%, and ~0.4%, respectively, in murine plasma and ~0.5%, ~0.2%, and ~0.05%, respectively, in human plasma. Estimated free plasma concentrations of regorafenib and M‐2, but not M‐5, exceeded the IC50 at human and murine VEGFR2, suggesting that regorafenib and M‐2 are the primary contributors to the pharmacologic activity of regorafenib in vivo.
Collapse
Affiliation(s)
- Dieter Zopf
- Drug Discovery, Bayer Pharma AG, Müllerstraße 178, Berlin, 13353, Germany
| | - Iduna Fichtner
- Experimental Pharmacology & Oncology GmbH, Robert-Rössle-Str. 10, Berlin-Buch, 13125, Germany
| | - Ajay Bhargava
- Shakti Bioresearch, 1 Bradley Road, STE 401, Woodbridge, Connecticut, 06525
| | - Wolfram Steinke
- Pharmacokinetic Imaging Consulting & Autoradiography Services, Halverscheid 13, D-58553, Halver, Germany
| | | | | | - Scott Wilhelm
- Bayer HealthCare Pharmaceuticals, 100 Bayer Blvd, Whippany, New Jersey, 07981
| | | | - Michael Gerisch
- Drug Discovery, Bayer Pharma AG, Müllerstraße 178, Berlin, 13353, Germany
| |
Collapse
|