Regorafenib

Regorafenib (BAY 73-4506) is a novel and orally active multikinase inhibitor of receptor tyrosine kinases VEGFR1, VEGFR2, VEGFR3, PDGFRβ, Kit, RET, Raf-1, B-RAF and B-RAFV600E with IC50 values of 13 nM/4.2 nM/46 nM, 22 nM, 7 nM, 1.5 nM, 2.5 nM, 28 nM and 19 nM [1].

VEGFR1/2/3 are vascular endothelial growth factor receptor plays an important role in the formation of normal and tumor vasculature. platelet-derived growth factor receptor-β (PDGFRβ) is a receptor for the platelet-derived growth factor family. Kit, RET and B-RAF are both receptor tyrosine kinases that encoded by proto-oncogenes [1].

Regorafenib (BAY 73-4506) is a novel and orally active receptor tyrosine kinases inhibitor. In NIH-3T3/VEGFR2 cells, regorafenib potently inhibited VEGFR2 autophosphorylation with IC50 value of 3 nM. Regorafenib also inhibited TIE2 and PDGFR-β autophosphorylation with IC50 values of 31 and 90 nM. Regorafenib potently inhibited KITK642E and RETC634W with IC50 values of ~20 and ~10 nM, respectively. In addition, regorafenib inhibited the proliferation of VEGF165-stimulated HUVECs with IC50 value of ~3 nM [1].

In GS9L glioblastoma xenografted rat model, regorafenib administered orally at 10 mg/kg significantly reduced the extravasation of Gadomer in the vasculature. In various preclinical human xenograft mice models, regorafenib exhibited potent dose-dependent tumor growth inhibition (TGI) [1]. In murine metastatic colorectal cancer (CRC) liver metastasis model, regorafenib significantly delayed disease progression by inhibiting the growth of liver metastases and preventing the formation of new metastases in other organs [2].

References:
[1].  Wilhelm SM, Dumas J, Adnane L, et al. Regorafenib (BAY 73-4506): a new oral multikinase inhibitor of angiogenic, stromal and oncogenic receptor tyrosine kinases with potent preclinical antitumor activity. Int J Cancer, 2011, 129(1): 245-255.
[2].  Schmieder R, Hoffmann J, Becker M, et al. Regorafenib (BAY 73-4506): antitumor and antimetastatic activities in preclinical models of colorectal cancer. Int J Cancer, 2014, 135(6): 1487-1496.

REGOSARC: Regorafenib versus placebo in doxorubicin-refractory soft-tissue sarcoma-A quality-adjusted time without symptoms of progression or toxicity analysis.[Pubmed:28295221]

Cancer. 2017 Jun 15;123(12):2294-2302.

BACKGROUND: In a placebo-controlled, randomized phase 2 trial (ClinicalTrials.gov identifier NCT01900743), Regorafenib improved progression-free survival (PFS) for patients with doxorubicin-pretreated advanced nonadipocytic sarcoma. A quality-adjusted time without symptoms of progression or toxicity (Q-TWiST) post hoc exploratory analysis was applied to provide an integrated measure of its clinical benefit. METHODS: In the base-case analysis, each patient's overall survival (OS) was partitioned into 3 mutually exclusive health states: the time with a grade 3 or 4 adverse event (TOX), the time without symptoms of disease or grade 3 or 4 toxicity from treatment, and the time after tumor progression or relapse. The time spent in each state was weighted with a health-state utility associated with that state and was summed to calculate the Q-TWiST. The stability of the base-case analysis was explored with several sensitivity analyses. RESULTS: In nonadipocytic sarcoma, the PFS was (4.0 months [2.6-5.5 months] with Regorafenib vs 1.0 month [0.9-1.8 months] with a placebo; hazard ratio, 0.36 [0.25-0.53]; P < .0001); the OS was 13.4 months (8.6-17.3 months) with Regorafenib and 9.0 months (6.8-12.5 months) with a placebo (hazard ratio, 0.67 [0.44-1.02]). With the classic definition of TOX (including all grade 3 and 4 clinical adverse events), the Q-TWiSTs were 8.0 months (7.0-9.0 months) with Regorafenib and 5.7 months (4.9-6.4 months) with a placebo (P < .001). CONCLUSIONS: For patients with doxorubicin-pretreated soft-tissue sarcoma, Regorafenib significantly improved quality-adjusted survival in comparison with a placebo. Cancer 2017;123:2294-2302. (c) 2017 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Regorafenib overcomes chemotherapeutic multidrug resistance mediated by ABCB1 transporter in colorectal cancer: In vitro and in vivo study.[Pubmed:28302530]

Cancer Lett. 2017 Jun 28;396:145-154.

Chemotherapeutic multidrug resistance (MDR) is a significant challenge to overcome in clinic practice. Several mechanisms contribute to MDR, one of which is the augmented drug efflux induced by the upregulation of ABCB1 in cancer cells. Regorafenib, a multikinase inhibitor targeting the RAS/RAF/MEK/ERK pathway, was approved by the FDA to treat metastatic colorectal cancer and gastrointestinal stromal tumors. We investigated whether and how Regorafenib overcame MDR mediated by ABCB1. The results showed that Regorafenib reversed the ABCB1-mediated MDR and increased the accumulation of [(3)H]-paclitaxel in ABCB1-overexpressing cells by suppressing efflux activity of ABCB1, but not altering expression level and localization of ABCB1. Regorafenib inhibited ATPase activity of ABCB1. In mice bearing resistant colorectal tumors, Regorafenib raised the intratumoral concentration of paclitaxel and suppressed the growth of resistant colorectal tumors. But Regorafenib did not induce cardiotoxicity/myelosuppression of paclitaxel in mice. Strategy to reposition one FDA-approved anticancer drug Regorafenib to overcome the resistance of another FDA-approved, widely used chemotherapeutic paclitaxel, may be a promising direction for the field of adjuvant chemotherapy. This study provides clinical rationale for combination of conventional chemotherapy and targeted anticancer agents.

Cost-Effectiveness Analysis of Regorafenib for Gastrointestinal Stromal Tumour (GIST) in Germany.[Pubmed:28361439]

Clin Drug Investig. 2017 Jun;37(6):525-533.

BACKGROUND: No study has compared the cost-effectiveness of active treatment options for unresectable or metastatic gastrointestinal stromal tumours in patients who progressed on or are intolerant to prior treatment with imatinib and sunitinib. The aim of this study was to estimate the cost-effectiveness of Regorafenib compared to imatinib rechallenge in this setting in Germany. METHODS: Hazard ratios for progression-free (PFS) and overall survival (OS) with Regorafenib versus imatinib rechallenge were estimated by indirect comparison. A state distribution model was used to simulate progression, mortality and treatment costs over a lifetime horizon. Drug acquisition costs and utilities were derived from clinical trial data and published literature; non-drug costs were not included. The outcomes measured were treatment costs, life-years (LYs) and quality-adjusted life-years (QALYs). RESULTS: The indirect comparison suggested that median PFS and OS were longer with Regorafenib compared to imatinib but results were not statistically significant. Regorafenib versus imatinib rechallenge was estimated to have hazard ratios of 0.58 (95% CI 0.31-1.11) for PFS and 0.77 (95% CI 0.34-1.77) for OS, with substantial uncertainty due to the rarity of the disease and small number of patients within the trials. Regorafenib treatment per patient over a lifetime horizon provided an additional 0.61 LYs and 0.42 QALYs over imatinib rechallenge, with additional direct drug costs of euro8,773. The incremental cost-effectiveness ratio was euro21,127 per QALY gained. At a cost-effectiveness threshold of euro50,000 per QALY, Regorafenib had a 67% probability of being cost-effective. CONCLUSION: Based on the currently available clinical data, this analysis suggests that Regorafenib is cost-effective compared with imatinib rechallenge in Germany.

Regorafenib (BAY 73-4506) is a multi-targeted receptor tyrosine kinase inhibitor with IC50s of 13/4.2/46, 22, 7, 1.5 and 2.5 nM for VEGFR1/2/3, PDGFRβ, Kit, RET and Raf-1, respectively.

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