VEGFR1 (IC50 = 13 nM); VEGFR2 (IC50 = 4.2 nM); VEGFR3 (IC50 = 46 nM); PDGFRβ (IC50 = 22 nM); Braf (IC50 = 28 nM); VEGFR2 (BRafV600E = 19 nM); Raf-1 (IC50 = 2.5 nM)

Regorafenib potently inhibits VEGFR2 autophosphorylation in NIH-3T3/VEGFR2 cells with an IC50 of 3 nM. Regorafenib has an IC50 of 90 nM and blocks PDGFR-β autophosphorylation in HAoSMCs following PDGF-BB stimulation. With an IC50 of 3 nM, vegf165-stimulated HUVEC proliferation is inhibited by rogorafenib[1]. With a 5 μM IC50, regorafenib inhibits the growth of Hep3B cells in a concentration-dependent manner. The JNK target phospho-c-Jun, but not total c-Jun, is subsequently upregulated by regulatorafenib in Hep3B cells[3].

Regorafenib effectively slows the growth of Colo-205 xenografts at doses between 10 and 100 mg/kg, with a TGI of 75% at day 14 at the 10 mg/kg dose. Regorafenib is highly effective in the MDA-MB-231 model at doses as low as 3 mg/kg, producing a significant TGI of 81%, which rises to 93% at doses of 10 and 30 mg/kg, where tumor stasis is reached[1].

Recombinant VEGFR2 (murine aa785–aa1367), VEGFR3 (murine aa818–aa1363), PDGFRβ (aa561–aa1106), Raf-1 (aa305–aa648) and BRafV600E (aa409–aa765) kinase domains are used in in vitro tests. At a constant 1 M Regorafenib concentration, the initial in vitro kinase inhibition profiling is carried out. Select responding kinases, such as VEGFR1 and RET, are used to calculate the 50% inhibitory concentration (IC50) values. Using a recombinant fusion protein of glutathione-S-transferase, the intracellular domain of TIE2, and the peptide biotin-Ahx-EPKDDAYPLYSDFG as substrate, the homogeneous time-resolved fluorescence (HTRF) assay is used to measure TIE2 kinase inhibition.

GIST 882 and TT cells are grown in RPMI medium with L-glutamine for proliferation assays, while MDA-MB-231, HepG2, and A375 cells are grown in DMEM that is always supplemented with 10% hiFBS. Trypsinized cells are plated at a density of 5×104 cells per well in 96-well plates containing complete media containing 10% FBS, and grown overnight at 37 °C. The incubation is continued for another 96 hours with the addition of vehicle or regorafenib, serially diluted in complete growth media to final concentrations between 10 μM and 5 nM, and 0.2% DMSO. Using CellTitre-GloTM, cell proliferation is measured.

Absorption, Distribution and Excretion
Cmax = 2.5 μg/mL; Tmax = 4 hours; AUC = 70.4 μg*h/mL; Cmax, steady-state = 3.9 μg/mL; AUC, steady-state = 58.3 μg*h/mL; The mean relative bioavailability of tablets compared to an oral solution is 69% to 83%.
Approximately 71% of a radiolabeled dose was excreted in feces (47% as parent compound, 24% as metabolites) and 19% of the dose was excreted in urine (17% as glucuronides) within 12 days after administration of a radiolabeled oral solution at a dose of 120 mg.
Regorafenib undergoes enterohepatic circulation with multiple plasma concentration peaks observed across the 24-hour dosing interval.

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Metabolism / Metabolites
Regorafenib is metabolized by CYP3A4 and UGT1A9. The main circulating metabolites of regorafenib measured at steady-state in human plasma are M-2 (N-oxide) and M-5 (N-oxide and N-desmethyl), both of them having similar in vitro pharmacological activity and steady-state concentrations as regorafenib. M-2 and M-5 are highly protein bound (99.8% and 99.95%, respectively). Regorafenib is an inhibitor of P-glycoprotein, while its active metabolites M-2 (N-oxide) and M-5 (N-oxide and N-desmethyl) are substrates of P-glycoprotein.

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Biological Half-Life
Regorafenib, 160 mg oral dose = 28 hours (14 - 58 hours); M2 metabolite, 160 mg oral dose = 25 hours (14-32 hours); M5 metabolite, 160 mg oral dose = 51 hours (32-72 hours);

Hepatotoxicity
In large clinical trials of regorafenib, elevations in serum aminotransferase levels were common, occurring in 39% to 45% of patients, and were greater than 5 times the upper limit of normal (ULN) in 3% to 6%. In addition, there have been several reports of clinically apparent liver injury arising during regorafenib therapy which was often severe and occasionally fatal, estimated to occur in 0.3% of treated subjects. For these reasons, routine monitoring of liver enzymes is recommended. Regorafenib induced liver injury can present in several different patterns or phenotypes. Some patients present within a few days of starting regorafenib with acute hepatic necrosis, high levels of serum aminotransferase and lactic dehydrogenase with mild jaundice, but prolongation of INR and signs of hepatic failure. The injury can be severe but is generally self-limited and recovery is rapid and complete. Other patients present with an acute viral hepatitis like pattern, hepatocelllar (or mixed) serum enzyme elevations and jaundice that can be prolonged and has been fatal in several instances. Autoimmune and immunoallergic features are uncommon. In addition, rare instances of regorafenib associated liver injury have presented with a sinusoidal obstruction-like syndrome or pseudocirrhosis, with marked hepatic nodularity and ascites that eventually improves or resolves. Finally, regorafenib, like other multi-kinase inhibitors [sunitinib, imatinib, sorafenib], has also been associated with episodes of hyperammonemic coma generally arising within a few days or weeks of starting and with rapid reversal upon stopping treatment.
Likelihood score: B (highly likely cause of clinically apparent liver injury).

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Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
No information is available on the clinical use of regorafenib during breastfeeding. Because regorafenib is 99.5% bound to plasma proteins, the amount in milk is likely to be low. However, one of its metabolites has a half-life of up to 70 hours, and might accumulate in the infant. The manufacturer recommends that breastfeeding be discontinued during regorafenib therapy and for 2 weeks after the final dose.
◉ Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

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Protein Binding
Regorafenib is highly bound (99.5%) to human plasma proteins.

[1]. 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]. Targeted therapy for metastatic renal cell carcinoma: current treatment and future directions. Ther Adv Med Oncol, 2010, 2(1), 39-49.

[3]. Fluoro-Sorafenib (Regorafenib) effects on hepatoma cells: growth inhibition, quiescence, and recovery. J Cell Physiol, 2013, 228(2), 292-297.

Regorafenib is a pyridinecarboxamide obtained by condensation of 4-[4-({[4-chloro-3-(trifluoromethyl)phenyl]carbamoyl}amino)-3-fluorophenoxy]pyridine-2-carboxylic acid with methylamine. Used for for the treatment of metastatic colorectal cancer in patients who have previously received chemotherapy, anti-EGFR or anti-VEGF therapy. It has a role as an antineoplastic agent, a tyrosine kinase inhibitor and a hepatotoxic agent. It is an aromatic ether, a pyridinecarboxamide, a member of monochlorobenzenes, a member of (trifluoromethyl)benzenes, a member of monofluorobenzenes and a member of phenylureas.
Regorafenib is an orally-administered inhibitor of multiple kinases. It is used for the treatment of metastatic colorectal cancer, advanced gastrointestinal stromal tumours, and hepatocellular carcinoma. FDA approved on September 27, 2012. Approved use of Regorafenib was expanded to treat Hepatocellular Carcinoma in April 2017.
Regorafenib anhydrous is a Kinase Inhibitor. The mechanism of action of regorafenib anhydrous is as a Kinase Inhibitor, and Cytochrome P450 2C9 Inhibitor, and Breast Cancer Resistance Protein Inhibitor, and UGT1A9 Inhibitor, and UGT1A1 Inhibitor.
Regorafenib is an oral multi-kinase inhibitor that is used in the therapy of refractory metastatic colorectal cancer, hepatocellular carcinoma and gastrointestinal stromal tumor. Regorafenib has been associated with frequent serum aminotransferase elevations during therapy and with rare, but sometimes severe and even fatal instances of clinically apparent liver injury.
Regorafenib Anhydrous is the anhydrous form of regorafenib, an orally bioavailable small molecule with potential antiangiogenic and antineoplastic activities. Regorafenib binds to and inhibits vascular endothelial growth factor receptors (VEGFRs) 2 and 3, and Ret, Kit, PDGFR and Raf kinases, which may result in the inhibition of tumor angiogenesis and tumor cell proliferation. VEGFRs are receptor tyrosine kinases that play important roles in tumor angiogenesis; the receptor tyrosine kinases RET, KIT, and PDGFR, and the serine/threonine-specific Raf kinase are involved in tumor cell signaling.
Regorafenib is the hydrate form of regorafenib, an orally bioavailable small molecule with potential antiangiogenic and antineoplastic activities. Regorafenib binds to and inhibits vascular endothelial growth factor receptors (VEGFRs) 2 and 3, and Ret, Kit, PDGFR and Raf kinases, which may result in the inhibition of tumor angiogenesis and tumor cell proliferation. VEGFRs are receptor tyrosine kinases that play important roles in tumor angiogenesis; the receptor tyrosine kinases RET, KIT, and PDGFR, and the serine/threonine-specific Raf kinase are involved in tumor cell signaling.
See also: Regorafenib Monohydrate (active moiety of).

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Drug Indication
Regorafenib is indicated for the treatment of patients with metastatic colorectal cancer (CRC) who have been previously treated with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy, an anti-VEGF therapy, and, if KRAS wild type, an anti-EGFR therapy. Regorafenib is also indicated for the treatment of patients with locally advanced, unresectable or metastatic gastrointestinal stromal tumour (GIST) who have been previously treated with imatinib mesylate and sunitinib malate. Regorafenib is also indicated for the treatment of patients with hepatocellular carcinoma (HCC) previously treated with sorafenib.
FDA Label
Stivarga is indicated as monotherapy for the treatment of adult patients with: metastatic colorectal cancer (CRC) who have been previously treated with, or are not considered candidates for, available therapies - these include fluoropyrimidine-based chemotherapy, an anti-VEGF therapy and an anti-EGFR therapy; unresectable or metastatic gastrointestinal stromal tumors (GIST) who progressed on or are intolerant to prior treatment with imatinib and sunitinib; hepatocellular carcinoma (HCC) who have been previously treated with sorafenib.
Treatment of all conditions contained in the category of malignant neoplasms (except haematopoietic and lymphoid tissue)

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Mechanism of Action
Regorafenib is a small molecule inhibitor of multiple membrane-bound and intracellular kinases involved in normal cellular functions and in pathologic processes such as oncogenesis, tumor angiogenesis, and maintenance of the tumor microenvironment. In in vitro biochemical or cellular assays, regorafenib or its major human active metabolites M-2 and M-5 inhibited the activity of RET, VEGFR1, VEGFR2, VEGFR3, KIT, PDGFR-alpha, PDGFR-beta, FGFR1, FGFR2, TIE2, DDR2, TrkA, Eph2A, RAF-1, BRAF, BRAFV600E , SAPK2, PTK5, and Abl at concentrations of regorafenib that have been achieved clinically. In in vivo models, regorafenib demonstrated anti-angiogenic activity in a rat tumor model, and inhibition of tumor growth as well as anti-metastatic activity in several mouse xenograft models including some for human colorectal carcinoma.

C₂₁H₁₆CL₂F₄N₄O₃

519.28

518.053

835621-07-3

Regorafenib;755037-03-7;Regorafenib monohydrate;1019206-88-2

11167602

White to off-white solid

6.968

3

8

5

33

686

0

Cl.O=C(NC1C(F)=CC(OC2C=C(C(NC)=O)N=CC=2)=CC=1)NC1C=C(C(F)(F)F)C(Cl)=CC=1

ACSWJKPZXNIVMY-UHFFFAOYSA-N

InChI=1S/C21H15ClF4N4O3.ClH/c1-27-19(31)18-10-13(6-7-28-18)33-12-3-5-17(16(23)9-12)30-20(32)29-11-2-4-15(22)14(8-11)21(24,25)26;/h2-10H,1H3,(H,27,31)(H2,29,30,32);1H

4-[4-[[4-chloro-3-(trifluoromethyl)phenyl]carbamoylamino]-3-fluorophenoxy]-N-methylpyridine-2-carboxamide;hydrochloride

BAY-734506 HCl; BAY 734506; BAY734506; Regorafenib HCl. Brand name: Stivarga

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: 2 mg/mL (3.85 mM) in 50% PEG300 50% Saline (add these co-solvents sequentially from left to right, and one by one), suspension solution; with sonication.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: 30% PEG400+0.5% Tween80+5% Propylene glycol : 30mg/mL

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 (Please use freshly prepared in vivo formulations for optimal results.)