Apatinib | Kinase Inhibitor | VEGFR-2 Inhibitor | KDR Inhibitor | Angiogenesis Inhibitor | Anti-Tumor Drug

Apatinib [N-[4-(1-cyano-cyclopentyl)phenyl]-2-(4-pyridylmethyl)amino-3-pyridine carboxamide] is an orally available, selective small molecule inhibitor of vascular endothelial growth factor-2 (VEGFR-2 also known as KDR) tyrosine kinase. It is more potent than Sunitinib in inhibiting VEGFR2 (IC₅₀ Apatinib, Sunitinib = 0.001, 0.005 uM) [1, 2].

Apatinib is an analogue of Valatinib and shows similar anti-angiogenic/anti-tumour efficacy. It binds with VEGFR-2 tyrosine kinase targeting the intracellular ATP binding site of the receptor, preventing phosphorylation and subsequent downstream signalling. Apatinib has shown a superior in vivo efficacy compared to Valatinib in xenograft models.

Apatinib has been approved by the Chinese Food and Drug Administration (CFDA) in October 2014 for the treatment of metastatic gastric carcinoma. It is an investigational cancer drug in many other countries including USA, EU etc and currently undergoing clinical trials as a potential targeted treatment for metastatic gastric carcinoma, metastatic breast cancer and advanced hepatocellular carcinoma.

Apatinib: 2D and 3D Structure

Angiogenesis, Tumor Angiogenesis and VEGFRs

Angiogenesis, the formation of new blood vessels from pre-existing ones, plays a central role in the process of tumor growth and metastasis. The proliferation of endothelium and formation of new blood vessels further the size of solid tumors. It is expected that blocking angiogenesis will be an efficient therapeutic approach against many tumor types.

Tumor angiogenesis plays a critical role in the malignant tumor growth and metastasis. When tumors grow beyond 1 mm³, angiogenesis or generation of vascular arborizations by budding from existing vessels is necessary to provide enough blood for the survival of tumor cells. The growth speed and tendency of metastasis of tumors are associated with the level of neovascularization factors and the quantity of nascent microvessels. Since the hypothesis “anti-angiogenesis therapy” was put forward by Folkman in early 1970s, people have made considerable progress in this field, and inhibiting angiogenesis of tumors has been universally accepted as a new anticancer strategy. 

Tyrosine kinase vascular endothelial growth factor (VEGF) and its receptor (VEGFR) play significantly important roles in angiogenesis of tumors, and they are both important targets in blocking angiogenesis of tumors. Vascular endothelial growth factor (VEGF) is the foremost factor in vivo promoting the angiogenesis. The binding of VEGF with vascular endothelial growth factor receptor (VEGFR) in endothelial cells leads to various reactions of angiogenesis, such as cells proliferation, cells metastasis, the increase of vascular permeability, and the move of endothelial cells precursors out of marrow. VEGFR family comprises VEGFR1 (Flt-1), VEGFR2 (KDR/Flk-1) and VEGFR3 (Flt-4). Promotion of the angiogenesis is mainly mediated by the bonded VEGF and VEGFR2 (KDR/Flk-1).

Compared with traditional cytotoxic drugs which inhibit the growth of tumors, angiogenesis targeting drugs are more specific and less toxic as well as helpful to overcome the drug resistance of tumors and can be used for the treatment of various tumors [3, 4].

Apatinib as Kinase Inhibitor

In vitro enzyme experiments showed that Apatinib was an even more selective inhibitor of VEGFR-2 than Sunitinib, with an IC₅₀ of 0.001 uM and 0.005 uM, respectively. Apatinib could also potently suppress the activities of Ret, c-Kit and c-Src with an IC₅₀ of 0.013 uM, 0.429 uM and 0.53 uM, respectively. Apatinib had no significant effects on EGFR, Her-2 or FGFR1 in concentrations up to 10 uM [1].

Summary

Common name: YN968D1; YN 968D1; YN-968D1

Trademarks: -

Molecular Formula: C24H23N5O

CAS Registry Number: 811803-05-1; 1218779-75-9 (mesylate)

CAS Name: N-[4-(1-cyano-cyclopentyl)phenyl]-2-(4-pyridylmethyl)amino-3-pyridine carboxamide

Molecular Weight: 397.48

SMILES:O=C(NC1=CC=C(C2(C#N)CCCC2)C=C1)C3=CC=CN=C3NCC4=CC=NC=C4

InChI Key: WPEWQEMJFLWMLV-UHFFFAOYSA-N

InChI: InChI=1S/C24H23N5O/c25-17-24(11-1-2-12-24)19-5-7-20(8-6-19)29-23(30)21-4-3-13-27-22(21)28-16-18-9-14-26-15-10-18/h3-10,13-15H,1-2,11-12,16H2,(H,27,28)(H,29,30)

Mechanism of Action: Kinase Inhibitor; KDR Inhibitor; Multi-Kinase Inhibitor

Activity: Treatment of Metastatic Gastric Carcinoma; Anti-cancer Agents; Angiogenesis Inhibitors

Status: Launched 2014 (China)

Chemical Class: Small-molecules; Nitrile containing; Pyrimidine containing

Originator: Advenchen Laboratories (USA)/ Jiangsu Hengrui Medicine Co. Ltd (China)

Apatinib Synthesis

US20040259916A1: It appears to be the industrial process.

Identification:

1H NMR (Estimated) for Apatinib

References:
1. Tian, S.; et al. YN968D1 is a novel and selective inhibitor of vascular endothelial growth factor receptor-2 tyrosine kinase with potent activity in vitro and in vivo. Cancer Sci 2011, 102(7), 1374-80. (FMO only)
2. Chen, G. Six membered amino-amide derivatives an angiogenisis inhibitors. US20040259916A1
3. Yuan, K.; et al. The salts of n-[4-(1-cyanocyclopentyl)phenyl]-2-(4-pyridyl methyl)amino-3-pyridinecarboxamide. WO2010031266A1
4. Sharma, P. S.; et al. VEGF/VEGFR pathway inhibitors as anti-angiogenic agents: present and future. Curr Cancer Drug Targets 2011, 11(5), 624-53. (FMO only)

Drugs in Clinical Pipeline: Motesanib

Motesanib [N-(2,3-dihydro-3,3-dimethyl-1H-indol-6-yl)-2-[(4-pyridinylmethyl)amino]-3-pyridinecarboxamide] is a potent, orally bioavailable, ATP-competitive nicotinamide-based inhibitor of human VEGFR2 when tested using in vitro kinase assays. Motesanib has broad activity against the human VEGFR family, including VEGFR1, VEGFR2, and VEGFR3 (IC₅₀ = 2 ± 0.7, 3 ± 0.5, and 6 ± 4 nM, respectively) and displays similar activity against human Kit (IC₅₀ = 8 ± 2 nM). The compound also displays activity against PDGFR (IC₅₀ = 84 ± 33 nM) and Ret (IC₅₀ = 59 ± 4nM), although the potency was reduced ~10-fold relative to the VEGFR family. The compound is highly selective against a broad range of ~47 other kinases tested, including EGFR, Src, and p38 kinase (IC₅₀ greater than 3 uM) [1].

The selectivity of Motesanib was preserved in cellular assays. Potent inhibition of receptor phosphorylation and functional responses was observed in biologically relevant cells. Motesanib potently inhibited VEGF-induced but not bFGF-induced proliferation of HUVECs with IC₅₀ values of 10 nM and greater than 3 uM, respectively. Similarly, Motesanib potently inhibited both PDGF-induced proliferation and SCF-induced c-kit phosphorylation with IC₅₀ values of 207 and 37 nM, respectively. Motesanib displayed no activity against unrelated kinases as evidenced by the lack of activity against EGF-induced EGFR phosphorylation in A431 cells (IC₅₀, greater than 25 uM). Importantly, incubation of A431 tumor cells for 3 days with up to 25 µM, Motesanib did not affect their viability as determined by Alamar Blue uptake [1].

The activity of Motesanib is as follows:

IC₅₀ (VEGFR1 enzyme assay) = 2 ± 0.7 nM

IC₅₀ (VEGFR2 enzyme assay) = 3 ± 0.5 nM

IC₅₀ (VEGFR3 enzyme assay) = 6 ± 4 nM

IC₅₀ (KIT enzyme assay) = 8 ± 2 nM

Common Name: Motesanib

Synonyms: AMG 706; AMG-706; AMG706

IUPAC Name: N-(2,3-dihydro-3,3-dimethyl-1H-indol-6-yl)-2-[(4-pyridinylmethyl)amino]-3-pyridinecarboxamide

CAS Number: 453562-69-1; 857876-30-3 (diphosphate)

Mechanism of Action: Kinase Inhibitor; pan-VEGFR Inhibitor; VEGFR Inhibitor

Indication: Various Cancers; Solid Tumors

Development Stage: Phase III

Company: Amgen/Takeda

Increased endothelial cell apoptosis in association with decreased blood vessel area were the first temporal events observed following administration of Motesanib. This was followed by significant increases in tumor cell apoptosis. The sequence of these observations is consistent with targeting of tumor-associated endothelial cells and blood vessels as a primary mechanism of the antitumor activity of Motesanib in the model systems explored.

References:

1. Polverino, A.; et. al. AMG 706, an oral, multikinase inhibitor that selectively targets vascular endothelial growth factor, platelet-derived growth factor, and kit receptors, potently inhibits angiogenesis and induces regression in tumor xenografts. Cancer Res 2006, 66(17), 8715-8721.

Drugs in Clinical Pipeline: Fruquintinib

Fruquintinib [6-((6,7-dimethoxyquinazolin-4-yl)oxy)-N,2-dimethylbenzofuran-3-carboxamide] is a novel oral small molecule that selectively inhibits vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3 and has demonstrated potent inhibitory effects on multiple human tumor xenografts [1]. In vitro, Fruquintinib demonstrated a highly potent and selective kinase profile against VEGF receptors 1, 2 and 3 (IC₅₀ = 33, 35 and 0.5 nM, respectively). In vivo, Fruquintinib demonstrated broad spectrum anti-tumor activity via oral dosing in multiple tumor xerografts such as BGC-823, BXPC-3 and A375. In low oral doses, Fruquintinib has potent inhibitory effects on multiple human tumor xenografts, including some refractory tumors such as pancreatic cancer and melanoma.

The activity of Fruquintinib is as follows:

IC₅₀ (VEGFR2 enzyme assay) = 35 nM

IC₅₀ (VEGFR3 enzyme assay) = 0.5 nM

IC₅₀ (VEGFR1 enzyme assay) = 33 nM

IC₅₀ (FGFR1 enzyme assay) = 181 nM

IC₅₀ (c-Kit  enzyme assay) = 458 nM

IC₅₀ (Ret enzyme assay) = 128 nM

Common Name: Fruquintinib

Synonyms: AUY HMPL-013; HMPL 013; HMPL013

IUPAC Name: 6-((6,7-dimethoxyquinazolin-4-yl)oxy)-N,2-dimethylbenzofuran-3-carboxamide

CAS Number: 1194506-26-7

Mechanism of Action: Kinase Inhibitor; pan-VEGFR Inhibitor

Indication: Various Cancers; Solid Tumors; Non-small Cell Lung Cancer; Gastric Cancer; Colorectal Cancer

Development Stage: Phase II

Company: Hutchison Medi Pharma (China)/Lilly Inc

Angiogenesis, the process of developing new blood vessels, is critical for tumor cell growth, survival, invasion and metastasis. The vascular endothelial growth factor (VEGF) and VEGF receptors (VEGFRs) play a pivotal role in tumor-related angiogenesis, and the VEGF/VEGFR pathway is an important target for anti-angiogenic drug development and tumor therapy. Inhibition of VEGF signaling in tumor vasculature therefore represents an exciting therapeutic strategy, with the potential to arrest the development of new blood vessels essential for tumor growth and metastasis [2].

Fruquintinib has high permeability without efflux. It shows moderate oral bioavailability of 42-53 % and T_max less than 4 h in mouse, rat, dog and monkey, with exposure-dose linearity proved in rats and dogs. No significant food effect is on dog pharmacokinetics (PK). Fruquintinib has moderately high tissue distribution. It majorly distributes in gastrointestinal tract, liver, kidney, adrenal and adipose. The plasma protein binding fraction is 88-95 % in mouse, rat, dog and human, invariable up to 10 µM. The in vivo clearance of Fruquintinib is low, consistent with the in vitro scaling. Three major oxidative metabolites were identified in liver microsomes of mouse, rat, dog, monkey and human. Fruquintinib has low risk of drug-drug interaction. It is predicted to have favorable human PK properties and low efficacious dose [3]. Analysis of Phase I pharmacokinetic data revealed that at the maximum tolerated dose of once daily oral administration Fruquintinib achieved complete VEGFR2 suppression (drug concentrations were maintained above that required to produce greater than 85% inhibition of VEGFR2 phosphorylation in mouse) for 24 hours/day [1].            

References:

1. Sun, Q.; et. al. Discovery of fruquintinib, a potent and highly selective small molecule inhibitor of VEGFR 1, 2, 3 tyrosine kinases for cancer therapy. Cancer Biol Ther 2014, 15(12), 1635-1645.
2. Sharma, P. S.; et. al. VEGF/VEGFR pathway inhibitors as anti-angiogenic agents: present and future. Curr Cancer Drug Targets. 2011, 11(5), 624-653. (Your's truly is an author here.)
3. Gu, Y.; et. al. Preclinical pharmacokinetics and disposition of a novel selective VEGFR inhibitor fruquintinib (HMPL-013) and the prediction of its human pharmacokinetics. Cancer Chemother Pharmacol 2014, 74(1), 95-115.

Drugs in Clinical Pipeline: Vatalanib

Vatalanib [N-(4-chlorophenyl)-4-(pyridine-4-ylmethyl)phthalazin-1-amine] is an orally bioavailable anilinophthalazine compound that has potent antineoplastic activity. Vatalanib binds to and inhibits the protein kinase domain of vascular endothelial growth factor receptors 1 and 2 (VEGFR 1 and VEGFR2); both receptor tyrosine kinases are involved in angiogenesis. This agent also binds to and inhibits related receptor tyrosine kinases, including platelet-derived growth factor (PDGF) receptor, c-Kit, and c-Fms [1]. Preclinical studies demonstrated antitumor activity against a broad range of cancer types, including colorectal, prostate, renal, hepatocellular, myeloma, recurrent glioblastoma multiform and ovarian. The compound has been investigated in phase I/II studies, alone and in combination with chemotherapy.

The activity of Vatalanib is as follows:

IC₅₀ (VEGFR2/KDR, cell-free assay) = 37 nM

IC₅₀ (VEGFR1/FLT1, cell-free assay) = 77 nM

IC₅₀ (VEGFR2/Flk1, cell-free assay) = 270 nM

IC₅₀ (PDGFRB, cell-free assay) = 580 nM

IC₅₀ (VEGFR3/FLT4, cell-free assay) = 660 nM

IC₅₀ (c-Kit, cell-free assay) = 730 nM

IC₅₀ (c-Fms, cell-free assay) = 1400 nM

Common Name: Vatalanib; Vatalanib dihydrochloride

Synonyms:  PTK787; PTK 787; PTK-787; ZK 222584; ZK222584; ZK-222584; CGP 79787; CGP-797870; ZK-232934; CGP79787D; PTK787/ZK 222584; CGP-79787

IUPAC Name: N-(4-chlorophenyl)-4-(pyridin-4-ylmethyl)phthalazin-1-amine

CAS Number: 212141-54-3; 212141-51-0 (dihydrochloride)

SMILES: C1=CC=C2C(=C1)C(=NN=C2NC3=CC=C(C=C3)Cl)CC4=CC=NC=C4.Cl.Cl

Mechanism of Action: Kinase Inhibitor; VEGFR-2 Inhibitor; KDR Inhibitor

Indication: Metastatic colorectal cancer and NSCLC

Development Stage: Phase II / III trials

Company: Novartis International AG/ Bayer Schering

Vascular endothelial growth factor (VEGF) is a signal protein produced by cells that stimulate vasculogenesis (formation of blood vessels occurring by de novo production of endothelial cells) and angiogenesis (formation of new blood vessels from pre-existing vessel). It is part of the system that restores the oxygen supply to tissues when blood circulation is inadequate. Its normal function is to create new blood vessels during embryonic development, new blood vessels after injury, muscle following exercise and new vessels to bypass blocked vessels. But, when VEGF is overexpressed, it can lead to disease. Solid cancers cannot grow beyond a limited size without an adequate blood supply, cancers that can express VEGF are able to grow and metastasize.

Vatalanib (INN, codenamed PTK787 or PTK/ZK) is being studied as a possible treatment for several types of cancer, particularly cancer that is at an advanced stage or has not responded to chemotherapy. Vatalanib targets all known VEGF receptors (VEGFR1, VEGFR2, VEGFR3), as well as platelet-derived growth factor receptor-beta (PDGFRB) and c-KIT, but is most selective for VEGFR-2. The compound is less potent against VEGFR1/Flt-1, 18-fold against VEGFR3/Flt-4 [1]. It is undergoing clinical trials for metastatic colorectal cancer and NSCLC.

Vatalanib was discovered through high-throughput screening. It has been extensively investigated in Phase I, II and III clinical trials. Encouraging data were obtained from phase II trials examining vatalanib monotherapy administered once or twice daily in previously treated patients with NSCLC [2]. Vatalanib was investigated in the treatment of metastatic colorectal cancer in double-blind, placebo-controlled, phase III studies: Colorectal Oral Novel Therapy for the Inhibition of Angiogenesis and Retarding of Metastases in First-line (CONFIRM-1 and 2) trials. These trials investigated the effect of 5-FU, leucovorin, and oxaliplatin, (FOLFOX-4) chemotherapy with or without vatalanib as second line therapy of patients with metastatic colorectal cancer. In CONFIRM-1 trials, participants had not yet received any treatment for their cancer; and CONFIRM-2, in which participants had received first-line treatment with irinotecan and fluoropyrimidines. Both trials result showed that the progression-free survival (PFS) time was significantly longer in the vatalanib arm in patients with high levels of lactate dehydrogenase (LDH, an enzyme used as a marker of tissue breakdown) [3, 4]. However, interim results from phase III trials of vatalanib in combination with FOLFOX 4 chemotherapy as a second-line treatment in CONFIRM-2 trials, suggested no significant benefit in overall survival (OS). Thus, multitargeted TKIs are yet to show survival benefit in phase II trials when combined with chemotherapeutics.

The possible reasons for why vatalanib treatment did not show a clear benefit with FOLFOX 4 regimen in metastatic colorectal cancer patients could be the simple explanation that it is not as effective an agent at administered doses, vatalanib has a considerably shorter half-life (approx. 6 h), and the phase III trials for vatalanib used a single daily dose of the drug. Contradicting these data, however, is the fact that pharmacokinetic data suggest that an active dose of vatalanib is maintained in the blood circulation for 24 h, and that it has a rapid and pronounced anti-vascular effect [5]. Another explanation could be the off-target effects (i.e. other than on the VEGF receptor kinases). For example, vatalanib might target PDGFR-beta on perivascular cells. This action was shown in mice to be beneficial for vascular targeting, since the PDGF-B-PDGFR-beta axis is known to control vascular stabilization/maturation by recruitment of supporting perivascular cells. Blocking PDGFR-beta, however, may interfere with vascular normalization, by blocking perivascular cell recruitment and excessive vessel pruning, and thus prevent the synergistic effect of combined therapy [6]. Thus, the clinical benefit of targeting perivascular cells in addition to endothelial cells with multi-targeted TKIs in the context of chemotherapy still remains unclear.

The adverse effects of vatalanib appear similar to those of other VEGF inhibitors. The most common side effects associated with vatalanib were observed to be high blood pressure, gastrointestinal upset (diarrhea, nausea, and vomiting), fatigue, and dizziness [7, 8].

References:

1. Wood, J. M.; et. al. PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration. Cancer Res 2000, 60(8), 2178-2189.

2.    Scagliotti, G.; Govindan, R. Targeting angiogenesis with multitargeted tyrosine kinase inhibitors in the treatment of non-small cell lung cancer. Oncologist 2010, 15(5), 436-446.

3.    Los, M.; Roodhart, J. M.; Voest, E. E. Target practice: lessons from phase III trials with bevacizumab and vatalanib in the treatment of advanced colorectal cancer. Oncologist 2007, 12(4), 443-450.

4.    Scott, E. N.; Meinhardt, G.; et al. Vatalanib: the clinical development of a tyrosine kinase inhibitor of angiogenesis in solid tumours. Expert Opin. Investig. Drugs 2007, 16(3), 367-379.

5.    Morgan, B.; et al. Dynamic contrast-enhanced magnetic resonance imaging as a biomarker for the pharmacological response of PTK787/ZK 222584, an inhibitor of the vascular endothelial growth factor receptor tyrosine kinases, in patients with advanced colorectal cancer and liver metastases: results from two phase I studies. J. Clin. Oncol. 2003, 21(21), 3955-3964.

6.    Jain, R. K. Molecular regulation of vessel maturation. Nat. Med. 2003, 9(6), 685-693.

7.    Mross, K.; et al. Phase I clinical and pharmacokinetic study of PTK/ZK, a multiple VEGF receptor inhibitor, in patients with liver metastases from solid tumours. Eur. J. Cancer 2005, 41(9), 1291-1299.

8.    Thomas, A. L.; et al. Phase I study of the safety, tolerability, pharmacokinetics, and pharmacodynamics of PTK787/ZK 222584 administered twice daily in patients with advanced cancer. J. Clin. Oncol. 2005, 23(18), 4162-4171.

9.    Murakami, M.; Kobayashi, S.; et. al. Tyrosine kinase inhibitor PTK/ZK enhances the antitumor effects of interferon-α/5-fluorouracil therapy for hepatocellular carcinoma cells. Ann. Surg. Oncol. 2011, 18(2), 589-596.

Drugs in Clinical Pipeline: Lucitanib

Lucitanib [6-[7-[(1-aminocyclopropyl)methoxy]-6-methoxyquinolin-4-yl]oxy-N-methylnaphthalene-1-carboxamide] is an oral, potent inhibitor of the tyrosine kinase activity of fibroblast growth factor receptors 1 through 3 (FGFR-1,2,3), vascular endothelial growth factor receptors 1 through 3 (VEGFR-1,2,3) and platelet-derived growth factor receptors alpha and beta (PDGFR- a,ß). As an inhibitor of FGFR-1,2,3, VEGFR-1,2,3 and PDGFR a/ß, and the role that each of these receptor kinases plays in tumor progression and metastasis formation, Lucitanib has the potential benefit of targeting three relevant pro-angiogenic growth factors in targeted patient populations identified by molecular markers.

Clovis Oncology holds exclusive development and commercial rights to lucitanib on a global basis, excluding China. Lucitanib rights to markets outside of the U.S. and Japan have been sublicensed to Les Laboratoires Servier (Servier).

Common Name: Lucitanib
Synonyms: CO-3810; S 80881; E-3810

IUPAC Name: 6-({7-[(1-aminocyclopropyl)methoxy]-6-methoxyquinolin-4-yl}oxy)-N- methylnaphthalene-1-carboxamide

CAS Number: 1058137-23-7
Mechanism of Action: Kinase Inhibitor; FGFR Inhibitor; VEGFR Inhibitor; PDGFR Inhibitor
Indication: Various cancers, tumors
Development Stage: Phase I/II

Company: Clovis Oncology

A Phase I/IIa clinical trial of Lucitanib was initiated in 2010 and has demonstrated multiple objective responses in FGFR1 gene-amplified breast cancer patients, and objective responses were also observed in patients with tumors often sensitive to VEGFR inhibitors, such as renal cell and thyroid cancer. FGFR amplification is common in a number of tumor types, including breast cancer and lung cancer, and it is intended to study Lucitanib in these cancers as well as other solid tumors exhibiting FGFR pathway activation. A broad Phase II development program has been initiated by Clovis and Servier in multiple indications, including advanced breast and lung cancers.