Weihan Zhang

Discovery of fruquintinib, a potent and highly selective small molecule inhibitor of VEGFR 1, 2, 3 tyrosine kinases for cancer therapy

VEGF/VEGFR signal axis has been proven to be an important target for development of novel cancer therapies. One challenging aspect in small molecular VEGFR inhibitors is to achieve sustained target inhibition at tolerable doses previously seen only with the long-acting biologics. It would require high potency (low effective drug concentrations) and sufficient drug exposures at tolerated doses so that the drug concentration can be maintained above effective drug concentration for target inhibition within the dosing period. Fruquintinib (HMPL-013) is a small molecule inhibitor with strong potency and high selectivity against VEGFR family currently in Phase II clinical studies. 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 >85% inhibition of VEGFR2 phosphorylation in mouse) for 24 hours/day. In this article, the preclinical data for fruquintinib will be described, including kinase enzyme activity and selectivity, cellular VEGFR inhibition and VEGFR-driven functional activity, in vivo VEGFR phosphorylation inhibition in the lung tissue in mouse and tumor growth inhibition in a panel of tumor xenograft and patient derive xenograft models in mouse. Pharmacokinetic and target inhibition data are also presented to provide a correlation between target inhibition and tumor growth inhibition.

Abstract 3371: Preclinical disposition and pharmacokinetics of volitinib, a novel selective cMet inhibitor .

Volitinib is a novel selective cMet inhibitor. This study is to evaluate its preclinical ADME/PK profile. Volitinib has high membrane permeability (Papp (A>B) 28×10 − 6 cm/s) without efflux transport across Caco-2 cell monolayer and exhibits negligible P-gp inhibition (IC 50 > 17 μM). Metabolic stability of volitinib in liver microsomes and S9 fractions of rat, dog, monkey and human was evaluated. Five phase I metabolites were observed in liver microsomes and S9 fractions of different species, and three major metabolites resulted from demethylation (M1), hydroxylation (M2) and mono-oxygenation (M3) were found to be mediated by multiple enzymes, including CYP450s and aldehyde oxidase. Rat was the most similar species to human in terms of the in vitro metabolism and metabolite profile. Metabolism is the main route of elimination for volitinib in rat due to the fact that the fecal, urinary and biliary excretion of the parent volitinib accounted for max max =1.9 h) and moderately low distribution (Vss=0.7 L/kg), the poor oral bioavailability (1.9%) of volitinib in monkey is considered to be the result of excessive first-pass extraction. Overall, volitinib exhibited favorable preclinical PK/ADME properties. Citation Format: Yi Gu, Yang Sai, Jian Wang, Sumei Xia, Guanglin Wang, Yuansheng Zhao, Li Zhang, Wenqing Yang, Guangxiu Dai, Weihan Zhang, Qisun Gong, Zhenping Tian, Weiguo Su. Preclinical disposition and pharmacokinetics of volitinib, a novel selective cMet inhibitor . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3371. doi:10.1158/1538-7445.AM2013-3371

Anti-tumor efficacy of theliatinib in esophageal cancer patient-derived xenografts models with epidermal growth factor receptor (EGFR) overexpression and gene amplification

Targeted therapy is not yet approved for esophageal cancer (EC). In this study, we first evaluated EGFR gene and protein expression in 70 Chinese EC patient tumor samples collected during surgery. We then established 23 patient-derived EC xenograft (PDECX) models and assessed the efficacy of theliatinib, a potent and highly selective EGFR inhibitor currently in Phase I clinical study, in 9 PDECX models exhibiting various EGFR expression levels. Immunohistochemical analysis showed that 50 patient tumor samples (71.4%) had high EGFR expression. Quantitative PCR showed that eight tumors (11.6%) had EGFR gene copy number gain, and fluorescence in situ hybridization (FISH) revealed that four tumors had EGFR gene amplification. These results suggest that EGFR protein may be overexpressed in many EC tumors without gene amplification. Also detected were rare hot-spot mutations in EGFR and PIK3CA, whereas no mutations were found in K-Ras or B-Raf. Theliatinib exhibited strong antitumor activity in PDECX models with high EGFR expression, including remarkable tumor regression in two PDECX models with both EGFR gene amplification and protein overexpression. However, the efficacy of theliatinib was diminished in models with PI3KCA mutations or FGFR1 overexpression in addition to high EGFR expression. This study demonstrates that theliatinib could potentially benefit EC patients with high EGFR protein expression without mutations or aberrant activities of associated factors, such as PI3KCA or FGFR1.Targeted therapy is not yet approved for esophageal cancer (EC). In this study, we first evaluated EGFR gene and protein expression in 70 Chinese EC patient tumor samples collected during surgery. We then established 23 patient-derived EC xenograft (PDECX) models and assessed the efficacy of theliatinib, a potent and highly selective EGFR inhibitor currently in Phase I clinical study, in 9 PDECX models exhibiting various EGFR expression levels. Immunohistochemical analysis showed that 50 patient tumor samples (71.4%) had high EGFR expression. Quantitative PCR showed that eight tumors (11.6%) had EGFR gene copy number gain, and fluorescence in situ hybridization (FISH) revealed that four tumors had EGFR gene amplification. These results suggest that EGFR protein may be overexpressed in many EC tumors without gene amplification. Also detected were rare hot-spot mutations in EGFR and PIK3CA, whereas no mutations were found in K-Ras or B-Raf. Theliatinib exhibited strong antitumor activity in PDECX models with high EGFR expression, including remarkable tumor regression in two PDECX models with both EGFR gene amplification and protein overexpression. However, the efficacy of theliatinib was diminished in models with PI3KCA mutations or FGFR1 overexpression in addition to high EGFR expression. This study demonstrates that theliatinib could potentially benefit EC patients with high EGFR protein expression without mutations or aberrant activities of associated factors, such as PI3KCA or FGFR1.

Abstract 1808: HM-032, a novel PI3K/mTOR dual inhibitor, is active on K-Ras/Raf mutation tumors through up-regulation of Bim

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL PIK3CA gene amplification and mutations have been identified in many types of tumors, suggesting the deregulation of PI3K/AKT/mTOR axis plays pivotal roles in tumorigenesis and development. K-Ras/Raf mutation is recognized as one of the key drug resistant factors for tumors against TKIs. HM-032 was reported here as a potent, selective and reversible ATP-competitive PI3K/mTOR dual inhibitor with special apoptotic activity in tumor cells harboring K-Ras mutations. HM-032 showed potent kinase inhibition with IC50 of 0.0008, 0.002, 0.001, 0.002 and 0.001 µM on PI3Kα, β, δ, ≤ and mTOR, respectively. In human prostate PC3 cells, it inhibited p-AKTS473, p-S6 and p-4EPB1 with IC50s of 0.002, 0.015 and 0.056 μM. Of the 89 tumor cell lines from lung, colon, breast, ovarian, and other tumor types, it was found that tumor cells with HER2 gene amplification, or PIK3CA mutation were relatively more sensitive to HM-032. Attractively, HM-032 showed apoptotic induction activity in the tumor cells harboring Ras/Raf mutations through inhibiting p-Erk and increasing gene expression of pro-apoptotic protein Bim. This result suggested that HM-032 might bring benefits to patients carrying K-Ras/Raf mutations in the clinic. Consistent with in vitro studies, HM-032 exhibited significant tumor growth inhibition in a dose dependent manner on multiple human xenograft models, including breast tumor MDA-MB-361(PIK3CAE545K, Her2 amplification), lung tumors H460 (PIK3CAE545K, K-RasQ61H) and A549 (LKB1 del, K-RasG12S), and glioblastoma U87MG (PTEN del) after 3 weeks oral dosing. Correspondingly, decrease of p-AKT and p-S6 was observed in the tumor xenograft tissues upon treatment with HM-032. In addition, HM-032 exhibited unique in vivo PK properties characterized by low clearance and long t1/2, which supported the intermittent dosing schedule in xenograft models. Based on the pre-clinical study results, HM-032 is anticipated to be a promising agent against solid tumors including carrying Ras/Raf mutations. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1808. doi:1538-7445.AM2012-1808

Abstract 4499: HM5016699, a novel and selective PI3K/mTOR dual inhibitor

PI3KCA gene amplification and mutations have been identified in many types of tumors, suggesting the dysregulation of PI3K/AKT/mTOR axis plays pivotal roles in tumorigenesis and development. Reported here is the discovery of HM5016699 as a potent, reversible ATP-competitive PI3K/mTOR dual inhibitor for treatment of cancer. HM5016699 showed potent kinase inhibition with IC50 of 0.01, 0.206, 0.052, 0.051 and 0.059 µM on PI3Kα, β, γ, Δ and mTOR, respectively. It demonstrated high selectivity on PI3K family and mTOR over a panel of 274 kinases. Of the 67 tumor cell lines screened from lung, colon, breast, ovarian, and other tumor types, we found that the tumor cells with HER2 gene amplification or PTEN loss tended to be sensitive to HM5016699, while the tumor cells harboring PI3KCA mutations and wild type Ras/Raf were mostly sensitive to the compound. HM5016699 could also show p-Erk inhibition and apoptotic induction at higher concentrations in the tumor cells harboring Ras/Raf mutations, suggesting it might bring benefits to patients carrying Ras/Raf mutations in the clinic. Consistent with in vitro studies, HM5016699 exhibited dose dependent tumor growth inhibition on multiple human xenografts models. It was found that the tumors with PIK3CA mutation or PTEN deletion were highly sensitive to HM5016699 with ED50s ranging from 0.6 to 1.8 mg/kg in U87MG (pTEN null), SKOV3 (H1047) and H1975 (G118D), whereas in tumors with Ras/Raf mutations, such as DLD-1(G13D), A549 (G12S) and HT-29(V600E), its ED50s were from 3.0 to 15.0 mg/kg. The decreased phosphorylation of AKT and S6 was observed in the tumor xenograft tissues treated with HM5016699, which was well-correlated with compound exposure. Therefore, we concluded that HM5016699 demonstrated both in vitro and in vivo activity through acting on PI3K/mTOR pathway. HM5016699 exhibited a favorable pharmacokinetic profile and acceptable safety window in rats. The pre-clinical study results suggest that HM5016699 could be a promising anti-cancer agent. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4499. doi:10.1158/1538-7445.AM2011-4499