Design and Structure−Activity Relationship of a New Class of Potent VEGF Receptor Tyrosine Kinase Inhibitors

Abstract

A series of substituted 4-anilinoquinazolines and related compounds were synthesized as potential inhibitors of vascular endothelial growth factor (VEGF) receptor (Flt and KDR) tyrosine kinase activity. Enzyme screening indicated that a narrow structure-activity relationship (SAR) existed for the bicyclic ring system, with quinazolines, quinolines, and cinnolines having activity and with quinazolines and quinolines generally being preferred. Substitution of the aniline was investigated and clearly indicated that small lipophilic substituents such as halogens or methyl were preferred at the C-4' position. Small substituents such as hydrogen and fluorine are preferred at the C-2' position. Introduction of a hydroxyl group at the meta position of the aniline produced the most potent inhibitors of Flt and KDR tyrosine kinases activity with IC(50) values in the nanomolar range (e.g. 10, 12, 13, 16, and 18). Investigation of the quinazoline C-6 and C-7 positions indicates that a large range of substituents are tolerated at C-7, whereas variation at the C-6 is more restricted. At C-7, neutral, basic, and heteroaromatic side chains led to very potent compounds, as illustrated by the methoxyethoxy derivative 13 (IC(50) < 2 nM). Our inhibitors proved to be very selective inhibitors of Flt and KDR tyrosine kinase activity when compared to that associated with the FGF receptor (50- to 3800-fold). Observed enzyme profiles translated well with respect to potency and selectivity for inhibition of growth factor stimulated proliferation of human umbilical vein endothelial cells (HUVECs). Oral administration of selected compounds to mice produced total plasma levels 6 h after dosing of between 3 and 49 microM. In vivo efficacy was demonstrated in a rat uterine oedema assay where significant activity was achieved at 60 mg/kg with the meta hydroxy anilinoquinazoline 10. Inhibition of growth of human tumors in athymic mice has also been demonstrated: compound 34 inhibited the growth of established Calu-6 lung carcinoma xenograft by 75% (P < 0.001, one tailed t-test) following daily oral administration of 100 mg/kg for 21 days.

Inhibition of renal cell carcinoma angiogenesis and growth by antisense oligonucleotides targeting vascular endothelial growth factor

“…Its expression level has been associated with a variety of tumours and correlated to treatment outcome (Maeda et al, 1996;Gasparini et al, 1997). To date, attempts to abrogate the angiogenic activity of VEGF have focused on inactivating VEGF through the use of antibodies (Kim et al, 1993;Mordenti et al, 1999) and soluble receptors (Lin et al, 1998), inhibiting VEGF receptor tyrosine kinases (Hennequin et al, 1999) or suppressing VEGF message (Ellis et al, 1996;Smyth et al, 1997;Nguyen et al, 1998). The latter relied on antisense oligonucleotides or antisense RNA (Eguchi et al, 1991;Mercola and Cohen, 1995;Phillips and Zhang, 2000) to modulate gene expression by disrupting RNA expression.…”

Complete Structure of an Increasing Capillary Permeability Protein (ICPP) Purified from Vipera lebetina Venom

“…Receptor Tyrosine Kinase Assays-The ability of VTKI to inhibit the kinase activity associated with the VEGF receptors R1 (Flt-1) and R2 (KDR), the FGF receptor FGFR1, and the EGF receptor was determined using a previously described enzyme-linked immunosorbent assay (17). Receptor tyrosine kinases used in isolated enzyme assays were generated as insect cell lysates following cell infection with recombinant baculoviruses containing kinase domains.…”

Structural studies of B-type Aurora kinase inhibitors using computational methods

“…Modification of the R1 substituent at the C7 position of the quinazoline inhibitors is known to profoundly influence their activity and selectivity [51][52][53][54] . The R1 substituent accesses the solvent channel, explaining why a wide range of strongly polar groups is tolerated, provided that a suitable linear spacer is included between the solubilizing group and the quinazoline.…”