Drug-like property optimization: Discovery of orally bioavailable quinazoline-based multi-targeted kinase inhibitors.

In an effort to develop new cancer therapeutics, we have reported clinical candidate BPR1K871 (1) as a potentanticancercompound in MOLM-13 and MV4-11 leukemia models, as well as in colorectal and pancreatic animal models. As BPR1K871 lacks oral bioavailability, we continued searching for orally bioavailable analogs through drug-like property optimization. We optimized both the physicochemical properties (PCP) as well as in vitro rat liver microsomal stability of 1, with concomitant monitoring of aurora kinase enzyme inhibition as well as cellular anti-proliferative activity in HCT-116 cell line. Structural modification at the 6- and 7-position of quinazoline core of 1 led to the identification of 34 as an orally bioavailable (F% = 54) multi-kinase inhibitor, which exhibits potent anti-proliferative activity against various cancer cell lines. Quinazoline 34 is selected as a promising oral lead candidate for further preclinical evaluation.

Discovery of a Furanopyrimidine-Based Epidermal Growth Factor Receptor Inhibitor (DBPR112) as a Clinical Candidate for the Treatment of Non-Small Cell Lung Cancer.

Epidermal growth factor receptor (EGFR)-targeted therapy in non-small cell lung cancer represents a breakthrough in the field of precision medicine. Previously, we have identified a lead compound, furanopyrimidine 2, which contains a (S)-2-phenylglycinol structure as a key fragment to inhibit EGFR. However, compound 2 showed high clearance and poor oral bioavailability in its pharmacokinetics studies. In this work, we optimized compound 2 by scaffold hopping and exploiting the potent inhibitory activity of various warhead groups to obtain a clinical candidate, 78 (DBPR112), which not only displayed a potent inhibitory activity against EGFRL858R/T790M double mutations but also exhibited tenfold potency better than the third-generation inhibitor, osimertinib, against EGFR and HER2 exon 20 insertion mutations. Overall, pharmacokinetic improvement through lead-to-candidate optimization yielded fourfold oral AUC better that afatinib along with F = 41.5%, an encouraging safety profile, and significant antitumor efficacy in in vivo xenograft models. DBPR112 is currently undergoing phase 1 clinical trial in Taiwan.

Discovery of BPR1K871, a quinazoline based, multi-kinase inhibitor for the treatment of AML and solid tumors: Rational design, synthesis, in vitro and in vivo evaluation.

The design and synthesis of a quinazoline-based, multi-kinase inhibitor for the treatment of acute myeloid leukemia (AML) and other malignancies is reported. Based on the previously reported furanopyrimidine 3, quinazoline core containing lead 4 was synthesized and found to impart dual FLT3/AURKA inhibition (IC50 = 127/5 nM), as well as improved physicochemical properties. A detailed structure-activity relationship study of the lead 4 allowed FLT3 and AURKA inhibition to be finely tuned, resulting in AURKA selective (5 and 7; 100-fold selective over FLT3), FLT3 selective (13; 30-fold selective over AURKA) and dual FLT3/AURKA selective (BPR1K871; IC50 = 19/22 nM) agents. BPR1K871 showed potent anti-proliferative activities in MOLM-13 and MV4-11 AML cells (EC50 ~ 5 nM). Moreover, kinase profiling and cell-line profiling revealed BPR1K871 to be a potential multi-kinase inhibitor. Functional studies using western blot and DNA content analysis in MV4-11 and HCT-116 cell lines revealed FLT3 and AURKA/B target modulation inside the cells. In vivo efficacy in AML xenograft models (MOLM-13 and MV4-11), as well as in solid tumor models (COLO205 and Mia-PaCa2), led to the selection of BPR1K871 as a preclinical development candidate for anti-cancer therapy. Further detailed studies could help to investigate the full potential of BPR1K871 as a multi-kinase inhibitor.

Anti-influenza drug discovery: identification of an orally bioavailable quinoline derivative through activity- and property-guided lead optimization.

From a high-throughput screening (HTS) hit with inhibitory activity against virus-induced cytophathic in the low micromolar range, we have developed a potent anti-influenza lead through careful optimization without compromising the drug-like properties of the compound. An orally bioavailable compound was identified as a lead agent with nanomolar activity against influenza, representing a 140-fold improvement over the initial hit.

Anti-influenza drug discovery: structure-activity relationship and mechanistic insight into novel angelicin derivatives.

By using a cell-based high throughput screening campaign, a novel angelicin derivative 6a was identified to inhibit influenza A (H1N1) virus induced cytopathic effect in Madin-Darby canine kidney cell culture in low micromolar range. Detailed structure-activity relationship studies of 6a revealed that the angelicin scaffold is essential for activity in pharmacophore B, while meta-substituted phenyl/2-thiophene rings are optimal in pharmacophore A and C. The optimized lead 4-methyl-9-phenyl-8-(thiophene-2-carbonyl)-furo[2,3-h]chromen-2-one (8g, IC(50) = 70 nM) showed 64-fold enhanced activity compared to the high throughput screening (HTS) hit 6a. Also, 8g was found effective in case of influenza A (H3N2) and influenza B virus strains similar to approved anti-influenza drug zanamivir (4). Preliminary mechanistic studies suggest that these compounds act as anti-influenza agents by inhibiting ribonucleoprotein (RNP) complex associated activity and have the potential to be developed further, which could form the basis for developing additional defense against influenza pandemics.

Synthesis and evaluation of 3-aroylindoles as anticancer agents: metabolite approach.

BPR0L075 (2) is a potential anticancer drug candidate designed from Combretastatin A-4 (1) based on the bioisosterism principle. Metabolites of 2, proposed from in vitro human microsome studies, were synthesized, leading to the identification of metabolite-derived analogue 10 with 40-350 pM potency against various cancer cell lines. Insights gained from the major inactive metabolite of 2 led to the development of 29, with better pharmacokinetics and improved potency in the tumor xenograft model than 2.

Concise synthesis and structure-activity relationships of combretastatin A-4 analogues, 1-aroylindoles and 3-aroylindoles, as novel classes of potent antitubulin agents.

The synthesis and study of the structure-activity relationships of two new classes of synthetic antitubulin compounds based on 1-aroylindole and 3-aroylindole skeletons are described. Lead compounds 3, 10, and 14 displayed potent cytotoxicities with IC50 = 0.9-26 nM against human NUGC3 stomach, MKN45 stomach, MESSA uterine, A549 lung, and MCF-7 breast carcinoma cell lines. The inhibition of proliferation correlated with in vitro polymerization inhibitory activities. Structure-activity relationships revealed that 6-methoxy substitution of 3-aroylindoles and 5-methoxy substitution of 1-aroylindoles contribute to a significant extent for maximal activity by mimicking the para substitution of the methoxy group to the carbonyl group in the case of aminobenzophenones. Addition of a methyl group at the C-2 position on the indole ring exerts an increased potency. The 3,4,5-trimethoxybenzoyl moiety was necessary for better activity but not essential and can be replaced by 3,5-dimethoxybenzoyl and 3,4,5-trimethoxybenzyl moieties. We conclude that 1- and 3-aroylindoles constitute an interesting new class of antitubulin agents with the potential to be clinically developed for cancer treatment.

Synthesis and structure-activity relationships of 3-aminobenzophenones as antimitotic agents.

A new series of 3-aminobenzophenone compounds as potent inhibitors of tubulin polymerization was discovered based on the mimic of the aminocombretastatin molecular skeleton. Lead compounds 5 and 11, with alkoxy groups at the C-4 position of B-ring, were potent cytotoxic agents and inhibitors of tubulin polymerization through the binding to the colchicine-binding site of tubulin. The corresponding antitubulin activities of 5 and 11 were similar to or greater than combretastatin A-4 and AVE-8063. Replacement of the methoxy group with a chloro group in the B ring of aminobenzopheneones (3, 8, and 9) caused drastic decrease in cytotoxic and antitubulin activity except in compounds 4 and 10, which could result from a unique alignment between chloro and amino groups located at the para position to each other. SAR information revealed that introduction of an amino group at the C-3 position in B ring of benzophenones, in addition to a methoxy group at the C-4 position, plays an important role for maximal cytotoxicity.