Cellular Antiproliferative Activity Research Articles

Orally bioavailable styryl derivative of rohitukine-N-oxide inhibits CDK9/T1 and the growth of pancreatic cancer cells

The chromone alkaloid is one of the classical pharmacophores for cyclin-dependent kinases (CDKs) and represents the first CDK inhibitor to reach clinical trials. Rohitukine (1), a chromone alkaloid isolated from Dysoxylum binectariferum inspired the discovery of several clinical candidates. The N-oxide derivative of rohitukine occurs naturally, with no reports on its biological activity. Herein, we report isolation, biological evaluation, and synthetic modification of rohitukine N-oxide for CDK9/T1 inhibition and antiproliferative activity in cancer cells. Rohitukine N-oxide (2) inhibits CDK9/T1 (IC50 7.6 μM) and shows antiproliferative activity in the colon and pancreatic cancer cells. The chloro-substituted styryl derivatives, 2b, and 2l, inhibit CDK9/T1 with IC50 values of 0.17 and 0.15 μM, respectively. These derivatives display cellular antiproliferative activity in HCT 116 (colon) and MIA PaCa-2 (pancreatic) cancer cells with GI50 values of 2.5–9.7 μM with excellent selectivity over HEK293 (embryonic kidney) cells. Both analogs induce cell death in MIA PaCa-2 cells via inducing intracellular ROS production, reducing mitochondrial membrane potential, and inducing apoptosis. These analogs are metabolically stable in liver microsomes and have a decent oral pharmacokinetics in BALB/c mice. The molecular modeling studies indicated their strong binding at the ATP-binding site of CDK7/H and CDK9/T1.

9 Caged rucaparib: cancer directed delivery of PARPi

Poly (ADP-ribose) polymerase inhibitors (PARPi) have revolutionized the treatment of ovarian cancer, improving progression free survival in the upfront and recurrent setting. Unfortunately, due to side effects patients often require dose reductions or altogether discontinue PARPi therapy. Additionally, due to bone marrow toxicity, PARPi cannot be effectively combined with chemotherapy. Recently, it was demonstrated that a ferrous iron-activated MEK inhibitor can circumvent MEKi related toxicity in non-tumorigenic tissues. Therefore, we developed a ferrous iron-activated form of rucaparib to target cancer cells while mitigating PARPi toxicity. Normal cells maintain a lower concentration of intracellular labile ferrous iron (Fe(II)) as compared with cancer cells. We introduced an Fe(II)-sensitive 1,2,4-trioxolane moiety at a reactive amine in rucaparib, creating a Fe(II)-activatable form of rucaparib (TRX-Ruc). A negative control, Di-Ruc, that cannot be activated by Fe(II), was also synthesized. Both compounds were then tested for their ability to inhibit PARP using a cell-free PARP1 assay. Cellular antiproliferative activity was tested in UWB –/– (BRCA1- deficient ovarian cancer cells) using the CellTiterGlo viability assay, and intracellular inhibition of PARP was evaluated with a parylation Western blot. In the cell free PARP1 inhibitor assay, the IC50 of rucaparib was 2.9 nM while TRX-Ruc had significantly decreased potency, with an IC50 of 92.3 nM. Di-Ruc had no inhibitory effect as expected. UWB –/– viability was decreased by rucaparib and TRX-Ruc with an equivalent IC50 of approximately 300 nM while Di-Ruc only had an effect at very high concentrations. To ensure the mechanism of TRX-Ruc on cell viability was due to PARP inhibition, a parylation western was performed. Both rucaparib and TRX-Ruc inhibited parylation while the negative control, Di-Ruc had only minimal effects. The addition of an Fe(II)-sensitive “TRX” moiety on rucaparib significantly reduces the biochemical activity of rucaparib in the absence of Fe(II). However, in an ovarian cancer cell line, the activity of TRX-ruc is restored leading to decreased cell viability, which we demonstrated was realized through the inhibition of PARP. This new Fe(II)-sensitive compound is an exciting and novel approach to deliver PAPRi specifically to cancer cells, potentially reducing toxicity and allowing effective combinations of PARPi with other cytotoxic therapies.

AF8c, a Multi-Kinase Inhibitor Induces Apoptosis by Activating DR5/Nrf2 via ROS in Colorectal Cancer Cells.

Simple SummaryAF8c, a lapatinib hybrid quinazoline-based EGFR/HER2 inhibitor, was chosen to scrutinize its antiproliferative activity in colorectal cancer (CRC) cells. We found that AF8cinduced apoptosis in CRC cells via diverse mechanisms. In addition to inhibiting the phosphorylation of the ErbB family, AF8c increased the mRNA and protein levels of death receptor 5 (DR5) in vitro and in vivo. In addition, AF8c upregulated several ER stress proteins and the redox-sensitive nuclear respiratory factor 2 alpha subunit (Nrf2) in a p53-dependent manner. We also found that the AF8c-induced increase in the levels of Nrf2, DR5, and apoptosis was diminished by p53 downregulation or knockdown. Furthermore, AF8c showed higher antiproliferative activity than lapatinib in the CRC mouse model in vivo. Therefore, our results suggest AF8c as a highly effective polypharmacological small molecule with an encouraging safety profile, both in vitro and in vivo, for further evaluation as a treatment of CRC.Our team has previously reported a series of quinazoline-based lapatinib hybrids as potent kinase-targeting anticancer agents. Among them, AF8c showed a relatively safe profile in colorectal cancer (CRC) cells. In this study, we delineate a novel anticancer activity of AF8c in CRC cells. AF8c mediated p53-dependent apoptosis of CRC cells via the generation of endoplasmic reticulum (ER) stress and reactive oxygen species (ROS), as well as activation of nuclear respiratory factor 2 alpha subunit (Nrf2) and death receptor 5 (DR5), among others. The silencing of DR5 attenuated the expression levels of Nrf2 and partially inhibited AF8c-induced apoptosis. Additionally, upregulation of Nrf2 by AF8c evoked apoptosis through a decrease in antioxidant levels. Treatment of a CRC mice model with AF8c also resulted in the upregulation of DR5, Nrf2, and CHOP proteins, subsequently leading to a significant decrease in tumor burden. In comparison with lapatinib, AF8c showed higher cellular antiproliferative activity at the tested concentrations in CRC cells and synergized TRAIL effects in CRC cells. Overall, our results suggest that AF8c-induced apoptosis may be associated with DR5/Nrf2 activation through ER stress and ROS generation in CRC cells. These findings indicate that AF8c represents a promising polypharmacological molecule for the treatment of human CRC.

Abstract 5691: Preclinical evaluation of TFX05-01, a selective AKR1C3- targeted prodrug for solid tumor

Abstract Objective: Aldo-keto reductase 1C3 (AKR1C3), is a member of the aldo-keto reductase superfamily, catalyzing the NADP(H)-dependent stereospecific reduction of various aldehydes and ketones. AKR1C3 is overexpressed in a variety of cancer cells, including hepatocellular carcinoma (HCC), castration-resistant prostate cancer (CRPC), and leukemia cells. This study is to investigate the in vitro and in vivo antitumor activity of TFX05-01, a selective AKR1C3-activated anticancer prodrug, in preclinical models of AKR1C3 overexpressing cells. The studies provide solid foundation for nomination of TFX05-01 for clinical trials. Method: Enzymatic activation of TFX05-01 was investigated in vitro using recombinant human AKR1C3. Cellular anti-proliferative activity was evaluated with a range of AKR1C3 overexpressed or low expressed cell lines. The in vivo antitumor activity was evaluated in various CDX mouse models with high expression of AKR1C3, including HepG2 and castration-resistant prostate VCaP, as well as PDX leukemia models Result: TFX05-01 is a prodrug which selectively releases a DNA alkylating agent (TFX05-01A) upon exposure to AKR1C3. TFX05-01 inhibited cell proliferation in several AKR1C3 overexpressed HCC cell lines with an IC50 ≤ 100 nM. In contrast, TFX05-01 showed much lower anti-proliferative activity in low or no AKR1C3 expressed cells with an IC50 value greater than 1 μM. The cytotoxic potency of TFX05-01 in cancer cells correlates with the level of AKR1C3 expression, and the cytotoxic activity of TFX05-01 was inhibited when used in combination with a specific AKR1C3 inhibitor (IC50: 0.7 nM without inhibitor vs 188 nM with inhibitor in SNU-878 cells). TFX05-01 showed antitumor efficacy in AKR1C3 highly expressed HepG2 subcutaneously implanted xenograft model (TGI = 97% @2 mpk, QW, 3 doses IV). Concomitant PK studies showed that the concentration of active metabolites (TFX05-01A) in tumor was significantly higher (15~50 times) than that in plasma, which correlates with the selective release of the active DNA alkylating agent upon exposure to AKR1C3 in tumor tissues. Conclusion: TFX05-01 is a novel selective AKR1C3-activated prodrug, which is different from traditional non-selective alkylating agents for cancer therapy. Preclinical studies have shown profound in vivo efficacy of TFX05-01 in AKR1C3 overexpressed mouse tumor xenograft models without marked toxicity. TFX05-01 represents a novel treatment option for AKR1C3 expressing solid cancers. Preclinical GLP safety evaluations were promising and TFX05-01 was nominated for clinical trials. Citation Format: Charles Z Ding, Zhe Cai, Wei Sha. Preclinical evaluation of TFX05-01, a selective AKR1C3- targeted prodrug for solid tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5691.

Discovery of Indole-Containing Benzamide Derivatives as HDAC1 Inhibitors with In Vitro and In Vivo Antitumor Activities

Targeting histone deacetylases (HDACs) has become an important focus in cancer inhibition. The pharmacophore of HDAC inhibitors (HDACis) reported so far is composed of three parts: a zinc-binding group (ZBG), a hydrophobic cavity-binding linker, and a surface-recognition cap interacting with HDAC surface located at the rim of active site cavity. This study aims to discover novel HDAC1 inhibitors with potent antitumor activities through modifying the cap and ZBG based on the structures of two marketed oral HDACis: chidamide and entinostat (MS-275). In this work, a series of benzamide derivatives were designed, synthesized, and evaluated for their antitumor activity. The structures of novel compounds were confirmed by 1H NMR (nuclear magnetic resonance) and ESI-MS (electrospray ionization mass spectrometry), and all target compounds were tested in both HDAC1 enzymatic inhibitory activity and cellular antiproliferative activity. Our data showed that the potent compound 3j exhibited good HDAC1 enzyme inhibitory activity and high antitumor cell proliferation activity against a selected set of cancer cells (PC-3, HCT-116, HUT-78, Jurkat E6–1, A549, Colo205, and MCF-7 cells) with no observed effects on human normal cells. In particular, compound 3j inhibited HDAC1 over the other tested HDAC isoforms (HDAC2, HDAC6, and HDAC8). Encouraged by this, the safety characteristics, molecular docking, preliminary pharmacokinetic characteristics, and antitumor effect in vivo of compound 3j were further investigated. Our data showed that compound 3j demonstrated acceptable safety profiles and favorable oral pharmacokinetic properties. Moreover, compound 3j could bind well with HDAC1 and showed significant antitumor activity in a PC-3 tumor xenograft model in vivo, though not as potent as positive control entinostat (MS-275). In summary, 3j might have therapeutic potential for the treatment of human cancers.

Discovery of Potent Orally Bioavailable WD Repeat Domain 5 (WDR5) Inhibitors Using a Pharmacophore-Based Optimization.

WD repeat domain 5 (WDR5) is a nuclear scaffolding protein that forms many biologically important multiprotein complexes. The WIN site of WDR5 represents a promising pharmacological target in a variety of human cancers. Here, we describe the optimization of our initial WDR5 WIN-site inhibitor using a structure-guided pharmacophore-based convergent strategy to improve its druglike properties and pharmacokinetic profile. The core of the previous lead remained constant while a focused SAR effort on the three pharmacophore units was combined to generate a new in vivo lead series. Importantly, this new series of compounds has picomolar binding affinity, improved cellular antiproliferative activity and selectivity, and increased kinetic aqueous solubility. They also exhibit a desirable oral pharmacokinetic profile with manageable intravenous clearance and high oral bioavailability. Thus, these new leads are useful probes toward studying the effects of WDR5 inhibition.

Ruthenium-based assemblies incorporating tetrapyridylporphyrin panels: a photosensitizer delivery strategy for the treatment of rheumatoid arthritis by photodynamic therapy.

Ruthenium-based assemblies containing tetrapyridylporphyrins (TPyP) in their structure have been evaluated as photosensitizers (PS) to treat rheumatoid arthritis (RA) by photodynamic therapy (PDT). TPyP is useless by itself as a PS due to its low solubility in biological media, however, incorporated in metallacages it can be internalized in cells. The study shows a cellular antiproliferative activity in fibroblast-like synoviocyte (FLS) in the lower nanomolar range in the presence of light, and no dark toxicity at 1 μM concentration, thus having an excellent photoactivity index. The presence of diamagnetic (Zn2+) and paramagnetic (Co2+) metals in the center of TPyP impairs the effectiveness of PDT, showing no (Co) or reduced (Zn) photoactivity. A total of five metallacages with different structural characteristics have been evaluated, and our results suggest that the incorporation of PS in metalla-assemblies is not only an elegant method to increase solubility in biological media for TPyP but also appears to be an efficient hybrid system to treat RA by PDT.

Discovery of quinazolinyl-containing benzamides derivatives as novel HDAC1 inhibitors with in vitro and in vivo antitumor activities

A series of quinazolinyl-containing benzamide derivatives were designed, synthesized and evaluated for their in vitro histone deacetylase 1 (HDAC1) inhibitory activities. Compounds 11a surpassed the known class I selective HDAC inhibitor MS-275 in both HDAC1 enzymatic inhibitory activity and cellular anti-proliferative activity against a selected set of cancer cell types (Hut78, K562, Hep3B and HCT116 cells) with no observed effects on human normal cells. In particular, compound 11a inhibited HDAC1 over the other tested HDACs isoforms (HDAC2, HDAC6 and HDAC8) with acceptable safety profiles. Moreover, compound 11a displayed favorable oral pharmacokinetic properties and showed significant antitumor activity in the A549 tumor xenograft model in vivo.

Abstract 1970: Preclinical candidate TQB3824, a small molecule inhibitor of CDC7, shows strong antitumor efficacy in colorectal and pancreatic tumor models

Abstract Objective: Cell division cycle 7 (CDC7), a receptor serine/threonine kinase which features high-affinity with protein DBF4, plays an important role in DNA replication and DNA damage response via MCM2 phosphorylation. CDC7 has been reported to be up-regulated by about 50% in various human cancers and is being investigated as a therapeutic target in clinical trials. The purpose of this study is to investigate the in-vitro and in-vivo antitumor activities of TQB3824, a small molecule of CDC7 kinase inhibitor, in preclinical models with CDC7 overexpression. Method: Kinase inhibition activities of TQB3824 were determined with CDC7/DBF4 kinase assays. Cellular anti-proliferative activities were evaluated in COLO205 cell line and NCI-H226 cell line, which features CDC7 overexpression and no CDC7 expression, respectively. Three CDX models, colorectal cancer COLO205/SW620 and pancreatic cancer CAPAN-1 with KRAS mutation, were used to test the efficacy of TQB-3824 in vivo. Result: TQB3824 showed potent activities in both kinase inhibition and COLO205 cell anti-proliferation, with IC50 of 2.9 nM and 14.5 nM, separately. In contrast, TQB3824 showed much weaker anti-proliferative activity in NCI H226 cells with IC50 of 8154 nM. TQB3824 displayed strong antitumor efficacy in CDC7 highly expressed colorectal cancer CDX model COLO205 (TGI = 77% @5 mpk, BID), SW620 CDX model (TGI = 100% @5 mpk, BID), and pancreatic cancer CAPAN-1 CDX model (TGI = 115% @6 mpk, BID). Conclusion: We have identified a novel potent CDC7 inhibitor TQB3824, which shows high antitumor efficacy in CDC7 overexpressed solid tumor models. TQB3824 represents a promising clinical candidate for treating solid tumors with high CDC7 expression. Citation Format: Gang Li, Xiquan Zhang, Ling Yang, Xin Tian, Zhong xiong, Lihong Hu, Yuanfeng xia, Chi-chung chan, Charles Z. Ding, Shuhui Chen. Preclinical candidate TQB3824, a small molecule inhibitor of CDC7, shows strong antitumor efficacy in colorectal and pancreatic tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1970.

Abstract 2054: Characterization of TQB3823, a differentiated PARP inhibitor with anti-tumor activity in BRCA-deficiency cancer models

Abstract Objective: Homology-directed repair (HDR) pathway is the major DNA double-strand break repair pathway. BRCA-deficiency impairs this pathway, and combination with Poly(ADP-ribose) polymerase (PARP) inhibition results in cell death. This process is known as “synthetic lethality”. A proportion of breast cancer, ovarian cancer and other solid tumor patients carrying BRCA-mutated gene receive benefits from PARP inhibitors. In this study, we present in vitro activity and in vivo efficacy data of a novel small molecule PARP inhibitor, TQB3823 to support it as our clinical candidate. Method: Enzyme inhibition activities of TQB3823 were determined in PARP1/PARP2/Tankyrase 1 assays. Cellular anti-proliferative activity and selectivity were evaluated in MDA-MB-436 cell line with BRCA1 mutation and BRCA wild type MDA-MB-231 cell line. Antitumor efficacy of TQB3823 was investigated in BRCA1 mutated MDA-MB-436 breast cancer CDX model. Result: TQB3823 showed high potency and selectivity at both enzymatic and cellular level. IC50 of TQB3823 in PARP1/PARP2/Tankyrase 1 assays are 2.8/0.9/629.3 nM, respectively. It inhibited proliferation of BRCA1 mutant MDA-MB-436 cell with IC50 of 9.6 nM. In contrast, TQB3823 showed little anti-proliferative activity in BRCA-wild type MDA-MB-231 cell with IC50 >10 μM. TQB3823 demonstrated antitumor efficacy in dose dependent fashions with tumor regression was observed at 25 mg/kg in MDA-MB-436 CDX model. The level of antitumor effects was superior to niraparib at the same dose in the same study. DNA trapping experiments revealed similar potency to olaparib indicative of low toxicity. Conclusion: We have identified a novel, potent and selective PARP inhibitor TQB3823, which inhibits the proliferation of BRCA mutant cells but spares the wild type cells. In vivo study in a BRCA-deficiency tumor model confirms the high in vivo efficacy of this molecule. In conclusion, TQB3823 represents a promising differentiated clinical candidate for treating solid cancers with homology directed repair. Citation Format: Hu Yanbin, Zhang Xiquan, Yang Ling, Tian Xin, Li Gang, Hu Lihong, Charles Z. Ding, Xia Yuanfeng, Li Wei, Yin Shanshan, Chen Ying, Wu Songliang, Chen Shuhui. Characterization of TQB3823, a differentiated PARP inhibitor with anti-tumor activity in BRCA-deficiency cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2054.

Preclinical evaluation of WXSH0011, a selective small molecule dual inhibitor of FGFR/c-Met.

e15641 Background: FGFRs (fibroblast growth factor receptors) are a family of receptor tyrosine kinases. c-Met is a receptor tyrosine kinase with a high-affinity ligand, hepatocyte growth factor/scatter factor (HGF/SF). Aberrations in the FGFR pathway are associated with a variety of human cancers. c-Met and HGF have been implicated in carcinogenesis and metastatic tumor progression because of their ability to enhance angiogenesis, cancer cell proliferation, migration, and invasion. WXSH0011 is an orally bioavailable novel potent and selective FGFR/c-Met dual kinase inhibitor, which displayed significant antitumor activity in preclinical models of solid cancer with FGFRs/c-Met overexpression. Preclinical studies demonstrated that WXSH0011 has potential to be effective in solid cancer, such as HCC and Gastric. Methods: Kinase inhibiting activity of WXSH0011 was determined with FGFRs/ c-Met kinase assays. Cellular anti-proliferative activity was evaluated with FGFR overexpressed NCl-H1581, SNU-16, RT112/84, Hep3B, c-Met overexpressed MHCC97H, EBC-1 cell line and FGFR, c-Met both overexpressed PDC cell line (LI-03-0141 (HCC) and ST-02-0063 (Gastric) PDC). The antitumor activity of WXSH0011 was evaluated in vivo cell derived-xenograft (CDX) models of Gastric Cancer SNU-16 and HCC Hep3B. Results: WXSH0011 displayed potent kinase inhibiting activity for FGFR1/2/3/4 and c-Met/ with IC50 0.19 nM/0.21 nM/1.15 nM/1.49 nM /15.9 nM, respectively. WXSH0011 inhibited cell proliferation in FGFR overexpressed NCl-H1581, SNU-16, RT112/84, Hep3B with IC50 10 nM, 3 nM, 2 nM, 63 nM, c-Met overexpressed MHCC97H and EBC-1 cell line with IC50 0.832 µM, 0.52 µM, FGFR, c-Met dual overexpressed LI-03-0141 (HCC) and ST-02-0063 (Gastric) PDC with IC50 0.19 µM, 0.08 µM. Kinome panel screening revealed that WXSH0011 demonstrated good overall kinase selectivity. WXSH0011 showed antitumor efficacy in gastric cancer SNU-16 (TGI = 100% @5 mpk, BID), as well as in the liver cancer Hep3B model (TGI = 86.92% @20 mpk, QD). Conclusions: We have identified a novel selective and potent dual FGFR/c-Met inhibitor WXSH0011. Preclinical studies shows antitumor efficacy of WXSH0011 in gastric and liver cancer models. It is currently at IND submission stage.

Preclinical evaluation of SC0245, a small molecule inhibitor of ATR kinase.

e15642 Background: The ataxia telangiectasia and Rad3-related (ATR) kinase is a member of the phosphoinositide 3-kinase related kinase (PIKK) family. ATR plays an important role in maintaining genome integrity during DNA replication through the activation of Chk1, and regulation of the DNA damage response (DDR). Replication stress (RS) is a major source of genomic instability in cancer, and targeting the RS-response kinase ATR has emerged as a promising antitumor approach. The purpose of this study was to investigate the antitumor activity of SC0245, a small molecule inhibitor of ATR kinase, in preclinical models of ATM pathway or ARID1A deficient solid tumors. Methods: The kinase inhibiting activity of SC0245 was determined using the ATR/ATRIP(h) complex assays. The cellular anti-proliferative activity was evaluated with tumor cells which was ATM pathway or ARID1A deficient. The in vivo antitumor activity of SC0245 was evaluated in ATM pathway or ARID1A deficient cell-derived xenograft (CDX) mouse models of gastric cancer (SNU-601) and colorectal adenocarcinoma (LoVo). Results: SC0245 displayed potent kinase inhibiting activity for ATR/ATRIP complex with IC50 14 nM, and had outstanding selectivity in the 104 onco-kinase panels. SC0245 significantly inhibited cell proliferation in ATM pathway or ARID1A deficient LoVo cells with IC50 0.163 μM, SNU-601 cells with IC50 0.218 μM. SC0245 showed excellent pharmacokinetics (PK) features with oral bioavailability ( > 80%) in mouse, rat and dog. Moreover, in the SNU601 and LoVo CDX mouse models, SC0245 oral administration significantly inhibited tumor growth, with better efficacy than AZD6738. Conclusions: SC0245, a novel potent ATR kinase inhibitor, has marked antitumor efficacy in the ATM pathway or ARID1A deficient solid tumor animal models, and has outstanding PK properties. SC0245 represents a promising clinical candidate for treating solid cancers, such as gastric and colorectal cancers.

Preclinical evaluation of SC0191, a small molecule inhibitor of Wee1 kinase.

e15637 Background: TP53 mutation is common in cancer cells, especially in small cell lung cancer (SCLC) and pancreatic cancer (PC). The G1 checkpoint function is lost in these cancer cells, which more rely on G2 checkpoint to repair damaged DNA. Wee1 is a serine/threonine kinase, which phosphorylates the Tyr15 locus of CDC2, inhibits the activity of CDC2, and stays in the G2 phase. Wee1 inhibition can promote the cells with DNA damage into the M phase, thus driving the TP53 mutant cancer cells to apoptosis. The purpose of this study was to investigate the in vitro and in vivo antitumor activity of SC0191, a small molecule inhibitor of Wee1 kinase, in preclinical models of SCLC and PC with TP53 mutation. Methods: The kinase inhibiting activity of SC0191 was determined using the Wee1 kinase assays. The cellular anti-proliferative activity was evaluated with TP53 mutant NCI-H446 SCLC and BxPC-3 PC cell lines. The in vivo antitumor activity of SC0191 was evaluated in the NCI-H446 and BxPC-3 cells-derived xenograft (CDX) mouse models, respectively. Results: SC0191 displayed potent kinase inhibiting activity for Wee1 with IC50 22.3 nM. SC0191 significantly inhibited tumor cell proliferation in TP53 mutant NCI-H446 cells with IC50 231.1 nM and BxPC-3 cells with IC50 223.8 nM. Moreover, SC0191 oral administration showed significant antitumor efficacy which was better than AZD1775, in the NCI-H446 and BxPC-3 CDX mouse models, respectively. Conclusions: A novel Wee1 inhibitor, SC0191, has demonstrated excellent antitumor efficacy in TP53 mutant solid cancer preclinical studies, and represents a promising clinical candidate for treating solid tumors, such as SCLC and PC.

Discovery of coumarin derivatives as potent and selective cyclin-dependent kinase 9 (CDK9) inhibitors with high antitumour activity

Specific inhibition of CDK9 is considered a promising strategy for developing effective anticancer therapeutics. However, most of the reported CDK9 inhibitors are still at an early stage of development and lack selectivity against other CDKs. Herein, we discovered coumarin derivative 30i as a potent CDK9 inhibitor with high selectivity (8300-fold over CDK7). Binding mode analysis illustrated that the substituent coumarin moiety is a critical group for CDK9 selectivity by occupying a flexible hinge/αD region, which is sterically hindered in other CDKs. Compound 30i showed excellent cellular antiproliferative activity, moderate pharmacokinetic property and low hERG inhibition. Moreover, 30i significantly induced tumour growth inhibition in a dose-dependent manner without causing an obvious loss of body weight in an MV4-11 xenograft mice model. Altogether, these results suggest that 30i may serve as a potential acute myeloid leukaemia (AML) therapeutics by selectively targeting CDK9.

Novel 1H-pyrazolo[3,4-d]pyrimidin-6-amino derivatives as potent selective Janus kinase 3 (JAK3) inhibitors. Evaluation of their improved effect for the treatment of rheumatoid arthritis.

Selective JAK3 inhibitors have been shown to have a potential benefit in the treatment of autoimmune disorders. Here we report the identification of a series of pyrazolopyrimidine derivatives as potent JAK3 inhibitors that exploit a unique cysteine (Cys909) residue in JAK3. Most of these compounds (13k, 13n and 13t), displayed stronger anti-JAK3 kinase activity and selectivity than tofacitinib. Furthermore, the most active inhibitor 13t (IC50=0.1nM), also exhibited favourable selectivity for JAK3 in a panel of 9 kinases which contain the same cysteine. In a series of cytokinestimulated cellular analysis, compound 13t, could potently block the JAK3-STAT signaling pathway. Further biological studies, including cellular antiproliferative activity assays and a rat adjuvant-induced arthritis model for in vivo evaluation, also indicated its efficacy and low toxicity in the treatment of rheumatoid arthritis. The results of these experimental explorations suggested that 13t is a promising lead compound for the development of selective JAK3 inhibitor with therapeutic potential in rheumatoid arthritis.

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.

Facile synthesis and anti-proliferative activity evaluation of quinoxaline derivatives

A series of “drug-like” compounds based on quinoxaline scaffold with arylsulfonyl hydrazinyl, arylformyl hydrazinyl or arylsulfonyl groups at C-2 and aryloxy groups at C-3, were synthesized in 4 or 5 steps involving cyclization, chlorination and coupling reactions. Cellular anti-proliferative activities of these quinoxaline derivatives in vitro were determined, which revealed that the inhibitory potency and selectivity of 6f was comparable to that of the positive control.

Comparative Assessment of Phenolic Profiles, Cellular Antioxidant and Antiproliferative Activities in Ten Varieties of Sweet Potato (Ipomoea Batatas) Storage Roots.

Sweet potato is the sixth most important crop widely cultivated around the world with abundant varieties. Different varieties gain different phenolic profiles which has drawn researchers’ attention for its unique health benefits. Our study evaluated the phenolic profiles, total and cellular antioxidant activities, antiproliferative activities, and cytotoxicity in 10 cultivated varieties of sweet potato in different colours. Among fourteen metabolites detected in our study, hyperoside, ferulic acid and caffeic acid were considered as prominent in SPSRs. According to the principle component analysis, phytochemical composition of HX22, YS15 and YS7 was quite similar. The results also evidenced that purple-fleshed varieties, such as YS43, YZ7 and YY153, have higher total phenolics content and corresponding stronger total antioxidant capacities as well as cellular antiproliferative activities against human liver cancer HepG2 cells than other varieties. The extremely significant correlation between phenolics and total antioxidant activity was also revealed by Pearson correlation analysis (p < 0.05). However, no significant relevance was found between intracellular antioxidant activity and total phenolic content or flesh colour of sweet potatoes.

Identification and Assessments of Novel and Potent Small-Molecule Inhibitors of EED-EZH2 Interaction of Polycomb Repressive Complex 2 by Computational Methods and Biological Evaluations.

Polycomb repressive complex 2 (PRC2) is an attractive drug target for anti-cancer treatment. Among the three core subunits (EZH2, EED and SUZ12) of PRC2, EZH2 is the catalytic subunit that methylates histone H3 lysine 27 (H3K27), while EED is the regulatory subunit. Besides the small-molecule inhibitors of EZH2, those targeting the protein-protein interaction (PPI) between EZH2 and EED have also been reported. Here, for the first time, we have identified the key residues that contributed most to the EED-EZH2 binding affinity by molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) calculations based on the 200 ns molecular dynamics simulation. Moreover, we report the identification of two novel and potent small-molecule inhibitors (35 and 49) of EZH2-EED interaction (bottom interaction surface) by virtual screening and biological evaluations. Binding modes of the two identified molecules with EED were probed by molecular docking. Additionally, 35 and 49 displayed cellular antiproliferative activity against diffuse large B-cell lymphoma (DLBCL) cancer cell line Toledo whose cell growth was driven by aberrant PRC2 activity. Our findings have provided structural insights for the design of novel EZH2-EED interaction inhibitors to regulate the activity of PRC2 complex.

A fluorine scan on the Zn2+-binding thiolate side chain of HDAC inhibitor largazole: Synthesis, biological evaluation, and molecular modeling

Based on the unique role of a common unit in a family of sulfur-containing natural histone deacetylases (HDACs) inhibitors, we have chosen largazole as an example of these inhibitors and adopted a “fluorine scan” strategy towards modification of this common unit. Thus a set of fluoro largazole analogues has been designed, synthesized and evaluated in enzymatic as well as cellular assays. The preliminary results indicate that introduction of fluorine at the various position of the unit has an important impact on the activity and selectivity of HDACs. Unlike other modifications which often led to significant reduction or complete loss of activity as reported in the literature, most of these fluoro thiols have displayed comparable or enhanced activity and selectivity in enzymatic assays. Two of the sulfhydryl esters have also exhibited excellent inhibitory activity in cellular assays with a few selected cell lines. The C19-fluorinated analogue has been further studied by immunoblot analysis, confirming that it is a potent selective class I HDAC inhibitor and supporting that the potent cellular antiproliferative activity is due to HDAC inhibition. The molecular docking study reveals that introducing fluorine at the C19 position does not change the original interactions, but might have made a subtle change in binding conformation, resulting in an obvious improvement in activity.