Evaluation of a multi-kinase inhibitor KRC-108 as an anti-tumor agent in vitro and in vivo

Recent synthetic strategies for the functionalization of fused bicyclic heteroaromatics using organo-Li, -Mg and -Zn reagents

This review highlights the use of functionalized organo-Li, -Mg and -Zn reagents for the construction and selective functionalization of 5- and 6-membered fused bicyclic heteroaromatics. Special attention is given to the discussion of advanced syntheses for the preparation of highly functionalized heteroaromatic scaffolds, including quinolines, naphthyridines, indoles, benzofurans, benzothiophenes, benzoxazoles, benzothiazoles, benzopyrimidines, anthranils, thienothiophenes, purine coumarins, chromones, quinolones and phthalazines and their fused heterocyclic derivatives. The organometallic reagents used for the desired functionalizations of these scaffolds are generally prepared in situ using the following methods: (i) through directed selective metalation reactions (DoM), (ii) by means of halogen/metal exchange reactions, (iii) through oxidative metal insertions (Li, Mg, Zn), and (iv) by transmetalation reactions (organo-Li and Mg transmetalations with ZnCl2 or ZnO(Piv)2). The resulting reactive organometallic reagents allow a wide range of C-C, C-N and C-X cross-coupling reactions with different electrophiles, employing in particular Kumada or Negishi protocols among other transition metal (Pd, Ni, Co, Cu, Cr, Fe, etc.)-catalyzed processes. In addition, key developments concerning selective metalation techniques will be presented, which rely on the use of RLi, LDA and TMP metal bases. These methods are now widely employed in organic synthetic chemistry and have proven to be particularly valuable for drug development programs in the pharmaceutical industry. New and improved protocols have resulted in many Li, Mg and Zn organyls now being compatible with functionalized aryl, heteroaryl, alkenyl, alkynyl and alkyl compounds even in the presence of labile functional groups, making these reagents well-suited for C(sp2)-C(sp2), C(sp2)-C(sp) and C(sp2)-C(sp3) cross-coupling reactions with fused heteroaryl halides. In addition, the use of some transition metal-catalyzed processes occasionally allows a reversed role of the reactants in cross-coupling reactions, providing alternative synthetic routes for the preparation of fused heteroaromatic-based bioactive drugs and natural products. In line with this, this article points to novel methods for the functionalization of bicyclic heteroaromatic scaffolds by organometallic reagents that have been published in the period 2010-2023.

Synthesis, Antimicrobial Activity, and Molecular Modeling Studies of Some Benzoxazole Derivatives

Background:

The need to develop novel antimicrobial agents is apparent as infectious diseases are increasing and resistance is rapidly developing against the drugs used in the treatment.

Objective:

This study aimed at the synthesis, antimicrobial susceptibility testing, and computational elucidation of the mechanism of action of benzoxazole derivatives. It also aimed to compare the results obtained in this study with the previous studies by our group. This would pave the way for designing novel molecules with better antimicrobial activity. The other goal was pharmacophore analysis and in silico ADMET analysis of them.

Methods:

In this study, synthesis, antimicrobial susceptibility testing, molecular docking, pharmacophore analysis, and ADMET prediction were carried out.

Results:

The antimicrobial activity studies demonstrated that the synthesized compounds were active against standard strains and clinical isolates at high concentrations. Then, the antimicrobial testing results were compared to similar benzoxazoles tested by our group previously. Benzoxazole derivatives without a methylene bridge between oxazole and phenyl ring were found to be more active than those with the methylene bridge. This was also confirmed by molecular modeling undertaken in this study. The computational results indicated that the antibacterial activity could be achieved by DNA gyrase inhibition. Pharmacophore analysis showed that hydrogen bond acceptor (HBA), hydrogen bond donor (HBD), and hydrophobicity features would contribute to the inhibition. In addition, in silico ADMET property investigation of the compounds exhibited that they had the desired pharmacokinetics.

Conclusion:

Although antibacterial activity by inhibiting DNA gyrase is selective, the synthesized compounds were active at much higher concentrations than the standards. Therefore, in prospective antimicrobial studies, it is better to focus on benzoxazole derivatives without the methylene bridge. Since the compounds had suitable in silico ADMET properties, screening them against the other pharmacologic activities should be carried out. It is recommended to support the molecular modeling results with in vitro or in vivo studies.

Characterization of KRC-108 as a TrkA Kinase Inhibitor with Anti-Tumor Effects

Tropomyosin receptor kinase A (TrkA) protein is a receptor tyrosine kinase encoded by the NTRK1 gene. TrkA signaling mediates the proliferation, differentiation, and survival of neurons and other cells following stimulation by its ligand, the nerve growth factor. Chromosomal rearrangements of the NTRK1 gene result in the generation of TrkA fusion protein, which is known to cause deregulation of TrkA signaling. Targeting TrkA activity represents a promising strategy for the treatment of cancers that harbor the TrkA fusion protein. In this study, we evaluated the TrkA-inhibitory activity of the benzoxazole compound KRC-108. KRC-108 inhibited TrkA activity in an in vitro kinase assay, and suppressed the growth of KM12C colon cancer cells harboring an NTRK1 gene fusion. KRC-108 treatment induced cell cycle arrest, apoptotic cell death, and autophagy. KRC-108 suppressed the phosphorylation of downstream signaling molecules of TrkA, including Akt, phospholipase Cγ, and ERK1/2. Furthermore, KRC-108 exhibited anti-tumor activity in vivo in a KM12C cell xenograft model. These results indicate that KRC-108 may be a promising therapeutic agent for Trk fusion-positive cancers.

Biological activity of 3-(2-benzoxazol-5-yl)alanine derivatives

Searching for new drugs is still a challenge for science, mainly because of civilization development and globalization which promote the rapid spread of diseases, which is particularly dangerous in the case of infectious ones. Moreover, readily available already known antibiotics are often overused or misused, possibly contributing to the increase in the number of multidrug-resistant microorganisms. A consequence of this is the need for new structures of potential drugs. One of them is a benzoxazole moiety, a basic skeleton of a group of fluorescent heterocyclic compounds already widely used in chemistry, industry, and medicine, which is also present in naturally occurring biologically active compounds. Moreover, synthetic benzoxazoles are also biologically active. Considering all of that, a large group of non-proteinogenic amino acids based on 3-(2-benzoxazol-5-yl)alanine skeleton was studied in search for new antimicrobial and anticancer agents. Screening tests revealed that antibacterial potential of 41 compounds studied is not very high; however, they are selective acting only against Gram-positive bacteria (B. subtilis). Moreover, almost half of the studied compounds have antifungal properties, also against pathogens (C. albicans). Most of studied compounds are toxic to both normal and cancer cells. However, in a few cases, toxicity to normal cells is much lower than for cancer cells indicating these compounds as future anticancer agents. The research carried out on such a large group of compounds allowed to establish a structure–activity relationship which enables to select candidates for further modifications, necessary to improve their biological activity and obtain a new lead structure with potential for therapeutic use.

Development of small-molecule tropomyosin receptor kinase (TRK) inhibitors for NTRK fusion cancers

Tropomyosin receptor kinase A, B and C (TRKA, TRKB and TRKC), which are well-known members of the cell surface receptor tyrosine kinase (RTK) family, are encoded by the neurotrophic receptor tyrosine kinase 1, 2 and 3 (NTRK1, NTRK2 and NTRK3) genes, respectively. TRKs can regulate cell proliferation, differentiation and even apoptosis through the RAS/MAPKs, PI3K/AKT and PLCγ pathways. Gene fusions involving NTRK act as oncogenic drivers of a broad diversity of adult and pediatric tumors, and TRKs have become promising antitumor targets. Therefore, achieving a comprehensive understanding of TRKs and relevant TRK inhibitors should be urgently pursued for the further development of novel TRK inhibitors for potential clinical applications. This review focuses on summarizing the biological functions of TRKs and NTRK fusion proteins, the development of small-molecule TRK inhibitors with different chemotypes and their activity and selectivity, and the potential therapeutic applications of these inhibitors for future cancer drug discovery efforts.

In vitro and in vivo pharmacokinetic characterization of LMT-28 as a novel small molecular interleukin-6 inhibitor

Objective

Interleukin-6 (IL-6) is a T cell-derived B cell stimulating factor which plays an important role in inflammatory diseases. In this study, the pharmacokinetic properties of LMT-28 including physicochemical property, in vitro liver microsomal stability and an in vivo pharmacokinetic study using BALB/c mice were characterized.

Methods

LMT-28 has been synthesized and is being developed as a novel therapeutic IL-6 inhibitor. The physicochemical properties and in vitro pharmacokinetic profiles such as liver microsomal stability and Madin-Darby canine kidney (MDCK) cell permeability assay were examined. For in vivo pharmacokinetic studies, pharmacokinetic parameters using BALB/c mice were calculated.

Results

The logarithm of the partition coefficient value (LogP; 3.65) and the apparent permeability coefficient values (P_app; 9.7×10⁻⁶ cm/s) showed that LMT-28 possesses a moderate-high cell permeability property across MDCK cell monolayers. The plasma protein binding rate of LMT-28 was 92.4% and mostly bound to serum albumin. The metabolic half-life (t_1/2) values of LMT-28 were 15.3 min for rat and 21.9 min for human at the concentration 1 μM. The area under the plasma drug concentration-time curve and C_max after oral administration (5 mg/kg) of LMT-28 were 302±209 h·ng/mL and 137±100 ng/mL, respectively.

Conclusion

These data suggest that LMT-28 may have good physicochemical and pharmacokinetic properties and may be a novel oral drug candidate as the first synthetic IL-6 inhibitor to ameliorate mammalian inflammation.

Insights into Current Tropomyosin Receptor Kinase (TRK) Inhibitors: Development and Clinical Application

The use of kinase-directed precision medicine has been heavily pursued since the discovery and development of imatinib. Annually, it is estimated that around ∼20 000 new cases of tropomyosin receptor kinase (TRK) cancers are diagnosed, with the majority of cases exhibiting a TRK genomic rearrangement. In this Perspective, we discuss current development and clinical applications for TRK precision medicine by providing the following: (1) the biological background and significance of the TRK kinase family, (2) a compilation of known TRK inhibitors and analysis of their cocrystal structures, (3) an overview of TRK clinical trials, and (4) future perspectives for drug discovery and development of TRK inhibitors.

Characterization of the aminopyridine derivative KRC-180 as a JAK2 inhibitor

Janus kinase 2 (JAK2) is a non-receptor tyrosine kinase that regulates the signal transducer and activator of transcription (STAT) signaling pathway. Deregulation of JAK2 signaling has previously been observed in hematologic malignancies, including erythroleukemia. In the present study, an aminopyridine derivative compound, KRC-180, exhibited direct inhibition of the JAK2 protein at the catalytic site, as demonstrated using in vitro kinase activity assays and docking analyses. In addition, KRC-180 reduced the phosphorylation of STAT3 and STAT5, downstream signaling molecules of JAK2. The growth of HEL92.1.7 erythroleukemia cells harboring a constitutively activated form of JAK2 was suppressed by KRC-180 treatment; KRC-180 induced apoptotic cell death and cell cycle arrest. The results of the present study indicate that KRC-180 is a JAK2 inhibitor with anti-leukemic properties.

Resistance to the c-Met inhibitor KRC-108 induces the epithelial transition of gastric cancer cells

Investigation of the mechanisms of resistance to targeted therapies is essential as resistance acquired during treatment may lead to relapse or refractoriness to the therapy. Our previous study identified the small molecule KRC-108 as a result of efforts to find an anticancer agent with c-Met-inhibitory activity. In the present study, the changes accompanying resistance to KRC-108 were investigated in the gastric cancer cell line MKN-45 and its KRC-108-resistant clones by western blot and immunofluorescence analyses. Increased expression of the c-Met protein was observed in KRC-108-resistant cells compared with that of the parental cells, and the phosphorylation of c-Met also increased in cell lines resistant to KRC-108. Resistance to the c-Met inhibitor was associated with cell morphological changes: MKN-45 parental cells, which had a round and poorly differentiated morphology, were altered to exhibit an epithelial cell-like phenotype in KRC-108-resistant clones. Consistent with the transition to an epithelial morphology, the expression of E-cadherin was increased in resistant cells. Using immunoprecipitation, an interaction between E-cadherin and the c-Met protein was observed in the KRC-108-resistant cells. Immunohistochemical analysis of human gastric carcinoma tissues revealed the co-expression of E-cadherin and c-Met. These results suggest that the epithelial transition in KRC-108-resistant cells is mediated by recruiting E-cadherin to c-Met protein. Thus, the present study identified a mechanism used by cancer cells to confer resistance to anticancer agents.

Effects of KRC-108 on the Aurora A activity and growth of colorectal cancer cells

Aurora A is involved in regulating multiple steps of mitosis. Over-expression of Aurora A is related to tumorigenesis and poor prognosis. KRC-108 is a novel multi-kinase inhibitor which has anti-tumor activity in vivo. In this study, we identified the inhibitory effects of KRC-108 on Aurora A kinase and growth-inhibitory characteristics of KRC-108. The in vitro kinase activity assay, immunoblot, and immunofluorescence analyses demonstrated that KRC-108 inhibited Aurora A activity. KRC-108 exhibited cytotoxicity against human colorectal cancer cell line HT-29. Colony formation assays showed that KRC-108 reduced the colony growth of HT-29 cells. KRC-108 also inhibited migration of HT-29 cells. The expression levels of cyclin B1 and CDC2 were decreased by KRC-108 in HT-29 cells. Cell cycle analysis and flow cytometry indicated that the inhibitory effects of KRC-108 on cell growth are due to induction of G2/M arrest and apoptosis by inhibition of Aurora A. KRC-108 induces cell-cycle arrest and apoptosis in colorectal cancer cell line by Aurora A inhibition. The reported in vivo anti-tumor effects of KRC-108 might partly be due to anti-Aurora A effects. This study suggests that KRC-108 has potential for development as an anti-tumor agent, although further studies are needed.

Inhibition of tumor growth and metastasis in non-small cell lung cancer by LY2801653, an inhibitor of several oncokinases, including MET

PURPOSE

Lung cancer is the leading cause of cancer-related death worldwide. Sustained activation, overexpression, or mutation of the MET pathway is associated with a poor prognosis in a variety of tumors, including non-small cell lung cancer (NSCLC), implicating the MET pathway as a potential therapeutic target for lung cancer. Previously, we reported on the development of LY2801653: a novel, orally bioavailable oncokinase inhibitor with MET as one of its targets. Here, we discuss the evaluation of LY2801653 in both preclinical in vitro and in vivo NSCLC models. Experimental Design/

RESULTS

Treatment with LY2801653 showed tumor growth inhibition in tumor cell lines and patient-derived tumor xenograft models as a single agent (37.4%-90.0% inhibition) or when used in combination with cisplatin, gemcitabine, or erlotinib (66.5%-86.3% inhibition). Mechanistic studies showed that treatment with LY2801653 inhibited the constitutive activation of MET pathway signaling and resulted in inhibition of NCI-H441 cell proliferation, anchorage-independent growth, migration, and invasion. These in vitro findings were confirmed in the H441 orthotopic model where LY2801653 treatment significantly inhibited both primary tumor growth (87.9% inhibition) and metastasis (64.5% inhibition of lymph node and 67.7% inhibition of chest wall). Tumor-bearing animals treated with LY2801653 had a significantly greater survival time (87% increase compared with the vehicle-treated mice). In the MET-independent NCI-H1299 orthotopic model, treatment with LY2801653 showed a significant inhibition of primary tumor growth but not metastasis.

CONCLUSIONS

Collectively, these results support clinical evaluation of LY2801653 in NSCLCs and suggest that differences in the MET activation of tumors may be predictive of response.