Revisiting Aurora Kinase B: A promising therapeutic target for cancer therapy.

Cancer continues to be a major health concern globally, although the advent of targeted therapy has revolutionized treatment options. Aurora Kinase B is a serine-threonine kinase that has been explored as an oncology therapeutic target for more than two decades. Aurora Kinase B inhibitors show promising biological results in in-vitro and in-vivo experiments. However, there are no inhibitors approved yet for clinical use, primarily because of the side effects associated with Aurora B inhibitors. Several studies demonstrate that Aurora B inhibitors show excellent synergy with various chemotherapeutic agents, radiation therapy, and targeted therapies. This makes it an excellent choice as an adjuvant therapy to first-line therapies, which greatly improves the therapeutic window and side effect profile. Recent studies indicate the role of Aurora B in some deadly cancers with limited therapeutic options, like triple-negative breast cancer and glioblastoma. Herein, we review the latest developments in Aurora Kinase B targeted research, with emphasis on its potential as an adjuvant therapy and its role in some of the most difficult-to-treat cancers.

Comprehensive insights into rheumatoid arthritis: Pathophysiology, current therapies and herbal alternatives for effective disease management.

Rheumatoid arthritis is a chronic autoimmune inflammatory disease characterized by immune response overexpression, causing pain and swelling in the synovial joints. This condition is caused by auto-reactive antibodies that attack self-antigens due to their incapacity to distinguish between self and foreign molecules. Dysregulated activity within numerous signalling and immunological pathways supports the disease's development and progression, elevating its complexity. While current treatments provide some alleviation, their effectiveness is accompanied by a variety of adverse effects that are inherent in conventional medications. As a result, there is a deep-rooted necessity to investigate alternate therapeutic strategies capable of neutralizing these disadvantages. Medicinal herbs display a variety of potent bioactive phytochemicals that are effective in the complementary management of disease, thus generating an enormous potency for the researchers to delve deep into the development of novel phytomedicine against autoimmune diseases, although additional evidence and understanding are required in terms of their efficacy and pharmacodynamic mechanisms. This literature-based review highlights the dysregulation of immune tolerance in rheumatoid arthritis, analyses the pathophysiology, elucidates relevant signalling pathways involved, evaluates present and future therapy options and underscores the therapeutic attributes of a diverse array of medicinal herbs in addressing this severe disease.

Novel hydroxybenzylamine-deoxyvasicinone hybrids as anticholinesterase therapeutics for Alzheimer's disease.

A series of novel 2-hydroxybenzylamine-deoxyvasicinone hybrid analogs (8a-8n) have been synthesized and evaluated as inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), and as inhibitors of amyloid peptide (Aß1-42) aggregation, for treatment of Alzheimer's disease (AD). These dual acting compounds exhibited good AChE inhibitory activities ranging from 0.34 to 6.35 µM. Analogs8g and 8n were found to be the most potent AChE inhibitors in the series with IC50values of 0.38 µM and 0.34 µM, respectively. All the analogs (8a-8n) exhibited weak BuChE inhibitory activities ranging from 14.60 to 21.65 µM. Analogs8g and 8n exhibited BuChE with IC50values of 15.38 µM and 14.60 µM, respectively, demonstrating that these analogs were greater than 40-fold more selective for inhibition of AChE over BuChE. Additionally, compounds8g and 8n were also found to be the best inhibitors of self-induced Aß1-42 peptide aggregation with IC50values of 3.91 µM and 3.22 µM, respectively; 8g and 8n also inhibited AChE-induced Aß1-42 peptide aggregation by 68.7% and 72.6%, respectively. Kinetic analysis and molecular docking studies indicate that analogs 8g and 8n bind to a new allosteric pocket (site B) on AChE. In addition, the observed inhibition of AChE-induced Aß1-42 peptide aggregation by 8n is likely due to allosteric inhibition of the binding of this peptide at the CAS site on AChE. Overall, these results indicate that 8g and 8n are examples of dual-acting lead compounds for the development of highly effective anti-AD drugs.

FCX-146, a potent allosteric inhibitor of Akt kinase in cancer cells: Lead optimization of the second-generation arylidene indanone scaffold.

Akt, a serine-threonine protein kinase, is regulated by class-I PI3K signaling. Akt regulates a wide variety of cell processes including cell proliferation, survival, and angiogenesis through serine/threonine phosphorylation of downstream targets including mTOR and glycogen-synthase-kinase-3-beta (GSK3ß). Targeting cancer-specific overexpression of Akt protein could be an efficient way to control cancer-cell proliferation. However, the ATP-competitive inhibitors are challenged by the highly conserved ATP binding site, and by competition with high cellular concentrations of ATP. We previously developed an allosteric inhibitor, 2-arylidene-4, 7-dimethyl indan-1-one (FXY-1) that showed promising activity against several lung cancer models. In this work, we designed a congeneric series of molecules based on FXY-1 and optimized lead based on computational, in vitro assays. Computational screening followed by enzyme-inhibition and cell-proliferation assays identified a derivative (FCX-146) as a new lead molecule with threefold greater potency than the parent compound. FCX-146 increased apoptosis in HL-60 cells, mediated in part through decreased expression of antiapoptotic Bcl-2 protein and increased levels of Bax-2 and Caspase-3. Molecular-dynamic simulations showed stable binding of FCX-146 to an allosteric (i.e., noncatalytic) pocket in Akt. Together, we propose FCX-146 as a potent second-generation arylidene indanone compound that binds to the allosteric pocket of Akt and potently inhibits its activation.

Pyrazolopyridine-based kinase inhibitors for anti-cancer targeted therapy.

The need for effective cancer treatments continues to be a challenge for the biomedical research community. In this case, the advent of targeted therapy has significantly improved therapeutic outcomes. Drug discovery and development efforts targeting kinases have resulted in the approval of several small-molecule anti-cancer drugs based on ATP-mimicking heterocyclic cores. Pyrazolopyridines are a group of privileged heterocyclic cores in kinase drug discovery, which are present in several inhibitors that have been developed against various cancers. Notably, selpercatinib, glumetinib, camonsertib and olverembatinib have either received approval or are in late-phase clinical studies. This review presents the success stories employing pyrazolopyridine scaffolds as hinge-binding cores to address various challenges in kinase-targeted drug discovery research.

Kinase inhibitor macrocycles: a perspective on limiting conformational flexibility when targeting the kinome with small molecules.

Methods utilized for drug discovery and development within the kinome have rapidly evolved since the approval of imatinib, the first small molecule kinase inhibitor. Macrocycles have received increasing interest as a technique to improve kinase inhibitor drug properties evident by the FDA approvals of lorlatinib, pacritinib, and repotrectinib. Compared to their acyclic counterparts, macrocycles can possess improved pharmacodynamic and pharmacokinetic properties. This review highlights clinical success stories when implementing macrocycles in kinase-based drug discovery and showcases that macrocyclization is a clinically validated drug discovery strategy when targeting the kinome.

An innovative approach for predicting pandemic hotspots in complex wastewater networks using graph theory coupled with fuzzy logic.

Early prediction of COVID-19 infected communities (potential hotspots) is essential to limit the spread of virus. Diagnostic testing has limitations in big populations because it cannot deliver information at a fast enough rate to stop the spread in its early phases. Wastewater based epidemiology (WBE) experiments showed promising results for brisk detection of 'SARS CoV-2' RNA in urban wastewater. However, a systematic and targeted approach to track COVID-19 virus in the complex wastewater networks at a community level is lacking. This research combines graph network (GN) theory with fuzzy logic to determine the chances of a specific community being a COVID-19 hotspot in a wastewater network. To detect 'SARS-CoV-2' RNA, GN divides wastewater network into communities and fuzzy logic-based inference system is used to identify targeted communities. For the propose of tracking, 4000 sample cases from Minnesota (USA) were tested based on various contributing factors. With a probability score of greater than 0.8, 42% of cases were likely to be designated as COVID-19 hotspots based on multiple demographic characteristics. The research enhances the conventional WBE approach through two novel aspects, viz. (1) by integrating graph theory with fuzzy logic for quick prediction of potential hotspot along with its likelihood percentage in a wastewater network, and (2) incorporating the uncertainty associated with COVID-19 contributing factors using fuzzy membership functions. The targeted approach allows for rapid testing and implementation of vaccination campaigns in potential hotspots. Consequently, governmental bodies can be well prepared to check future pandemics and variant spreading in a more planned manner. Supplementary Information: The online version contains supplementary material available at 10.1007/s00477-023-02468-3.

FLT3 inhibitors for acute myeloid leukemia: successes, defeats, and emerging paradigms.

FLT3 mutations are one of the most common genetic aberrations found in nearly 30% of acute myeloid leukemias (AML). The mutations are associated with poor prognosis despite advances in the understanding of the biological mechanisms of AML. Numerous small molecule FLT3 inhibitors have been developed in an effort to combat AML. Even with the development of these inhibitors, the five-year overall survival for newly diagnosed AML is less than 30%. In 2017, midostaurin received FDA approval to treat AML, which was the first approved FLT3 inhibitor in the U.S. and Europe. Following, gilteritinib received FDA approval in 2018 and in 2019 quizartinib received approval in Japan. This review parallels these clinical success stories along with other pre-clinical and clinical investigations of FLT3 inhibitors.

Discovery of N-Trisubstituted Pyrimidine Derivatives as Type I RET and RET Gatekeeper Mutant Inhibitors with a Novel Kinase Binding Pose.

Mutations of the rearranged during transfection (RET) kinase are frequently reported in cancer, which make it as an attractive therapeutic target. Herein, we discovered a series of N-trisubstituted pyrimidine derivatives as potent inhibitors for both wild-type (wt) RET and RETV804M, which is a resistant mutant for several FDA-approved inhibitors. The X-ray structure of a representative inhibitor with RET revealed that the compound binds in a unique pose that bifurcates beneath the P-loop and confirmed the compound as a type I inhibitor. Through the structure-activity relationship (SAR) study, compound 20 was identified as a lead compound, showing potent inhibition of both RET and RETV804M. Additionally, compound 20 displayed potent antiproliferative activity of CCDC6-RET-driven LC-2/ad cells. Analysis of RET phosphorylation indicated that biological activity was mediated by RET inhibition. Collectively, N-trisubstituted pyrimidine derivatives could serve as scaffolds for the discovery and development of potent inhibitors of type I RET and its gatekeeper mutant for the treatment of RET-driven cancers.

Pyrazoloadenine Inhibitors of the RET Lung Cancer Oncoprotein Discovered by a Fragment Optimization Approach.

A fragment-based drug-discovery approach was used on a pyrazoloadenine fragment library to uncover new molecules that target the RET (REarranged during Transfection) oncoprotein, which is a driver oncoprotein in ∼2 % of non-small-cell lung cancers. The fragment library was screened against the RET kinase and LC-2/ad (RET-driven), KM-12 (TRKA-driven matched control) and A549 (cytotoxic control) cells to identify selective scaffolds that could inhibit RET-driven growth. An unsubstituted pyrazoloadenine fragment was found to be active on RET in a biochemical assay, but reduced cell viability in non-RET-driven cell lines (EC50 =1 and 3 µM, respectively). To increase selectivity for RET, the pyrazoloadenine was modeled in the RET active site, and two domains were identified that were probed with pyrazoloadenine fragment derivatives to improve RET affinity. Scaffolds at each domain were merged to generate a novel lead compound, 8 p, which exhibited improved activity and selectivity for the RET oncoprotein (A549 EC50 =5.92 µM, LC-2/ad EC50 =0.016 µM, RET IC50 =0.000326 µM).

Targeting Rearranged during Transfection in Cancer: A Perspective on Small-Molecule Inhibitors and Their Clinical Development.

Rearranged during transfection (RET) is a receptor tyrosine kinase essential for the normal development and maturation of a diverse range of tissues. Aberrant RET signaling in cancers, due to RET mutations, gene fusions, and overexpression, results in the activation of downstream pathways promoting survival, growth, and metastasis. Pharmacological manipulation of RET is effective in treating RET-driven cancers, and efforts toward developing RET-specific therapies have increased over the last 5 years. In 2020, RET-selective inhibitors pralsetinib and selpercatinib achieved clinical approval, which marked the first approvals for kinase inhibitors specifically developed to target the RET oncoprotein. This Perspective discusses current development and clinical applications for RET precision medicine by providing an overview of the incremental improvement of kinase inhibitors for use in RET-driven malignancies.

Targeted activity of the small molecule kinase inhibitor Pz-1 towards RET and TRK kinases.

We have recently described Pz-1, a benzimidazole-based type-2 RET and VEGFR2 inhibitor. Based on a kinome scan, here we show that Pz-1 is also a potent (IC50 < 1 nM) TRKA/B/C inhibitor. Pz-1 potently inhibited proliferation of human cancer cells carrying either RET- or TRKA oncoproteins (IC50 ~ 1 nM), with a negligible effect against RET- and TRKA-negative cells. By testing mutations, known to mediate resistance to other compounds, RET G810R/S, but not L730I/V, E732K, V738A and Y806N, showed some degree of resistance to Pz-1. In the case of TRKA, G595R and F589L, but not G667C, showed some degree of resistance. In xenograft models, orally administered Pz-1 almost completely inhibited RET- and TRKA-mutant tumours at 1-3 mg/kg/day but showed a reduced effect on RET/TRKA-negative cancer models. The activity, albeit reduced, on RET/TRKA-negative tumours may be justified by VEGFR2 inhibition. Tumours induced by NIH3T3 cells transfected by RET G810R and TRKA G595R featured resistance to Pz-1, demonstrating that RET or TRKA inhibition is critical for its anti-tumourigenic effect. In conclusion, Pz-1 represents a new powerful kinase inhibitor with distinct activity towards cancers induced by oncogenic RET and TRKA variants, including some mutants displaying resistance to other drugs.

Discovery of imidazo[1,2-a]pyridine-thiophene derivatives as FLT3 and FLT3 mutants inhibitors for acute myeloid leukemia through structure-based optimization of an NEK2 inhibitor.

FMS-like tyrosine kinase 3 (FLT3) with an internal tandem duplication (ITD) mutation has been validated as a driver lesion and a therapeutic target for acute myeloid leukemia (AML). Currently, several potent small-molecule FLT3 kinase inhibitors are being evaluated or have completed evaluation in clinical trials. However, many of these inhibitors are challenged by the secondary mutations on kinase domain, especially the point mutations at the activation loop (D835) and gatekeeper residue (F691). To overcome the resistance challenge, we identified a novel series of imidazo[1,2-a]pyridine-thiophene derivatives from a NIMA-related kinase 2 (NEK2) kinase inhibitor CMP3a, which retained inhibitory activities on FTL3-ITDD835V and FLT3-ITDF691L. Through this study, we identified the imidazo[1,2-a]pyridine-thiophene derivatives as type-I inhibitors of FLT3. Moreover, we observed compound 5o as an inhibitor displaying equal anti-proliferative activities against FLT3-ITD, FTL3-ITDD835Y and FLT3-ITDF691L driven acute myeloid leukemia (AML) cell lines. Meanwhile, the apoptotic effects of compound supported its mechanism of anti-proliferative action. These results indicate that the imidazo[1,2-a]pyridine-thiophene scaffold is promising for targeting acquired resistance caused by FLT3 secondary mutations and compound 5o is an interesting lead in this direction.

The Exploration of Chirality for Improved Druggability within the Human Kinome.

Chirality is important in drug discovery because stereoselective drugs can ameliorate therapeutic difficulties including adverse toxicity and poor pharmacokinetic profiles. The human kinome, a major druggable enzyme class has been exploited to treat a wide range of diseases. However, many kinase inhibitors are planar and overlap in chemical space, which leads to selectivity and toxicity issues. By exploring chirality within the kinome, a new iteration of kinase inhibitors is being developed to better utilize the three-dimensional nature of the kinase active site. Exploration into novel chemical space, in turn, will also improve drug solubility and pharmacokinetic profiles. This perspective explores the role of chirality to improve kinome druggability and will serve as a resource for pioneering kinase inhibitor development to address current therapeutic needs.

Discovery of SP-96, the first non-ATP-competitive Aurora Kinase B inhibitor, for reduced myelosuppression.

Aurora Kinase B is a serine-threonine kinase known to be overexpressed in several cancers, with no inhibitors approved for clinical use. Herein, we present the discovery and optimization of a series of novel quinazoline-based Aurora Kinase B inhibitors. The lead inhibitor SP-96 shows sub-nanomolar potency in Aurora B enzymatic assays (IC50 = 0.316 ± 0.031 nM). We identified the important pharmacophore features resulting in selectivity against receptor tyrosine kinases. Particularly, SP-96 shows >2000 fold selectivity against FLT3 and KIT which is important for normal hematopoiesis. This could diminish the adverse effect of neutropenia reported in the clinical trials of the Aurora B inhibitor Barasertib, which inhibits FLT3 and KIT in addition to Aurora B. Enzyme kinetics of SP-96 shows non-ATP-competitive inhibition which makes it a first-in-class inhibitor. Further, SP-96 shows selective growth inhibition in NCI60 screening, including inhibition of MDA-MD-468, a Triple Negative Breast Cancer cell line.

Pyrrolo[2,3-d]pyrimidine derivatives as inhibitors of RET: Design, synthesis and biological evaluation.

Gene fusions and point mutations of RET kinase are crucial for driving thoracic cancers, including thyroid cancer and non-small cell lung cancer. Various scaffolds based on different heterocycles have been synthesized and evaluated as RET inhibitors. In this work, we investigate pyrrolo[2,3-d]pyrimidine derivatives for inhibition of RET-wt, drug resistant mutant RET V804M and RET gene fusion driven cell lines. Several compounds were synthesized and the structure activity relationship was extensively studied to optimize the scaffold. Thieno[2,3-d]pyrimidine, a bioisostere of pyrrolo[2,3-d]pyrimidine, was also explored for the effect on RET inhibition. We identified a lead compound, 59, which shows low nanomolar potency against RET-wt and RET V804M. Further 59 shows growth inhibition of LC-2/ad cells which RET-CCDC6 driven. We also determined that 59 is a type 2 inhibitor of RET and demonstrated its ability to inhibit migration of tumor cells. Based on computational studies, we proposed a binding pose of 59 in RET pocket and have quantified the contributions of individual residues for its binding. Together, 59 is an important lead compound which needs further evaluation in biological studies.

Bioisosteric Discovery of NPA101.3, a Second-Generation RET/VEGFR2 Inhibitor Optimized for Single-Agent Polypharmacology.

RET receptor tyrosine kinase is a driver oncogene in human cancer. We recently identified the clinical drug candidate Pz-1, which targets RET and VEGFR2. A key in vivo metabolite of Pz-1 is its less active demethylated pyrazole analogue. Using bioisosteric substitution methods, here, we report the identification of NPA101.3, lacking the structural liability for demethylation. NPA101.3 showed a selective inhibitory profile and an inhibitory concentration 50 (IC50) of <0.003 µM for both RET and VEGFR2. NPA101.3 inhibited phosphorylation of all tested RET oncoproteins as well as VEGFR2 and proliferation of cells transformed by RET. Oral administration of NPA101.3 (10 mg/kg/day) completely prevented formation of tumors induced by RET/C634Y-transformed cells, while it weakened, but did not abrogate, formation of tumors induced by a control oncogene (HRAS/G12V). The balanced synchronous inhibition of both RET and VEGFR2, as well the resistance to demethylation, renders NPA101.3 a potential clinical candidate for RET-driven cancers.

Structural Characterization of the Aurora Kinase B "DFG-flip" Using Metadynamics.

Aurora kinase B (AKB), a Ser/Thr kinase that plays a crucial role in mitosis, is overexpressed in several cancers. Clinical inhibitors targeting AKB bind to the active DFG "in" conformation of the kinase. It would be beneficial, however, to understand if AKB is susceptible to type II kinase inhibitors that bind to the inactive, DFG "out" conformation, since type II inhibitors achieve higher kinome selectivity and higher potency in vivo. The DFG "out" conformation of AKB is not yet experimentally determined which makes the design of type II inhibitors exceedingly difficult. An alternate approach is to simulate the DFG "out" conformation from the experimentally determined DFG "in" conformation using atomistic molecular dynamics (MD) simulation. In this work, we employed metadynamics (MTD) approach to simulate the DFG "out" conformation of AKB by choosing the appropriate collective variables. We examined structural changes during the DFG-flip and determined the interactions crucial to stabilize the kinase in active and inactive states. Interestingly, the MTD approach also identified a unique transition state (DFG "up"), which can be targeted by small molecule inhibitors. Structural insights about these conformations is essential for structure-guided design of next-generation AKB inhibitors. This work also emphasizes the usefulness of MTD simulations in predicting macromolecular conformational changes at reduced computational costs.

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.

Catalyst free, C-3 functionalization of imidazo[1,2-a]pyridines to rapidly access new chemical space for drug discovery efforts.

Multicomponent reactions (MCRs) are robust tools for the rapid synthesis of complex, small molecule libraries for use in drug discovery and development. By utilizing MCR chemistry, we developed a protocol to functionalize the C-3 position of imidazo[1,2-a]pyridine through a three component, decarboxylation reaction involving imidazo[1,2-a]pyridine, glyoxalic acid, and boronic acid.