Design, synthesis and biological evaluation of novel 7H-pyrrolo[2,3-d]pyrimidine derivatives as potential FAK inhibitors and anticancer agents

FAK inhibitors in cancer, a patent review - an update on progress

INTRODUCTION

Focal adhesion kinase (FAK) is a cytoplasmic non-receptor tyrosine kinase over-expressed in various malignancies which is related to various cellular functions such as adhesion, metastasis and proliferation.

AREAS COVERED

There is growing evidence that FAK is a promising therapeutic target for designing inhibitors by regulating the downstream pathways of FAK. Some potential FAK inhibitors have entered clinical phase research.

EXPERT OPINION

FAK could be an effective target in medicinal chemistry research and there were a variety of FAKIs have been patented recently. Here, we updated an overview of design, synthesis and structure-activity relationship of chemotherapeutic FAK inhibitors (FAKIs) from 2017 until now based on our previous work. We hope our efforts can broaden the understanding of FAKIs and provide new ideas and insights for future cancer treatment from medicinal chemistry point of view.

Targeting focal adhesion kinase (FAK) for cancer therapy: FAK inhibitors, FAK-based dual-target inhibitors and PROTAC degraders

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, plays an essential role in regulating cell proliferation, migration and invasion through both kinase-dependent enzymatic function and kinase-independent scaffolding function. The overexpression and activation of FAK is commonly observed in various cancers and some drug-resistant settings. Therefore, targeted disruption of FAK has been identified as an attractive strategy for cancer treatment. To date, numerous structurally diverse inhibitors targeting distinct domains of FAK have been developed, encompassing kinase domain inhibitors, FERM domain inhibitors, and FAT domain inhibitors, with several FAK inhibitors advanced to clinical trials. Moreover, given the critical role of FAK scaffolding function in signal transduction, FAK-targeted PROTACs have also been developed. Although no current FAK-targeted therapeutics have been approved for the market, the combination of FAK inhibitors with other anticancer drugs has shown considerable promise in the clinic. This review provides an overview of current drug discovery strategies targeting FAK, including the development of FAK inhibitors, FAK-based dual-target inhibitors and proteolysis-targeting chimeras (PROTACs) in both literature and patent applications. Accordingly, their design and optimization process, mechanisms of action and biological activities are discussed to offer insights into future directions of FAK-targeting drug discovery in cancer therapy.

Design, synthesis, and biological evaluation of diaminopyrimidine derivatives as novel focal adhesion kinase inhibitors

Focal adhesion kinase (FAK) is a cytoplasmic non-receptor protein tyrosine kinase that belongs to the family of focal adhesion complexes and is responsible for the development of various tumors. Herein, 24 diaminopyrimidine derivatives were designed and synthesized based on TAE-226. Several compounds with good activity were further evaluated regarding their antiproliferative activities against two cancer cells with high FAK expression. Compound A12 showed potent anticancer activity against A549 and MDA-MB-231 cell lines with IC50 values of 130 nM and 94 nM, respectively. In vitro metabolic stability and cytochrome P450 (CYP) inhibition assays showed that A12 exhibited favorable stability and weak inhibitory activity on CYP isoforms. Preliminary evaluation of kinase selectivity showed that A12 was a multi-kinase inhibitor. The acute toxicity in vivo indicated that A12 possessed acceptable safety. Compound A12 was also selected for molecular docking studies and the prediction of molecular properties and drug-like properties. These results indicated that compound A12 could be used as a potential lead compound targeting FAK for further development.

Design, synthesis and biological evaluation of 4-arylamino-pyrimidine derivatives as focal adhesion kinase inhibitors

A novel series of 4-arylamino-pyrimidine derivatives were designed and synthesized as focal adhesion kinase (FAK) inhibitors under the strategy of structure-based drug design. Most compounds performed excellent anti-proliferative activity against U87-MG cells. Especially, compounds 8d and 9b revealed the highest activity with IC50 values of 0.975 μM and 1.033 μM, which was much potent than the positive control TAE-226 (IC50 = 2.659 μM). On the other hand, the total 27 compounds exhibited low inhibition against human normal 2BS cells. Moreover, compounds 8d and 9b showed outstanding activity against FAK with IC50 values of 0.2438 nM and 0.2691 nM, which was very close to TAE-226 (IC50 = 0.1390 nM). Further studies proved that compounds 8d and 9b could induce U87-MG cell early apoptosis and arrest the cell at G2/M phase. The action mechanism indicated that they could significantly inhibit U87-MG cell clone formation, cell migration, and FAK phosphorylation. Molecular docking and molecular dynamics simulation investigations suggested that compounds 8d and 9b could firmly occupy the ATP binding site of FAK. These findings supported the further researches of compounds 8d and 9b as FAK inhibitors for antitumor drug discovery.

Discovery of novel pyrrolo [2,3-d] pyrimidine derivatives as potent FAK inhibitors based on cyclization strategy

Focal adhesion kinase (FAK), a non-receptor tyrosine kinase, plays a pivotal role in tumor invasion and metastasis. Many FAK inhibitors had been reported, but the development of FAK inhibitors in clinical studies are still limited. To facilitate the discovery of FAK modulators and further elucidate the role of FAK in cancer metastasis, it is necessary to discover a novel, potent and selective FAK inhibitor. In this study, a series of FAK inhibitors with novel scaffold were designed and synthesized based on cyclization strategy. Here, we reported compound 10b (HMC-18NH) with excellent inhibition of FAK (IC50 = 9.9 nM) and anticancer activity against several cancer cell lines including BxPC-3, PANC-1, MCF-7, MDA-MB-231, U-87MG, HepG2, HCT-15 and A549. Extraordinary, compound 10b showed the best cytotoxic effects against A549 with the IC50 value of 0.8 μM. In addition, 10b exhibited effective invasion and migration suppression in A549 cells. Further investigations revealed that compound 10b potently induced and promoted apoptosis in a dose-dependent manner and arrested A549 cells in the G2/M phase. Collectively, these results suggest that 10b is a promising FAK inhibitor and serve as a lead compound which deserve for further optimization.

Development of Cell Permeable NanoBRET Probes for the Measurement of PLK1 Target Engagement in Live Cells

PLK1 is a protein kinase that regulates mitosis and is both an important oncology drug target and a potential antitarget of drugs for the DNA damage response pathway or anti-infective host kinases. To expand the range of live cell NanoBRET target engagement assays to include PLK1, we developed an energy transfer probe based on the anilino-tetrahydropteridine chemotype found in several selective PLK inhibitors. Probe 11 was used to configure NanoBRET target engagement assays for PLK1, PLK2, and PLK3 and measure the potency of several known PLK inhibitors. In-cell target engagement for PLK1 was in good agreement with the reported cellular potency for the inhibition of cell proliferation. Probe 11 enabled the investigation of the promiscuity of adavosertib, which had been described as a dual PLK1/WEE1 inhibitor in biochemical assays. Live cell target engagement analysis of adavosertib via NanoBRET demonstrated PLK activity at micromolar concentrations but only selective engagement of WEE1 at clinically relevant doses.

Development of Cell Permeable NanoBRET Probes for the Measurement of PLK1 Target Engagement in Live Cells

PLK1 is a protein kinase that regulates mitosis and is both an important oncology drug target and a potential anti target of drugs for the DNA damage response pathway or anti-infective host kinases. To expand the range of live cell NanoBRET target engagement assays to include PLK1 we developed an energy transfer probe based on the anilino-tetrahydropteridine chemotype found in several selective PLK inhibitors. Probe 11 was used to configure NanoBRET target engagement assays for PLK1, PLK2, and PLK3 and measure the potency of several known PLK inhibitors. In cell target engagement for PLK1 was in good agreement with the reported cellular potency for inhibition of cell proliferation. Probe 11 enabled investigation of the promiscuity of adavosertib, which had been described as a dual PLK1/WEE1 inhibitor in biochemical assays. Live cell target engagement analysis of adavosertib by NanoBRET demonstrated PLK activity at micromolar concentrations but only selective engagement of WEE1 at clinically relevant doses.

The Development of FAK Inhibitors: A Five-Year Update

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase over-expressed in different solid cancers. In recent years, FAK has been recognized as a new target for the development of antitumor agents, useful to contrast tumor development and metastasis formation. To date, studies on the role of FAK and FAK inhibitors are of great interest for both pharmaceutical companies and academia. This review is focused on compounds able to block FAK with different potencies and with different mechanisms of action, that have appeared in the literature since 2017. Furthermore, new emerging PROTAC molecules have appeared in the literature. This summary could improve knowledge of new FAK inhibitors and provide information for future investigations, in particular, from a medicinal chemistry point of view.

Acid Catalyzed N-Alkylation of Pyrazoles with Trichloroacetimidates

N-Alkyl pyrazoles are important heterocycles in organic and medicinal chemistry, demonstrating a wide range of biological activity. A new method for the N-alkylation of pyrazoles has been developed using trichloroacetimidate electrophiles and a Brønsted acid catalyst. These reactions provide ready access to N-alkyl pyrazoles which are present in a variety of medicinally relevant lead structures. Benzylic, phenethyl and benzhydryl trichloroacetimidates provide good yields of the N-alkyl pyrazole products. Unsymmetrical pyrazoles provide a mixture of the two possible regioisomers, with the major product being controlled by sterics. This methodology provides an alternative to other alkylation methods that require strong base or high temperature.

Design, synthesis and biological evaluation of 7-((7H-pyrrolo[2,3-d]pyrimidin-4-yl)oxy)-2,3-dihydro-1H-inden-1-one derivatives as potent FAK inhibitors for the treatment of ovarian cancer

Focal adhesion kinase (FAK) promotes tumor progression by intracellular signal transduction and regulation of gene expression and protein turnover, which is a compelling therapeutic target for various cancer types, including ovarian cancer. However, the clinical responses of FAK inhibitors remain unsatisfactory. Here, we describe the discovery of FAK inhibitors using a scaffold hopping strategy. Structure-activity relationship (SAR) exploration identified 36 as a potent FAK inhibitor, which exhibited inhibitory activities against FAK signaling in vitro. Treatment with 36 not only decreased migration and invasion of PA-1 cells, but also reduced expression of MMP-2 and MMP-9. Moreover, 36 inhibited tumor growth and metastasis, and no obvious adverse effects were observed during the in vivo study. These results revealed the potential of FAK inhibitor 36 for treatment of ovarian cancer.

Photocytotoxicity and photoinduced phosphine ligand exchange in a Ru(ii) polypyridyl complex

Two new tris-heteroleptic Ru(ii) complexes with triphenylphosphine (PPh₃) coordination, cis-[Ru(phen)₂(PPh₃)(CH₃CN)]²⁺ (1a, phen = 1,10-phenanthroline) and cis-[Ru(biq)(phen)(PPh₃)(CH₃CN)]²⁺ (2a, biq = 2,2′-biquinoline), were synthesized and characterized for photochemotherapeutic applications. Upon absorption of visible light, 1a exchanges a CH₃CN ligand for a solvent water molecule. Surprisingly, the steady-state irradiation of 2a followed by electronic absorption and NMR spectroscopies reveals the photosubstitution of the PPh₃ ligand. Phosphine photoinduced ligand exchange with visible light from a Ru(ii) polypyridyl complex has not previously been reported, and calculations reveal that it results from a trans-type influence in the excited state. Complexes 1a and 2a are not toxic against the triple negative breast cancer cell line MDA-MB-231 in the dark, but upon irradiation with blue light, the activity of both complexes increases by factors of >4.2 and 5.8, respectively. Experiments with PPh₃ alone show that the phototoxicity observed for 2a does not arise from the released phosphine ligand, indicating the role of the photochemically generated ruthenium aqua complex on the biological activity. These complexes represent a new design motif for the selective release of PPh₃ and CH₃CN for use in photochemotherapy.

New Ru(ii) complexes exhibit selective ligand dissociation driven by an excited state trans-type influence. The complexes are not toxic to triple-negative breast cancer cells in the dark, but induce cell death upon irradiation with visible light.

Identification of Thieno[3,2-d]pyrimidine Derivatives as Dual Inhibitors of Focal Adhesion Kinase and FMS-like Tyrosine Kinase 3

Focal adhesion kinase (FAK) is overexpressed in highly invasive and metastatic cancers. To identify novel FAK inhibitors, we designed and synthesized various thieno[3,2-d]pyrimidine derivatives. An intensive structure-activity relationship (SAR) study led to the identification of 26 as a lead. Moreover, 26, a multitargeted kinase inhibitor, possesses excellent potencies against FLT3 mutants as well as FAK. Gratifyingly, 26 remarkably inhibits recalcitrant FLT3 mutants, including F691L, that cause drug resistance. Importantly, 26 is superior to PF-562271 in terms of apoptosis induction, anchorage-independent growth inhibition, and tumor burden reduction in the MDA-MB-231 xenograft mouse model. Also, 26 causes regression of tumor growth in the MV4-11 xenograft mouse model, indicating that it could be effective against acute myeloid leukemia (AML). Finally, in an orthotopic mouse model using MDA-MB-231, 26 remarkably prevents metastasis of orthotopic tumors to lymph nodes. Taken together, the results indicate that 26 possesses potential therapeutic value against highly invasive cancers and relapsed AML.

FAK inhibitors as promising anticancer targets: present and future directions

FAK, a nonreceptor tyrosine kinase, has been recognized as a novel target class for the development of targeted anticancer agents. Overexpression of FAK is a common occurrence in several solid tumors, in which the kinase has been implicated in promoting metastases. Consequently, designing and developing potent FAK inhibitors is becoming an attractive goal, and FAK inhibitors are being recognized as a promising tool in our armamentarium for treating diverse cancers. This review comprehensively summarizes the different classes of synthetically derived compounds that have been reported as potent FAK inhibitors in the last three decades. Finally, the future of FAK-targeting smart drugs that are designed to slow down the emergence of drug resistance is discussed.

Drug Discovery Targeting Focal Adhesion Kinase (FAK) as a Promising Cancer Therapy

FAK is a nonreceptor intracellular tyrosine kinase which plays an important biological function. Many studies have found that FAK is overexpressed in many human cancer cell lines, which promotes tumor cell growth by controlling cell adhesion, migration, proliferation, and survival. Therefore, targeting FAK is considered to be a promising cancer therapy with small molecules. Many FAK inhibitors have been reported as anticancer agents with various mechanisms. Currently, six FAK inhibitors, including GSK-2256098 (Phase I), VS-6063 (Phase II), CEP-37440 (Phase I), VS-6062 (Phase I), VS-4718 (Phase I), and BI-853520 (Phase I) are undergoing clinical trials in different phases. Up to now, there have been many novel FAK inhibitors with anticancer activity reported by different research groups. In addition, FAK degraders have been successfully developed through “proteolysis targeting chimera” (PROTAC) technology, opening up a new way for FAK-targeted therapy. In this paper, the structure and biological function of FAK are reviewed, and we summarize the design, chemical types, and activity of FAK inhibitors according to the development of FAK drugs, which provided the reference for the discovery of new anticancer agents.

Pyrimidine: a review on anticancer activity with key emphasis on SAR

Background

Cancer is a global health challenge, it impacts the quality of life and its treatment is associated with several side effects. Resistance of the cancer cells to the existing drugs has led to search for novel anticancer agents. Pyrimidine, a privileged scaffold, is part of living organisms and plays vital role in various biological procedures as well as in cancer pathogenesis. Due to resemblance in structure with the nucleotide base pair of DNA and RNA, it is recognized as valuable compound in the treatment of cancer.

Main text

Many novel pyrimidine derivatives have been designed and developed for their anticancer activity in the last few years. The present review aims to focus on the structure activity relationship (SAR) of pyrimidine derivatives as anticancer agent from the last decade.

Conclusion

This review intends to assist in the development of more potent and efficacious anticancer drugs with pyrimidine scaffold.

Graphical abstract

New Insights on Fak and Fak Inhibitors

BACKGROUND

Focal adhesion kinase (Fak) is a cytoplasmic protein tyrosine kinase overexpressed and activated in different solid cancers; it has shown an important role in metastasis formation, cell migration, invasion and angiogenesis and consequently it has been proposed as a potential target in cancer therapy, particularly in a metastatic phase. In recent years, different investigations have highlighted the importance of new Fak inhibitors as potential anti-cancer drugs, but other studies evidenced its role in different pathologies related to the cardiac function or viral infection.

METHODS

An extensive bibliographic research (104 references) has been done concerning the structure of Fak, its importance in tumor development, but also in other pathologies currently under study. The compounds currently subjected to clinical studies were therefore treated using the appropriate databases. Finally, the main chemical scaffolds currently under preclinical investigation were analyzed, focusing on their molecular structures and on the activity structure relationships (SAR).

RESULTS

At the moment, only a few reversible ATP-competitive inhibitors are under investigation in pre-clinical studies and clinical trials. Other compounds, with different chemical scaffolds, are investigated to obtain more active and selective Fak inhibitors. This mini-review is a summary of different Fak functions in cancer and other pathologies; the compounds today in clinical trials and the recent chemical scaffolds (also included in patents) giving the most interesting results are investigated. In addition, PROTAC molecules are reported.

CONCLUSION

All reported results evidenced that additional studies are necessary to design and synthesize new selective and more active compounds, although promising information has been obtained from associations between Fak inhibitors and other different anti- cancer drugs. In addition, the other important roles evidenced, both at the nuclear level and in non-cancerous cells, make this protein an increasingly important target in pharmaceutical chemistry.

Design, synthesis, and cytotoxic activity of novel 2H-imidazo[1,2-c]pyrazolo[3,4-e]pyrimidine derivatives

In this study, a series of novel 2H-imidazo [1, 2-c] pyrazolo [3, 4-e] pyrimidine derivatives were designed, synthesized, and evaluated for their cytotoxic activities. The in vitro cell growth inhibition assay of the target compounds indicated their selectivity in inhibiting the proliferation of blood tumor cells (K562, U937) and solid tumor cells (HCT116, HT-29). Compound 9b exhibited the highest antiproliferative activities against K562 (IC₅₀ = 5.597 µM) and U937 (IC₅₀ = 3.512 µM). Based on the flow cytometry assays, compound 9b caused obvious induction of cell apoptosis and cell arrest at the S phase. Furthermore, western blot analysis revealed that compound 9b upregulated the expression of Bax, downregulated the levels of Bcl-2, and further activated caspase-3 in K562 cells. Therefore, compound 9b may be a potential anticancer agent that deserves further investigation.

Focal Adhesion Kinase Fine Tunes Multifaced Signals toward Breast Cancer Progression

Breast cancer represents the most common diagnosed malignancy and the main leading cause of tumor-related death among women worldwide. Therefore, several efforts have been made in order to identify valuable molecular biomarkers for the prognosis and prediction of therapeutic responses in breast tumor patients. In this context, emerging discoveries have indicated that focal adhesion kinase (FAK), a non-receptor tyrosine kinase, might represent a promising target involved in breast tumorigenesis. Of note, high FAK expression and activity have been tightly correlated with a poor clinical outcome and metastatic features in several tumors, including breast cancer. Recently, a role for the integrin-FAK signaling in mechanotransduction has been suggested and the function of FAK within the breast tumor microenvironment has been ascertained toward tumor angiogenesis and vascular permeability. FAK has been also involved in cancer stem cells (CSCs)-mediated initiation, maintenance and therapeutic responses of breast tumors. In addition, the potential of FAK to elicit breast tumor-promoting effects has been even associated with the capability to modulate immune responses. On the basis of these findings, several agents targeting FAK have been exploited in diverse preclinical tumor models. Here, we recapitulate the multifaceted action exerted by FAK and its prognostic significance in breast cancer. Moreover, we highlight the recent clinical evidence regarding the usefulness of FAK inhibitors in the treatment of breast tumors.

In silico design of novel FAK inhibitors using integrated molecular docking, 3D-QSAR and molecular dynamics simulation studies

Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase that plays a crucial role in integrin signaling that regulates essential cellular functions including growth, motility, proliferation and survival in different types of cells. Interestingly, it has also shown to be up-regulated in various types of tumors, hence it has emerged as a significant therapeutic target for the development of selective inhibitors. In present work, with the aim of achieving further insight into the structural characteristics required for the FAK inhibitory activity, a combined approach of molecular modeling studies including molecular docking, three-dimensional quantitative structure activity relationship (3D-QSAR) and molecular dynamics (MD) simulation were carried out on a series of 7H-pyrrolo[2,3-d]pyrimidine and thieno[3,2-d]pyrimidine FAK inhibitors. The probable binding modes and interactions of inhibitors into the FAK active site were predicted by molecular docking. The 3D-QSAR models were developed using the comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods, with three ligand-based, docking-based and receptor-based alignment techniques. Both CoMFA and CoMSIA models obtained from receptor-based alignment were superior to the ones obtained by other alignment methods. However, the CoMSIA model (q² = 0.679, r² = 0.954 and r²_pred = 0.888) depicted almost better predictive ability than the CoMFA model (q² = 0.617, r² = 0.932 and r²_pred = 0.856). The contour map analysis revealed the relationship between the structural features and inhibitory activity. The docking results and CoMFA and CoMSIA contour maps were in good accordance. Based on the information obtained from the molecular docking and contour map analysis, a series of novel FAK inhibitors were designed that showed better predicted inhibitory activity than the most potent compound 31 in the data set. Finally, the stability of the reference molecule 31 and the designed compounds D15 and D27 were evaluated through a 30 ns of MD simulation and their binding free energies were calculated using the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method. The result of MD simulation and binding free energy decomposition demonstrated the important role of van der Waals interactions alongside H-bond ones that were in consistent with the docking and contour maps analysis results. In sum, the results from this study may provide a significant insight for developing more effective novel FAK inhibitors.Communicated by Ramaswamy H. Sarma.

Progress in the Development of Small Molecular Inhibitors of Focal Adhesion Kinase (FAK)

Focal adhesion kinase (FAK) is a nonreceptor intracellular tyrosine kinase that plays an essential role in cancer cell adhesion, survival, proliferation, and migration through both its enzymatic activities and scaffolding functions. Overexpression of FAK has been found in many human cancer cells from different origins, which promotes tumor progression and influences clinical outcomes in different classes of human tumors. Therefore, FAK has been considered as a promising target for small molecule anticancer drug development. Many FAK inhibitors targeting different domains of FAK with various mechanisms of functions have been reported, including kinase domain inhibitors, FERM domain inhibitors, and FAT domain inhibitors. In addition, FAK-targeting PROTACs, which can induce the degradation of FAK, have also been developed. In this Perspective, we summarized the progress in the development of small molecular FAK inhibitors and proposed the perspectives for the future development of agents targeting FAK.

Focal adhesion kinase: Insight into its roles and therapeutic potential in oesophageal cancer

Oesophageal cancer is associated with high morbidity and mortality rates because it is highly invasive and prone to recurrence and metastasis, with a five-year survival rate of <20%. Therefore, there is an urgent need for new methods aimed at improving therapeutic intervention. Several studies have shown that targeted therapy may be effective for the treatment of oesophageal cancer. Focal adhesion kinase (FAK), a non-receptor tyrosine kinase with kinase activity and scaffolding function, could be overexpressed in a variety of solid tumours, including oesophageal cancer. FAK participates in survival, proliferation, progression, adhesion, invasion, migration, epithelial-to-mesenchymal transition, angiogenesis, DNA damage repair, and other biological processes through multiple signalling pathways in cancer cells. It plays an important role in the occurrence and development of tumours and has been linked to the prognosis of oesophageal cancer. FAK has been suggested as a potential therapeutic target in oesophageal cancer; thus, the combination of FAK inhibitors with chemotherapy, radiotherapy, and immunotherapy is expected to prolong the survival of patients. This paper presents a brief overview of the structure of FAK and its potential role in oesophageal cancer, providing a rationale for the future application of FAK inhibitors in the treatment of the disease.

Discovery of 7H-pyrrolo[2,3-d]pyridine derivatives as potent FAK inhibitors: Design, synthesis, biological evaluation and molecular docking study

Focal adhesion kinase (FAK) is an intracellular non-receptor tyrosine kinase responsible for development of various tumor types. Aiming to explore new potent inhibitors, two series of 2,4-disubstituted-7H-pyrrolo[2,3-d]pyrimidine derivatives were designed and synthesized on the base of structure-based design strategy. Biological evaluation indicated that most of these new compounds could potently inhibit FAK kinase, leading to the promising inhibitors against the proliferation of U-87MG, A-549, and MDA-MB-231 cancer cell lines. Among them, the optimized compound 18h potently inhibited the enzyme (IC₅₀ = 19.1 nM) and displayed stronger potency than TAE-226 in U-87MG, A-549 and MDA-MB-231 cells, with IC₅₀ values of 0.35, 0.24, and 0.34 μM, respectively. Compound 18h is a multi-target kinase inhibitor. Furthermore, compound 18h also exhibited relatively less cytotoxicity (IC₅₀ = 3.72 μM) toward a normal human cell line, HK2. According to the flow cytometry and wound healing assay results, compound 18h effectively induced apoptosis and G0/G1 phase arrest of MDA-MB-231 cells and suppressed the migration of U-87MG, A-549 and MDA-MB-231 cells. The docking study of compound 18h was performed to elucidate its possible binding modes and to provide a structural basis for the further structural guidance design of FAK inhibitors. Collectively, these data support the further development of compound 18h as a lead compound for FAK-targeted anticancer drug discovery.

Design, synthesis, biological evaluation and molecular docking study of novel thieno[3,2-d]pyrimidine derivatives as potent FAK inhibitors

A series of 2,7-disubstituted-thieno[3,2-d]pyrimidine derivatives were designed, synthesized and evaluated as novel focal adhesion kinase (FAK) inhibitors. The novel 2,7-disubstituted-thieno[3,2-d]pyrimidine scaffold has been designed as a new kinase inhibitor platform that mimics the bioactive conformation of the well-known diaminopyrimidine motif. Most of the compounds potently suppressed the enzymatic activities of FAK and potently inhibited the proliferation of U-87MG, A-549 and MDA-MB-231 cancer cell lines. Among these derivatives, the optimized compound 26f potently inhibited the enzyme (IC₅₀ = 28.2 nM) and displayed stronger potency than TAE-226 in U-87MG, A-549 and MDA-MB-231 cells, with IC₅₀ values of 0.16, 0.27, and 0.19 μM, respectively. Compound 26f also exhibited relatively less cytotoxicity (IC₅₀ = 3.32 μM) toward a normal human cell line, HK2. According to the flow cytometry results, compound 26f induced the apoptosis of MDA-MB-231 cells in a dose-dependent manner and effectively arrested MDA-MB-231 cells in G0/G1 phase. Further investigations revealed that compound 26f potently suppressed the migration of MDA-MB-231 cells. Collectively, these data support the further development of compound 26f as a lead compound for FAK-targeted anticancer drug discovery.