Evaluation of WO2017098421: GSK’s benzothiazine compounds as CD73 inhibitor filings

Small molecular CD73 inhibitors: Recent progress and future perspectives

The occurrence and development of the tumor are very complex biological processes. In recent years, a large number of research data shows that CD73 is closely related to tumor growth and metastasis. It has been confirmed that the cascade hydrolysis of extracellular ATP to adenosine is one of the most important immunosuppressive regulatory pathways in the tumor microenvironment. The metabolite adenosine can mediate immunosuppression by activating adenosine receptor (such as A2A) on effector Immune cells and enable tumor cells to achieve immune escape. Therefore, attenuating or completely removing adenosine-mediated immunosuppression in the tumor microenvironment by inhibiting CD73 is a promising approach in the treatment of solid tumors. This paper focuses on the research progress of CD73 enzyme and CD73 small molecule inhibitors, and is expected to provide some insights into the development of small-molecule antitumor drugs targeting CD73.

Advances in CD73 inhibitors for immunotherapy: Antibodies, synthetic small molecule compounds, and natural compounds

Tumors, a disease with a high mortality rate worldwide, have become a serious threat to human health. Exonucleotide-5'-nucleotidase (CD73) is an emerging target for tumor therapy. Its inhibition can significantly reduce adenosine levels in the tumor microenvironment. It has a better therapeutic effect on adenosine-induced immunosuppression. In the immune response, extracellular ATP exerts immune efficacy by activating T cells. However, dead tumor cells release excess ATP, overexpress CD39 and CD73 on the cell membrane and catabolize this ATP to adenosine. This leads to further immunosuppression. There are a number of inhibitors of CD73 currently under investigation. These include antibodies, synthetic small molecule inhibitors and a number of natural compounds with prominent roles in the anti-tumor field. However, only a small proportion of the CD73 inhibitors studied to date have successfully reached the clinical stage. Therefore, effective and safe inhibition of CD73 in oncology therapy still holds great therapeutic potential. This review summarizes the currently reported CD73 inhibitors, describes their inhibitory effects and pharmacological mechanisms, and provides a brief review of them. It aims to provide more information for further research and development of CD73 inhibitors.

2,1-Benzothiazine - (quinolin/thiophen)yl hydrazone frameworks as new monoamine oxidase inhibitory agents; synthesis, in vitro and in silico investigation

Two series of new 2,1-benzothiazine derivatives have been synthesized by condensation of 4-hydrazono-1-methyl-3,4-dihydro-1H-benzo[c][1,2]thiazine 2,2-dioxide (5) with 2-chloroquinoline-3-carbaldehydes and acetylthiophenes to acquire new heteroaryl ethylidenes 7(a-f) and 9(a-k) in excellent yields. After characterization by FTIR, ¹H NMR, ¹³C NMR and elemental analyses, the newly synthesized analogues were investigated against monoamine oxidase enzymes (MAO A and MAO B). The titled compounds exhibited activity in the lower micromolar range among which 9e was the most potent compound against MAO A with IC₅₀ of 1.04 ± 0.01 μM whereas 9h proved to be the most potent derivative against MAO B with an IC₅₀ value of 1.03 ± 0.17 μM. Furthermore, in vitro results were further endorsed by molecular docking studies to determine the interaction between the potent compounds and the enzyme active site. These newly synthesized compounds represent promising hits for the development of safer and potent lead molecules for therapeutic use against depression and other neurological diseases.

Design and Synthesis of Tri-substituted Imidazole Derivatives as CD73 Inhibitors for Their Anticancer Activity

Background:

Monoclonal antibodies licensed by the US Food and Drug Administration (FDA) target diverse biological targets relevant to immuno-oncology, and small compounds in clinical trials target various aspects of immuno-oncology. Several small compounds that target CD73 are at various stages of clinical studies. Several imidazoles are currently being utilized to treat malignancies, including Dacarbazine, Zoledronic acid, Mercaptopurine, and others. As a result, we evaluated the cytotoxicity of modified tri-phenyl imidazoles against breast cancer cell lines, as well as conducted virtual tests.

Methods:

We used Accelrys Drug Discovery Studio 3.5 software to undertake molecular docking, ADMET, and molecular properties studies on 68 proposed imidazole derivatives. The synthesized compounds' binding mechanisms were investigated against the CD73 protein (PDB Code: 4H1S). To find the drugs with the best pharmacokinetics, researchers assessed ADMET solubility, BBB penetration, hepatotoxicity, PPB binding, and polar surface area. The MDA-MB-231 breast cancer cell line was treated with these produced compounds, and the MTT test method was used to determine the IC50 values.

Results:

The selected 14 compounds showed good binding in the active site of CD73 by forming Hbonds with amino acid residues, according to molecular docking studies. Breast cancer cell lines were treated with substituted tri-phenyl imidazole derivatives, which displayed anticancer activity. Compounds 3a and 3h, which had an electron-donating group at the 2nd and 3rd positions and p-substitutions of the chloro and nitro groups, respectively, showed considerable anticancer action.

Conclusion:

Fourteen imidazole derivatives were produced and tested against breast cancer cell lines based on in-silico research. The MDA-MB-231 cell line was strongly suppressed by compounds 3a and 3h. In-vitro enzyme inhibition experiments revealed that only 3h demonstrated considerable inhibition.

A Novel CD73 Inhibitor SHR170008 Suppresses Adenosine in Tumor and Enhances Anti-Tumor Activity with PD-1 Blockade in a Mouse Model of Breast Cancer

Introduction

CD73 and adenosine support growth-promoting neovascularization, metastasis, and survival in cells, and promote anti-PD-1 mAb therapy-induced immune escape. Consequently, developing a CD73 inhibitor as monotherapy and a potential beneficial combination partner with immune-checkpoint inhibitors needs investigation.

Methods

CD73 inhibitors were evaluated in vitro with soluble and membrane-bound CD73 enzymes, as well as its PD biomarker responses in human peripheral blood mononuclear cells (PBMC) by flow cytometry and ELISA. The binding modes of the molecules were analyzed via molecular modeling. The anti-tumor activity and synergistic effect of SHR170008 in combination with anti-PD-1 mAb were evaluated in a syngeneic mouse breast cancer model.

Results

SHR170008 was discovered during the initial structural modifications on the link between the ribose and the α-phosphate of AMPCP, which significantly improved the stability of the compound confirmed by the metabolite identification study. Further modifications on the adenine base of AMPCP improved the potency due to forming stronger interactions with CD73 protein. It exhibited potent inhibitory activities on soluble and endogenous membrane-bound CD73 enzymes, and induced IFNγ production, reversed AMP-suppressed CD25⁺ and CD8⁺/CD25⁺ expression, and enhanced granzyme B production on CD8⁺ T cells in human PBMC. SHR170008 showed dose-dependent anti-tumor efficacy with suppression of adenosine in the tumors in EMT6 mouse breast tumor model. The increase of adenosine in tumor tissue by anti-PD-1 mAb alone was suppressed by SHR170008 in the combination groups. Simultaneous inhibition of CD73 and PD-1 neutralization synergistically enhanced antitumor immunity and biomarkers in response, and exposures of SHR170008 were correlated with the efficacy readouts.

Conclusion

Our findings suggest that CD73 may serve as an immune checkpoint by generating adenosine, which suppresses the antitumor activity of anti-PD-1 mAb, and inhibition of CD73 may be a potential beneficial combination partner with immune-checkpoint inhibitors to improve their therapeutic outcomes in general.

Identification of Phelligridin-Based Compounds as Novel Human CD73 Inhibitors

As an emerging immune checkpoint, CD73 has received more attention in the past decade. Inhibition of CD73 enzymatic activity can enhance antitumor immunity. Several CD73 inhibitors have been identified by in vitro assays in recent years, but they remain premature for clinical application, indicating that more novel CD73 inhibitors should be studied. Herein, we aimed to identify novel CD73 inhibitors that hopefully are suitable drug candidates by using computer-aided drug discovery and enzymatic-based assays. Five-hundred molecules with high binding affinity were retrieved from the Chemdiv-Plus database by using a structure-based virtual screening approach. Then, we analyzed the drug properties of these molecules and obtained 68 small molecules based on the oral noncentral nervous system (CNS) drug profile. The inhibition rates of these molecules against CD73 enzymatic activities were determined at a concentration of 100 μM, and 20 molecules had an inhibition rate greater than 20%, eight of which were dose-dependent, with IC50 values of 6.72-172.1 μM. Among the screening hits, phelligridin-based compounds had the best experimental inhibition values. Modeling studies indicate that the phelligridin group is sandwiched by the rings of F417 and F500 residues. The identified inhibitors have a molecular weight of approximately 500 Dal and are predicted to form primarily hydrogen bonds with CD73 in addition to hydrophobic stacking interactions. In conclusion, novel inhibitors with satisfactory drug properties may serve as lead compounds for the development of CD73-targeting drugs, and the binding modes may provide insight for phelligridin-based drug design.

4-Substituted-1,2,3-triazolo nucleotide analogues as CD73 inhibitors, their synthesis, in vitro screening, kinetic and in silico studies

Three series of nucleotide analogues were synthesized and evaluated as potential CD73 inhibitors. Nucleobase replacement consisted in connecting the appropriate aromatic or purine residues through a triazole moiety that is generated from 1,3-dipolar cycloaddition. The first series is related to 4-substituted-1,2,3-triazolo-β-hydroxyphosphonate ribonucleosides. Additional analogues were also obtained, in which the phosphonate group was replaced by a bisphosphonate pattern (P-C-P-C, series 2) or the ribose moiety was removed leading to acyclic derivatives (series 3). The β-hydroxyphosphonylphosphonate ribonucleosides (series 2) were found to be potent inhibitors of CD73 using both purified recombinant protein and cell-based assays. Two compounds (2a and 2b) that contained a bis(trifluoromethyl)phenyl or a naphthyl substituents proved to be the most potent inhibitors, with IC₅₀ values of 4.8 ± 0.8 µM and 0.86 ± 0.2 µM, compared to the standard AOPCP (IC₅₀ value of 3.8 ± 0.9 µM), and were able to reverse the adenosine-mediated immune suppression on human T cells. This series of compounds illustrates a new type of CD73 inhibitors.

Targeting Metabolism of Extracellular Nucleotides via Inhibition of Ectonucleotidases CD73 and CD39

In the tumor microenvironment, unusually high concentrations of extracellular adenosine promote tumor proliferation through various immunosuppressive mechanisms. Blocking adenosine production by inhibiting nucleotide-metabolizing enzymes, such as ectonucleotidases CD73 and CD39, represents a promising therapeutic strategy that may synergize with other immuno-oncology mechanisms and chemotherapies. Emerging small-molecule ectonucleotidase inhibitors have recently entered clinical trials. This Perspective will outline challenges, strategies, and recent advancements in targeting this class with small-molecule inhibitors, including AB680, the first small-molecule CD73 inhibitor to enter clinical development. Specific case studies, including structure-based drug design and lead optimization, will be outlined. Preclinical data on these molecules and their ability to enhance antitumor immunity will be discussed.

Synthesis, crystal structure and docking studies of tetracyclic 10-iodo-1,2-dihydroisoquinolino[2,1-b][1,2,4]benzothiadiazine 12,12-dioxide and its precursors

The title compound, 10-iodo-1,2-dihydroisoquinolino[2,1-b][1,2,4]benzothiadiazine 12,12-dioxide, C₁₅H₁₁IN₂O₂S (8), was synthesized via the metal-free intramolecular N-iodosuccinimide (NIS)-mediated radical oxidative sp³-C-H aminative cyclization of 2-(2'-aminobenzenesulfonyl)-1,3,4-trihydroisoquinoline, C₁₅H₁₆N₂O₂S (7). The amino adduct 7 was prepared via a two-step reaction, starting from the condensation of 2-nitrobenzenesulfonyl chloride (4) with 1,2,3,4-tetrahydroisoquinoline (5), to afford 2-(2'-nitrobenzenesulfonyl)-1,3,4-trihydroisoquinoline, C₁₅H₁₄N₂O₄S (6), in 82% yield. The catalytic hydrogenation of 6 with hydrogen gas, in the presence of 10% palladium-on-charcoal catalyst, furnished 7. Products 6-8 were characterized by their melting points, IR and NMR (¹H and ¹³C) spectroscopy, and single-crystal X-ray diffraction. The three compounds crystallized in the monoclinic space group, with 7 exhibiting classical intramolecular hydrogen bonds of 2.16 and 2.26 Å. All three crystal structures exhibit centrosymmetric pairs of intermolecular C-H...π(ring) and/or π-π stacking interactions. The docking studies of molecules 6, 7 and 8 with deoxyribonucleic acid (PDB id: 1ZEW) revealed minor-groove binding behaviours without intercalation, with 7 presenting the most favourable global energy of the three molecules. Nonetheless, molecule 8 interacted strongly with the DNA macromolecule, with an attractive van der Waals energy of -15.53 kcal mol^-1.

Targeting adenosinergic pathway and adenosine A2A receptor signaling for the treatment of COVID-19: A hypothesis

The most serious health issue today is the rapid outbreak of Coronavirus Disease 2019 (COVID-19). More than 6,973,427 confirmed cases were diagnosed in nearly 213 countries and territories around the world and two international conveyances, causing globally over 400,000 deaths. Epidemiology, risk factors, and clinical characteristics of COVID-19 patients have been identified, but the factors influencing the immune system against COVID-19 have not been well established. Upon infection or cell damage, high amounts of adenosine triphosphate (ATP) are released from damaged cells, which serve as mediators of inflammation through purinergic cell surface receptor signaling. As a protective mechanism to prevent excessive damage to host tissue, adenosine counteracts ATP's effects by adenosine receptor stimulation to suppress the pro-inflammatory response. Adenosine is seen as a major obstacle to the efficacy of immune therapies, and the adenosinergic axis components are critical therapeutic targets for cancer and microbial infections. Pharmacologic inhibitors or antibodies specific to adenosinergic pathway components or adenosine receptors in microbial and tumor therapy have shown efficacy in pre-clinical studies and are entering the clinical arena. In this review, we provide a novel hypothesis explaining the potential for improving the efficiency of innate and adaptive immune systems by targeting adenosinergic pathway components and adenosine A_2A receptor signaling for the treatment of COVID-19.

CD73: an emerging checkpoint for cancer immunotherapy

CD73 is a novel immune checkpoint associated with adenosine metabolism that promotes tumor progression by suppressing antitumor immune response and promoting angiogenesis. The inhibition of CD73, in combination with immune checkpoint blockade, targeted therapy or conventional therapy, improves antitumor effects in numerous preclinical mouse models of cancer. Emerging evidence suggests that the combination of anti-CD73 and immune checkpoint blockade has promising clinical activity in patients with advanced solid tumors. In this review, we will discuss the specific role of CD73 on both tumor cells and nontumor cells in regulating tumor immunity and tumorigenesis and provide an update on the current view of the antitumor activity of targeting CD73 by mAb or small molecule selective inhibitors in preclinical and clinical settings.

Complex regulation of ecto-5'-nucleotidase/CD73 and A2AR-mediated adenosine signaling at neurovascular unit: A link between acute and chronic neuroinflammation

The review summarizes available data regarding the complex regulation of CD73 at the neurovascular unit (NVU) during neuroinflammation. Based on available data we propose the biphasic pattern of CD73 regulation at NVU, with an early attenuation and a postponed up-regulation of CD73 activity. Transient attenuation of CD73 activity on leukocyte/vascular endothelium and leukocyte/astrocyte surface, required for the initiation of a neuroinflammatory response, may be effectuated either by catalytic inhibition of CD73 and/or by shedding of the CD73 molecule from the cell surface, while postponed induction of CD73 is effectuated by transcriptional up-regulation of Nt5e and posttranslational modifications. Neuroinflammatory conditions are also associated with significant enhancement and gain-of-function of A_2AR-mediated adenosine signaling. However, in contrast to the temporary prevalence of A_2AR over A₁R signaling during an acute inflammatory response, prolonged induction of A_2AR and resulting perpetual CD73/A_2AR coupling may be a contributing factors in the transition between acute and chronic neuroinflammation. Thus, pharmacological targeting of the CD73/A_2AR axis may attenuate inflammatory response and ameliorate neurological deficits in chronic neuroinflammatory conditions.

Structure-Activity Relationship of Purine and Pyrimidine Nucleotides as Ecto-5'-Nucleotidase (CD73) Inhibitors

Cluster of differentiation 73 (CD73) converts adenosine 5'-monophosphate to immunosuppressive adenosine, and its inhibition was proposed as a new strategy for cancer treatment. We synthesized 5'- O-[(phosphonomethyl)phosphonic acid] derivatives of purine and pyrimidine nucleosides, which represent nucleoside diphosphate analogues, and compared their CD73 inhibitory potencies. In the adenine series, most ribose modifications and 1-deaza and 3-deaza were detrimental, but 7-deaza was tolerated. Uracil substitution with N³-methyl, but not larger groups, or 2-thio, was tolerated. 1,2-Diphosphono-ethyl modifications were not tolerated. N⁴-(Aryl)alkyloxy-cytosine derivatives, especially with bulky benzyloxy substituents, showed increased potency. Among the most potent inhibitors were the 5'- O-[(phosphonomethyl)phosphonic acid] derivatives of 5-fluorouridine (4l), N⁴-benzoyl-cytidine (7f), N⁴-[ O-(4-benzyloxy)]-cytidine (9h), and N⁴-[ O-(4-naphth-2-ylmethyloxy)]-cytidine (9e) ( K_i values 5-10 nM at human CD73). Selected compounds tested at the two uridine diphosphate-activated P2Y receptor subtypes showed high CD73 selectivity, especially those with large nucleobase substituents. These nucleotide analogues are among the most potent CD73 inhibitors reported and may be considered for development as parenteral drugs.

Targeting the CD73-adenosine axis in immuno-oncology

The ectonucleotidases CD39 and CD73 are cell surface enzymes that catabolize the breakdown of extracellular ATP into adenosine. As such, they constitute critical components of the extracellular purinergic pathway and play important roles in maintaining tissue and immune homeostasis. With the coming of age of cancer immunotherapy, ectonucleotidases and adenosine receptors have emerged as novel therapeutic targets to enhance antitumor immune responses. With early-phase clinical trials showing promising results, it is becoming increasingly important to decipher the distinct mechanisms-of-action of adenosine-targeting agents, identify patients that will benefit from these agents and rationally develop novel synergistic combinations. Given the broad expression of ectonucleotidases and adenosine receptors, a better understanding of cell-specific roles will also be key for successful implementation of this new generation of immuno-oncology therapeutics. We here review the latest studies on the roles of CD73 and adenosine in cancer with a focus on cell-specific function. We also discuss ongoing clinical trials and future avenues for adenosine-targeting agents.

Synthesis, characterization, monoamine oxidase inhibition, molecular docking and dynamic simulations of novel 2,1-benzothiazine-2,2-dioxide derivatives

In this research work, we report the synthesis and biological evaluation of two new series of 1-benzyl-4-(benzylidenehydrazono)-3,4-dihydro-1H-benzo[c] [1,2]thiazine 2,2-dioxides and 1-benzyl-4-((1-phenylethylidene)hydrazono)-3,4-dihydro-1H-benzo[c][1,2]thiazine 2,2-dioxides. The synthetic plan involves the mesylation of methyl anthranilate with subsequent N-benzylation of the product. The methyl 2-(N-benzylmethylsulfonamido)benzoate was subjected to cyclization reaction in the presence of sodium hydride to obtain 1-benzyl-1H-benzo[c][1,2]thiazin-4(3H)-one 2,2-dioxide which was treated with hydrazine hydrate to get corresponding hydrazone precursor. Finally, the titled compounds were obtained by reaction of hydrazone with various substituted aldehydes and ketones. The synthesized derivatives were subjected to carry out their inhibition activities against monoamine oxidases along with modelling investigations to evaluate their binding interactions and dynamic stability during the docking studies. The inhibition profile of potent compounds was found as competitive for both the isozymes. The compounds were more selective inhibitors of MAO-A as compared to MAO-B. Moreover, drug likeness profile of the derivatives was evaluated to have an additional insight into the physicochemical properties. The molecular dynamic simulations predicted the behaviour of amino acids with the active site residues.