A new synthesis of di- and trisubstituted pyrroles was achieved by treating in situ generated vinylogous diazoesters and readily available nitriles with a catalytic amount of silver(I) antimony ...hexafluoride at room temperature. This method showcased the potential of utilizing silver(I) carbenoids in preparing heterocyclic compounds.
CD73 (ecto-5′-nucleotidase) has emerged as an attractive target for cancer immunotherapy of many cancers. CD73 catalyzes the hydrolysis of adenosine monophosphate (AMP) into highly immunosuppressive ...adenosine that plays a critical role in tumor progression. Herein, we report our efforts in developing orally bioavailable and highly potent small-molecule CD73 inhibitors from the reported hit molecule 2 to lead molecule 20 and then finally to compound 49. Compound 49 was able to reverse AMP-mediated suppression of CD8+ T cells and completely inhibited CD73 activity in serum samples from various cancer patients. In preclinical in vivo studies, orally administered 49 showed a robust dose-dependent pharmacokinetic/pharmacodynamic (PK/PD) relationship that correlated with efficacy. Compound 49 also demonstrated the expected immune-mediated antitumor mechanism of action and was efficacious upon oral administration not only as a single agent but also in combination with either chemotherapeutics or checkpoint inhibitor in the mouse tumor model.
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are recommended components of preferred combination antiretroviral therapies used for the treatment of HIV. These regimens are extremely ...effective in suppressing virus replication. Structure-based optimization of diaryl ether inhibitors led to the discovery of a new series of pyrazolo3,4-cpyridazine NNRTIs that bind the reverse transcriptase enzyme of human immunodeficiency virus-1 (HIV-RT) in an expanded volume relative to most other inhibitors in this class. The binding mode maintains the β13 and β14 strands bearing Pro236 in a position similar to that in the unliganded reverse transcriptase structure, and the distribution of interactions creates the opportunity for substantial resilience to single point mutations. Several pyrazolopyridazine NNRTIs were found to be highly effective against wild-type and NNRTI-resistant viral strains in cell culture.
Non‐nucleoside reverse transcriptase inhibitors (NNRTIs) are part of the preferred treatment regimens for individuals infected with HIV. These NNRTI‐based regimens are efficacious, but the most ...popular NNRTIs have a low genetic barrier to resistance and have been associated with adverse events. There is therefore still a need for efficacious antiviral medicines that facilitate patient adherence and allow durable suppression of viral replication. As part of an extensive program targeted toward the discovery of NNRTIs that have favorable pharmacokinetic properties, good potency against NNRTI‐resistant viruses, and a high genetic barrier to drug resistance, we focused on the optimization of a series of diaryl ether NNRTIs. In the course of this effort, we employed molecular modeling to design a new set of NNRTIs that that are active against wild‐type HIV and key NNRTI‐resistant mutant viruses. The structure–activity relationships observed in this series of compounds provide insight into the structural features required for NNRTIs that inhibit the replication of a wide range of mutant viruses. Selected compounds have promising pharmacokinetic profiles.
As part of a program focused on the discovery of NNRTIs for the treatment of HIV infection, we concentrated on the optimization of a series of diaryl ether compounds. The structure–activity relationships observed in this series of compounds provide insight into the structural features required for inhibiting the replication of a wide range of mutant viruses.
New pyridone non-nucleoside reverse transcriptase inhibitors (NNRTIs) were prepared and several flexible routes to this class of inhibitor were identified. These NNRTIs were active inhibitors of the ...replication of wild-type and NNRTI-resistant HIV. Structure-based drug design was used to optimize the activity of the compounds against NNRTI-resistant mutants. The co-crystal structure of inhibitor 2b in the NNRTI binding pocket of HIV reverse transcriptase (HIVRT) is also described.
Abstract
Introduction: High adenosine (ADO) in the tumor microenvironment suppresses the immune response against cancer cells by inhibiting immune effector functions and promoting the development of ...immunosuppressive cells. Extracellular ADO can be generated from ATP released by cells undergoing stress or death through the combined actions of the ecto-nucleotidases CD39 (ATP to AMP) and CD73 (AMP to ADO). Inhibition of ADO production via CD73 is a promising therapeutic approach for the treatment of cancer.
Methods: The potency of CB-708 was evaluated against recombinant CD73 and CD73-expressing cells using a malachite green assay. Selectivity against related ecto-nucleotidases was also assessed. Inhibition of CD73 in plasma was measured using LC/MS to assess conversion of 15N5-AMP into 15N5-ADO. The ability to reverse AMP-mediated immune suppression of human CD8+ T cells was determined by adding exogenous AMP during T cell activation. T cell proliferation was assayed by flow cytometry and cytokine levels were measured by ELISA. The EG7 syngeneic tumor model was used to assess the therapeutic effect of CB-708.
Results: CB-708 is an orally bioavailable small molecule inhibitor that can potently inhibit both soluble human CD73 (IC50 = 170 pM) and cell-bound human CD73 (IC50 = 210 pM), but does not inhibit human CD39 (IC50>10 µM), ENTPD2 (IC50>10 µM), nor ENTPD3 (IC50>10 µM). CB-708 retained high potency in the presence of plasma and reversed AMP-mediated suppression of human CD8+ T cell proliferation and production of IFNγ (EC50 = 4.5 nM) and granzyme B (EC50 = 5.6 nM) in vitro. Orally administered CB-708 had dose-dependent single-agent tumor growth inhibition in the EG7 mouse syngeneic tumor model and that was associated with pharmacodynamic inhibition of plasma CD73. Enhanced tumor growth inhibition was observed when anti-PD-L1 was combined with a highly related analog of CB-708 in the EG7 model.
Conclusion: CB-708 is an orally bioavailable and highly potent small molecule inhibitor of CD73. CB-708 reverses the immunosuppressive effects of AMP-derived ADO in vitro and in vivo and leads to anti-tumor activity as a monotherapy. CB-708 is expected to enter clinical development in 2019.
Citation Format: Clarissa C. Lee, Deepthi Bhupathi, Roland J. Billedeau, Jason Chen, Lijing Chen, Ethan D. Emberley, Matthew I. Gross, Tony Huang, Weiqun Li, Yong Ma, Andrew L. Mackinnon, Amani Makkouk, Gisele M. Marguier, Silinda Neou, Francesco Parlati, Natalija Sotirovska, Timothy F. Stanton, Susanne M. Steggerda, Jing Zhang, Winter Zhang, Jim Li. Reversal of adenosine-mediated immune suppression by CB-708, an orally bioavailable and potent small molecule inhibitor of CD73 abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4134.
A solid-phase approach to the rapid synthesis of di- and tripeptide-like hydroxamic acids is presented. These compounds are shown to be potent inhibitors of procollagen C-proteinase (PCP).
The cover picture shows a cut-away view of a diaryl ether non-nucleoside reverse transcriptase inhibitor (cyan) bound to HIV reverse transcriptase. The cartoon representation of the DNA template ...(teal) and primer (gold) strands, as well as the incoming nucleotide molecule, are shown as landmarks and aligned from a separate structure (PDB code 1RTD). Binding of the non-nucleoside inhibitor interferes with the precise alignment and dynamics of the growing strand and the polymerase catalytic center. For more details, see the Full Paper by Z. K. Sweeney et al. on p. 88 ff.
New pyridone non-nucleoside reverse transcriptase inhibitors (NNRTIs) were prepared and several flexible routes to this class of inhibitor were identified. These NNRTIs were active inhibitors of the ...replication of wild-type and NNRTI-resistant HIV. Structure-based drug design was used to optimize the activity of the compounds against NNRTI-resistant mutants. The co-crystal structure of inhibitor
2b
in the NNRTI binding pocket of HIV reverse transcriptase (HIVRT) is also described.
New pyridone non-nucleoside reverse transcriptase inhibitors (NNRTIs) were prepared, and several flexible routes to this class of inhibitor were identified.
