GlaxoSmithKline (France)

A bromoindazole was reported with the ability to rapidly and extensively kill Mycobacterium tuberculosis (Mtb) in vitro, but only in the presence of sublethal levels of reactive nitrogen species (RNS) (Warrier et al., ACS Infectious Diseases 1:585-560, 2015). After learning that that compound was poorly tolerated in mice, we identified a diaryl-aminoindazole with even more pronounced ability to kill Mtb in vitro in an RNS-dependent manner, along with RNS-dependent mycobactericidal activity against Mycobacterium avium and RNS-dependent mycobacteristatic activity against Mycobacterium abscessus. The compound was orally bioavailable and well tolerated in mice. However, 4- to 8-week treatment of mice with the diaryl-aminoindazole did not reduce their pulmonary burden of Mtb. Possible explanations include the low levels of compound detected in plasma at trough and the low levels of RNS detected in the lungs of these mice.

ABSTRACT There is currently a public health crisis due to the rise of multi-drug-resistant tuberculosis cases, as well as the rise in number of deaths from tuberculosis. To achieve the United Nations Sustainable Development Goal of ending the tuberculosis epidemic by 2030, new treatments are urgently required. We previously reported the discovery of 49 , a pre-clinical candidate that acted through inhibition of the Mycobacterium tuberculosis lysyl-tRNA synthetase (LysRS). In this report, the full medicinal chemistry program is reviewed from the original hit through to the optimised lead. The work was guided by the first crystal structure of M. tuberculosis LysRS. The physicochemical and pharmacokinetic properties were optimised to afford compounds suitable for evaluation in mouse efficacy models of tuberculosis and with the potential for clinical development.

Most human pathogenic Leishmania species are zoonotic agents; therefore, sand fly-based control strategies are essential to prevent parasite circulation. Here, we used the Delftia tsuruhatensis TC1 strain, that inhibits the development of Plasmodium in mosquitoes, but in the context of Leishmania-infected sand flies. We show that D. tsuruhatensis TC1 colonizes the midgut of Phlebotomus duboscqi sand flies and impacts the development of L. major parasites, independently of the colonization timing. This phenotype is likely an indirect consequence of D. tsuruhatensis colonization, related with the induction of sand fly gut dysbiosis. Importantly, Leishmania-infected, D. tsuruhatensis-fed sand flies are less able to transmit L. major parasites and cause disease in mice. Modelling supports the disruption of disease endemicity in the field, highlighting D. tsuruhatensis as a promising agent for the control of leishmaniasis.

Bromodomains are structural folds present in all eukaryotic cells that bind to other proteins recognizing acetylated lysines. Most proteins with bromodomains are part of nuclear complexes that interact with acetylated histone residues and participate in regulating DNA replication, transcription, and repair through chromatin structure remodeling. Bromodomain inhibitors are small molecules that bind to the hydrophobic pocket of bromodomains, interfering with the interaction with acetylated histones. Using a fluorescent probe, we have developed an assay to select inhibitors of the bromodomain factor 2 ofTrypanosoma cruzi(TcBDF2) using fluorescence polarization. Initially, a library of 28,251 compounds was screened in an endpoint assay. The top 350 ranked compounds were further analyzed in a dose-response assay. From this analysis, 7 compounds were obtained that had not been previously characterized as bromodomain inhibitors. Although these compounds did not exhibit significative trypanocidal activity, all showedbona fideinteraction withTcBDF2 with dissociation constants between 1 and 3 uM validating these assays to search for bromodomain inhibitors.

Drug resistance remains a major obstacle to malaria control and eradication efforts, necessitating the development of novel therapeutic strategies to treat this disease. Drug combinations based on collateral sensitivity, wherein resistance to one drug causes increased sensitivity to the partner drug, have been proposed as an evolutionary strategy to suppress the emergence of resistance in pathogen populations. In this study, we explore collateral sensitivity between compounds targeting the Plasmodium dihydroorotate dehydrogenase (DHODH). We profiled the cross-resistance and collateral sensitivity phenotypes of several DHODH mutant lines to a diverse panel of DHODH inhibitors. We focus on one compound, TCMDC-125334, which was active against all mutant lines tested, including the DHODH C276Y line, which arose in selections with the clinical candidate DSM265. In six selections with TCMDC-125334, the most common mechanism of resistance to this compound was copy number variation of the dhodh locus, although we did identify one mutation, DHODH I263S, which conferred resistance to TCMDC-125334 but not DSM265. We found that selection of the DHODH C276Y mutant with TCMDC-125334 yielded additional genetic changes in the dhodh locus. These double mutant parasites exhibited decreased sensitivity to TCMDC-125334 and were highly resistant to DSM265. Finally, we tested whether collateral sensitivity could be exploited to suppress the emergence of resistance in the context of combination treatment by exposing wildtype parasites to both DSM265 and TCMDC-125334 simultaneously. This selected for parasites with a DHODH V532A mutation which were cross-resistant to both compounds and were as fit as the wildtype parent in vitro. The emergence of these cross-resistant, evolutionarily fit parasites highlights the mutational flexibility of the DHODH enzyme.

This regulatory post-marketing surveillance (PMS) was organized to identify the safety and effectiveness of ambrisentan in the Korean population. This was an open-label, multi-center PMS conducted from 31 institutions in Korea for 6 years from August 2015 to 2021, to evaluate the use of ambrisentan for the treatment of pulmonary arterial hypertension (PAH). Inclusion criteria are Korean subjects with the World Health Organization functional classification (WHO Fc) II or III PAH who are new users or repeated users with ambrisentan (Volibris®) Tablet 5 or 10 mg per day (age >18 years old). A total of 293 cases were analyzed. The overall incidence of adverse events (AE) was 52.22% and adverse drug reactions (ADR) was 10.92%. Severe AEs occurred in 20.82% of patients. However, only 2 subjects (0.68%) reported serious ADR. The difference in AE incidence was statistically significant for concomitant medications other than PAH medications in the safety analysis and the new users (p = 0.0041 and p = 0.0299, respectively) and elderly population in the repeated users (p = 0.0319). Among the long-term 223 subjects, the WHO Fc II and III were 41.26% and 58.74% before ambrisentan, and changed after treatment to 3.09%, 66.05%, and 30.86% for Fc I/II/III, respectively. 217 of 249 subjects (87.15%) considered their symptoms to have 'improved' after the last administration. In real-world practice, ambrisentan demonstrated tolerable safety and favorable effectiveness in PAH patients in Korea. Age and concomitant drug use can affect the occurrence of AE.

Leishmaniasis is a parasitic disease that affects more than 1 million people worldwide annually, predominantly in resource-limited settings. The challenge in compound development is to exhibit potent activity against the intracellular stage of the parasite (the stage present in the mammalian host) without harming the infected host cells. We have identified a compound series (pyrazolopyrrolidinones) active against the intracellular parasites of Leishmania donovani and L. major; the causative agents of visceral and cutaneous leishmaniasis in the Old World, respectively. In this study, we performed medicinal chemistry on a newly discovered antileishmanial chemotype, with over 100 analogs tested. Studies included assessments of antileishmanial potency, toxicity towards host cells, and in vitro ADME screening of key drug properties. Members of the series showed high potency against the deadliest form, visceral leishmaniasis (approximate EC50 ≥ 0.01 μM without harming the host macrophage up to 10.0 μM). In comparison, the most efficient monotherapy treatment for visceral leishmaniasis is amphotericin B, which presents similar activity in the same assay (EC50 = 0.2 μM) while being cytotoxic to the host cell at 5.0 μM. Continued development of this compound series with the Discovery Partnership with Academia (DPAc) program at the GlaxoSmithKline Diseases of the Developing World (GSK DDW) laboratories found that the compounds passed all of GSK's criteria to be defined as a potential lead drug series for leishmaniasis. Here, we describe preliminary structure-activity relationships for antileishmanial pyrazolopyrrolidinones, and our progress towards the identification of candidates for future in vivo assays in models of visceral and cutaneous leishmaniasis.