MmpL3 Inhibition as a Promising Approach to Develop Novel Therapies against Tuberculosis: A Spotlight on SQ109, Clinical Studies, and Patents Literature

Antibiotic resistance in Mycobacterium tuberculosis alters tolerance to cell wall-targeting inhibitors

Background

A limited ability to eliminate drug-resistant strains of Mycobacterium tuberculosis is a major contributor to the morbidity of TB. Complicating this problem, little is known about how drug resistance-conferring mutations alter the ability of M. tuberculosis to tolerate antibiotic killing. Here, we investigated if drug-resistant strains of M. tuberculosis have an altered ability to tolerate killing by cell wall-targeting inhibitors.

Methods

Bacterial killing and MIC assays were used to test for antibiotic tolerance and synergy against a panel of drug-resistant M. tuberculosis strains.

Results

Our results demonstrate that vancomycin and thioacetazone exhibit increased killing of diverse drug-resistant strains. Mutations in mmaA4 and mmpL3 increased vancomycin killing, which was consistent with vancomycin synergizing with thioacetazone and MmpL3-targeting inhibitors. In contrast, mutations in the mce1 operon conferred tolerance to vancomycin.

Conclusions

Overall, this work demonstrates how drug-resistant strains experience perturbations in cell-wall production that alters their tolerance to killing by cell wall-targeting inhibitors.

Advances in Diagnostics and Drug Discovery against Resistant and Latent Tuberculosis Infection

Latent tuberculosis infection (LTBI) represents a subclinical, asymptomatic mycobacterial state affecting approximately 25% of the global population. The substantial prevalence of LTBI, combined with the risk of progressing to active tuberculosis, underscores its central role in the increasing incidence of tuberculosis (TB). Accurate identification and timely treatment are vital to contain and reduce the spread of the disease, forming a critical component of the global strategy known as "End TB." This review aims to examine and highlight the most recent scientific evidence related to new diagnostic approaches and emerging therapeutic treatments for LTBI. While prevalent diagnostic methods include the tuberculin skin test (TST) and interferon gamma release assay (IGRA), WHO's approval of two specific IGRAs for Mycobacterium tuberculosis (MTB) marked a significant advancement. However, the need for a specific test with global application viability has propelled research into diagnostic tests based on molecular diagnostics, pulmonary immunity, epigenetics, metabolomics, and a current focus on next-generation MTB antigen-based skin test (TBST). It is within these emerging methods that the potential for accurate distinction between LTBI and active TB has been demonstrated. Therapeutically, in addition to traditional first-line therapies, anti-LTBI drugs, anti-resistant TB drugs, and innovative candidates in preclinical and clinical stages are being explored. Although the advancements are promising, it is crucial to recognize that further research and clinical evidence are needed to solidify the effectiveness and safety of these new approaches, in addition to ensuring access to new drugs and diagnostic methods across all health centers. The fight against TB is evolving with the development of more precise diagnostic tools that differentiate the various stages of the infection and with more effective and targeted treatments. Once consolidated, current advancements have the potential to transform the prevention and treatment landscape of TB, reinforcing the global mission to eradicate this disease.

Synthesis and Structure-Activity Relationships of a New Class of Oxadiazoles Targeting DprE1 as Antitubercular Agents

The continuing prevalence of drug-resistant tuberculosis threatens global TB control programs, highlighting the need to discover new drug candidates to feed the drug development pipeline. In this study, we describe a high-throughput screening hit (4-benzylpiperidin-1-yl)(1-(5-phenyl-1,3,4-oxadiazol-2-yl)piperidin-4-yl)methanone (P1) as a potent antitubercular agent. Structure-activity guided synthesis led to the discovery of several analogs with high in vitro potency. P1 was found to have promising potency against many drug-resistant strains, as well as drug-susceptible clinical isolates. It also showed cidality against Mtb growing in host macrophages. Whole genome sequencing of genomic DNA from resistant mutants raised to P1 revealed mutations in decaprenylphosphoryl-β-d-ribose 2'-oxidase (DprE1). This novel oxadiazole scaffold expands the set of chemical tools for targeting a well-validated pathway to treat tuberculosis.

Trofinetide for Rett Syndrome: Highlights on the Development and Related Inventions of the First USFDA-Approved Treatment for Rare Pediatric Unmet Medical Need

Rett syndrome (RTT) is a rare disability causing female-oriented pediatric neurodevelopmental unmet medical need. RTT was recognized in 1966. However, over the past 56 years, the United States Food and Drug Administration (USFDA) has authorized no effective treatment for RTT. Recently, Trofinetide was approved by the USFDA on 10 March 2023 as the first RTT treatment. This article underlines the pharmaceutical advancement, patent literature, and prospects of Trofinetide. The data for this study were gathered from the PubMed database, authentic websites (Acadia Pharmaceuticals, Neuren Pharmaceuticals, and USFDA), and free patent databases. Trofinetide was first disclosed by Neuren Pharmaceuticals in 2000 as a methyl group containing analog of the naturally occurring neuroprotective tripeptide called glycine-proline-glutamate (GPE). The joint efforts of Acadia Pharmaceuticals and Neuren Pharmaceuticals have developed Trofinetide. The mechanism of action of Trofinetide is not yet well established. However, it is supposed to improve neuronal morphology and synaptic functioning. The patent literature revealed a handful of inventions related to Trofinetide, providing excellent and unexplored broad research possibilities with Trofinetide. The development of innovative Trofinetide-based molecules, combinations of Trofinetide, patient-compliant drug formulations, and precise MECP2-mutation-related personalized medicines are foreseeable. Trofinetide is in clinical trials for some neurodevelopmental disorders (NDDs), including treating Fragile X syndrome (FXS). It is expected that Trofinetide may be approved for treating FXS in the future. The USFDA-approval of Trofinetide is one of the important milestones for RTT therapy and is the beginning of a new era for the therapy of RTT, FXS, autism spectrum disorder (ASD), brain injury, stroke, and other NDDs.

Insights into substrate transport and water permeation in the mycobacterial transporter MmpL3

Mycobacteria, such as Mycobacterium tuberculosis, are characterized by a uniquely thick and waxy cell envelope that consists of two membranes, with a variety of mycolates comprising their outer membrane (OM). The protein Mycobacterial membrane protein Large 3 (MmpL3) is responsible for the transport of a primary OM component, trehalose monomycolate (TMM), from the inner (cytoplasmic) membrane (IM) to the periplasmic space, a process driven by the proton gradient. Although multiple structures of MmpL3 with bound substrates have been solved, the exact pathway(s) for TMM or proton transport remains elusive. Here, employing molecular dynamics simulations we investigate putative pathways for either transport species. We hypothesized that MmpL3 will cycle through similar conformational states as the related transporter AcrB, which we used as targets for modeling the conformation of MmpL3. A continuous water pathway through the transmembrane region was found in one of these states, illustrating a putative pathway for protons. Additional equilibrium simulations revealed that TMM can diffuse from the membrane into a binding pocket in MmpL3 spontaneously. We also found that acetylation of TMM, which is required for transport, makes it more stable within MmpL3's periplasmic cavity compared with the unacetylated form.

Highlights on the Development, Related Patents, and Prospects of Lenacapavir: The First-in-Class HIV-1 Capsid Inhibitor for the Treatment of Multi-Drug-Resistant HIV-1 Infection

The multidrug-resistant (MDR) human immunodeficiency virus 1 (HIV-1) infection is an unmet medical need. HIV-1 capsid plays an important role at different stages of the HIV-1 replication cycle and is an attractive drug target for developing therapies against MDR HIV-1 infection. Lenacapavir (LEN) is the first-in-class HIV-1 capsid inhibitor approved by the USFDA, EMA, and Health Canada for treating MDR HIV-1 infection. This article highlights the development, pharmaceutical aspects, clinical studies, patent literature, and future directions on LEN-based therapies. The literature for this review was collected from PubMed, authentic websites (USFDA, EMA, Health Canada, Gilead, and NIH), and the free patent database (Espacenet, USPTO, and Patent scope). LEN has been developed by Gilead and is marketed as Sunlenca (tablet and subcutaneous injection). The long-acting and patient-compliant LEN demonstrated a low level of drug-related mutations, is active against MDR HIV-1 infection, and does not reveal cross-resistance to other anti-HIV drugs. LEN is also an excellent drug for patients having difficult or limited access to healthcare facilities. The literature has established additive/synergistic effects of combining LEN with rilpivirine, cabotegravir, islatravir, bictegravir, and tenofovir. HIV-1 infection may be accompanied by opportunistic infections such as tuberculosis (TB). The associated diseases make HIV treatment complex and warrant drug interaction studies (drug-drug, drug-food, and drug-disease interaction). Many inventions on different aspects of LEN have been claimed in patent literature. However, there is a great scope for developing more inventions related to the drug combination of LEN with anti-HIV/anti-TB drugs in a single dosage form, new formulations, and methods of treating HIV and TB co-infection. Additional research may provide more LEN-based treatments with favorable pharmacokinetic parameters for MDR HIV-1 infections and associated opportunistic infections such as TB.

QcrB inhibition as a potential approach for the treatment of tuberculosis: A review of recent developments, patents, and future directions

The unmet medical need for drug-resistant tuberculosis (DRTB) is a significant concern. Accordingly, identifying new drug targets for tuberculosis (TB) treatment and developing new therapies based on these drug targets is one of the strategies to tackle DRTB. QcrB is an innovative drug target to create treatments for DRTB. This article highlights QcrB inhibitors and their therapeutic compositions for treating TB. The literature for this article was gathered from PubMed and free patent databases utilizing different keywords related to QcrB inhibitor-based inventions. The data was collected from the conceptualization of telacebec (2010) QcrB to December 2022. A little interesting and encouraging research has been performed on QcrB inhibitors. Telacebec and TB47 are established QcrB inhibitors in the clinical trial. The inventive QcrB inhibitor-based drug combinations can potentially handle DRTB and reduce the TB therapy duration. The authors anticipate great opportunities in fostering QcrB inhibitor-based patentable pharmaceutical inventions against TB. Drug repurposing can be a promising strategy to get safe and effective QcrB inhibitors. However, developing drug resistance, drug tolerance, and selectivity of QcrB inhibitors for Mtb will be the main challenges in developing effective QcrB inhibitors. In conclusion, QcrB is a promising drug target for developing effective treatments for active, latent, and drug-resistant TB. Many inventive and patentable combinations and compositions of QcrB inhibitors with other anti-TB drugs are anticipated as future treatments for TB.

Structure-Activity Relationship of Novel Pyrimidine Derivatives with Potent Inhibitory Activities against Mycobacterium tuberculosis

Discovery of novel antitubercular drugs is an effective strategy against drug-resistant tuberculosis (TB). Our previous study has identified LPX-16j as a novel antitubercular compound. Herein, we perform a comprehensive structure-activity relationship (SAR) based on LPX-16j, indicating that the central pyrimidine ring moiety was crucial for the antitubercular activities of its derivatives, and replacing the naphthyl group with hydrophobic substitutes was well tolerated. The representative derivative 5a exhibited potent activity against H37Ra, H37Rv, and clinical drug-resistant TB with minimum inhibitory concentration (MIC) values of 0.5-1.0 μg/mL. Meanwhile, 5a showed an acceptable safety in vivo and displayed a favorable oral bioavailability with a value of 40.7%. The differential scanning fluorescence, isothermal titration calorimetry, and molecular docking assays indicated that PknB could be one of the targets of compound 5a. Overall, this study identified 5a as a novel promising lead compound with the potential to develop candidates for the treatment of drug-resistant TB.