Driving the Way to Tuberculosis Elimination: The Essential Role of Fundamental Research.

Tuberculosis has impacted human health for millennia. The World Health Organization estimated that, in 2014, 9.6 million people developed tuberculosis and 1.5 million people died from the disease. In May 2014, the World Health Assembly endorsed the new "End TB Strategy" that presents a pathway to tuberculosis elimination. The strategy outlines 3 areas of emphasis, one of which is intensified research and innovation. In this article we highlight the essential role for fundamental tuberculosis research in the future of tuberculosis diagnostics, treatment, and prevention. To maximize the impact of fundamental research, we must foster collaboration among all stakeholders engaged in tuberculosis research and control to facilitate open dialogue to assure that critical gaps in outcome-oriented science are identified and addressed. We present here a framework for future discussions among scientists, physicians, research and development specialists, and public health managers for the reinforcement of national and international strategies toward tuberculosis elimination.

Toward an Evidence-Based Nonclinical Road Map for Evaluating the Efficacy of New Tuberculosis (TB) Drug Regimens: Proceedings of a Critical Path to TB Drug Regimens-National Institute of Allergy and Infectious Diseases In Vivo Pharmacology Workshop for TB Drug Development.

Novel tuberculosis (TB) drug regimens are urgently needed, and their development will be enabled by improved preclinical approaches that more effectively inform and ensure safe selection of clinical candidates and drug combination/regimens. An evidence-based approach for the assessment of nonclinical models supporting TB drug development has been proposed by a joint partnership between the National Institute of Allergy and Infectious Diseases (NIAID) and the Critical Path to TB Drug Regimens (CPTR) Consortium.

Clinical research and development of tuberculosis diagnostics: moving from silos to synergy.

The development, evaluation, and implementation of new and improved diagnostics have been identified as critical needs by human immunodeficiency virus (HIV) and tuberculosis researchers and clinicians alike. These needs exist in international and domestic settings and in adult and pediatric populations. Experts in tuberculosis and HIV care, researchers, healthcare providers, public health experts, and industry representatives, as well as representatives of pertinent US federal agencies (Centers for Disease Control and Prevention, Food and Drug Administration, National Institutes of Health, United States Agency for International Development) assembled at a workshop proposed by the Diagnostics Working Group of the Federal Tuberculosis Taskforce to review the state of tuberculosis diagnostics development in adult and pediatric populations.

An array of target-specific screening strains for antibacterial discovery.

As the global threat of drug- and antibiotic-resistant bacteria continues to rise, new strategies are required to advance the drug discovery process. This work describes the construction of an array of Escherichia coli strains for use in whole-cell screens to identify new antimicrobial compounds. We used the recombination systems from bacteriophages lambda and P1 to engineer each strain in the array for low-level expression of a single, essential gene product, thus making each strain hypersusceptible to specific inhibitors of that gene target. Screening of nine strains from the array in parallel against a large chemical library permitted identification of new inhibitors of bacterial growth. As an example of the target specificity of the approach, compounds identified in the whole-cell screen for MurA inhibitors were also found to block the biochemical function of the target when tested in vitro.

Parallel synthesis of potent, pyrazole-based inhibitors of Helicobacter pylori dihydroorotate dehydrogenase.

The identification of several potent pyrazole-based inhibitors of bacterial dihydroorotate dehydrogenase (DHODase) via a directed parallel synthetic approach is described below. The initial pyrazole-containing lead compounds were optimized for potency against Helicobacter pylori DHODase. Using three successive focused libraries, inhibitors were rapidly identified with the following characteristics: K(i) < 10 nM against H. pylori DHODase, sub-microg/mL H. pylori minimum inhibitory concentration activity, low molecular weight, and >10 000-fold selectivity over human DHODase.

Safety and efficacy assessment of two new leprosy skin test antigens: randomized double blind clinical study.

BACKGROUND: New tools are required for the diagnosis of pre-symptomatic leprosy towards further reduction of disease burden and its associated reactions. To address this need, two new skin test antigens were developed to assess safety and efficacy in human trials. METHODS: A Phase I safety trial was first conducted in a non-endemic region for leprosy (U.S.A.). Healthy non-exposed subjects (n = 10) received three titrated doses (2.5 µg, 1.0 µg and 0.1 µg) of MLSA-LAM (n = 5) or MLCwA (n = 5) and control antigens [Rees MLSA (1.0 µg) and saline]. A randomized double blind Phase II safety and efficacy trial followed in an endemic region for leprosy (Nepal), but involved only the 1.0 µg (high dose) and 0.1 µg (low dose) of each antigen; Tuberculin PPD served as a control antigen. This Phase II safety and efficacy trial consisted of three Stages: Stage A and B studies were an expansion of Phase I involving 10 and 90 subjects respectively, and Stage C was then conducted in two parts (high dose and low dose), each enrolling 80 participants: 20 borderline lepromatous/lepromatous (BL/LL) leprosy patients, 20 borderline tuberculoid/tuberculoid (BT/TT) leprosy patients, 20 household contacts of leprosy patients (HC), and 20 tuberculosis (TB) patients. The primary outcome measure for the skin test was delayed type hypersensitivity induration. FINDINGS: In the small Phase I safety trial, reactions were primarily against the 2.5 µg dose of both antigens and Rees control antigen, which were then excluded from subsequent studies. In the Phase II, Stage A/B ramped-up safety study, 26% of subjects (13 of 50) showed induration against the high dose of each antigen, and 4% (2 of 50) reacted to the low dose of MLSA-LAM. Phase II, Stage C safety and initial efficacy trial showed that both antigens at the low dose exhibited low sensitivity at 20% and 25% in BT/TT leprosy patients, but high specificity at 100% and 95% compared to TB patients. The high dose of both antigens showed lower specificity (70% and 60%) and sensitivity (10% and 15%). BL/LL leprosy patients were anergic to the leprosy antigens. INTERPRETATION: MLSA-LAM and MLCwA at both high (1.0 µg) and low (0.1 µg) doses were found to be safe for use in humans without known exposure to leprosy and in target populations. At a sensitivity rate of 20-25% these antigens are not suitable as a skin test for the detection of the early stages of leprosy infection; however, the degree of specificity is impressive given the presence of cross-reactive antigens in these complex native M. leprae preparations. TRIAL REGISTRATION: ClinicalTrials.gov NCT01920750 (Phase I), NCT00128193 (Phase II).

The role of biomedical research in global tuberculosis control: gaps and challenges: A perspective from the US National Institute of Allergy and Infectious Diseases, National Institutes of Health.

Tuberculosis (TB) has been a persistent public health concern for hundreds of years. Despite advances in medicine and science, eliminating this disease has been beyond our reach. Several organizations, including the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), have expressed their commitment to advancing biomedical research in TB in order to increase our understanding of the causative pathogen and the disease. This basic knowledge is a critical first step in the development and implementation of new therapeutics, vaccines and diagnostics. Collaboration between researchers is a key component to accomplishing this goal; product development can no longer be limited to separate programs. Rather, the interconnectedness and possible combination of interventions must be investigated. This review will discuss ongoing TB research including NIAID's role, as well as future research that is needed to improve TB control. Emphasizing the importance of coordination among researchers, funders and advocacy groups, we aim to illustrate the fact that biomedical research, and particularly basic research, is a vital part of a complementary approach to eliminating TB across the globe.

Tuberculosis vaccine development: research, regulatory and clinical strategies.

In the past decade, while the global tuberculosis (TB) epidemic has continued to devastate mankind, considerable progress has nevertheless been made in the development of new and improved vaccines for this ancient disease. Recombinant bacillus Calmette-Guerin strains, DNA-based vaccines, live attenuated Mycobacterium tuberculosis vaccines and subunit vaccines formulated with novel adjuvants have shown promise in preclinical animal challenge models. Three of these vaccines are being evaluated at present in human clinical studies, and several other vaccine preparations are being targeted for clinical trials in the near future. Although the preclinical characterisation and testing of new TB vaccines has clearly led to exciting new findings, complex regulatory and clinical trial design issues remain as a challenge to TB vaccine development. This report reviews some of the exciting advances in TB research that have led to the development of new TB vaccines, and addresses the unique regulatory and clinical issues associated with the testing of novel anti-TB preparations in human populations.

Effects of metronidazole, tetracycline, and bismuth-metronidazole-tetracycline triple therapy in the Helicobacter pylori SS1 mouse model after 1 day of dosing: development of an H. pylori lead selection model.

We evaluated the effect of optimized doses and dosing schedules of metronidazole, tetracycline, and bismuth-metronidazole-tetracycline (BMT) triple therapy with only 1 day of dosing on Helicobacter pylori SS1 titers in a mouse model. A reduction of bacterial titers was observable with 22.5 and 112.5 mg of metronidazole per kg of body weight (as well as BMT) given twice daily and four times daily (QID). Two hundred milligrams of tetracycline per kilogram, given QID, resulted in only a slight reduction of H. pylori titers in the stomach. We argue that optimization of doses based on antimicrobial drug levels in the animal and shortened (1 or 2 days) drug administration can be used to facilitate early evaluation of putative anti-H. pylori drug candidates in lieu of using human doses and extended schedules (7 to 14 days), as can be deduced from the results seen with these antimicrobial agents.