Conference report: WHO meeting summary on mRNA-based tuberculosis vaccine development.

Tuberculosis (TB) is a global health emergency. Across the globe, approximately 2 billion people are currently infected with Mycobacterium tuberculosis (Mtb), and of those, 5-10% may progress to become ill and potentially transmit the bacterium. In 2021, nearly 10.6 million people developed TB disease and 1.6 million died. There is an urgent need for accelerated development of new TB-focused interventions, in particular, improved TB vaccines. However, progress in developing highly effective TB vaccines has been slow and is chronically under-resourced. The mRNA vaccine platform may offer an opportunity to accelerate development of new TB vaccines. In April 2023, the World Health Organization convened global experts to discuss the feasibility and potential value of mRNA-based vaccines for TB. Here we report on meeting deliberations related to the current TB vaccine pipeline and potential novel antigens, the status of efforts to identify correlates of protection, potential clinical development strategies and considerations for community acceptance of new TB vaccines based on this relatively new platform. The role of industry collaborations, ethics, social science, and responsibility to the global community regarding transparency and manufacturing capacity building were discussed through expert presentations and panel sessions. The overall conclusion of the meeting is that mRNA-based vaccines constitute a potentially powerful new tool for reducing the global burden of TB.

Clinical trials of tuberculosis vaccines in the era of increased access to preventive antibiotic treatment.

Approximately 10·6 million people worldwide develop tuberculosis each year, representing a failure in epidemic control that is accentuated by the absence of effective vaccines to prevent infection or disease in adolescents and adults. Without effective vaccines, tuberculosis prevention has relied on testing for Mycobacterium tuberculosis infection and treating with antibiotics to prevent progression to tuberculosis disease, known as tuberculosis preventive treatment (TPT). Novel tuberculosis vaccines are in development and phase 3 efficacy trials are imminent. The development of effective, shorter, and safer TPT regimens has broadened the groups eligible for TPT beyond people with HIV and child contacts of people with tuberculosis; future vaccine trials will be undertaken in an era of increased TPT access. Changes in the prevention standard will have implications for tuberculosis vaccine trials of disease prevention, for which safety and sufficient accrual of cases are crucial. In this paper, we examine the urgent need for trials that allow the evaluation of new vaccines and fulfil the ethical duty of researchers to provide TPT. We observe how HIV vaccine trials have incorporated preventive treatment in the form of pre-exposure prophylaxis, propose trial designs that integrate TPT, and summarise considerations for each design in terms of trial validity, efficiency, participant safety, and ethics.

Developing tuberculosis vaccines for people with HIV: consensus statements from an international expert panel.

New tuberculosis vaccine candidates that are in the development pipeline need to be studied in people with HIV, who are at high risk of acquiring Mycobacterium tuberculosis infection and tuberculosis disease and tend to develop less robust vaccine-induced immune responses. To address the gaps in developing tuberculosis vaccines for people with HIV, a series of symposia was held that posed six framing questions to a panel of international experts: What is the use case or rationale for developing tuberculosis vaccines? What is the landscape of tuberculosis vaccines? Which vaccine candidates should be prioritised? What are the tuberculosis vaccine trial design considerations? What is the role of immunological correlates of protection? What are the gaps in preclinical models for studying tuberculosis vaccines? The international expert panel formulated consensus statements to each of the framing questions, with the intention of informing tuberculosis vaccine development and the prioritisation of clinical trials for inclusion of people with HIV.

Comparing timelines and evidence available to support new TB, HIV, and HCV drug approvals: The same, only different.

BACKGROUND: Tuberculosis (TB), human immunodeficiency virus (HIV), and hepatitis C virus (HCV) share a global presence and propensity to disproportionately affect marginalized populations. However, over recent decades, many fewer drugs have been brought to market for TB than for the others. Although three new anti-TB drugs have been approved in the US or Europe in the last 10 years, uptake of these drugs has been limited. Using case examples of drugs developed recently for TB, HIV, and HCV, we explore possible reasons. We examine the use and effect of regulatory pathways intended to address weak economic incentives in the face of urgent, unmet needs; evaluate the extent of data underpinning authorizations for these indications; document development timelines and evidence available at the time of each approval; consider explanations for observed differences; and discuss the implications for clinical guidelines and use. METHODS AND FINDINGS: For each indication, we selected two drugs: one recently approved and one approved between 2012 and 2014, when the first new anti-TB drug from a novel class in more than 40 years received marketing authorization. We calculated time from first published peer-reviewed evidence of activity to date of approval; the number of phase 1, 2, and 3 trials; the number of trial participants randomized to treatment arms containing the drug; and the total number of participants in each trial from the individual drug approval packages. We found that the two TB drugs took longer to gain approval (8.0 and 19.2 years for bedaquiline and pretomanid, respectively) despite availing of special regulatory pathways meant to expedite approval, when compared to the HIV (2.6 years for dolutegravir and 4.7 years for doravirine) and HCV drugs (3.2 and 1.6 years for sofosbuvir and glecaprevir/pibrentasvir, respectively). Moreover, fewer participants were studied prior to TB drug approvals (380 and 879) than prior to approvals for HIV (1598 and 979) and for HCV (2291 and 2448) drugs. CONCLUSIONS: The dramatic disparities observed in TB drug development reaffirm the importance of several actions. Increased investment in TB research and development is necessary to rapidly advance drugs through the pipeline. Development plans and partnerships must provide safety and efficacy evidence on combinations and durations that are relevant to real-world use in heterogeneous populations. Reliable, validated surrogate markers of relapse-free cure are essential to decrease the duration and cost of TB treatment trials and increase the confidence and speed with which new regimens can advance. Lastly, regulators and normative bodies must maintain high evidentiary standards for authorization while ensuring timely and broad approval for TB drugs and regimens.

End-point definition and trial design to advance tuberculosis vaccine development.

Tuberculosis (TB) remains a leading infectious cause of death worldwide and the coronavirus disease 2019 pandemic has negatively impacted the global TB burden of disease indicators. If the targets of TB mortality and incidence reduction set by the international community are to be met, new more effective adult and adolescent TB vaccines are urgently needed. There are several new vaccine candidates at different stages of clinical development. Given the limited funding for vaccine development, it is crucial that trial designs are as efficient as possible. Prevention of infection (POI) approaches offer an attractive opportunity to accelerate new candidate vaccines to advance into large and expensive prevention of disease (POD) efficacy trials. However, POI approaches are limited by imperfect current tools to measure Mycobacterium tuberculosis infection end-points. POD trials need to carefully consider the type and number of microbiological tests that define TB disease and, if efficacy against subclinical (asymptomatic) TB disease is to be tested, POD trials need to explore how best to define and measure this form of TB. Prevention of recurrence trials are an alternative approach to generate proof of concept for efficacy, but optimal timing of vaccination relative to treatment must still be explored. Novel and efficient approaches to efficacy trial design, in addition to an increasing number of candidates entering phase 2-3 trials, would accelerate the long-standing quest for a new TB vaccine.

Building the concept for WHO Evidence Considerations for Vaccine Policy (ECVP): Tuberculosis vaccines intended for adults and adolescents as a test case.

Currently, no formal mechanisms or systematic approaches exist to inform developers of new vaccines of the evidence anticipated to facilitate global policy recommendations, before a vaccine candidate approaches regulatory approval at the end of pre-licensure efficacy studies. Consequently, significant delays may result in vaccine introduction and uptake, while post-licensure data are generated to support a definitive policy decision. To address the uncertainties of the evidence-to-recommendation data needs and to mitigate the risk of delays between vaccine recommendation and use, WHO is evaluating the need for and value of a new strategic alignment tool: Evidence Considerations for Vaccine Policy (ECVP). EVCPs aim to fill a critical current gap by providing early (pre-phase 3 study design) information on the anticipated clinical trial and observational data or evidence that could support WHO and/or policy decision making for new vaccines in priority disease areas. The intent of ECVPs is to inform vaccine developers, funders, and other key stakeholders, facilitating stakeholder alignment in their strategic planning for late stage vaccine development. While ECVPs are envisaged as a tool to support dialogue on evidence needs between regulators and policy makers at the national, regional and global level, development of an ECVP will not preclude or supersede the independent WHO's Strategic Advisory Group of Experts on Immunization (SAGE) evidence to recommendation (EtR) process that is required for all vaccines seeking WHO policy recommendation. Tuberculosis (TB) vaccine candidates intended for use in the adolescent and adult target populations comprise a portfolio of priority vaccines in late-stage clinical development. As such, TB vaccines intended for use in this target population provide a 'test case' to further develop the ECVP concept, and develop the first WHO ECVP considerations guidance.

Public investments in the clinical development of bedaquiline.

INTRODUCTION: In 2012, bedaquiline became the first new treatment from a novel class to be approved for tuberculosis in nearly five decades and is now a core component of the standard of care for multidrug-resistant tuberculosis. In addition to the originator pharmaceutical company, Janssen, a range of governmental and non-profit entities have contributed to the development of bedaquiline. MATERIALS AND METHODS: We identified various avenues of public investments in the development of bedaquiline: direct funding of clinical trials and a donation programme, tax credits and deductions, and revenues resulting from the priority review voucher (PRV) awarded to the originator. Data on investments were gathered through contact with study leads and/or funders; for non-responses, published average costs were substituted. The originator company's expenses were estimated by similar methods. Tax credits and deductions were calculated based on estimated originator trial costs and donation expenses. The value of the PRV was estimated by application of a published model. RESULTS: Public contributions through clinical trials funding were estimated at US$109-252 million, tax credits at US$22-36 million, tax deductions at US$8-27 million, administration of a donation programme at US$5 million, PRV revenues at US$300-400 million. Total public investments were US$455-747 million and originator investments were US$90-240 million (if capitalized and risk-adjusted, US$647-1,201 million and US$292-772 million, respectively). CONCLUSIONS: Estimating the investments in the development of a medicine can inform discussions regarding fair pricing and future drug development. We estimated that total public investments exceeded the originator's by a factor of 1.6-5.1.

Using theory of change frameworks to develop evaluation strategies for research engagement: results of a pre-pilot study.

INTRODUCTION: Inadequate community and stakeholder engagement can lead to accusations that research is unethical and can delay or slow research or translation of results to practice. Such experiences have led major funders as well as regulatory and advisory bodies to establish minimal requirements for community and stakeholder engagement in HIV and other clinical research. However, systematic efforts to formally evaluate the contributions and impact of particular practices are lacking. METHODS: A theory of change framework aligned with Good Participatory Practice for TB clinical trials was used to develop a set of measures for use in a minimally burdensome survey of trial implementing sites. The survey was pre-piloted with three TB trial sites in North America, South America and Asia to assess the feasibility of surveying global research sites in a systematic way, and to see if the measures captured informative variation in the use of engagement strategies and desired outcomes. Surveys were conducted at baseline and six months. In-depth interviews were conducted with site staff prior to the baseline survey to understand how sites conceptualized the concepts underlying the framework and the extent to which they viewed their work as aligned with the framework. RESULTS: Survey measures captured considerable variability in the intensity and variety of engagement strategies, both across sites and within sites over time, and moderate variability in outcomes. Interviews indicated that underlying concepts were often unfamiliar to staff at baseline, but the goals of engagement aligned well with existing values. CONCLUSIONS: Brief, targeted surveys of trial sites to characterize use of broad strategies, specific practices and some outcomes are a feasible option for evaluating good participatory practice. Additional testing is warranted to assess and enhance validity, reliability and predictive value of indicators. Options for collecting outcome measures through additional objective means should be explored.

A Community Perspective on the Inclusion of Pregnant Women in Tuberculosis Drug Trials.

Affecting both mother and the existing pregnancy, tuberculosis (TB) increases the likelihood of poor birth outcomes. Despite substantial clinical need for TB prevention and treatment, pregnant women remain neglected by research initiatives. As members of 3 community advisory boards that provide input into TB drug trials, we offer a community perspective on the inclusion of pregnant women in TB drug research and discuss (1) our perspective on the risk/benefit tradeoff of including pregnant women in research to address different forms of TB; (2) recent examples of progress in this area; (3) lessons learned from the human immunodeficiency virus research field, where pregnant women have enjoyed better-although imperfect-representation in research; and (4) recommendations for different stakeholders, including researchers, regulatory authorities, ethics committees, and policymakers.

Funding for tuberculosis research-an urgent crisis of political will, human rights, and global solidarity.

Tuberculosis (TB) killed more people in 2015 than any other single infectious agent, but funding for research to develop better prevention, diagnosis, and treatment methods for TB declined to its lowest level in 7 years. TB research and development (R&D) is woefully underfunded, a situation best viewed as a crisis of political will and a failure on the part of governments to see unmet innovation needs in the TB response as a human rights issue requiring immediate action. Over 60% of available money for TB R&D comes from public sources, and 67% of public money comes from a single country: the USA. The election of Donald Trump to the US presidency in November 2016 has introduced great uncertainty into the support that science generally, and TB research in particular, will receive in the coming years. Advocacy on the part of all actors-from civil society to TB-affected communities to scientists themselves-is urgently needed to increase US government support for TB research moving forward.

Falling Short of the Rights to Health and Scientific Progress: Inadequate TB Drug Research and Access.

The incorporation of human rights-based approaches into TB programs is gaining traction, but little work has explored the application of human rights norms and principles to TB research (a domain traditionally left to bioethics). TB research is gravely underfunded, and the scarcity of resources for TB drug development has contributed to the stubborn persistence of the TB epidemic and helped to create the conditions under which drug-resistant TB has developed and spread. This article shows how human rights-particularly human rights standards, norms, and principles related to the rights to health and benefits of scientific progress-can provide insight into understanding how underfunding TB drug research undermines efforts to secure access to safe, effective, and optimized treatment for all people with TB. By analyzing TB research in relation to the rights to health and scientific progress, we aim to clarify the legal obligations of governments to improve the TB drug research system, fund TB research, and make medical advances that result from research available to all people with TB.

Developing a Framework for Evaluating Ethical Outcomes of Good Participatory Practices in TB Clinical Drug Trials.

Good Participatory Practice Guidelines for TB Drug Trials (GPP-TB) were issued in 2012, based on similar guidelines for HIV prevention and reflecting growing acceptance of the importance of community engagement and participatory strategies in clinical research. Though the need for such strategies is clear, evaluation of the benefits and burdens are needed. Working with a diverse group of global TB stakeholders including advocates, scientists, and ethicists, we used a Theory of Change approach to develop an evaluation framework for GPP-TB that includes a clearly defined ethical goal, a set of powerful strategies derived from GPP-TB practices for achieving the goal, and outcomes connecting strategies to goal. The framework is a first step in systematically evaluating participatory research in clinical trials.