Current and Emerging Therapies for Pulmonary Tuberculosis

Enteric infectious diseases contribute to over 1 million annual deaths and rank among the top ten causes of death in children younger than 5 years.^1,2,3 Despite substantial global investment in prevention and control, the shifting global health landscape challenges sustained progress.^1,2,3 The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023 provides updated epidemiological estimates for enteric infectious diseases, assessing progress toward the Global Action Plan for the Prevention and Control of Pneumonia and Diarrhoea (GAPPD) mortality target of fewer than 20 deaths per 100,000 children younger than 5 years by 2025.^1,2,3

Current and Emerging Therapies

A systematic analysis for the GBD 2023 study examined the global burden of enteric infectious diseases, diarrhoeal diseases, and their corresponding aetiologies from 1990 to 2023.¹ Another review focused on primary ciliary dyskinesia in pediatric persons, describing it as a microscopic movement malady.²

Mahmood, Ashfaq, and Drain conducted a review specifically on current and emerging therapies for pulmonary tuberculosis in adults.³ This review addresses the therapeutic landscape for PTB, which is critical given the disease's global prevalence and the challenges associated with treatment, including drug resistance and treatment duration. The authors' abstract indicates an evaluation of the current status and a guide for future interventions in the context of infectious diseases.³ While the abstract does not detail specific drug names, trial designs, or efficacy statistics for PTB therapies, it signals an ongoing effort to understand and improve treatment outcomes for this condition. The broader context of infectious disease burden, as highlighted by the GBD 2023, underscores the importance of such therapeutic advancements.^1,2,3

The challenges in PTB treatment are multifaceted, encompassing the lengthy duration of current regimens, which often leads to poor adherence and subsequent treatment failure, and the escalating threat of drug-resistant tuberculosis (DR-TB). The standard short-course regimen for drug-susceptible PTB typically involves a 6-month course of isoniazid, rifampicin, pyrazinamide, and ethambutol. While effective for susceptible strains, this regimen is demanding for patients and healthcare systems alike. For DR-TB, particularly multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), treatment regimens are considerably longer, more toxic, and less effective, necessitating the development of novel therapeutic strategies.

Emerging Therapeutic Strategies and Future Directions

Emerging therapies for PTB are primarily focused on three key areas: shortening treatment duration, improving efficacy against drug-resistant strains, and enhancing tolerability. One promising avenue involves the repurposing of existing drugs and the development of new chemical entities with novel mechanisms of action. For instance, bedaquiline and delamanid represent newer antituberculosis drugs specifically approved for DR-TB, demonstrating improved outcomes in patients previously facing limited options. Their integration into revised treatment guidelines has marked a significant step forward, though challenges related to access and monitoring remain.

Beyond novel drug development, research is also exploring host-directed therapies (HDTs) and immunomodulatory approaches. HDTs aim to boost the host's immune response against Mycobacterium tuberculosis, potentially shortening treatment and preventing relapse. Examples include vitamin D supplementation, non-steroidal anti-inflammatory drugs (NSAIDs), and metformin, which are being investigated for their adjunctive roles in PTB treatment. While these approaches are still largely in the investigational phase, they offer a paradigm shift from solely targeting the pathogen to modulating the host's response, potentially leading to more durable cures and reduced drug toxicity.

Furthermore, the development of more accurate and rapid diagnostic tools is intrinsically linked to therapeutic advancements. Early and precise identification of drug susceptibility patterns is crucial for guiding appropriate treatment and preventing the amplification of resistance. Innovations in molecular diagnostics, such as rapid PCR-based tests and next-generation sequencing, are increasingly being deployed to inform clinical decisions, thereby optimizing therapeutic outcomes. The ongoing global effort to combat infectious diseases, as underscored by the GBD 2023, necessitates a continuous pipeline of research and development in both diagnostics and therapeutics to meet the evolving challenges posed by pathogens like M. tuberculosis. Future interventions will likely involve combination therapies that leverage new drugs, HDTs, and personalized treatment regimens guided by advanced diagnostics to achieve the ambitious goal of tuberculosis elimination.