Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis

Tuberculosis (TB) is a global pandemic that despite successful treatment and bacterial eradication can cause chronic ill health, such as pulmonary impairment after tuberculosis (PIAT) and cardiovascular disease (CVD). A recent Phase 2b double-blind randomised-controlled clinical trial shows that adjunctive doxycycline therapy is safe, accelerates resolution of inflammation, suppresses tissue damaging enzyme activity and decreases pulmonary cavity volume (1). We aim to determine if adjunctive doxycycline can reduce PIAT and improve cardiovascular outcomes in a fully powered Phase III trial of 8 weeks of adjunctive doxycycline alongside standard pulmonary TB (PTB) treatment. The investigators hypothesize that doxycycline inhibits tissue destruction in patients with PTB and thereby leads to improved lung function after treatment. Specific aims 1. To assess improvement in lung function as measured by forced expiratory volume (FEV1) predicted in PTB patients given doxycycline versus placebo. 2. To investigate whether doxycycline will hasten the resolution of pulmonary cavities measured by CT thorax 3. To investigate whether doxycycline can suppress inflammatory markers including matrix metalloproteinases 4. To investigate whether doxycycline can accelerate time to sputum conversion 5. To evaluate the effect of doxycycline on cardiovascular outcomes such as the incidence of acute coronary syndrome (ACS) and pulmonary hypertension 6. To investigate whether doxycycline improves TB drug concentrations in sputum and plasma. 7. To assess the safety profile of doxycycline with concurrent standard anti-tuberculous treatment.

NCT Number	NCT05473520
Lead Sponsor	National University Hospital, Singapore Collaborators: Tan Tock Seng Hospital, Hospital Queen Elizabeth, Malaysia, National University of Singapore, University Malaysia Sabah, Menggatal Health Clinic, Sabah, Malaysia, Luyang Health Clinic, Sabah, Malaysia
Conditions	Tuberculosis, Acute Coronary Syndrome, Pulmonary Hypertension (Diagnosis)
Enrollment	150 participants
Start Date	2023-05-24
Primary Completion	2030-01-31 (estimated)
Study Completion	2030-01-31 (estimated)
Updated on ClinicalTrials.gov	2026-06-09