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

Doxycycline Host-directed Therapy to Improve Lung Function and Decrease Tissue Destruction in Pulmonary Tuberculosis: A Phase III Randomized Control Trial (Doxy-TB)

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.

Study Overview

• Status: Recruiting
• Conditions: Tuberculosis; Acute Coronary Syndrome; Pulmonary Hypertension (Diagnosis)
• Intervention / Treatment: Drug: Doxycycline; Drug: Placebo

Detailed Description

In this Phase 3 double-blind randomised-controlled trial, doxycycline or placebo shall be given to 75 PTB patients in each arm for two months with a further follow-up of twenty-two months. Study sites are National University Hospital and TB Control Unit in Singapore and Luyang Health Clinic, Menggatal Health Clinic, and Inanam Health Clinic in Sabah, Malaysia. Lung function tests, non-contrast CT thorax, electrocardiograms and transthoracic echocardiograms will be performed at various time intervals. Induced sputum and plasma samples from all PTB patients shall be analysed for matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs) and monitored for sputum mycobacteria culture conversion. Whole blood will be analysed by transcriptomics for bulk RNAseq while a subset of patients' blood will be analysed using single-cell RNAsequencing. Blood tests will also be taken for Troponin-I and N-terminal pro-B-type natriuretic peptide. Accomplishing these specific aims will determine if doxycycline decreases PIAT by improving lung function, reducing pulmonary cavities and accelerating sputum culture conversion. We will also be able to assess the effect of doxycycline on development of pulmonary hypertension and acute coronary syndrome. The results will positively impact clinical practice and international guidelines including the World Health Organisation that we collaborate with, for the treatment of pulmonary TB.

• Study Type: Interventional
• Enrollment (Estimated): 150
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Srishti CHHABRA, MBBS BSc MRCP; Phone Number: +65 6908 2222; Email: srishti.chhabra@mohh.com.sg

Study Locations

• Malaysia
  • Sabah
    • Kota Kinabalu, Sabah, Malaysia
      • Not yet recruiting
      • Hospital Queen Elizabeth I
      • Contact: Nurul Ain Mohd Yaakub, Dr; Email: nurulainykb@moh.gov.my
      • Principal Investigator: Hema Yamini Devi Ramarmuty, Dr
    • Kota Kinabalu, Sabah, Malaysia
      • Active, not recruiting
      • Universiti Malaysia Sabah (UMS), Borneo Medical and Health Research Centre
    • Kota Kinabalu, Sabah, Malaysia
      • Active, not recruiting
      • Klinik Kesihatan Luyang
    • Kota Kinabalu, Sabah, Malaysia
      • Recruiting
      • Klinik Kesihatan Menggatal
      • Contact: Dr Siti Nor Aishah bt Abdul Rahim; Phone Number: +60192462367
      • Contact: Dr. Saravanan A/L Jayaraman; Phone Number: +60168040532
• Singapore
  • Singapore, Singapore, 119228
    • Recruiting
    • National University Hospital
    • Contact: Catherine ONG, MRCP PhD; Email: catherine_wm_ong@nuhs.edu.sg <catherine_wm_ong@nuhs.edu.sg>
  • Singapore, Singapore
    • Recruiting
    • TB Control Unit
    • Contact: Shera Tan, Dr; Phone Number: +65 6511 5131; Email: shera_tan@ttsh.com.sg
    • Principal Investigator: Shera Tan, Dr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 21 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No

Description

The recruitment target would be 150 patients, with 75 in each arm

Inclusion criteria: Patients should meet all criteria:

1. Aged 21 years and above
2. Patients receiving ≤ 7 days of TB treatment or about to start standard combination TB treatment
3. Confirmed pulmonary TB with positive acid-fast bacilli smear and/or positive nucleic acid amplification test (NAAT) and/or TB culture results
4. CXR demonstrating pulmonary involvement with cavity or cavities
5. Able to provide informed consent

Exclusion criteria:

1. HIV co-infection
2. Previous pulmonary TB
3. Severe, pre-existing lung disease such as pulmonary fibrosis, bronchiectasis, COPD and lung cancer
4. Pregnant or breast feeding
5. Allergies to tetracyclines
6. Patients on retinoic acid, neuromuscular blocking agents and pimozide which may increase risk of drug toxicity
7. Autoimmune disease and/or on systemic immunosuppressants
8. Use of any investigational or non-registered drug, vaccine or medical device other than the study drug within 182 days preceding dosing of study drug, or planned use during the study period
9. Enrolment in any other clinical trial involving a systemic drug or intervention involving the lung
10. Evidence of severe depression, schizophrenia or mania
11. ALT > 3 times upper limit of normal
12. Creatinine > 2 times upper limit of normal
13. Principal investigator assessment of lack of willingness to participate and comply with all requirements including follow-up of the protocol, or identification of any factor felt to significantly increase the participant's risk of suffering an adverse outcome

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Doxycycline + standard anti-tuberculous treatment; Doxycycline 100 mg twice daily with once daily anti-tuberculous treatment comprising of rifampicin 10 mg/kg, isoniazid 5 mg/kg, ethambutol 15 - 20 mg/kg, ± pyrazinamide 25 mg/kg and pyridoxine 10-50 mg per day according to managing physicians' discretion. Where needed, the drugs will be adjusted according to renal function. These will be given daily for 8 weeks. Subsequently doxycycline will be ceased and patients are to continue with their standard anti-tuberculous treatment and duration according to their managing physician	Drug: Doxycycline; A dose of 100 mg twice daily of doxycycline based on the recommended dose for adults which is commonly used for bacterial infections such as rickettsial infection, lyme disease and pelvic inflammatory disease.
Placebo Comparator: Placebo + standard anti-tuberculous treatment; Placebo twice daily with once daily anti-tuberculous treatment comprising of rifampicin 10 mg/kg, isoniazid 5 mg/kg, ethambutol 15-20 mg/kg, ± pyrazinamide 25 mg/kg and pyridoxine 10-50 mg per day according to managing physicians' discretion. Where needed, the drugs will be adjusted according to renal function. These will be given daily for 8 weeks. Subsequently placebo will be ceased and patients are to continue with their standard anti-tuberculous treatment and duration according to their managing physician.	Drug: Placebo; Placebo + standard anti-tuberculous treatment

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Forced expiratory volume in 1 second (FEV1) at 26 weeks measured by spirometry	- FEV1 at 26 weeks, expressed as a percentage predicted for age, sex, height and race will be measured by spirometry and will be compared between the doxycycline and placebo group	week 0 to 26

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sputum TB culture	Time taken in days for positivity of sputum TB culture using MGIT will be assessed	up to 8 weeks
Sputum matrix metalloproteinase (MMP) concentration	Change of sputum matrix metalloproteinase (MMP) concentration will be measured by Luminex array	up to 8 weeks
Sputum functional assays	Change in sputum functional assays by sputum collagenase and elastase assay will be assessed.	up to 8 weeks
Pharmacokinetics and pharmacodynamics of drug concentrations	Sputum and plasma drug concentration of rifampicin, isoniazid, ethambutol, pyrazinamide (if prescribed) and doxycycline for a subset PK/PD study	week 2
Sputum culture conversion	Time taken for sputum culture conversion (time taken for sputum cultures to turn negative) by liquid cultures will be investigated	up to 8 weeks
Forced expiratory volume in 1 second (FEV1) at 104 weeks measured by spirometry	Forced expiratory volume, expressed as a percentage predicted for age, sex, height and race will be measured by spirometry and will be compared between the doxycycline and placebo group will be measured at D0, week 8, week 26, week 52, week 78 and week 104.	104 weeks
Forced expiratory volume in 1 second divided by forced vital capacity (FEV1/FVC ratio)	Forced expiratory volume in 1 second divided by forced vital capacity (FEV1/FVC ratio) measured by spirometry	104 weeks
Safety profile	Incidence of Grade 3 or 4 adverse events and serious adverse events	week 0 to 12
Resolution of pulmonary cavities on CT scan	Proportion of patients in each study group with resolution of pulmonary cavities on CT scan done at 26, 52, 78, 104 weeks	104 weeks
Cumulative lung cavity volume	Change in cumulative lung cavity volume (in cm3) measured on CT scan	week 0 to 104
St George's Respiratory Questionnaire Score	Change in Quality-of-life score by the St George's Respiratory Questionnaire will be measured. Scores range from 0 to 100, with higher scores indicating more limitations.	week 0 to 104
Host transcriptome	Change of host transcriptome will be measured via bulk RNA sequencing. In addition, in the subset of patients recruited from Singapore, single-cell RNA sequencing (scRNAseq) will be performed for neutrophils and peripheral blood mononuclear cells on 10 patients each from the doxycycline and placebo arm, analysing 10,000 cells per sample.	week 0 to 104
Host plasma matrix metalloproteinase (MMP) concentration	Change in host plasma matrix metalloproteinase (MMP) concentration will be measured by Luminex array	week 0 to 104
Cardiac function and pulmonary hypertension	Cardiac function and pulmonary artery systolic pressure will be measured using 2D Echocardiogram and electrocardiogram at D0, week 26, week 52, week 78 and week 104. The time-to-development of pulmonary hypertension over 2 years follow-up will be calculated.	week 0 to 104
Measurement of Troponin I and NT-proBNP	HsTnI and NT-proBNP will be measured sequentially at Day 0, Week 2, 8, 26, 52, 78 and 104 to screen for cardiotoxicity, which will then be ascertained by review of source documents.	week 0 to 104

Collaborators and Investigators

• 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
• Investigators: Principal Investigator: Catherine Ong, MRCP PhD, National University Hospital, Singapore

Publications and helpful links

General Publications

• Miow QH, Vallejo AF, Wang Y, Hong JM, Bai C, Teo FS, Wang AD, Loh HR, Tan TZ, Ding Y, She HW, Gan SH, Paton NI, Lum J, Tay A, Chee CB, Tambyah PA, Polak ME, Wang YT, Singhal A, Elkington PT, Friedland JS, Ong CW. Doxycycline host-directed therapy in human pulmonary tuberculosis. J Clin Invest. 2021 Aug 2;131(15):e141895. doi: 10.1172/JCI141895.

Helpful Links

• Publication

Study record dates

Study Major Dates

• Study Start (Actual): May 24, 2023
• Primary Completion (Estimated): January 31, 2030
• Study Completion (Estimated): January 31, 2030

Study Registration Dates

• First Submitted: June 13, 2022
• First Submitted That Met QC Criteria: July 21, 2022
• First Posted (Actual): July 26, 2022

Study Record Updates

• Last Update Posted (Estimated): September 9, 2025
• Last Update Submitted That Met QC Criteria: September 2, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Infections; Respiratory Tract Diseases; Lung Diseases; Gram-Positive Bacterial Infections; Bacterial Infections; Bacterial Infections and Mycoses; Myocardial Ischemia; Hypertension; Actinomycetales Infections; Mycobacterium Infections; Pathological Conditions, Signs and Symptoms; Disease; Hypertension, Pulmonary; Tuberculosis; Acute Coronary Syndrome; Organic Chemicals; Substandard Drugs; Pharmaceutical Preparations; Hydrocarbons; Hydrocarbons, Cyclic; Polycyclic Aromatic Hydrocarbons; Hydrocarbons, Aromatic; Polycyclic Compounds; Naphthacenes; Tetracyclines; Doxycycline; Counterfeit Drugs
• Other Study ID Numbers: Phase III Doxy-TB

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No