Rifampicin Susceptible Pulmonary TuberculosisPhase 2NCT06041919
Evaluating the Early Bactericidal Activity, Safety and Tolerability of Nebulised RESP301 in Adults With Tuberculosis
A Phase 2 study testing RESP301 and HRZE in people with Rifampicin Susceptible Pulmonary Tuberculosis, run by Thirty Respiratory Limited at 1 site in South Africa.
Trial summary
A Phase 2, Single-Centre, Open-Label, Parallel Control Arm, Randomised Clinical Study to Evaluate the Early Bactericidal Activity (EBA), Safety and Tolerability of Nebulised RESP301 in Adults with Newly Diagnosed, Rifampicin Susceptible Pulmonary Tuberculosis Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Rifampicin Susceptible Pulmonary Tuberculosis
- What is being tested?
- RESP301 and HRZE
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteSouth Africa
- Study dates
- 27 Sep 2023to 6 Mar 2025
- Phase
- Phase 2
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Provide written, informed consent prior to all study-related procedures and agree to undergo all study procedures
- Body weight (in light clothing and with no shoes) between 40 and 90 kg, inclusive
- Newly diagnosed pulmonary TB
- Rifampicin susceptible pulmonary TB as determined by molecular testing
- Ability to produce an adequate volume of sputum as estimated from a pre-treatment overnight sputum collection sample (estimated 10 ml or more)
- Spirometry performed during screening with a FEV1 of ≥ 40%
- Be of non-childbearing potential or willing to use effective methods of contraception
Who cannot join
- HIV positive AND CD4 < 350 cells/mm3 OR are receiving antiviral therapy (ART)
- Methaemoglobin saturation (SpMet) >3%
- Female participant who is pregnant or breast-feeding
- Participants planning to conceive a child within the anticipated period of study participation and for at least 90 days after the last dose of IMP in the study
- Participation in other clinical studies with investigational agents within 8 weeks prior to screening
- Treatment received for this episode of TB with any drug active against M.tb
- Treatment with immunosuppressive medications such as TNF-alpha inhibitors within 2 weeks prior to screening, or systemic corticosteroids for more than 7 days within 2 weeks prior to screening.
- Treatment with nitric oxide and other nitric oxide donor agents, phosphodiesterase inhibitors and lung surfactant drugs, within 30 days prior to screening
Trial locations and contacts
1 site in 1 country.
South Africa1 site
TASK Clinical Research Centre
Cape Town, Bellville, 7531
About this study
Official title: A Phase 2 Study to Evaluate the Early Bactericidal Activity, Safety and Tolerability of Nebulised RESP301 in Adults With Newly Diagnosed, Rifampicin Susceptible Pulmonary Tuberculosis
A Phase 2, Single-Centre, Open-Label, Parallel Control Arm, Randomised Clinical Study to Evaluate the Early Bactericidal Activity (EBA), Safety and Tolerability of Nebulised RESP301 in Adults with Newly Diagnosed, Rifampicin Susceptible Pulmonary Tuberculosis
Read the detailed description
A total of approximately 15 participants will be recruited per treatment arm (total of approximately 75 participants in the study). Control arm participants will be split across sequential stages stages 1 and 2, with no stratification.
Stage 1: To determine the EBA of
- Treatment Arm 1 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered three times daily over 14 days
- Treatment Arm 2 (Control; n= 5) - HRZE taken orally once daily
On completion of Stage 1, recruitment will be paused and an interim analysis performed to determine whether the study should proceed to Stage 2.
Stage 2: To determine the EBA of
- Treatment Arm 2 (Control; n= 10) - HRZE taken orally once daily
- Treatment Arm 3 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered once daily over 14 days
- Treatment Arm 4 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered twice daily over 14 days
- Treatment Arm 5 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered three times daily in combination with HRZE taken orally once daily over 14 days
- Being tested
- RESP301, HRZE
- Keywords
- Early Bactericidal Activity (EBA)
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RESP301Drug
Nitric Oxide agent
HRZEDrug
isoniazid 75 mg (H), rifampicin 150 mg (R), pyrazinamide 400 mg (Z), ethambutol 275 mg (E)
| Study group | Role | What they receive |
|---|---|---|
| 1 (Active) | Experimental | Inhaled RESP301 6ml via nebulisation three times daily Receives: Drug: RESP301 |
| 2 (Control) | Active comparator | HRZE taken orally once daily Receives: Drug: HRZE |
| 3 (Active) | Experimental | Inhaled RESP301 6 ml via nebulisation once daily Receives: Drug: RESP301 |
| 4 (Active) | Experimental | Inhaled RESP301 6 ml via nebulisation twice daily Receives: Drug: RESP301 |
| 5 (Active) | Experimental | Inhaled RESP301 6 ml via nebulisation three times daily plus HRZE taken orally once dialy Receives: Drug: RESP301; Drug: HRZE |
What is being measured
The primary outcome is the main question the study is designed to answer.
Early Bactericidal Activity (EBA) of Inhaled RESP301 Measured as Time to Positivity (TTP)
Overnight sputum collection from which viable mycobacteria in the sample is quantified as TTP Observed EBA for 0-2, 0-7, 0-14, 0-15 and 14-15 days in TTP (hours) for treatment in each of the treatment groups
Measured: 0-2, 0-7, 0-14, 0-15 and 14-15 days
Secondary outcomes (2)
Early Bactericidal Activity (EBA) of Inhaled RESP301 Measured as Colony Forming Units (CFU)
Overnight sputum collection from which viable mycobacteria in the sample is quantified as CFU Observed EBA for 0-2, 0-7, 0-14, 0-15 and 14-15 days in CFU (Log10 CFU/mL) for treatment in each of the treatment groups
Measured: 0-2, 0-7, 0-14, 0-15 and 14-15 days
Safety and Tolerability of Inhaled RESP301 Measured as Number of Treatment Emergent Adverse Events (TEAEs)
Incidence of Treatment Emergent Adverse Events (TEAEs) will be presented by severity, drug relatedness, seriousness, leading to early withdrawal and leading to death.
Measured: Stage 1: Dosing period 14 days + Follow-up period 14 days. Stage 2: Participants did not enter the treatment phase due to early study termination
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Sep 2023
- Study start27 Sep 2023
- Primary completion24 Jul 2024
- Study completion6 Mar 2025
Why it stopped: Decision was made by the sponsor not to progress to Stage 2
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for Rifampicin Susceptible Pulmonary TuberculosisStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Parallel control arm, randomised clinical study in two sequential stages, with no stratification
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Thirty Respiratory Limited
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06041919
- Sponsor's protocol ID
- RESP30X-EBA
- Status last verified
- Jun 2025
- First submitted
- 21 Aug 2023
- Last updated
- 15 Jul 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: IPD is confidential until the CSR is published
Study at a glance
From the registry record, last updated by the sponsor on 15 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 2 Study to Evaluate the Early Bactericidal Activity, Safety and Tolerability of Nebulised RESP301 in Adults With Newly Diagnosed, Rifampicin Susceptible Pulmonary Tuberculosis
- ClinicalTrials.gov ID
- NCT06041919
- Acronym / sponsor ID
- RESP30X-EBA
- Keywords
- Early Bactericidal Activity (EBA)
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Decision was made by the sponsor not to progress to Stage 2
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Thirty Respiratory LimitedIndustry (pharma, biotech, devices)
- Study start
- 27 Sep 2023 (actual)
- Primary completion
- 24 Jul 2024 (actual)
- Study completion
- 6 Mar 2025 (actual)
- First posted
- 18 Sep 2023 (actual)
- Results
- Posted 15 Jul 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
A Phase 2, Single-Centre, Open-Label, Parallel Control Arm, Randomised Clinical Study to Evaluate the Early Bactericidal Activity (EBA), Safety and Tolerability of Nebulised RESP301 in Adults with Newly Diagnosed, Rifampicin Susceptible Pulmonary Tuberculosis
Detailed description
A total of approximately 15 participants will be recruited per treatment arm (total of approximately 75 participants in the study). Control arm participants will be split across sequential stages stages 1 and 2, with no stratification.
Stage 1: To determine the EBA of
- Treatment Arm 1 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered three times daily over 14 days
- Treatment Arm 2 (Control; n= 5) - HRZE taken orally once daily
On completion of Stage 1, recruitment will be paused and an interim analysis performed to determine whether the study should proceed to Stage 2.
Stage 2: To determine the EBA of
- Treatment Arm 2 (Control; n= 10) - HRZE taken orally once daily
- Treatment Arm 3 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered once daily over 14 days
- Treatment Arm 4 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered twice daily over 14 days
- Treatment Arm 5 (Active; n = 15) - inhaled RESP301 6 ml dosed via nebulisation administered three times daily in combination with HRZE taken orally once daily over 14 days
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 5
- Model description
- Parallel control arm, randomised clinical study in two sequential stages, with no stratification
| Arm | Type | Receives |
|---|---|---|
| 1 (Active) | Experimental | Drug: RESP301Inhaled RESP301 6ml via nebulisation three times daily |
| 2 (Control) | Active comparator | Drug: HRZEHRZE taken orally once daily |
| 3 (Active) | Experimental | Drug: RESP301Inhaled RESP301 6 ml via nebulisation once daily |
| 4 (Active) | Experimental | Drug: RESP301Inhaled RESP301 6 ml via nebulisation twice daily |
| 5 (Active) | Experimental | Drug: RESP301, Drug: HRZEInhaled RESP301 6 ml via nebulisation three times daily plus HRZE taken orally once dialy |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Provide written, informed consent prior to all study-related procedures and agree to undergo all study procedures
- Body weight (in light clothing and with no shoes) between 40 and 90 kg, inclusive
- Newly diagnosed pulmonary TB
- Rifampicin susceptible pulmonary TB as determined by molecular testing
- Ability to produce an adequate volume of sputum as estimated from a pre-treatment overnight sputum collection sample (estimated 10 ml or more)
Key exclusion criteria (8 listed)
- HIV positive AND CD4 < 350 cells/mm3 OR are receiving antiviral therapy (ART)
- Methaemoglobin saturation (SpMet) >3%
- Female participant who is pregnant or breast-feeding
- Participants planning to conceive a child within the anticipated period of study participation and for at least 90 days after the last dose of IMP in the study
- Participation in other clinical studies with investigational agents within 8 weeks prior to screening
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| RESP301Nitric Oxide agent | Drug | 1 (Active), 3 (Active), 4 (Active), 5 (Active) |
| HRZEisoniazid 75 mg (H), rifampicin 150 mg (R), pyrazinamide 400 mg (Z), ethambutol 275 mg (E) | Drug | 2 (Control), 5 (Active) |
Primary outcome
Early Bactericidal Activity (EBA) of Inhaled RESP301 Measured as Time to Positivity (TTP)
Time frame: 0-2, 0-7, 0-14, 0-15 and 14-15 days
Overnight sputum collection from which viable mycobacteria in the sample is quantified as TTP Observed EBA for 0-2, 0-7, 0-14, 0-15 and 14-15 days in TTP (hours) for treatment in each of the treatment groups
2 secondary outcomes
Early Bactericidal Activity (EBA) of Inhaled RESP301 Measured as Colony Forming Units (CFU)
Time frame: 0-2, 0-7, 0-14, 0-15 and 14-15 days
Safety and Tolerability of Inhaled RESP301 Measured as Number of Treatment Emergent Adverse Events (TEAEs)
Time frame: Stage 1: Dosing period 14 days + Follow-up period 14 days. Stage 2: Participants did not enter the treatment phase due to early study termination
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Jul 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No. IPD is confidential until the CSR is published
Related trials for Rifampicin Susceptible Pulmonary Tuberculosis
RecruitingPhase 3
A Study of Quabodepistat-containing Regimens for the Treatment of Drug-resistant Pulmonary Tuberculosis
Rifampicin-Resistant Pulmonary Tuberculosis, Multidrug-Resistant Pulmonary Tuberculosis
Not yet recruitingPhase 2
Therapeutic ID93 + GLA-SE Vaccination in Participants With Rifampicin-Susceptible Pulmonary TB
Tuberculosis, Pulmonary
Not yet recruitingPhase 2
A Trial of Stratified Patient-Centered Treatment Regimens for Active TB (SPECTRA-TB)
Tuberculosis
RecruitingPhase 2
Phase 2 Trial to Evaluate the Safety and Tolerability and Early Bactericidal Activity of RESP30TB in Tuberculosis
Pulmonary Tuberculoses
RecruitingPhase 3
Novel Triple-dose Tuberculosis Retreatment Regimen
Multidrug-resistant Tuberculosis, Pulmonary Tuberculosis
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing RESP301 and HRZE in people with Rifampicin Susceptible Pulmonary Tuberculosis, run by Thirty Respiratory Limited at 1 site in South Africa.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 15 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in South Africa. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 15 Jul 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Early Bactericidal Activity (EBA) of Inhaled RESP301 Measured as Time to Positivity (TTP) (time frame: 0-2, 0-7, 0-14, 0-15 and 14-15 days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jul 2025.