Chronic Refractory Cough (CRC) With Non-atopic AsthmaPhase 2NCT05660850
A Study To Evaluate The Efficacy, Safety, Pharmacokinetics, And Pharmacodynamic Effects Of GDC-6599 In Patients With Chronic Cough
A Phase 2 study testing GDC-6599 and Mannitol in people with Chronic Refractory Cough (CRC) With Non-atopic Asthma and CRC With Atopic Asthma, run by Genentech, Inc. at 18 sites in 4 countries.
Trial summary
This Phase IIa, multicenter, randomized, double-blind, placebo-controlled, crossover study will evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamic (PD) effects of GDC-6599 compared with placebo in patients with a history of chronic cough. Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Chronic Refractory Cough (CRC) With Non-atopic Asthma, CRC With Atopic Asthma, Unexplained Chronic Cough
- What is being tested?
- GDC-6599 and Mannitol
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 49 participants
- Where
- 18 sitesin 4 countries
- Study dates
- 22 Mar 2023to 20 Oct 2024
- 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 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Previous diagnosis of CRC, despite optimized treatment for asthma or COPD, or UCC for at least 1 year
- Chest X-ray or computed tomography (CT) scan thorax within 5 years prior to screening visit that confirms the absence of any clinically significant abnormality contributing to the chronic cough in the opinion of the investigator
- Cough severity VAS score ≥ 40 at screening visit
- Pre-bronchodilator forced expiratory volume in 1 second (FEV1) ≥ 60% of predicted at screening"
- Mannitol CDR ≥ 12 coughs/100 mg determined at screening visit mannitol challenge test
- For women of childbearing potential: agreement to remain abstinent or use contraception For men: agreement to remain abstinent or use a condom, and agreement to refrain from donating sperm
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- Inclusion Criteria for Patients with CRC with Atopic Asthma or Patients with CRC with Non-Atopic Asthma (Part A)
- Physician diagnosis of asthma for ≥ 12 months based upon GINA STEP 2-5
- Stable treatment with ICS therapy (GINA STEP 2) or ICS therapy and at least one additional controller (GINA STEP 3- 5) for ≥ 3 months
- Patients with atopic asthma (n = 20), based upon historic record of positive test for atopy (if available), or confirmed at screening by positive fluorescence enzyme immunoassay for specific IgE against at least one of the following five perennial aeroallergens: animal (cat dander, dog dander, cockroach), dust mite (Dermatophagoides farinae, Dermatophagoides pteronyssinus), and mold mix
- Patients with non-atopic asthma (n = 20), based upon historic record of negative test for atopy (if available), or confirmed at screening by negative ImmunoCAP test result for all five perennial aeroallergens: animal (cat dander, dog dander, cockroach), dust mite (Dermatophagoides farinae, Dermatophagoides pteronyssinus), and mold mix, and relevant local allergens, and no history of symptoms suggesting atopy
- Never or former smoker (≥ 6 months prior to screening) with < 20 pack-years or equivalent history
- Inclusion Criteria for Patients with CRC COPD-CB or Patients with CRC COPD (Part B)
- Diagnosis of COPD GOLD I-II ± CB
- Stable background treatment consisting of a bronchodilator medication and or stable ICS therapy for ≥ 12 weeks prior to screening visit
- Former smoker with ≥ 10 pack-years or equivalent history within 6 months of screening
- Post-bronchodilator FEV1/ forced vital capacity (FVC) ratio ≤ 0.70 at screening
- Chest X-ray or CT scan within 6 months prior to screening visit or during the screening period (prior to randomization [Study Visit 2]), that confirms the absence of clinically significant lung disease besides COPD
Who cannot join
- Pregnant or breastfeeding, or intention of becoming pregnant during the study or within 28 days after the final dose of GDC-6599
- History of diagnosed bleeding diathesis or easy bruising or bleeding
- Post-bronchodilator FEV1/ FVC ratio < 0.60 at screening visit (patients with CRC asthma and UCC only: Part A)
- History of significant hepatic impairment
- History of aspiration or recurrent pneumonia
- Respiratory infection (including upper respiratory infection) within 8 weeks prior to screening
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- Treatment with any strong inhibitor or inducer of CYP3A within 28 days or 5 drug-elimination half-lives, whichever is longer, prior to initiation of study drug
- Treatment with angiotensin-converting enzyme (ACE) inhibitor within 12 weeks prior to screening (Study Visit 1) through completion of the study
- Treatment with opioids (including codeine), pregabalin, gabapentin, amitriptyline, or nortriptyline for the treatment of cough within 2 weeks prior to screening (Study Visit 1) through completion of the study
- Treatment with cough suppressant medication within 2 weeks prior to screening (Study Visit 1) through completion of the study
- Known coronavirus 2019 (COVID-19) infection, persistent symptoms of known prior COVID-19 infection, and/or known positive COVID-19 test within at least 8 weeks prior to screening and randomization
- Clinical laboratory value outside the reference range for the test laboratory at screening
- Any serious medical condition or abnormality in clinical laboratory tests that, in the investigator's judgment, precludes the patient's safe participation in and completion of the study
- History of malignancy within 5 years prior to screening, except for appropriately treated carcinoma in situ of the cervix or non-melanoma skin carcinoma
Trial locations and contacts
18 sites in 4 countries.
18 sites in 4 countries
United States8 sites
Bellingham Asthma, Allergy & Immunology
Bellingham, Washington, 98225
Pioneer Clinical Studies
Coral Gables, Florida, 33134
Pharmaceutical Research & Consulting, Inc.
Dallas, Texas, 75231
Clinical Research Associates Of Central Pa , Llc
DuBois, Pennsylvania, 15801-2277
ADAC Research PA
Greenville, South Carolina, 29607
Southern California Institute For Respiratory
Los Angeles, California, 90048
California Medical Research Associates, Inc.
Northridge, California, 91324
Mayo Clinic
Rochester, Minnesota, 55905
United Kingdom7 sites
Belfast City Hospital
Belfast, BT9 7AB
West Walk Surgery
Bristol, BS37 4AX
Castle Hill Hospital
Cottingham, North Humberside, HU16 5JQ
Royal Infirmary of Edinburgh
Edinburgh, EH16 4SA
Glenfield Hospital
Leicester, LE3 9QP
Kings College Hospital
London, SE5 9RS
Queen Anne Street Medical Centre
London, W1G 8HU
Canada2 sites
McMaster University Medical Centre
Hamilton, Ontario, L8N 3Z5
Diex Recherche - Québec - HyperCore - PPDS
Québec
About this study
Official title: A Phase IIa, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Crossover Study To Evaluate The Efficacy, Safety, Pharmacokinetics, And Pharmacodynamic Effects Of GDC-6599 In Patients With Chronic Cough
This Phase IIa, multicenter, randomized, double-blind, placebo-controlled, crossover study will evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamic (PD) effects of GDC-6599 compared with placebo in patients with a history of chronic cough.
Read the detailed description
The main study (Part A) enrolled participants with chronic refractory cough (CRC) with asthma with/without atopy as well as participants with unexplained chronic cough (UCC); the substudy (Part B) enrolled participants with chronic obstructive pulmonary disease (COPD) with/without chronic bronchitis (CB).
The main objective of the study was was to evaluate the efficacy of GDC-6599, as compared with placebo, in participants with CRC with asthma or UCC (i.e. across all participants in main study - Part A, regardless of the disease background).
- Conditions
- Chronic Refractory Cough (CRC) With Non-atopic Asthma, CRC With Atopic Asthma, Unexplained Chronic Cough, CRC With Chronic Obstructive Pulmonary Disease, CRC With Chronic Obstructive Pulmonary Disease With Chronic Bronchitis
- Being tested
- GDC-6599, GDC-6599-matching placebo, Mannitol
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
GDC-6599Drug
Also called RO7441345
GDC-6599 will be administered Days 1- 14 and on Days 29-42 as film-coated tablets
GDC-6599-matching placeboOther
GDC-6599-matching placebo will be administered Days 1- 14 and on Days 29- 42. as film-coated tablets
MannitolDiagnostic test
Mannitol challenge tests will be performed during screening and at least 2.5 hours following study drug administration at Study Visits 2, 4, 5 and 7
| Study group | Role | What they receive |
|---|---|---|
| Part A: CRC Asthma atopic | Experimental | Patients with CRC atopic asthma will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5 Receives: Drug: GDC-6599; Other: GDC-6599-matching placebo; Diagnostic Test: Mannitol |
| Part A: CRC Asthma non-atopic | Experimental | Patients with CRC non-atopic asthma will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5 Receives: Drug: GDC-6599; Other: GDC-6599-matching placebo; Diagnostic Test: Mannitol |
| Part A: Unexplained Chronic Cough | Experimental | Patients with Unexplained Chronic Cough will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5 Receives: Drug: GDC-6599; Other: GDC-6599-matching placebo; Diagnostic Test: Mannitol |
| Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease | Experimental | Patients with Chronic Obstructive Pulmonary Disease will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5. Receives: Drug: GDC-6599; Other: GDC-6599-matching placebo; Diagnostic Test: Mannitol |
| Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis | Experimental | Patients with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5. Receives: Drug: GDC-6599; Other: GDC-6599-matching placebo; Diagnostic Test: Mannitol |
What is being measured
The primary outcome is the main question the study is designed to answer.
Part A: Cough Frequency Per Hour, Assessed Objectively Over 24 Hours Using VitaloJAK® Cough Recorder
Cough numbers were assessed by the VitaloJAK semi-automated cough-monitoring system. The VitaloJAK device recorded ambulatory audio for 24 hours from two channels, a lapel microphone (air) and a chest-facing sensor (skin). A software algorithm removed non-cough sounds from the 24-hour audio recordings, compressing the files to less than 10% (on average) of the original length enabling manual analysis to be completed more quickly. The recordings were reviewed by trained Vitalograph analysts who counted individual explosive cough sounds, yielding hourly and 24-hour objective cough count (OCCs). Cough frequency was calculated as the total number of coughs for the full 24 hours recording minus coughs flagged within Mute, Flagged Area, Device Not Attached and Recording Ended Early events divided by the full 24 hours recording minus Mute, Flagged Area, Device Not Attached and Recording Ended Early event time. The standard deviation (SD) reported here is geometric SD.
Measured: Baseline and Day 14 of Periods 1 and 2
Secondary outcomes (4)
Part A: Change From Baseline in the Severity of Cough, as Assessed Using Participant-reported Cough Severity Visual Analog Scale (VAS) Scores
Cough severity scores were assessed by the participants using VAS. The VAS was a single-item rating used for the subjective assessment of cough severity. Participants were asked to indicate the severity of their cough by marking a line on a scale between anchor statements of 'no cough' and 'worst cough'. The score was determined by measuring the distance on the line between the anchor and the participant's mark, providing a range of scores from 0-100. A higher score indicates greater severity.
Measured: Baseline to Day 14 of Periods 1 and 2
Part A: Change From Baseline in the Severity of Cough, as Assessed Using Participant-reported Cough Severity Numeric Response Scale (NRS) Scores
Cough severity scores were assessed by the participants using the NRS. Participants were asked to rate the severity of their cough in the last 24 hours from 0 (no cough) to 10 (worst cough). Higher scores indicates greater severity.
Measured: Baseline to Day 14 of Periods 1 and 2
Number of Participants With Adverse Events (AEs)
An AE was any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product, regardless of causal attribution. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.
Measured: From signing of informed consent form (ICF) until 28 days after the final dose of study drug (up to approximately 16 weeks)
Plasma Concentration of GDC-6599
Measured: Predose and 3 hours post dose on Days 1 and 14 of Periods 1 and 2 and Day 71 (Safety Follow-up Visit)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Dec 2022
- Study start22 Mar 2023
- Primary completion20 Oct 2024
- Study completion20 Oct 2024
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.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Chronic Refractory Cough (CRC) With Non-atopic AsthmaStudies of the same condition, open and under way.
- More trials run by Genentech, Inc.The sponsor's other registered studies.
- 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
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 49 participants (actual)
Sponsor and investigators
- Lead sponsor
- Genentech, Inc.
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Clinical Trials, Study director, Genetech
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05660850
- Sponsor's protocol ID
- GA43590
- Status last verified
- Nov 2025
- First submitted
- 7 Nov 2022
- Last updated
- 16 Dec 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Publications
Brown I, Tran T, Funwie A, Patel S, Dawson K, McKenzie M. Sexual orientation and gender identity data: An observational study assessing the feasibility of SOGI collection in clinical research and patient assistance programs. PLoS One. 2025 Oct 22;20(10):e0332805. doi: 10.1371/journal.pone.0332805. eCollection 2025.
PubMed 41124168
Study at a glance
From the registry record, last updated by the sponsor on 16 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase IIa, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Crossover Study To Evaluate The Efficacy, Safety, Pharmacokinetics, And Pharmacodynamic Effects Of GDC-6599 In Patients With Chronic Cough
- ClinicalTrials.gov ID
- NCT05660850
- Acronym / sponsor ID
- GA43590
- Conditions
- Chronic Refractory Cough (CRC) With Non-atopic Asthma, CRC With Atopic Asthma, Unexplained Chronic Cough, CRC With Chronic Obstructive Pulmonary Disease, CRC With Chronic Obstructive Pulmonary Disease With Chronic Bronchitis
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 49 participants (actual)
- Lead sponsor
- Genentech, Inc.Industry (pharma, biotech, devices)
- Study start
- 22 Mar 2023 (actual)
- Primary completion
- 20 Oct 2024 (actual)
- Study completion
- 20 Oct 2024 (actual)
- First posted
- 21 Dec 2022 (actual)
- Results
- Posted 16 Dec 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This Phase IIa, multicenter, randomized, double-blind, placebo-controlled, crossover study will evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamic (PD) effects of GDC-6599 compared with placebo in patients with a history of chronic cough.
Detailed description
The main study (Part A) enrolled participants with chronic refractory cough (CRC) with asthma with/without atopy as well as participants with unexplained chronic cough (UCC); the substudy (Part B) enrolled participants with chronic obstructive pulmonary disease (COPD) with/without chronic bronchitis (CB).
The main objective of the study was was to evaluate the efficacy of GDC-6599, as compared with placebo, in participants with CRC with asthma or UCC (i.e. across all participants in main study - Part A, regardless of the disease background).
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 5
| Arm | Type | Receives |
|---|---|---|
| Part A: CRC Asthma atopic | Experimental | Drug: GDC-6599, Other: GDC-6599-matching placebo, Diagnostic Test: MannitolPatients with CRC atopic asthma will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5 |
| Part A: CRC Asthma non-atopic | Experimental | Drug: GDC-6599, Other: GDC-6599-matching placebo, Diagnostic Test: MannitolPatients with CRC non-atopic asthma will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5 |
| Part A: Unexplained Chronic Cough | Experimental | Drug: GDC-6599, Other: GDC-6599-matching placebo, Diagnostic Test: MannitolPatients with Unexplained Chronic Cough will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5 |
| Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease | Experimental | Drug: GDC-6599, Other: GDC-6599-matching placebo, Diagnostic Test: MannitolPatients with Chronic Obstructive Pulmonary Disease will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5. |
| Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis | Experimental | Drug: GDC-6599, Other: GDC-6599-matching placebo, Diagnostic Test: MannitolPatients with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis will be randomized in a 1:1 ratio to receive GDC-6599 or placebo for 14 days during the first study period (Treatment Period 1, Study Visits 2-4). Following a 14-day washout period, patients will cross over to the second study period (Treatment Period 2, Study Visits 5-7) and will receive the alternate treatment (GDC-6599 or placebo) for 14 days starting at Study Visit 5. |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (18 listed)
- Previous diagnosis of CRC, despite optimized treatment for asthma or COPD, or UCC for at least 1 year
- Chest X-ray or computed tomography (CT) scan thorax within 5 years prior to screening visit that confirms the absence of any clinically significant abnormality contributing to the chronic cough in the opinion of the investigator
- Cough severity VAS score ≥ 40 at screening visit
- Pre-bronchodilator forced expiratory volume in 1 second (FEV1) ≥ 60% of predicted at screening"
- Mannitol CDR ≥ 12 coughs/100 mg determined at screening visit mannitol challenge test
Key exclusion criteria (14 listed)
- Pregnant or breastfeeding, or intention of becoming pregnant during the study or within 28 days after the final dose of GDC-6599
- History of diagnosed bleeding diathesis or easy bruising or bleeding
- Post-bronchodilator FEV1/ FVC ratio < 0.60 at screening visit (patients with CRC asthma and UCC only: Part A)
- History of significant hepatic impairment
- History of aspiration or recurrent pneumonia
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 |
|---|---|---|
| GDC-6599Also: RO7441345GDC-6599 will be administered Days 1- 14 and on Days 29-42 as film-coated tablets | Drug | Part A: CRC Asthma atopic, Part A: CRC Asthma non-atopic, Part A: Unexplained Chronic Cough, Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease, Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis |
| GDC-6599-matching placeboGDC-6599-matching placebo will be administered Days 1- 14 and on Days 29- 42. as film-coated tablets | Other | Part A: CRC Asthma atopic, Part A: CRC Asthma non-atopic, Part A: Unexplained Chronic Cough, Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease, Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis |
| MannitolMannitol challenge tests will be performed during screening and at least 2.5 hours following study drug administration at Study Visits 2, 4, 5 and 7 | Diagnostic test | Part A: CRC Asthma atopic, Part A: CRC Asthma non-atopic, Part A: Unexplained Chronic Cough, Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease, Part B: Chronic Refractory Cough with Chronic Obstructive Pulmonary Disease with Chronic Bronchitis |
Primary outcome
Part A: Cough Frequency Per Hour, Assessed Objectively Over 24 Hours Using VitaloJAK® Cough Recorder
Time frame: Baseline and Day 14 of Periods 1 and 2
Cough numbers were assessed by the VitaloJAK semi-automated cough-monitoring system. The VitaloJAK device recorded ambulatory audio for 24 hours from two channels, a lapel microphone (air) and a chest-facing sensor (skin). A software algorithm removed non-cough sounds from the 24-hour audio recordings, compressing the files to less than 10% (on average) of the original length enabling manual analysis to be completed more quickly. The recordings were reviewed by trained Vitalograph analysts who counted individual explosive cough sounds, yielding hourly and 24-hour objective cough count (OCCs). Cough frequency was calculated as the total number of coughs for the full 24 hours recording minus coughs flagged within Mute, Flagged Area, Device Not Attached and Recording Ended Early events divided by the full 24 hours recording minus Mute, Flagged Area, Device Not Attached and Recording Ended Early event time. The standard deviation (SD) reported here is geometric SD.
4 secondary outcomes
Part A: Change From Baseline in the Severity of Cough, as Assessed Using Participant-reported Cough Severity Visual Analog Scale (VAS) Scores
Time frame: Baseline to Day 14 of Periods 1 and 2
Part A: Change From Baseline in the Severity of Cough, as Assessed Using Participant-reported Cough Severity Numeric Response Scale (NRS) Scores
Time frame: Baseline to Day 14 of Periods 1 and 2
Number of Participants With Adverse Events (AEs)
Time frame: From signing of informed consent form (ICF) until 28 days after the final dose of study drug (up to approximately 16 weeks)
Plasma Concentration of GDC-6599
Time frame: Predose and 3 hours post dose on Days 1 and 14 of Periods 1 and 2 and Day 71 (Safety Follow-up Visit)
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Dec 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41124168Brown I, Tran T, Funwie A, Patel S, Dawson K, McKenzie M. Sexual orientation and gender identity data: An observational study assessing the feasibility of SOGI collection in clinical research and patient assistance programs. PLoS One. 2025 Oct 22;20(10):e0332805. doi: 10.1371/journal.pone.0332805. eCollection 2025.
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.
Clinical Trials study director
Genetech
18 sites in 4 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing GDC-6599 and Mannitol in people with Chronic Refractory Cough (CRC) With Non-atopic Asthma and CRC With Atopic Asthma, run by Genentech, Inc. at 18 sites in 4 countries.
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 18 inclusion and 14 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: finished, as of the sponsor's last update on 16 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 18 sites in United States, United Kingdom, Canada, Australia. 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 16 Dec 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?
Part A: Cough Frequency Per Hour, Assessed Objectively Over 24 Hours Using VitaloJAK® Cough Recorder (time frame: Baseline and Day 14 of Periods 1 and 2). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05660850, which also lists 1 linked publication.
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 16 Dec 2025; AzTrials last refreshed its copy on 6 Nov 2026.