A Phase 3 interventional study of Tozorakimab and Placebo in Viral Lung Infection and Acute Respiratory Failure, sponsored by AstraZeneca. Recruiting at 473 sites in 39 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-30.
Sponsored by AstraZeneca · Phase 3, Interventional, and Treatment
The purpose of this study is to evaluate the effect of tozorakimab, as an add-on to SoC in patients with viral lung infection requiring supplemental oxygen, on the prevention of death or progression to IMV/ECMO.
1,387 studies on the registry are indexed under Respiratory Distress Syndrome; 283 are open to participants now.
This study's planned enrollment of 3,527 is above the median of 60 across 822 interventional studies indexed under Respiratory Distress Syndrome.
Browse Respiratory Distress Syndrome studies →AstraZeneca is the lead sponsor of 3,499 studies on the registry; 270 are open to participants now.
Of its 368 completed or terminated interventional studies of FDA-regulated products, 178 (48%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Hypoxaemia is defined as:
SpO2 ≤ 90% OR
SpO2 ≤ 92% AND one or both of the following:
Radiographic infiltrates by CXR/CT compatible with viral lung infection per investigator judgement.
Use of accessory muscles of respiration or RR (respiratory rate) > 22.
- Patient remains hypoxaemic at randomisation requiring treatment with supplemental oxygen.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Approximately 2870 participants will be randomized in a 1:1 ratio. Arm 1 (n=approximately 1435) will receive a single dose of tozorakimab.
Drug: Tozorakimab
Approximately 2870 participants will be randomized in a 1:1 ratio. Arm 2 (n=approximately 1435) will receive matching placebo.
Drug: Placebo
Single IV dose of tozorakimab on Day 1.
Also known as: MEDI3506
Single IV dose of matching placebo on Day 1.
Proportion of participants who die or progress to Invasive Mechanical Ventilation (IMV) / Extracorporeal Membrane Oxygen (ECMO)
To evaluate the effect of tozorakimab versus placebo as an add on to Standard of Care (SoC) in participants with viral lung infection requiring supplemental oxygen on the prevention of death or progression to IMV/ECMO.
Time frame: by Day 28
Proportion of participants who die
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on all-cause mortality.
Time frame: by Day 60
Number of days alive and outside of Intensive Care Unit (ICU)
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on ICU stay.
Time frame: over 28 day period
Number of days alive and free of supplemental oxygen
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on the duration of oxygen supplementation.
Time frame: over 28 day period
Time to death or progression to Invasive Mechanical Ventilation (IMV) / Extracorporeal Membrane Oxygen (ECMO)
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on prolonging time to death or IMV/ECMO.
Time frame: over 28 day and 60 day period
Proportion of participants who die or progress to Invasive Mechanical Ventilation (IMV) / Extracorporeal Membrane Oxygen (ECMO)
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on prolonging time to death or IMV/ECMO.
Time frame: by Day 60
Time to death (all cause)
To evaluate the effect of Tozorakimab versus Placebo as add-on to Standard of Care (SoC) on prolonging time to death.
Time frame: over 28 day and 60 day period
Proportion of participants who die
To evaluate the effect of Tozorakimab versus Placebo as add-on to Standard of Care (SoC) on prolonging time to death.
Time frame: by Day 28
Number of days alive and free of Invasive Mechanical Ventilation (IMV) / Extracorporeal Membrane Oxygen (ECMO)
To evaluate the effect of Tozorakimab versus placebo as add-on to Standard of Care (SoC) on ventilator use.
Time frame: over 28 day and 60 day period
Number of days alive and ventilator free
To evaluate the effect of Tozorakimab versus placebo as add-on to Standard of Care (SoC) on ventilator use.
Time frame: over 28 day and 60 day period
Proportion of participants with Intensive Care Unit (ICU) admission or death
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on ICU admissions.
Time frame: by Day 28
Proportion of participants with Intensive Care Unit (ICU) admission or death
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on ICU admissions.
Time frame: by Day 60
Proportion of participants alive and discharged
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on duration of hospitalisation.
Time frame: by Day 28
Proportion of participants alive and discharged
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on duration of hospitalisation.
Time frame: by Day 60
Time to discharge
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on duration of hospitalisation.
Time frame: over 28 day and 60 day period
Time to being off supplemental oxygen
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on duration of hospitalisation.
Time frame: over 28 day and 60 day period
World Health Organization (WHO) 10-category ordinal Clinical Progression Scale
To evaluate the effect of tozorakimab versus placebo as add-on to Standard of Care (SoC) on clinical status as assessed by the Investigator using WHO 10-category ordinal Clinical Progression Scale (0 least severe to 10 most severe).
Time frame: by Day 60
Presence of anti-drug antibodies
To evaluate the immunogenicity (presence of tozorakimab anti-drug antibodies in blood serum) in participants with viral lung infection requiring supplemental oxygen.
Time frame: over 60 day period
Baseline serum interleukin-33/soluble Suppression of Tumorgenicity 2 (IL-33/sST2) complex levels relative to primary endpoint
To evaluate the use of baseline serum IL-33/sST2 complex levels (U/mL) to predict treatment response with tozorakimab versus placebo as add on to Standard of Care (SoC).
Time frame: Day 1
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Showing the first 100 of 473 sites across 39 countries. Choose a country and city above to see the rest.
Plan to share: Yes — Qualified researchers can request access to anonymized individual patient-level data from AstraZeneca group of companies sponsored clinical trials via the request portal. All request will be evaluated as per the AZ disclosure commitment: https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure. Yes, indicates that AZ are accepting requests for IPD, but this does not mean all requests will be shared.
Supporting information: Study protocol, Statistical analysis plan
Time frame: AstraZeneca will meet or exceed data availability as per the commitments made to the EFPIA Pharma Data Sharing Principles. For details of our timelines, please rerefer to our disclosure commitment at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.
Access criteria: When a request has been approved AstraZeneca will provide access to the deidentified individual patient-level data in an approved sponsored tool . Signed Data Sharing Agreement (non-negotiable contract for data accessors) must be in place before accessing requested information. Additionally, all users will need to accept the terms and conditions of the SAS MSE to gain access. For additional details, please review the Disclosure Statements at https://astrazenecagrouptrials.pharmacm.com/ST/Submission/Disclosure.
Data sharing details ↗ · astrazenecagroup-dt.pharmacm.com
No publications or documents are linked to this record.
Started Dec 2022 (actual). Primary completion is estimated for Nov 2027, 58 months after the start.
Of 39 phase 3 interventional studies under Respiratory Distress Syndrome, half reached primary completion within 29 months of starting (the median), counting those still running; a quarter within 14 and three quarters within 46. This study's planned 58 months is above that.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
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Studies of the drug tested here: Tozorakimab
Respiratory Distress Syndrome →