Safety and Efficacy of AON-D21 in Severe Community-Acquired Pneumonia.

Study summary

The goal of this clinical trial is to compare the safety and efficacy of AON-D21 versus placebo, both on top of standard of care, in patients with severe community acquired pneumonia admitted to ICU (or similar unit). The main questions to answer are: * The safety and tolerability of AON-D21 vs placebo. * The efficacy of AON-D21vs placebo. * The pharmacokinetics of AON-D21. * The pharmacodynamics of AON D21. * To identify biomarkers for patient stratification and analyses in future trials.

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Key things to know

Main goalTreatment

This describes the study’s primary purpose.

What is being studiedAON-D21 and Placebo

The study team can explain what participation involves.

Who it may be forCommunity-acquired Pneumonia

These are broad labels—not an eligibility decision.

Checked against the public recordLast updated Mar 18, 2026 · Source: ClinicalTrials.gov

Is enrollment open?Completed

Ask the study team to confirm whether enrollment is open.

What kind of study?Phase 2

Interventional

Where is it offered?27 U.S. locations

Locations may change over time.

Who runs it?Aptarion Biotech AG

Study sponsor

Study overview

What this study is about

Purpose: Treatment
Study type: Interventional
Phase: Phase 2
Sponsor: Aptarion Biotech AG
Interventions being studied: Drug: AON-D21; Drug: Placebo

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How this study is categorized

These labels come from structured fields and exact terms in the public record.

Public criteria

Who may be able to participate

The sponsor separates these requirements into two groups. You do not need to interpret them alone—use them to guide a conversation with the study team.

Requirements people may need to meetInclusion criteria

Community-acquired pneumonia, confirmed or suspected of bacterial or viral origin.
Admitted to an ICU (or similar unit).
Requiring respiratory support by HFO ≥ 30 L/min with FiO2 ≥ 30% or NIV or IMV or ECMO.
CRP ≥ 50 mg/L.
PaO2/FiO2 ratio ≤ 150 mmHg.
Treatment initiation no more than 48 h after initiation of respiratory support (HFO ≥ 30 L/min with FiO2 ≥ 30%, NIV, IMV or ECMO).
Written informed consent.
Age ≥ 18 years to ≤ 85 years.
Body mass index ≥ 17.5 kg/m² and ≤ 40 kg/m².
For female participants of childbearing potential, agreement to use dual methods of contraception until Day 60.
For male participants with female partners of childbearing potential, agreement to use barrier method of contraception until Day 60 and to refrain from donating sperm during the study and for 3 months after the last infusion.

Reasons someone may not be able to joinExclusion criteria

Refractory septic shock.
Not expected to survive 72 hours.
Hospital-acquired or ventilator-associated pneumonia or known or suspected pneumonia due to aspiration or other physical injury or trauma or tuberculosis.
Known or suspected hypersensitivity to AON-D21 or any components of the formulation used (e.g., PEG, mannitol or EDTA) or a history of clinically relevant allergy requiring continuous treatment, or of anaphylaxis.
Known fibrotic lung disease, bronchiectasis or any other known severe chronic respiratory disease.
Active malignant disease.
Factors other than a pathogen suspected or confirmed to be causative for the respiratory insufficiency.
Hepatocellular injury defined by an ALT or AST value ≥ 3 times the ULN. Known acute or chronic liver disease with Child-Pugh C (See Appendix 13.6.2).
Any medical disease or condition that, in the opinion of the investigator(s), compromises the participant's safety or compromises the interpretation of the results.
Receiving chronic immunosuppressive therapy in relevant doses.
Known immunodeficiency disease/condition.
Nursing and pregnant women (defined as the state after conception until the termination of gestation, screened in all women of child-bearing potential with a chorionic gonadotrophin (hCG) blood test (local laboratory).
Current or recent participation in an investigational trial.
Systemic treatment with any complement inhibitor.
Known complement deficiency.
Unlikely to remain at the investigational site beyond 96 h.

Important: This is the sponsor’s public criteria, not a determination of eligibility. The study team must review your individual situation.

Study sites

U.S. locations

University of Alabama at Birmingham Heersink School of MedicineBirmingham, Alabama
Cliniques Universitaires Saint-LucBrussels
Clinique Saint PierreOttignies
Centre Hospitalier ArgenteuilArgenteuil
Centre Hospitalier Départemental VendéeLa Roche-sur-Yon
CHU DupuytrenLimoges
Centre Hospitalier de MelunMelun
Hotel Dieu - CHU NantesNantes
Assistance Publique-Hopitaux de Paris (AP-HP)Paris
Nouvel Hôpital CivilStrasbourg
CHRU de Tours Hôpital BretonneauTours
Hôpital Nord Franche ComtéTrévenans

Source and freshness
Processed from ClinicalTrials.gov. Last public update: Mar 18, 2026. Always confirm current availability with the study team.

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