In short
SIR9900 is an investigational medicine being studied in a phase 2 clinical trial for VEXAS syndrome, a rare autoinflammatory disease. The trial, authorised in the EU, plans to enrol 110 participants and is split into two parts: a dose-ranging part and an efficacy and safety part. Researchers are testing two oral doses of SIR9900 against placebo.
Key points
- Phase 2 trial authorised in the EU for VEXAS syndrome.
- Plans to enrol 110 participants.
- Tests two oral doses of SIR9900, 20 mg and 30 mg, against placebo.
- Part A measures safety, tolerability, and dose selection; Part B measures efficacy and safety.
- Primary outcome in Part B is overall clinical response (OCR) up to week 24.
What is SIR9900?
SIR9900 is an investigational substance, meaning it has not been authorised as a medicine. It is being studied in a phase 2 clinical trial for VEXAS syndrome, a rare autoinflammatory condition. The trial record lists the substance under the name SIR9900, with a placebo used as a comparison arm. The registry data does not provide a chemical class or mechanism of action for SIR9900.
How does SIR9900 work?
The available trial record does not describe how SIR9900 works at a molecular level. No mechanism of action, target, or pharmacological class is stated in the source data. The trial is designed to evaluate its safety, tolerability, and activity in people with VEXAS syndrome, but the way the substance acts in the body is not explained in the registry.
Which conditions is SIR9900 used or studied for?
- VEXAS syndrome – a rare autoinflammatory disease that the phase 2 trial is specifically designed to study.
How is SIR9900 given?
SIR9900 is given orally in the clinical trial. The intervention is described as "Drug: SIR9900 10mg (30 mg milligram(s), ORAL)". The brief summary states that two dose levels, 20 mg and 30 mg, are being compared to placebo in Part A of the study. The trial record does not provide further details on pharmaceutical form beyond the oral route.
What do the clinical trials show?
One authorised phase 2 trial of SIR9900 is listed in the EU Clinical Trials Information System. It plans to enrol 110 participants with VEXAS syndrome and is divided into two parts.
Part A is a dose-ranging study. It evaluates the safety, tolerability, and activity of two dose levels of SIR9900, 20 mg and 30 mg, compared to placebo. The aim is to select the optimal dose for Part B. The primary outcomes for Part A include the incidence and severity of treatment-emergent adverse events, serious adverse events, and clinically significant laboratory abnormalities. It also measures the proportion of participants with early treatment failure, defined as the inability to taper glucocorticoids to 10 mg per day or less, early termination before overall clinical response, or the occurrence of a protocol-defined flare.
Part B is an efficacy and safety study. It evaluates the efficacy and safety of the selected dose from Part A compared to placebo. The primary outcome is the proportion of participants achieving overall clinical response (OCR) up to the end of week 24.
The trial is currently in the Authorised status, meaning it has received regulatory approval to proceed but may not yet be recruiting participants.
What side effects are known?
The trial record does not list known side effects of SIR9900. The study itself is designed to collect information on adverse events, including treatment-emergent adverse events and serious adverse events, as part of its primary outcomes in Part A. No supplementary sources with side effect data were provided.