GNW-Adhoc: Idorsia announces the results of REACT a Phase 3 study of clazosentan in patients following aneurysmal subarachnoid hemorrhage

    ^Ad hoc announcement pursuant to Art. 53 LR
Allschwil, Switzerland - February 6, 2023
Idorsia Ltd (SIX: IDIA) today announces the initial findings of REACT, a Phase
3 study which investigated the efficacy and safety of clazosentan in preventing
clinical deterioration due to delayed cerebral ischemia, in patients following
aneurysmal subarachnoid hemorrhage (aSAH). The study did not meet the primary
endpoint. The company will fully analyze the efficacy and safety data to
understand this unexpected result.
Jean-Paul Clozel, MD and Chief Executive Officer of Idorsia, commented:
"I am very disappointed with the negative result of REACT. The study was based
on strong scientific and medical rationale and executed diligently by a
committed team of experts at Idorsia and by the investigators. On behalf of
everyone at Idorsia, I'd like to thank the investigator teams and expert
advisors for their tireless support to conduct this study in such a challenging
medical condition."
The company will publish the data and interpretation in scientific literature in
due course.
About the REACT study(1) NCT03585270
(https://clinicaltrials.gov/ct2/show/NCT03585270)
REACT, a multicenter, double-blind, randomized, placebo-controlled, parallel-
group, Phase 3 study with clazosentan in patients with aneurysmal subarachnoid
hemorrhage (aSAH), assessed the efficacy and safety of clazosentan in preventing
clinical deterioration due to delayed cerebral ischemia, in adult patients
following aSAH. REACT included patients aged 18 to 70 years with World
Federation of Neurological Societies grades 1-4 after recovery from the
aneurysm-securing procedure and "thick and diffuse clots" on the admission CT
scan. REACT randomized 409 patients - treated either with microsurgical clipping
or endovascular coiling aneurysm securing procedures - in a 1:1 ratio to receive
placebo or clazosentan 15 mg/h. Patients were enrolled in the REACT study at 74
sites in 15 countries across North America and Europe. In general, the standard
of care for managing aSAH was allowed, and the administration of nimodipine
(oral or intravenous) was permitted if it was routine standard of care at the
site.
Notes to the editor
Clazosentan in aSAH(2-4)
An aSAH involves sudden life-threatening bleeding occurring in the subarachnoid
space. It is caused by the rupture of an aneurysm - a weak, bulging spot on the
wall of a cerebral artery. An emergency procedure (endovascular coiling or
microsurgical clipping) is required to secure the aneurysm to prevent
rebleeding.
The subarachnoid bleeding and subsequent release of endothelin-1 - a potent
vasoconstrictor produced mainly by the neighboring vascular endothelium - can
lead to cerebral vasospasm (constriction of arteries in the brain), which
usually starts 3 days after aSAH onset and peaks in intensity between 8 and 11
days. This diminishes blood flow to the brain, and about one-third of all aSAH
patients consequently experience worsening of their neurological condition.
Cerebral vasospasm is one of the leading secondary causes of disability in
patients with aSAH.
Clazosentan is a fast-acting, endothelin A (ET(A)) receptor antagonist, that
Idorsia has developed as a continuous intravenous infusion for the prevention of
clinical deterioration due to delayed cerebral ischemia (DCI) in patients
following aSAH. Clazosentan is approved for the prevention of cerebral
vasospasm, vasospasm-related cerebral infarction, and cerebral ischemic symptoms
after aSAH in Japan.
Previous global clinical studies with clazosentan(5)(-8)
Several studies have built our understanding of the role of clazosentan in
preventing cerebral vasospasm. In 2006, results were reported for clazosentan in
the prevention of angiographic vasospasm in patients with aSAH. The Phase 2
dose-finding study, CONSCIOUS 1, demonstrated dose-dependent prevention of
vasospasm.
This was followed by two Phase 3 studies, CONSCIOUS-2 and CONSCIOUS-3, to assess
the effect of clazosentan on the incidence of cerebral vasospasm-related
morbidity and all-cause mortality. In 2010, CONSCIOUS-2 showed that the 5 mg/h
dose of clazosentan was too low and did not allow a statistically significant
treatment effect to be observed, resulting in the premature termination of
CONSCIOUS-3. However, an exploratory analysis of the data collected in
CONSCIOUS-3 showed that a higher dose of clazosentan (15 mg/h) significantly
reduced cerebral vasospasm-related morbidity and all-cause mortality, with a
44% relative risk reduction (p=0.0074). The 15 mg/h dose also significantly
reduced the incidence of delayed ischemic neurological deficit (DIND), with a
54% relative risk reduction (p=0.0038). In addition, clazosentan reduced the
need for rescue therapy for vasospasm. Clazosentan did not improve long-term
clinical outcome in that study.
The studies confirmed the well-documented safety profile of clazosentan, which
has now been administered to more than 2000 patients around the world in a
controlled clinical setting. The side effects of clazosentan can be managed
according to clear protocol guidelines: hypotension can be mitigated using blood
pressure control with vasopressors in the ICU, while lung complications (such as
pulmonary edema) can be managed by avoiding excessive fluid administration so as
to maintain euvolemia.
Key literature
 1. Bruder et al, BMC Neurology, 2022
 2. Thompson et al, Neurology and Therapy, 2022
 3. Chalet et al, Neurology and Therapy, 2023
 4. Juif et al, Frontiers in Pharmacology, 2021
 5. Vajkoczy et al, J Neurosurg, 2005
 6. Macdonald et al, Stroke, 2008
 7. Macdonald et al, Lancet Neurology 2011
 8. Macdonald et al, Stroke, 2012
About Idorsia
Idorsia Ltd is reaching out for more - We have more ideas, we see more
opportunities, and we want to help more patients. In order to achieve this, we
will develop Idorsia into a leading biopharmaceutical company, with a strong
scientific core.
Headquartered near Basel, Switzerland - a European biotech-hub - Idorsia is
specialized in the discovery, development and commercialization of small
molecules to transform the horizon of therapeutic options. Idorsia has a broad
portfolio of innovative drugs in the pipeline, an experienced team of
professionals covering all disciplines from bench to bedside, state-of-the-art
facilities, and a strong balance sheet - the ideal constellation to translate
R&D efforts into business success.
Idorsia was listed on the SIX Swiss Exchange (ticker symbol: IDIA) in June 2017
and has over 1200 highly qualified specialists dedicated to realizing our
ambitious targets.
For further information, please contact
Andrew C. Weiss
Senior Vice President, Head of Investor Relations & Corporate Communications
Idorsia Pharmaceuticals Ltd, Hegenheimermattweg 91, CH-4123 Allschwil
+41 58 844 10 10
investor.relations@idorsia.com (mailto:investor.relations@idorsia.com) ?
media.relations@idorsia.com (mailto:media.relations@idorsia.com) ?
www.idorsia.com
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