Cereno Scientific has received an official endorsement from the US Food and Drug Administration (FDA) for its planned Phase IIb clinical trial of CS1, its pulmonary arterial hypertension (PAH) therapy.
This green light follows a Type C meeting with the FDA held in April. The Swedish company noting that the decision positions the biotech firm for further regulatory interaction and clinical development progress.
The endorsement validates the company’s proposed clinical development path and clears the way for the larger, placebo-controlled Phase IIb trial scheduled to begin in the first half of 2026.
“This is a very exciting milestone for our pipeline,” said Rahul Agrawal, Chief Medical Officer and Head of R&D at Cereno Scientific. “Receiving an FDA endorsement for the CS1 program at this stage in development paves the way for continued progress, not just toward the upcoming Phase IIb trial, but also for eventual Phase III and regulatory approval.”
CS1, an orally administered histone deacetylase (HDAC) inhibitor, works through epigenetic modulation—a mechanism that sets it apart from existing PAH therapies that primarily manage symptoms. It is designed to offer disease-modifying benefits for patients suffering from PAH, a rare and life-threatening condition marked by high blood pressure in the arteries of the lungs.
In contrast to existing therapies that primarily alleviate symptoms, CS1 aims to address the underlying causes of PAH by reversing pathological vascular remodeling in the pulmonary arteries and improving the right heart function.
Trial Design
The Phase IIb study will be a larger, placebo-controlled trial intended to confirm the promising results observed in the Phase IIa trial, which concluded successfully in 2024. In the earlier trial, CS1 was well tolerated, with a favorable safety profile and preliminary signs of clinical efficacy.
Additional data from the phase IIa study were shared following completion of the clinical study report. The results showed sustained improvements in REVEAL 2.0 risk scores, functional capacity, and patient-reported quality of life – early indicators of long-term therapeutic benefit. Further data analysis also revealed early signs of improved right ventricular function, which is a key predictive factor for survival in PAH.
An expanded access program is currently ongoing with 10 patients from the Phase IIa trial, providing further insight into the long-term effects of CS1.
In addition to CS1, Cereno’s pipeline includes CS014, an HDAC inhibitor in Phase I development for conditions like idiopathic pulmonary fibrosis (IPF), and CS585, a selective IP receptor agonist in preclinical development.
