Cereno Scientific has submitted the clinical trial protocol for its planned global Phase 2b study of lead candidate CS1 in pulmonary arterial hypertension (PAH) to the US Food and Drug Administration (FDA). The move brings the Swedish biotech closer to advancing its epigenetic-based treatment into the next stage of clinical development.

The Phase 2b trial will further evaluate the safety, tolerability and efficacy of CS1, a histone deacetylase inhibitor (HDACi) being developed as an oral therapy targeting the root mechanisms of PAH through epigenetic modulation. It will build on results from the completed Phase 2a study, in which CS1 showed a favourable safety and tolerability profile along with positive efficacy signals such as reverse vascular remodelling, improved right heart function and enhanced quality of life.

Rahul Agrawal, chief medical officer and head of R&D at Cereno Scientific, said: “The submission of the protocol marks a major milestone and underscores the focus, commitment and outstanding collaboration across our team and global CRO. This protocol has been developed in alignment with the FDA’s feedback from our recent Type C meeting, and we now look forward to the agency’s review ahead of initiating the trial.”

PAH is a rare, progressive and life-threatening condition that causes high blood pressure in the pulmonary arteries, leading to right heart failure and premature death. Current therapies largely manage symptoms, leaving a significant unmet need for disease-modifying options.

Sten Sörensen, chief executive of Cereno Scientific, added: “This milestone moves us closer to our goal of delivering a first-in-class therapy that targets the root mechanisms of PAH through epigenetic modulation. With CS1, we have an opportunity to potentially change the treatment paradigm for patients facing this devastating disease.”

Cereno Scientific expects FDA clearance to proceed following the agency’s standard 30-day review period. The Phase 2b trial, to be conducted in collaboration with an international contract research organisation, is scheduled to begin during the first half of 2026 as part of the company’s global development programme for CS1.