What the initial insights from the EAP mean for the continued development of CS1 – an explanation for investors

Cereno Scientific has presented initial insights from an Expanded Access Program (EAP), in which patients with pulmonary arterial hypertension (PAH) were treated with the drug candidate CS1 for 12 months. The results confirm a favorable safety and tolerability profile during long-term treatment and are consistent with previously reported findings from the Phase IIa study.

In this article, we explain what the results mean, why they are important, and how they strengthen the value proposition of CS1.

What is an Expanded Access Program (EAP)?

An Expanded Access Program (EAP) is a regulatory-approved program that enables patients to continue treatment with a drug candidate after completion of a clinical study.

In this case, the EAP allowed patients who participated in the three-month Phase IIa study to continue treatment with CS1 for an additional 12 months. The program was initiated following requests from both patients and treating physicians. At the same time, the program enables the collection of important long-term data, particularly regarding safety and tolerability.

What do the EAP insights show?

The initial insights from the EAP show that:

• CS1 was well tolerated during long-term treatment 
• No unexpected safety-related observations were identified 
• No deaths were reported 
• No treatment discontinuations were considered related to CS1 

Six out of ten patients completed the full 12 months of continuous treatment. The reasons why the remaining patients discontinued the study early were not considered related to CS1.

Overall, these observations are consistent with the clinical results previously reported from the Phase IIa study.

In PAH, where many existing treatments can be associated with challenges during long-term use, there remains a significant medical need for safer, well-tolerated treatment alternatives. The favorable safety and tolerability profile demonstrated by CS1 after 12 months of treatment is therefore an important observation.

The three-month Phase IIa study showed that CS1 had a favorable safety and tolerability profile and demonstrated promising efficacy signals, including:

• Improvements in right ventricular function 
• Improved functional class 
• Improved quality of life 
• Signs of reverse vascular remodeling 

Together, the Phase IIa study and the EAP provide up to 15 months of treatment data, contributing to a broader clinical understanding of CS1 and strengthening the value proposition of the drug candidate.

How does this strengthen the value proposition of CS1?

The combined Phase II clinical data strengthens several key aspects of CS1’s value proposition:

• A favorable safety and tolerability profile, including during long-term treatment 
• Positioning as an oral, once-daily treatment 
• Potential to be disease-modifying by addressing underlying disease mechanisms 

This is particularly relevant in PAH, where there remains a significant need for new therapies capable of impacting disease progression..

What are the next steps in development?

Cereno Scientific is currently continuing preparations for a global, placebo-controlled Phase IIb study of CS1 in PAH, planned to start in June 2026.

At the same time, additional analyses from the EAP are ongoing, including an exploratory imaging sub-study using Fluidda’s technology. These results are planned to be communicated during the second quarter of 2026 and are expected to contribute further understanding of the treatment effects.

Summary

The 12-month EAP results confirm CS1’s favorable safety and tolerability profile during long-term treatment and are consistent with previously reported clinical findings.

Together with the Phase IIa data, this means that CS1 now has up to 15 months of clinical treatment experience, strengthening both the scientific foundation and the overall value proposition ahead of the next stage of development.