Sareum Holdings Finalizes Dosing in Phase 2-Enabling Toxicology Study for SDC-1801, Targeting Psoriasis

Advancement of SDC-1801 Through Critical Toxicology Phase

Sareum Holdings has reached a significant regulatory milestone by completing dosing in the Phase 2-enabling toxicology programme for SDC-1801, its lead clinical-stage candidate. Restarted in February 2026, the toxicology study has progressed on schedule and is now entering data analysis. This achievement moves the programme closer to initiating clinical trials in autoimmune disease patients.

The company’s disciplined capital management is evident as it completed this phase using existing cash reserves, maintaining momentum in its pipeline development strategy. The transition from dosing to data review will allow regulatory authorities to assess the safety profile of SDC-1801 ahead of Phase 2 clinical trial applications.

Selective TYK2/JAK1 Inhibitor with Focus on Autoimmune Disorders

SDC-1801 is designed as a selective oral inhibitor targeting TYK2 and JAK1 kinases, positioning it as a best-in-class agent within the JAK kinase inhibitor class. The dual inhibition mechanism aims to deliver therapeutic benefits across multiple autoimmune diseases, with psoriasis identified as the initial clinical focus. Psoriasis affects millions worldwide and presents a substantial market opportunity due to the ongoing need for more effective and better-tolerated treatments.

This targeted approach leverages the advantages of selective TYK2/JAK1 inhibition, potentially offering improved efficacy and safety compared to broader JAK inhibitors. By concentrating on psoriasis initially, Sareum aims for a streamlined regulatory and clinical development pathway, potentially accelerating market entry and laying groundwork for expansion into other autoimmune conditions.

Phase 1 Results Support Safety and Dosing Regimen

Phase 1 clinical trials of SDC-1801 demonstrated a pharmacokinetic profile compatible with once-daily dosing, enhancing patient convenience and adherence. Importantly, no safety concerns emerged during these early studies, providing a solid foundation for further development.

Dr John Reader, Sareum’s Chief Scientific Officer, highlighted that completing the toxicology programme is a key milestone building on the encouraging Phase 1 data. The combined human safety data and animal toxicology results position SDC-1801 well for regulatory submission to initiate Phase 2 trials in psoriasis patients.

Regulatory Preparation and Q4 2026 Completion Goal

Sareum is concurrently advancing chemistry, manufacturing, and controls (CMC) and formulation development activities alongside toxicology data analysis. These efforts are critical components of the Phase 2-enabling regulatory package, which will be submitted to agencies such as the UK’s MHRA or equivalent international bodies. Targeting Q4 2026 for package completion represents a major de-risking event, enabling regulatory clearance to start Phase 2 clinical trials.

CMC work includes establishing manufacturing processes and quality control standards, while formulation development focuses on optimizing drug presentation to patients. These parallel workstreams illustrate Sareum’s efficient regulatory preparation, positioning the company to potentially initiate Phase 2 trials by late 2026 or early 2027, subject to approval.

Diverse Pipeline and Kinase Inhibitor Portfolio Strategy

Beyond SDC-1801, Sareum is developing SDC-1802, another TYK2/JAK1 inhibitor targeting haematological cancers, expanding the therapeutic scope of its kinase inhibitor platform. Additionally, a preclinical programme targeting neuroinflammatory diseases such as multiple sclerosis and Parkinson’s disease has been launched, broadening the company’s reach into neurology indications involving inflammatory pathways.

Sareum also holds licensing rights to SRA737, a clinical-stage Checkpoint kinase 1 inhibitor focused on cancer cell replication and DNA damage repair, providing oncology exposure through a distinct mechanism. This diversified portfolio reduces development risk and creates multiple value opportunities across autoimmune, cancer, and neuroinflammatory disease areas.

Capital Efficiency and Use of Existing Funds

The company emphasized that the Phase 2-enabling toxicology programme was completed using existing cash resources, reflecting strong capital discipline and financial planning. This approach preserves shareholder value by avoiding dilution and maintaining a solid cash runway.

Executive Chairman Dr Stephen Parker noted that this disciplined execution keeps Sareum on track to meet Phase 2-enabling milestones within budget. Investors will monitor cash position as the company approaches Q4 2026, particularly regarding funding needs for Phase 2 trial initiation.

Psoriasis Market Potential and Strategic Indication Choice

Focusing on psoriasis as the initial indication aligns with a targeted strategy to capture value in a large dermatology market. Affecting 2-3% of developed market populations, psoriasis presents millions of patients requiring ongoing treatment. Despite existing biologics targeting TNF-alpha and interleukin pathways, there remains demand for novel therapies with improved efficacy and safety.

Psoriasis offers a well-characterized clinical and regulatory pathway, facilitating faster development timelines compared to more complex autoimmune diseases. Successful Phase 2 results could support expansion into additional autoimmune indications, leveraging the same mechanism of action.

Cambridge-Based Biotech Listed on AIM

Sareum Holdings plc is headquartered in Cambridge, UK, and trades on the London Stock Exchange’s AIM market under ticker SAR. Cambridge’s biotech cluster provides access to academic collaborations, talent, and infrastructure. The AIM listing offers capital market access with a lighter regulatory framework, supporting flexible clinical development strategies.

As a clinical-stage biotech, Sareum currently has no product sales revenue, relying on milestone achievements for financial sustainability. Progress toward the Q4 2026 Phase 2-enabling milestone will be a key investor focus for assessing the company’s value and risk profile.

Upcoming Steps in SDC-1801 Development

Following dosing completion, Sareum’s priorities include toxicology data analysis and finalizing CMC and formulation activities for regulatory submission. The company targets Q4 2026 for full Phase 2-enabling package completion, enabling initiation of Phase 2 clinical trials in psoriasis patients potentially by late 2026 or early 2027.

Phase 2 trials will evaluate efficacy using validated measures such as the Psoriasis Area and Severity Index (PASI), further assess safety and tolerability, and optimize dosing. Positive Phase 2 outcomes would pave the way for Phase 3 pivotal trials to support regulatory approval and commercialization.