Sareum Holdings plc

("Sareum" or the "Company")

Positive Data from SDC-1801 Phase 1 Clinical Trial

Cambridge, UK, 1 July 2024 - Sareum Holdings plc (AIM: SAR), a clinical-stage biotechnology company developing next-generation kinase inhibitors for autoimmune disease and cancer, is pleased to announce positive topline data from its Phase 1a clinical trial of SDC-1801, a dual TYK2/JAK1 kinase inhibitor being developed as a potential new therapeutic for a range of autoimmune diseases.

Following the dosing of the final cohort in the Multiple Ascending Dose stage of the trial, and review of the initial data by the Safety Review Committee, the Company reports that:

·    Blood plasma levels of SDC-1801 significantly in excess of the predicted therapeutic exposure were achieved, with a half-life of between 17 and 20 hours observed, which suggests that once-daily dosing will be possible*

·    No deaths or serious adverse events due to SDC-1801 were reported

·    Although data remains blinded, there appear to be no significant changes in blood cell counts or increases in serum creatinine levels, which may be dose limiting side-effects of brepocitinib, currently the most advanced TYK2/JAK1 dual inhibitor

*Half-life is an estimation of the time it takes for an initial concentration of SDC-1801 to be reduced by half in the body.

The Company expects that further data, unblinded from drug/placebo recipients, including details of any mild or moderate adverse events and biomarkers of TYK2 and/or JAK1 inhibition, will be available in Q3 2024.

Dr Tim Mitchell, Chief Executive Officer of Sareum, commented: "We are delighted that the dosing of subjects in the SDC-1801 clinical trial has been completed successfully and without any serious adverse events. We look forward to building a strong data package to advance SDC-1801 to the next stage of its development."

Dr John Reader, Chief Scientific Officer of Sareum, added: "The success of this stage of the clinical trial demonstrates that high blood levels of a dual TYK2/JAK1 kinase inhibitor can be achieved without serious side effects. Together with the long half-life observed, we believe this potentially gives SDC-1801 significant advantages over its competitors. We're grateful to the volunteers who participated in this trial, and to the clinical staff who enabled its timely completion."

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For Further Information:

The information contained within this announcement is deemed by the Company to constitute inside information as stipulated under the Market Abuse Regulation (EU) No. 596/2014 as it forms part of United Kingdom domestic law by virtue of the European Union (Withdrawal) Act 2018, as amended by virtue of the Market Abuse (Amendment) (EU Exit) Regulations 2019.

About Sareum

Sareum Holdings (AIM: SAR) is a clinical-stage biotechnology company developing next generation kinase inhibitors for autoimmune disease and cancer.

The Company is focused on developing next generation small molecules which modify the activity of the JAK kinase family and have best-in-class potential. Its lead candidate, SDC-1801, simultaneously inhibits TYK2 and JAK1. SDC-1801 is a potential treatment for a range of autoimmune diseases and is currently completing Phase 1 clinical development.

Sareum is also developing SDC-1802, a TYK2/JAK1 inhibitor with a potential application for cancer immunotherapy.

Sareum Holdings plc is based in Cambridge, UK, and is listed on the AIM market of the London Stock Exchange, trading under the ticker SAR. For further information, please visit the Company's website at www.sareum.com.