Expansion of SVN-015 into depression

Demonstrates antidepressant-like activity benchmarked against fluoxetine (Prozac®), supporting potential in patients with inadequate SSRI response

Solvonis Therapeutics plc (LSE: SVNS), an emerging biopharmaceutical company developing novel medicines for high-burden central nervous system ("CNS") disorders, announces the expansion of its investigational compound SVN-015 into the treatment of depression, supported by preclinical data demonstrating antidepressant-like activity benchmarked against fluoxetine.

Key highlights:

• SVN-015 expanded into depression following positive preclinical data in validated rodent behavioural models
• Antidepressant-like activity benchmarked against fluoxetine after 14-day, once-daily dosing
• SVN-015 is a novel Serotonin-Dopamine Reuptake Inhibitor ("SDRI") designed to engage pathways central to mood, motivation and reward processing
• Supports potential in patients with inadequate response to SSRIs in depression, including symptoms such as anhedonia and reduced motivation
• SVN-015 is expected to be developed as a once-daily oral therapy suitable for at-home use, aligned with standard antidepressant treatment cycles

In a direct preclinical evaluation, SVN-015 demonstrated antidepressant-like activity comparable to fluoxetine following 14-day, once-daily dosing in validated rodent behavioural models widely used to assess antidepressant activity. Fluoxetine, a selective serotonin reuptake inhibitor ("SSRI"), is one of the most established benchmark compounds in antidepressant drug development.

SVN-015 is a novel Serotonin-Dopamine Reuptake Inhibitor ("SDRI"), with patent applications filed, designed to engage pathways central to mood regulation, motivation, and reward processing. Despite widespread SSRI use, many patients fail to achieve adequate symptom control, particularly for symptoms such as anhedonia (feeling emotionally flat), reduced motivation, and impaired reward function. According to the U.S. National Institute of Mental Health (NIMH), Major Depressive Disorder ("MDD") affects more than 20 million adults in the United States annually, and tens of millions more across major international markets, including Europe and Japan.

SVN-015 is expected to be developed as a once-daily oral therapy suitable for at-home use, intended to support continuous symptom management within standard antidepressant treatment cycles. Its delivery model and reimbursement pathway are intended to align with established SSRI therapies, with potential advantages in scalability, patient access and long-term adherence.

As previously announced, SVN-015 has also been independently selected for evaluation within the U.S. National Institute on Drug Abuse ("NIDA") Addiction Treatment Discovery Program for stimulant use disorders, providing external, non-dilutive validation of the compound's pharmacological profile in a separate CNS indication. This programme is separate from Solvonis' research on depression.

Anthony Tennyson, Chief Executive Officer, commented: "Demonstrating antidepressant-like activity versus a gold-standard SSRI following repeat dosing is a notable preclinical signal, supporting SVN-015's expansion into research and development of small molecule therapies for depression."

Professor David Nutt, Chief Scientific Officer, added: "These data are highly encouraging and reflect a mechanistically grounded approach engaging both serotonergic and dopaminergic systems. Demonstrating antidepressant-like effects under repeat-dose conditions supports further development of SVN-015 and the broader SDRI class as a potential new class of antidepressant medicines."