1 domain / 2 areas / 1 specialization
Clexio Biosciences
Clexio Biosciences is a private Israeli clinical-stage CNS company founded in 2018 by Teva Pharmaceuticals R&D veterans. Their lead programme CLE-100 is a once-daily oral tablet formulation of esketamine for MDD — distinguished from the FDA-approved Spravato (intranasal, in-clinic) by enabling outpatient, at-home use. Phase 2 CLEO study results showed a promising safety profile and encouraging efficacy specifically in post-COVID MDD subgroups; the Phase 2 SOLEO study (NCT06340958, higher dose, stricter treatment-resistance criteria) enrolled first patients April 2024 and reached 50% enrollment by December 2024. CLE-100 holds multiple US method-of-use patents (2024). In December 2025, Clexio spun out its muscarinic agonist programme (CLE-905) into a new entity, Syremis Therapeutics, which raised $165M Series A co-led by Dexcel Pharma and Third Rock Ventures. Co-founders Kogan, Levy, and Kagan simultaneously lead Syremis; Clexio continues independently with CLE-100 and preclinical CLE-043.
Development Programmes
2CLE-100 (Oral Esketamine)
EsketamineMajor depressive disorder (inadequate antidepressant response)
Programme Tracker
Major Depressive Disorder (MDD)
SOLEO Phase 2 (NCT06340958) enrolling at US sites; oral esketamine once daily x4 weeks in patients with inadequate response to ≥2 antidepressants
Milestones
Phase II started
CompletedActual: Jun 1, 2024
SOLEO Phase 2 (NCT06340958) initiated; oral esketamine adjunct to antidepressants; US multi-centre
Why it matters: SOLEO is designed to generate registration-enabling efficacy data for oral esketamine as an adjunct to standard antidepressants — the same patient population as Spravato but with the convenience of oral dosing. Success would address the major commercial limitation of intranasal esketamine (clinic-only administration).
Watch next: SOLEO primary endpoint results (HAM-D change from baseline at 4 weeks)
Phase II topline
CompletedActual: Oct 1, 2023
CLEO Phase 2 (NCT04103892) results presented at ASCP: 130 subjects randomised across 32 US sites; safety profile confirmed; post-acute COVID subgroup showed promising efficacy signal
Why it matters: CLE-100 is an oral esketamine (S-ketamine) formulation designed for once-daily home dosing — bypassing the intranasal/IV administration burden of Spravato. CLEO safety data enables the SOLEO Phase 2b with a larger sample and primary efficacy endpoint.
Recorded Events
Jun 1, 2024: Phase II started
Oct 1, 2023: Phase II topline
CLE-905 (M1/M4 Muscarinic Agonist)
Schizophrenia
Programme Tracker
Schizophrenia
Licensed to Syremis Therapeutics (spinout, Q2 2024); Syremis raised $165M Series A (Dec 2025); Phase 1 underway under Syremis as ST-905; Clexio retains internal development rights
Milestones
Licensing deal
CompletedActual: Jun 1, 2024
CLE-905 spun out to Syremis Therapeutics (Q2 2024); renamed ST-905 at Syremis
Why it matters: CLE-905 is a potent dual M1/M4 preferential muscarinic agonist for schizophrenia — the same validated mechanism as KarXT/Cobenfy (FDA-approved 2024). Syremis was founded by former Karuna Therapeutics team members (who developed KarXT), giving ST-905/CLE-905 the highest-possible team pedigree for this mechanism.
Funding milestone
CompletedActual: Dec 1, 2025
Syremis Therapeutics raises $165M Series A (December 2025)
Why it matters: $165M Series A led by former Karuna leadership validates ST-905's potential to compete with or improve upon KarXT in the schizophrenia market. Clexio retains value from this spinout through equity/milestone payments.
Watch next: Syremis Phase 1 FIH results for ST-905; Clexio CLE-905 internal Phase 1 timeline
Recorded Events
Dec 1, 2025: Funding milestone
Jun 1, 2024: Licensing deal
Quick Facts
- Type
- Private Biotech
- Lead Stage
- Phase II
- Website
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