This study evaluates the safety and tolerability of 3 dose levels of ABL-101 and supplemental oxygen in acute stroke patients.

Only a small proportion of patients are currently suitable for treatment with "clot busting" drugs after a stroke. Being able to visualise potentially rescuable brain tissue on scanning may allow more people to be treated. Currently available methods require extra time to acquire and are not therefore widely used. By carrying significant extra oxygen to the brain, the ABL-101 molecule may not only allow the visualisation of salvageable tissue, but also prevent progression of stroke damage in and have an additional direct benefit on tissue survival. Studies in animal models of stroke show smaller areas of stroke damage after ABL-101. There is therefore a rationale for testing this molecule in stroke patients, both as a diagnostic method, and also as a potential therapeutic agent.

Inclusion Criteria:

• Aged ≥18 years.
• Males or females not of child-bearing potential defined as being post-menopausal based on cessation of regular menses for a minimum of 12 consecutive months with no alternative cause, permanently sterilised (e.g. hysterectomy, bilateral tubal occlusion, bilateral salpingectomy), or having medically confirmed ovarian failure.
• Ischaemic stroke <72h after onset.
• Previous functional independence (estimated mRS <3).
• Capacity to consent.

Exclusion Criteria:

• Women of child bearing potential.
• Contraindications to MRI scanning (eg cardiac pacemaker, ferromagnetic implants, known hypersensitivity to gadolinium containing contrast media).
• Known allergy to ABL-101 or any of its constituents, (including egg phospholipids).
• Clinical need for, or contraindication to, supplemental oxygen.
• Known impaired renal function (eGFR <30ml/min) precluding radiological contrast.
• Known thrombocytopaenia (platelet count <150x109) or history of platelet function disorder.
• Known intercurrent infection.
• Known severe COPD or cardiac failure (eg significantly limiting exercise capacity or requiring hospitalisation within the preceding 12 months).
• Known significant liver disease (eg liver failure or cirrhosis, chronic infectious or autoimmune hepatitis, or transaminases >3 times upper limit of normal).
• Any current medical condition causing impaired immunity (eg HIV infection, hyposplenism) or use of systemic immunosuppressant medication except for inhaled, nasal intra-articular or topical corticosteroids) on an ongoing basis or within the preceding 30 days.
• Any medical condition potentially limiting survival within the study follow-up period.
• Participation in another CTIMP within preceding 90 days.