SISTER is a research study for patients who have had an ischemic stroke, a type of stroke caused by a blockage in a blood vessel in the brain. The study will test a medicine called TS23, which is an experimental drug, to see if it is safe and if it works better than a placebo (a harmless pill with no medicine). TS23 is a special protein that might help treat strokes. To join, participants must be 18 years or older and have had a stroke within the last 24 hours. The study lasts about 90 days, and you will visit the doctor several times.

• The study will happen at up to 50 locations and will include 300 people.
• Participants will be checked for safety and improvements 30 hours after getting the drug.
• You cannot join if you are planning other stroke treatments or have certain health issues.