STEP is a Randomized, Multifactorial, Adaptive Platform trial that seeks to optimize the care of patients with acute ischemic stroke (AIS) due to large or medium vessel occlusions (LVOs and MVOs).STEP is a registry-based trial; it uses data from existing registries to record information for a subset of the trial Case Report Form (CRF). Additional registry data from non-randomized STEP patients may be used for trial screening, planning, and generalizability assessment purposes.

The research is being done to determine if an investigational drug called "TS23" is safe and effective for the treatment of patients with an ischemic stroke that do not meet the criteria for standard treatments to remove the clot. The best dose of TS23 for these patients is unknown. Prior studies have shown that TS23 works without increasing safety concerns.