Approved thrombolytic agents are limited in their use for the treatment of acute ischemic stroke (AIS) due to their benefit-risk profile beyond 4.5 h since last known normal (LKN). TMS-007 is a small molecule, SMTP family member with a novel mode of action: promotion of plasminogen-fibrin binding to enhance physiological thrombolysis while inhibiting inflammation at the site of thrombosis. TMS-007 may extend the treatment time window based on nonclinical pharmacological evidence. We evaluated TMS-007 in a randomized, placebo-controlled, double-blind, dose-escalation phase 2a study. TMS-007 or placebo was administered as a single intravenous infusion at a dose of 1, 3, or 6 mg/kg to AIS patients who were ineligible for t-PA or thrombectomy within 12 h of LKN. The number of patients allocated to placebo and TMS-007 at doses 1, 3, and 6 mg/kg were 38, 6, 18, and 28, respectively. The combined TMS-007 dosing group (Group T; n = 52) was compared with placebo group (Group P; n = 38). The average age was ~72 years old and time since LKN to treatment was ~9 h in both groups (not significantly different). The incidence of symptomatic intracranial hemorrhage (ICH) with worsening NIHSS score of <=4 points per site physician (primary endpoint) was 0% in Group T compared to 3% (n = 1) in Group P. The number of ICH event within 24 h, including symptomatic and asymptomatic, was 6 in Group T and 5 in Group P. Total number of AE was 207 in Group T and 162 in Group P, with gastrointestinal diseases as the most common events in both groups (n = 40 and 32, respectively). TMS-007 was associated with a significant improvement in functional independence at 90 days (secondary endpoint): 40% of patients in Group T achieved a score of 0 or 1 on the mRS, compared to 18% in Group P (p < 0.05). Recanalization, defined by any improvement in arterial occlusive lesion score on magnetic resonance angiography in those with visible occlusion at baseline per central neuroradiologist, occurred in 58.3% (14/24) of Group T compared to 26.7% (4/15) of Group P (odds-ratio, 4.23; 95% CI, 0.99 to 18.07). TMS-007 was generally safe and well tolerated up to 6 mg/kg. TMS-007 may expand the treatment time window for the treatment of AIS. Due to the small study size, more data on efficacy is warranted in patients with visible occlusion.