Phase II studies of the glycine antagonist GV150526 in acute stroke : the North American experience. The North American Glycine Antagonist in Neuroprotection (GAIN) Investigators.
GV150526, a selective glycine site antagonist, reduces infarct volume in rats with focal cerebral ischemia. Safety and efficacy in humans with acute stroke are being investigated. We sought to further explore the safety, pharmacokinetics, and preliminary outcome of GV150526 treatment in patients with a clinical diagnosis of acute stroke. Two trials were conducted in North America. The North American Glycine Antagonist in Neuroprotection trial (GAIN 1) (GLYA2001; United States only) was designed as a sequential dose escalation study. GAIN 2 (GLYA2005; United States and Canada) was designed to further assess the safety of the highest dose tolerated in GAIN 1. Both trials were randomized (2:1), double-blind, and placebo controlled. Treatment was started within 12 hours of symptom onset; patients with both ischemic stroke and primary intracerebral hemorrhage were included in both trials. The dose escalation study (GAIN 1) completed 3 dosing tiers. Enrollment was suspended before escalation to the fourth tier because of laboratory reports of transiently elevated bilirubin levels in a concurrent European study that employed the dose targeted for this tier. After review by an independent safety committee of the worldwide safety data, the second study (GAIN 2) commenced. One hundred nine patients were randomized and dosed with study drug, either an 800-mg loading dose followed by 200 mg every 12 hours for 3 days of GV150526 or placebo. The incidence of serious adverse events was similar in the drug and placebo groups. Mild irritation at the infusion site and symptoms suggestive of mild and reversible altered mentation were reported more frequently in the GV150526 group than in the placebo group. Hyperbilirubinemia was reported in 6% of GV150526-treated patients compared with 3% of placebo-treated patients. Outcome at 4 weeks after stroke was better in GV150526-treated patients, but the studies were not powered to show statistical significance, and the baseline neurological deficits in the GV150526-treated patients were less severe. These preliminary studies suggest that GV150526 is well tolerated by patients with suspected acute stroke. Further pivotal studies testing the efficacy and safety of GV150526 in acute stroke are ongoing.