Introduction: Sanguinate is a dual-action oxygen transfer and carbon monoxide-releasing agent with efficacy in animal models of focal brain ischemia and established safety in health volunteers. We performed a dose-escalation study in subarachnoid hemorrhage (SAH) patients at risk for delayed cerebral ischemia (DCI) to evaluate tolerability and explore efficacy in improving cerebral blood flow (CBF) and flow-metabolism balance to vulnerable brain regions.
Methods: 12 subjects were studied over three dose tiers: 160mg/kg, 240 mg/kg, and 320 mg/kg, with close safety evaluation prior to proceeding to higher doses. After baseline 15O-PET measurement of global and regional CBF and oxygen extraction fraction (OEF), Sanguinate was infused over two hours; PET was repeated immediately after and again at 24-hours. Vulnerable brain regions were defined as those with baseline OEF ≥ 0.5.
Results: Sanguinate infusion resulted in a significant but transient rise in mean arterial pressure (115±15 to 127±13 mm Hg) that was not dose-dependent. No adverse physiologic or clinical effects were observed with infusion at any dose. Global CBF did not rise significantly after Sanguinate (42.6±7 to 45.9±9 ml/100g/min, p=0.18). However, in the 28% of regions classified as vulnerable, Sanguinate resulted in a significant rise in CBF (42.2±11 to 51.2±18) and reduction in OEF (0.6±0.1 to 0.5±0.11, both p<0.001). The increase in regional CBF was only seen with the two higher doses but OEF improved in all tiers. However, response was attenuated at 24-hours.
Conclusions: We safely administered a novel oxygen transport and vasodilating agent to a cohort of patients with SAH. Sanguinate infusion appeared to improve CBF and flow-metabolism balance in vulnerable brain regions and warrants further study in those at-risk for DCI. Higher or repeat dosing may be required for sustained efficacy.