Cerebral Sinus Venous Thrombosis due to Asparaginase Therapy

Cyclosporine-A-Induced Intracranial Thrombotic Complications: Systematic Review and Cases Report

This study reported two cases of intracranial thrombotic events of aplastic anemia (AA) under therapy with cyclosporine-A (CsA) and reviewed both drug-induced cerebral venous thrombosis (CVT) and CsA-related thrombotic events systematically. We searched PubMed Central (PMC) and EMBASE up to Sep 2019 for publications on drug-induced CVT and Cs-A-induced thrombotic events. Medical subject headings and Emtree headings were used with the following keywords: "cyclosporine-A" and "cerebral venous thrombosis OR cerebral vein thrombosis" and "stroke OR Brain Ischemia OR Brain Infarction OR cerebral infarction OR intracerebral hemorrhage OR intracranial hemorrhage." We found that CsA might be a significant risk factor in inducing not only CVT but also cerebral arterial thrombosis in patients with AA.

Design and Characterization of Erwinia Chrysanthemi l-Asparaginase Variants with Diminished l-Glutaminase Activity

Current FDA-approved l-asparaginases also possess significant l-glutaminase activity, which correlates with many of the toxic side effects of these drugs. Therefore, l-asparaginases with reduced l-glutaminase activity are predicted to be safer. We exploited our recently described structures of the Erwinia chrysanthemi l-asparaginase (ErA) to inform the design of mutants with diminished ability to hydrolyze l-glutamine. Structural analysis of these variants provides insight into the molecular basis for the increased l-asparagine specificity. A primary role is attributed to the E63Q mutation that acts to hinder the correct positioning of l-glutamine but not l-asparagine. The substitution of Ser-254 with either an asparagine or a glutamine increases the l-asparagine specificity but only when combined with the E63Q mutation. The A31I mutation reduces the substrate Km value; this is a key property to allow the required therapeutic l-asparagine depletion. Significantly, an ultra-low l-glutaminase ErA variant maintained its cell killing ability. By diminishing the l-glutaminase activity of these highly active l-asparaginases, our engineered ErA variants hold promise as l-asparaginases with fewer side effects.