etirinotecan pegol etirinotecan pegol etirinotecan pegol (trade name onzeald) is a drug developed by nektar therapeutics for the treatment of certain kinds of breast cancer with brain metastases. the european medicines agency refused to grant it a marketing authorisation in 2017. etirinotecan pegolclinical datatrade namesonzealdother namesnktr-102routes ofadministrationintravenous infusionatc codel01ce03 (who) pharmacokinetic dataprotein bindingnonemetabolitesirinotecan and its metaboliteselimination half-life38 daysexcretionmostly via kidneysidentifierscas number848779-32-8drugbankdb14951uniilj16641sftkeggd10367chemical and physical dataformulac153h176n20o36n (n≈113)molar mass20,900–24,900 g/mol it works as a topoisomerase i inhibitor. chemically, it consists of four units of irinotecan (a topoisomerase i inhibitor in use since the late 1990s) linked by carboxymethyl glycine and polyethylene glycol (peg) chains to a central pentaerythritol ether, resulting in a much longer biological half-life (38 days) than that of irinotecan. it is formulated as a dihydrochloride and with 1.2 units of trifluoroacetate.