Sacituzumab Govitecan in Recurrent Glioblastoma

Subjects are expected to participate for up to treatment duration with continued follow up for survival until one year after the last dose of study drug. The total duration of the active part of the study for each subject will be approximately 18 weeks, divided as follows: * Up to 3 weeks predose (screening period) * 3-week treatment periods of Sacituzumab govitecan * Study termination visit 3-4 weeks after last dose of study medication When a subject has completed the study termination or early termination visit, he/she and/or a family member will be contacted for survival information every 3 months until one year from last study dose.