Extension Study of UC-961 (Cirmtuzumab) for Patients With Chronic Lymphocytic Leukemia Treated Previously With UC-961

This is an open-label extension study to determine the safety and tolerability of cirmtuzumab given to participants who enrolled and completed the initial phase 1 trial in CLL without a dose-limiting toxicity. UC-961 is administered by intravenous infusion every 14 days for 4 doses, then every 28 days for 4 doses, after which responses will be assessed. Patients with an objective response (meeting working group criteria for partial response or complete response) will continue at the same dose and schema. Patients with stable disease or progressive disease are eligible to increase the dose of UC-961 for another 6-month course. Duration of UC-961 administration is until disease progression, treatment intolerance, or lack of clinical benefit.