Dose-escalation schedule for AB002 phase 1 clinical study. Subjects were screened and those who met the eligibility criteria were randomized to receive either AB002 or placebo at a 4:1 ratio, except for cohort 1, in which the ratio was 4:2 to include 2 sentinel subjects (1 active and 1 placebo). Each cohort was dosed sequentially. Prior to dose escalation, all safety data were collected from each subject through day 14 and reviewed by the safety review committee during a dose-escalation safety review meeting.