Dose-escalation and Food Effect Study of ZT006 in Healthy, Overweight and Obese Participants

ZT006 is an oral, long-acting glucagon-like peptide-1. This first-in-human study is designed to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of ZT006 in healthy, overweight and obese participants. The study comprises three parts, i.e. single dose-escalation, multiple dose-escalation, food effect on the pharmacokinetics of ZT006. In the single dose-escalation study, participants will receive a single dose (ZT006 dose level 1 - 5 or corresponding placebo) of ZT006 under fasted condition. A higher dose can only be given after obtaining acceptable safety and tolerability data for at least 7 days after the previous dose. After study drug administration, there will be a 7-day in-house period for safety observation and pharmacokinetics samples collection. Participants will join ambulatory visits until 42 days post-dose. In the multiple dose-escalation study, participants will receive a daily dose of ZT006 or corresponding placebo over 42 days in a dose up-titration fashion according to the following regimen: * Cohort 1: dose level 1 - dose level 2 - dose level 3 * Cohort 2: dose level 1 - dose level 2 - dose level 3 - dose level 4 * Cohort 3: dose level 2 - dose level 3 - dose level 4 * Cohort 4: dose level 2 - dose level 3 - dose level 4 - dose level 5 Dosing of a cohort with higher drug exposure can only be done after evaluation of safety and tolerability data for at least 14 days after the first dose in the previous cohort. Participants will join ambulatory visits until 35 days after the last dose. To evaluate the food effect on the pharmacokinetics of ZT006, participants who have received single dose of ZT006 or placebo of dose level 4 in the single dose-escalation study will receive another dose of ZT006 or placebo after a high fat, high caloric breakfast.