HS-20118

Main study objectives: 1. SAD study: To evaluate the safety and tolerability of HS-20118 after single oral dose escalation in healthy subjects; 2. MAD study: To evaluate the safety and tolerability of HS-20118 after multiple oral dose escalation in patients with moderate to severe plaque psoriasis; Secondary study objectives: 1. SAD study: To evaluate the pharmacokinetic (PK) characteristics and immunogenicity characteristics of HS-20118 after single oral dose escalation in healthy subjects; 2. MAD study: To evaluate the efficacy, pharmacokinetic (PK) characteristics and immunogenicity characteristics of HS-20118 after multiple oral dose escalation in patients with moderate to severe plaque psoriasis; Exploratory study objectives: 1. SAD study: To evaluate the pharmacodynamic (PD) characteristics of HS-20118 after single oral dose escalation in healthy subjects; 2. SAD study: To evaluate the food effect of HS-20118. 3. MAD study: To evaluate the pharmacodynamic (PD) characteristics of HS-20118 after multiple oral escalating doses in patients with moderate to severe plaque psoriasis.