A Phase I Study to Evaluate the Safety,Tolerability, Pharmacokinetics, and Efficacy of YL211 in Patients With Advanced Solid Tumors

To evaluate nature and frequency of AEs of YL211 in patients with advanced solid tumors according to NCI CTCAE version 5.0,To evaluate nature and frequency of DLTs in part 1.,ORR assessed using RECIST version 1.1,To determine the MTD and select the recommended expansion dose(s) (RED(s)) of YL211 in patients with advanced solid tumors

This is a multicenter, open-label, Phase 1 study. The study will enroll subjects with
 advanced solid tumors. It consists of three parts. Part 1 is dose-escalation part. In part 1,
 the safety and tolerability of YL211 in patients with selected advanced solid tumors will be
 evaluated and the MTD and RED will be determined.
 
 Part 2 is backfill enrollment part. We will further estimate the safety and efficacy of YL211
 in patients with selected adcance tumor to select the RED(s) of YL211.
 
 Part 3 is dose-expansion part. In this part, we will further evaluate the safety and efficacy
 of YL211 at the MTD/RED(s) in patients with selected advanced solid tumors YL211 will be
 administered intravenously (IV) until criteria of treatment discontinuation are met.