Assessment of Safety and Preliminary Efficacy With BAT6021 in Solid Tumor Patients in China

Main purpose: * To evaluate the safety and tolerability of BAT6021 injection in the treatment of locally advanced or metastatic solid tumors with single drug or combined with tislelizumab(anti PD-1 monoclonal antibody); * Explore the maximum tolerated dose (MTD) or maximum dosing dose (MAD) of BAT6021 injection monotherapy or in combination with tislelizumab and provide recommended dose and reasonable dosing regimen for phase II or subsequent clinical studies. Secondary purpose: * To evaluate the pharmacokinetic (PK) characteristics of BAT6021 injection with single or multiple doses of tislelizumab in patients with locally advanced or metastatic solid tumors; * Evaluate the immunogenicity of BAT6021 injection; * To evaluate the pharmacodynamics of BAT6021 injection; * Preliminary evaluation of the anti-tumor efficacy of BAT6021 injection alone or in combination with tislelizumab.