Assess the Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of IPM514 in Patients with Esophageal Squamous Cell Carcinoma

Drug：IPM514 Intramuscular Injection A total of 7 administrations, including 2 cycles of vaccination with each cycle at QW × 3 doses; there is a 2-weeks interval between the two cycles, then followed by a boost dose 3 weeks after the 2'nd cycle.

Drug：IPM514 Intramuscular Injection Drug：tislelizumab intravenous administration The usage and dosage of the tislelizumab will be based on the drug instructions. IPM514 administration is planned to be concomitant with PD-1 antibody and to be stopped after 9 doses of treatment, while the PD-1 antibody will be continuously administered for a maximum of 1 year.

Drug：IPM514 Intramuscular Injection Drug：tislelizumab intravenous administration Drug：cisplatin intravenous administration Drug：paclitaxel intravenous administration In this stage, subjects will receive the treatment of IPM514 combined with Tislelizumab, cisplatin and paclitaxel. All four drugs will be administered once every 3 weeks (± 1 day). IPM514 will be administered for the first time on D0, and Tislelizumab, cisplatin and paclitaxel will be administered for the first time on D3 (the administration order: Tislelizumab - paclitaxel - cisplatin). IPM514 will be administered a total of 3 times, and PD-1 antibody, cisplatin and paclitaxel will all be administered a total of 2 times (that is, IPM514 is administered on D0/D21/D42, and Tislelizumab, paclitaxel and cisplatin are administered on D3/D24).