This is a multicenter, open-label phase I/II study, divided into 2 parts:

Part 1 involves a dose-escalation study of ZG006 in which the safety and tolerability of ZG006 in patients with advanced small cell lung cancer or neuroendocrine carcinoma are explored. Upon completion of Part 1, investigators and the sponsor will discuss and determine two recommended phase II doses (RP2D) based on safety, preliminary efficacy, and pharmacokinetic results for use in Part 2.

Part 2 is a phase II dose-expansion study of ZG006, aiming to investigate the efficacy and safety of ZG006 in patients with Neuroendocrine Carcinoma.

Inclusion Criteria:

• Fully understand the study and voluntarily sign the informed consent form;
• Male or female 18~75 years of age;
• Eastern Cooperative Oncology Group(ECOG) Performance Status of 0 or 1;
• Life expectancy ≥ 3 months.

Exclusion Criteria:

• Participants were deemed unsuitable for participating in the study by the investigator for any reason.