This is a multicenter, open-label Phase I/II study consisting of two parts:

Part 1 is a Phase I dose-escalation study of ZG006, aimed at evaluating the safety and tolerability of ZG006 in Participants with advanced small-cell lung cancer or neuroendocrine carcinoma. Upon completion of Part 1, the investigators and sponsor will jointly determine two preliminary recommended Phase II doses for Part 2, based on the available safety, preliminary efficacy, and pharmacokinetic data.

Part 2 is a Phase II dose-expansion study of ZG006, designed to explore and confirm the efficacy and safety of ZG006 monotherapy in advanced small-cell lung cancer.

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;
• Participants with histologically or cytologically confirmed advanced solid tumors who also fulfill the following: Part 1: advanced small-cell lung cancer (SCLC) or neuroendocrine carcinoma.Part 2: advanced SCLC.Specifically for Part 2 Cohort 1: de-novo SCLC (composite SCLC excluded).Stage 2 restricted to third-line or later.Cohort 2: transformed SCLC.Cohort 3: large-cell neuroendocrine carcinoma of the lung and composite SCLC.

Exclusion Criteria:

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