This is an first-in-human, Phase I clinical study aimed at evaluating the safety, tolerability, PK, immunogenicity, and preliminary antitumor efficacy of AK146D1 for injection in advanced solid tumors.

Inclusion Criteria:

1. Be able to understand and voluntarily sign the written informed consent form.
2. Aged of ≥ 18 years and ≤75 years.
3. ECOG PS 0 or 1.
4. The expected lifespan is ≥3 months.
5. Histologically-confirmed unresectable advanced solid tumors with disease progression or intolerance to standard treatment or no standard treatment available.
6. At least one measurable lesion according to RECIST v1.1.
7. Have sufficient organ function.
8. Females subjects must not be pregnant at screening or have evidence of non-childbearing potential. Agree to use medically accepted methods of contraception

Exclusion Criteria:

1. Having other active malignancies within 3 years.
2. Currently participating in another interventional clinical study.
3. Presence of active metastases to the central nervous system. For patients with asymptomatic brain metastasis or stable symptoms after treatment can be included.
4. Having received any treatment targeting Trop2 or Nectin4 or any treatment with topoisomerase I inhibitor agents.
5. Having received systemic anti-tumor treatment within 4 weeks or 1 cycle interval of the regimen or major surgical operations within 4 weeks before the first administration.
6. Toxicity of previous antineoplastic therapy has not resolved to NCI CTCAE 5.0 grade 1 or lower.
7. Subjects with clinically significant cardiovascular or cerebrovascular diseases or risks.
8. Subjects with active autoimmune diseases requiring systemic treatment within 2 years.
9. Known active infection requiring antibodies treatment within 2 weeks, or severe infection within 4 weeks prior to the first dose.
10. Known to be positive for HIV and other infections.
11. Previous history of severe hypersensitivity reactions.
12. Live attenuated vaccines were received within 4 weeks.
13. Subjects with a history of mental illness and incapacitated or limited capacity.
14. Any disease or condition that, in the opinion of the investigator, would compromise subject safety or interfere with study assessments.