• Provision of informed consent form (ICF) prior to any study-specific procedures.

• Men or women ≥ 18 years old when signed ICF.

• Eastern Cooperative Oncology Group (ECOG) performance status (PS)0-1

• Life expectancy of ≥ 3 months, in the opinion of the Investigator.

• Pathologically documented advanced solid tumor, including but not limited to advanced lung cancer, pancreatic cancer, colorectal cancer, esophageal cancer, and breast cancer, etc.

• The tumor tissue should be provided for folate receptor α (FRα) and transient receptor potential cation channel subfamily V member 6 (TRPV6) immunohistochemistry (IHC) testing, optional for low dose level (≤ 2.0 mg/kg) of phaseⅠa. Tumor FRα and TRPV6 expression as determined by an IHC assay performed by a central laboratory on previously obtained archival tumor tissue or tissue obtained from a biopsy at screening.

• Subjects must have received prior standard therapy appropriate for their tumor type and stage of disease, or in the opinion of the investigator, would be unlikely to tolerate or derive clinically meaningful benefit from appropriate standard of care therapy, or absence of standard therapy.

• Progress of disease per response evaluation criteria in solid tumors (RECIST) 1.1 after the last anti-tumor treatment (solid tumors).

• At least one measurable soft tissue lesion per RECIST 1.1, lesions received prior radiotherapy can be regarded as measurable only when occurring conclusive progression after radiotherapy, optional for low dose level (≤ 2.0 mg/kg) of Phase Ⅰa.

⁃ Adequate bone marrow and organ function, defined as:

∙ Absolute neutrophil count (ANC) ≥ 1.5 × 109/L.

‣ Platelet count ≥ 100 × 109/L.

‣ Hemoglobin (Hb) ≥ 90 g/L.

‣ Total bilirubin (TBIL) ≤ 1.5 × upper limit of normal (ULN), or ≤ 2 × ULN for subjects with liver metastases.

‣ Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 1.5 × ULN, or ≤ 2 × ULN for subjects with liver metastases.

‣ Creatinine clearance (CCr) ≥ 60 mL/min as calculated using Cockcroft-Gault formula

⁃ Women of child-bearing potential (WOCBP) or male subjects whose spouse is WOCBP need to adopt a medically approved contraceptive measure (such as intra-uterine device (IUD), contraceptive pill, or condom) throughout the study and for at least 3 months in males and 6 months in females after the last dose of CBP-1019.