A Phase Ia/ Ib Study of HS387 in Subjects With Advanced Solid Tumors

Inclusion Criteria: * Subjects must meet all of the following inclusion criteria to be eligible for participation in this study: 1. Men or women ≥18 years old and ≤75 years old. 2. Subjects with advanced solid tumors who have failed or are intolerant to standard treatment, or have no standard therapy. 3. Survival expectation is ≥ 3 months. 4. Eastern Cooperative Oncology Group (ECOG) performance status 0 to 1. 5. Phase Ⅰa: Subjects with advanced solid tumors have at least one evaluable lesion according to RECIST 1.1. Phase Ⅰb: Subjects with advanced solid tumors have at least one measurable lesion according to RECIST 1.1. 6. Subjects with adequate organ function at the time of screening. 7. Serum pregnancy test (for female of childbearing potential) negative prior to first dosing of study treatment. Male and female subjects of childbearing potential must agree to use effective methods of contraception throughout the study and for 3 months after the last dose of the investigational product. Exclusion Criteria: * Subjects will be excluded if they meet any of the following criteria: 1. Has received other investigational drugs or treatments not yet approved for marketing within 4 weeks prior to the first administration. 2. Has active infection. 3. Has meningeal metastases or symptomatic central nervous system (CNS) metastases. 4. Significant impairment of oral drug absorption. 5. Has interstitial lung disease. 6. Pregnant or lactating women. 7. Known history of allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation. 8. Has a major surgical procedure within 4 weeks prior to the first administration. 9. Has a treatment history of KIF18A inhibitor. 10. In the opinion of the Investigator, there are other factors that the subject is unsuitable for participation in this clinical study.