This is a Phase 1 and Phase 2 study to evaluate the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of INV-6452 in adult patients with Hormone Receptor Positive, Human Epidermal Growth Factor Receptor 2 Negative (HR+/HER2-) advanced/metastatic breast cancer or locally advanced/metastatic solid tumor.

Inclusion Criteria:

1. Written informed consent obtained.
2. Adult patients aged ≥ 18 years.
3. Patients with histologically or cytologically confirmed unresectable locally advanced or metastatic solid tumors, who have disease progression following standard-of-care therapy, are intolerant to standard treatment, or have no available standard treatment options (e.g., HR+/HER2- breast cancer, Cyclin E1-overexpressing solid tumors and other solid tumors).
4. Agree to provide available archived FFPE tumor tissue specimens or voluntarily accept pre-treatment tumor biopsy (Phase Ⅱ).
5. Have RECIST 1.1-defined measurable lesions.
6. Has a life expectancy of > 3 months.
7. ECOG performance status 0-1.
8. Adequate marrow, liver and kidney function.
9. Meet the study's specified contraceptive requirements.

Exclusion Criteria:

1. Have a second primary malignancy.
2. Patients with primary CNS tumors or CNS metastases with prior local treatment failure.
3. Have received any anti-tumor therapy or participated in other therapeutic clinical trial within 28 days prior to the first dose of study drug.
4. Has undergone major surgery within 28 days prior to the first dose of study drug.
5. Prior anti-tumor therapy-related toxicities have not recovered to protocol-specified grades.
6. Diagnosed with immunodeficiency or received any form of immunosuppressive therapy within 7 days prior to the first dose.
7. Patients with other severe and persistent underlying medical conditions as assessed by the Investigator.
8. Have protocol-defined clinically significant cardiovascular diseases.
9. Prolonged QTcF interval.
10. Have any medical conditions likely to impair digestion and absorption of the investigational product.
11. Patients with poorly managed blood glucose levels and blood pressure.
12. Clinically significant abnormal serum potassium or sodium as judged by the investigator.
13. Have experienced a severe concurrent infection 14 days prior to the first dose of study drug.
14. Confirmed infection with HIV, HBV or HCV.
15. Are currently receiving any other investigation agent.
16. Have received prior CDK2 inhibitors.
17. Patients with known hypersensitivity to the study drug or any of its components.
18. History of allogenic tissue or solid organ transplant.
19. Are unwilling or unable to comply with procedures required in this protocol.
20. Has other severe systemic diseases or for other reasons deemed ineligible for participation in this clinical trial by the investigator.