A Study of QLC5508 Combinations in Patients With Advanced Solid Tumors

Inclusion Criteria:

• At least 18 years of age at screening;

• Histologically or cytologically confirmed advanced solid tumors:

Dose escalation part will enroll participants who have progressed on or are intolerant to available standard therapies.

Dose expansion part will enroll participants who have not received prior treatment for advanced/metastatic diseases.

• At least one measurable target lesion according to RECIST v1.1

• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0~1

• Life expectancy ≥12 weeks

• Female or male participants should be willing to use appropriate contraceptivemeasures throughout the study;

• Female participants should have a negative blood pregnancy test within 7 days priorto the first dose or have evidence of non-childbearing potential;

• A signed written Informed Consent Form

Exclusion Criteria:

• . Received or undergoing any of the following treatment:

1. Previous or current treatment with B7-H3 targeted therapy

2. Previous or current treatment with topoisomerase I inhibitors

3. Previous treatment with cytotoxic chemotherapy, investigational agents,traditional Chinese medicine with an anti-tumor indication and antitumor drugswithin 14 days prior to the first dose

4. Previous treatment with macromolecular antitumor drugs within 28 days prior tothe first dose f. Radiotherapy with a limited field of radiation within 2 weeks prior to the firstdose; or more than 30% of the bone marrow irradiation, or large-scale radiotherapywithin 4 weeks prior to the first dose e. Pleural effusion or ascites requiringclinical intervention; or presence of pericardial effusion f. Major surgery within 4weeks prior to the first dose g. Brain metastases; leptomeningeal or brainstemmetastases; or spinal cord compression

• Unresolved AEs ≥ Grade 2 (CTCAE v5.0) from prior therapy except for alopecia andresidual neuropathy

• Previous or concurrent primary malignancies

• Inadequate bone marrow reserve or organ dysfunction

• Evidence of cardiovascular risk

• Evidence of current severe or uncontrolled systemic diseases

• Severe infection within 4 weeks prior to the first dose; or uncontrolled activeinfection at screening

• Known or suspected interstitial lung disease; or other moderate to severe pulmonarydiseases that significantly impair respiratory function and may interfere with thedetection or management of drug-related pulmonary toxicity

• High risk of gastrointestinal or abdominal bleeding 10. Gastrointestinal diseases ofclinical significance within 3 months prior to the first dose

• History of severe neuropathy or mental disorders

• History of severe hypersensitivity reaction, severe infusion reaction oridiosyncrasy to drugs chemically related to QLC5508 or any of the components ofQLC5508

• Unlikely to comply with study procedures and requirements in the opinion of theinvestigator

• Any disease or condition that, in the opinion of the investigator, would compromiseparticipant safety or interfere with study assessments