This study will evaluate the safety, tolerability, pharmacokinetics, and immunogenicity of QLF3108 and will make a preliminary assessment of the anti-tumor activity of QLF3108 in patients with advanced solid tumor.

This is a single-arm, open-label, Phase 1, dose escalation and Pharmacokinetics (PK) expansion study of QLF3108 in subjects with advanced solid tumor, to determine the dose-limiting toxicity (DLT), the maximum tolerated dose (MTD) and establish a recommended Phase 2 dose (RP2D) of QLF3108. The purpose of this study is to describe the safety and tolerability, assess pharmacokinetics parameters and immunogenicity, and assess the anti-tumor activity of QLF3108 in subjects with advanced solid tumor.

Inclusion Criteria:

1. The volunteer has fully given informed consent to the study and voluntarily signed the informed consent form prior to trial.
2. ≥18 years old and body weight ≥40 kg; Female or male.
3. Histologically or cytologically documented advanced solid tumor;
4. Failed to standard therapy or intolerance, or lack standard therapy advanced solid tumors.
5. Eastern Cooperative Oncology Group（ECOG） performance status of 0 or 1.
6. Life expectancy of at least 12 weeks.
7. Adequate hematologic and end organ function.
8. Female subjects who are not pregnant or not breastfeeding. A negative blood pregnancy test for females of childbearing potential within 7 days prior to first dosing.
9. Male and female subjects of childbearing potential must agree to use highly effective method of contraception during the entire course of the study and within 180 days after the end of the study.

Exclusion Criteria:

1. Patients that have previously received cancer therapy within 4 weeks prior to the first dose of the investigational drug.
2. Patient has received other investigational drug or other clinical trial treatment within 4 weeks prior to the first dose of the investigational drug.
3. Active autoimmune disease that has required systemic treatment within 2 years prior to this study.
4. A live vaccine or live attenuated vaccine was administered within 30 days prior to the first dose of the investigational drug.
5. Patients with Adverse Events(AEs) from previous treatment that have not recovered to ≤1(CTCAE 5.0）; or are unstable status.
6. Severe concomitant medical condition for bowel obstruction, or implanted colon stent during screening period.
7. Patients with a history of HIV positive or other immunodeficiency. Or patients with the history of organ transplant or allogeneic bone marrow (excluding corneal transplantation).
8. Patients with a history of psychiatric disorders, or epilepsy or dementia, drug or alcohol abuse, may impact patient completion of the study.
9. Patients may interfere with the interpretation of study results as determined by the investigator, or are unable to participate in the whole study, or deemed unsuitable by the investigator.