This is a Phase 1, open label, non-randomised, dose-escalation single agent study with expansion cohorts for dose confirmation/safety and preliminary efficacy of QLS31901 in advanced or metastatic malignancies

Study Design: This open label, multicenter, first in human study consists of 2 parts. Part 1 is a dose escalation to find the recommended dose for the expansion.

Part 2 is a dose expansion to confirm the dose of QLS31901 through further evaluation of safety, tolerability, Pk, preliminary antitumor activity, and functional target engagement.

The study includes three periods: Screening( up to 28 days prior to the first dose of study drug); Treatment(first dose of study drug with treatment cycles of 28 days); and Follow-up ( 30days 、60days and 90 days after the last dose) including survival follow-up checks every 3 months up to 12 months after the death of patient or the end of this clinical trial .

Inclusion Criteria:

1. Age: 18 to 75 years, male or female.
2. Eastern Cooperative Oncology Group (ECOG) score of 0-1.
3. Life expectancy ≥ 12 weeks.
4. At least one measurable lesion by imaging according to RECIST v1.1 evaluation criteria
5. Patients who failed standard treatment or were absent of standard treatment and have a pathologically confirmed advanced malignant tumor.
6. Sufficient organ function before the first dose of the investigational product

Exclusion Criteria:

1. Prior anti-cancer immunotherapy(Those who have received PD1 / PDL1 can be included in this study).
2. Known allergy to the investigational product or any excipient or severe anaphylaxis to other monoclonal antibodies.
3. Received any of the following treatments or drugs prior to the first dose of the study:
4. Symptomatic CNS metastasis, leptomeningeal metastases, or spinal cord compression due to metastasis before signing of the informed consent form.
5. Patients with uncontrollable severe exudation (thoracic cavity, pericardium, abdominal cavity);
6. Presence of active autoimmune disease or has a history of autoimmune disease (including but not limited to: autoimmune hepatitis, interstitial pneumonia, uveitis, enteritis, hepatitis, hypophysitis, vasculitis, nephritis, hyperthyroidism, hypothyroidism [patients whose condition can be controlled by thyroid hormone replacement therapy can be enrolled]; Subjects suffer from skin diseases that does not require systemic treatment, such as vitiligo, psoriasis, alopecia, type I diabetes, or childhood asthma that has completely alleviated and does not require any adult intervention can be enrolled. Asthmatic patients requiring bronchodilators for medical intervention cannot be enrolled);