This is an open-label, Phase Ⅰ study of QL1706H in patients with advanced solid tumors. The study will evaluate the pharmacokenetics, safety, tolerability and preliminary efficacy of QL1706H.

The study is composed of 2 parts. Part 1 is a dose-escalation study to explore the pharmacokenetics (PK), safety, and tolerability of QL1706H. Part 2 of the study will explore the PK characteristics of differente intervals and sites of administration. All the PK parameters will determine the recommended Phase 2 dose (RP2D).

The study was divided into screening/baseline, treatment and follow-up periods. Safety monitoring will be conducted throughout the study period.

Inclusion Criteria:

• Subjects participate voluntarily and sign informed consent.
• Patients with Pathologically confirmed metastatic or recurrent malignant solid tumors, failure or intolerance of at least first-line treatment and unsuitable for radical treatment such as surgery
• Subject has at least one measurable lesion according to RECIST (V1.1) evaluation criteria.
• Eastern Cooperative Oncology Group (ECOG) score was 0 or 1.
• The extension of life is more than 3 months
• Vital organs' function is adequate for enrolling
• Subjects agree to use effective contraceptive measures.Women who have not been pregnant or breastfeeding.
• Before the first use of the investigational drug, all the reversible toxicity of the previous antitumor therapy returned to ≤1 (according to CTCAE V5.0),Excluding any grade of hair loss and pigmentation, grade 2 or less peripheral sensory neuropathy, and other abnormalities that the investigator and/or sponsor assessed to outweigh the risk of toxicity.

Exclusion Criteria:

• Active autoimmune diseases that exist within 2 years prior to the first use of the investigational drug and require systemic treatment.
• There are known past grade 3 or 4 immune-related adverse events associated with antitumor immunotherapy.
• Symptomatic central nervous system (CNS) metastasis, pia metastasis or spinal cord compression due to metastasis prior to signing informed consent.
• Subjects with any of the following cardiovascular diseases that seriously endanger the safety of the subjects or affect the completion of the study
• Subjects with diseases that are planned to be treated with systemic corticosteroids or other immunosuppressive drugs during the study period
• Prior treatment with cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) inhibitor combined with programmed cell death protein-1 (PD-1) inhibitor, or CTLA-4 inhibitor combined with PD-L1 inhibitor.
• Had received chemotherapy, targeted therapy, biotherapy, endocrine therapy, immunotherapy and other anti-tumor treatments within 4 weeks before the first use of experimental drugs
• Subjects with positive antibodies to HIV;Treponema pallidum antibody positive;HBsAg positive patients with VIRAL DEoxy ribonucleic acid (HBV DNA) >2000 IU/ mL or 10^4 copy number/mL should receive antiviral therapy according to local treatment guidelines and be willing to receive antiviral therapy throughout the study period.Hepatitis C virus antibody positive and viral ribonucleic acid (HCV RNA) positive