This is a Phase I open-label, multicenter study to evaluate the safety, tolerability, pharmacokinetics (PK), immunogenicity and antitumor activity of JS015 in patients with advanced solid tumors. The Recommended dose for phase II trial （RP2D） was determined based on the safety, pharmacokinetics, and initial efficacy data of the dose escalation and extension.

Inclusion Criteria:

1. Willing to participate in this study and provide written informed consent;
2. Histologically- or cytologically-confirmed advanced solid tumors considered failure to the standard treatment, or with no standard treatment, or not available to standard treatment;
3. At least one measurable lesion according to RECIST 1.1;
4. Life expectancy ≥ 3 months;
5. Eastern Cooperative Oncology Group (ECOG) 0 or 1;
6. Adequate organ function;
7. Treatment related toxicities due to prior anti-cancer therapy including surgery and radiotherapy must be ≤ grade 1;
8. Women of childbearing age must confirm that the serum pregnancy test is negative within 7 days before the first dose; Male and female patients of child bearing potential will to use abstinence or an effective method of contraception throughout the treatment period and for 90 days following the last dose of study drug;

Exclusion Criteria:

1. Allergy or contraindication to JS015 and its ingredients;
2. Has a known additional malignancy in the last 5 years.
3. Pregnancy or lactation;
4. History of immunodeficiency, including human immunodeficiency virus(HIV) test positive, or known history of allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation;
5. Brain or meningeal metastases
6. Pleural effusion, peritoneal effusion or pericardial effusion that required treatment (such as puncture, drainage)
7. Severe cardiovascular and cerebrovascular diseases;
8. Previous antineoplastic therapy meets washout requirements.
9. Severe infection (Criteria for the evaluation of common adverse events(CTC AE) 5.0>2 grade) occurred within 28 days before the first study administration; Active infection or unexplained fever > 38.5°C ;
10. Has active tuberculosis or hepatitis B (HBV) or hepatitis C (HCV);
11. moderate to severe that seriously affect lung function;
12. Other serious physical or mental diseases or laboratory abnormalities, or alcoholism, drug abuse, etc.,