Inclusion Criteria:
1. Voluntarily participate in clinical research; fully understand the study and voluntarily sign the informed consent; willing to follow and have the ability to complete all trial procedures;
2. Male or female, aged ≥18 years;
3. Malignant mesothelioma confirmed by histology, without indication for surgery;
4. Have not received systemic anti-tumor therapy in the past (if the subject has received neoadjuvant or adjuvant chemotherapy in the past, the last treatment time must be more than 6 months from the time of recurrence);
5. Sufficient organ function;
6. Eastern Cooperative Oncology Group (ECOG) physical status (PS) score is 0-1;
7. Expected survival period ≥ 12 weeks;
8. There is at least one measurable lesion (malignant pleural mesothelioma is based on mRECIST version 1.1, and malignant mesothelioma in other parts is based on RECIST version 1.1).
Exclusion Criteria:
1. History of severe allergic diseases, severe drug (including unmarked test drug) allergy history, or known allergy to any component of the drug in this study;
2. Brain parenchymal metastases or meningeal metastases with clinical symptoms, judged by the investigators as not suitable for inclusion;
3. Had other active malignant tumors within 5 years before starting the study drug treatment, except for malignant tumors that can be treated locally and cured (such as skin basal cell or squamous cell carcinoma, superficial or non-invasive bladder cancer), cervical carcinoma in situ, breast ductal carcinoma in situ, papillary thyroid carcinoma);
4. Currently there are uncontrollable pleural, pericardial, and peritoneal effusions, and those with catheter drainage also need to be excluded;
5. Unexplained fever \> 38.5°C before starting the study treatment (judged by the investigator, fever caused by tumor can be included in the group);
6. There is uncontrollable tumor-related pain, and those who need analgesic treatment should have a stable analgesic treatment plan at the time of screening; asymptomatic metastatic lesions, if they grow further, may cause dysfunction or intractable pain (such as current and spinal cord compression unrelated epidural metastases), local therapy should be considered before screening if appropriate;
7. Currently have clear interstitial lung disease or non-infectious pneumonia, except radiation pneumonitis caused by local radiotherapy;
8. There are active infections;
9. Have a history of immunodeficiency, including a positive test for human immunodeficiency virus (HIV) antibodies;
10. Positive for syphilis antibody;
11. Expect to receive any other forms of anti-tumor drug treatment during the trial period;
12. Those who have received allogeneic hematopoietic stem cell transplantation or organ transplantation in the past;
13. Pregnant or lactating women;
14. According to the investigator's judgment, the subject's basic condition may increase the risk of receiving the study drug treatment, or cause confusion for the explanation of the toxic reaction and AE;
15. Other investigators think that they are not suitable to participate in this trial.
