Tislelizumab Combined With Chemotherapy in the Treatment of Bone Metastases of Unknown Primary

Inclusion Criteria: 1. Willing and able to provide written informed consent/consent for the trial. 2. Be at least 18 years old on the day of signing the informed consent. 3. Patients with bone metastases from cancer of unknown primary (BMCUP) diagnosed according to the criteria defined in the clinical practice guidelines of the European Society of Medical Oncology (ESMO) in 2015 and confirmed by imaging and histology to have bone metastases that cannot be completely resected. 4. Did not receive systemic treatment. 5. Have at least one measurable lesion according to RECIST1.1, willing to agree to archived tumor (in formalin fixed paraffin-embedded (FFPE) block) or fresh tumor material (cryogenic refrigerator or liquid nitrogen storage). 6. ECOG performance level 0 or 1 point. 7. The expected survival time is ≥3 months. 8. Adequate organ and bone marrow functions (all screening tests should be performed within 10 days of the start of treatment) :A) Absolute neutrophil count ≥1.5x109 /L.B) Platelet ≥100x109 /L.C) Hemoglobin ≥9g/dL(≥90g/L).D) No blood transfusion or erythropoietin dependence (within 7 days of evaluation).E) Serum creatinine ≤1.5x upper normal limit (ULN) or creatinine level \> 1.5xULn, creatinine clearance ≥60 ml/min (creatinine clearance should be calculated according to institutional criteria).F) Patients with serum total bilirubin ≤1.5xULN or total bilirubin level \> 1.5ULN, direct bilirubin ≤ULN.G) Aspartate aminotransferase ≤2.5xULN(if liver metastasis is present).H) Alanine aminotransferase ≤2.5xULN(if liver metastasis is present).I) Albumin ≥2.5g/dL.J) International standardized ratio (INR) or prothrombin time ≤1.5xULN(if subject is being treated with anticoagulant, prothrombin time or partial prothrombin time should be within the range expected for treatment with anticoagulant).K) Activated partial thrombin time ≤1.5xULN(prothrombin time or partial prothrombin time should be within the expected therapeutic range of anticoagulant use).L) Women with reproductive potential should undergo a mandatory serum-negative pregnancy within 72 hours prior to receiving the first dose of the study drug.M) Fertile female subjects must be willing to use appropriate contraceptive methods during the study up to 120 days after the last use of the study drug.Note: Abstinence is acceptable if this is the subject's usual lifestyle and preferred method of contraception.N) Male subjects with reproductive potential must consent to use appropriate contraceptive methods from the first study treatment until 120 days after the last study treatment. Exclusion Criteria: 1. Unknown primary lesion of squamous cells. 2. in suspected lymphoma (e.g., leukocyte common antigen staining), malignant melanoma (for example, according to dye and beta hCG), gonads germ cell tumor (such as AFP and human chorionic gonadotropin), sarcoma (such as cell keratin and vimentin staining), neuroendocrine tumor (such as chromaffin granulocyte and synaptic staining).And male prostate cancer (e.g., prostate specific antigen staining). 3. apply to specific treatment, the patients of group (for example, only axillary lymph node metastasis of adenocarcinoma patients, peritoneal papillary serous carcinoma patients, only involving the neck, or groin lymph nodes of patients with squamous cell carcinoma, prompt germ cell tumors and beta hCG and/or AFP levels of patients with poorly differentiated carcinoma, and involves a single potentially resectable cancer patients). 4. Currently participating in and receiving study therapy, or participating in a study formulation and receiving study therapy or using study drug within 4 weeks of the first dose. 5. Confirmed immunodeficiency or receiving documented systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior to receiving the first dose of tirelizumab. 6. Have active tuberculosis. 7. Have an allergic reaction to the study drug. 8. One has received radiotherapy within 14 days before the first treatment. If the subjects received radiotherapy, they must fully recover from the toxicity and / or complications caused by the intervention, according to the judgment of a qualified investigator, before starting the treatment. 9. Have received chemotherapy treatment. 10. Subjects must fully recover from surgery and related complications in the judgment of a qualified investigator prior to the initiation of treatment. 11. There is another known malignancy developing or requiring aggressive treatment.Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin, squamous cell carcinoma of the skin that has received potential treatment, or cervical carcinoma in situ. 12. Active central nervous system (CNS) metastases and/or cancerous meningitis are known.Brain metastasis treated subjects as long as they received in a stable condition (in the treatment of at least four weeks before the first trials there was no evidence of progress examined by CT or MRI brain, any neurological symptoms has returned to baseline), there was no evidence of brain metastases from new or expanded, and at least 7 days prior to treatment did not use steroids, can attend the test.This exception does not include cancerous meningitis, which is excluded regardless of clinical stability. 13. Active autoimmune disease requiring systematic treatment (i.e. disease improvers, corticosteroids, or immunosuppressants) within the past two years. 14. Having (noninfectious) pneumonia or a history of current pneumonia. 15. There is an active infection that requires systematic treatment. 16. History or current evidence of any condition, treatment or laboratory abnormality that is likely to confound the results of the study or interfere with the subject's participation throughout the study, or any history or evidence of any condition, treatment or laboratory abnormality that, in the opinion of a qualified investigator for the treatment, would not be in the subject's best interest to participate. 17. A known mental or substance abuse disorder interferes with compliance with test requirements. 18. The subject is pregnant or breast-feeding, or plans to become pregnant or a father during the expected duration of the trial, beginning with pre-screening or screening 120 calendar days after the last trial treatment and continuing 120 calendar days after the last trial treatment. 19. Once have received anti-PD-1, anti-PD-L1 or anti-PD-L2 preparation treatment. 20. A known history of human immunodeficiency virus (HIV). 21. Active hepatitis B (e.g., HBsAg reaction) or hepatitis C (e.g., detection of HCVRNA) is known. 22. Live vaccine should be administered within 30 calendar days of the planned initiation of study treatment. 23. Have a history of organ and/or bone marrow transplantation.