Efficacy and Safety of Cadonilimab Plus Anlotinib in Advanced STS That Failed the Previous First-line Standard Treatment

Inclusion Criteria: 1. Male or female, aged ≥18 years . 2. Voluntarily sign written informed consent. 3. Advanced or unresectable soft tissue sarcomas confirmed by pathology mainly include liposarcoma, leiomyosarcoma, synovial sarcoma, undifferentiated pleomorphic sarcoma / malignant fibrous histiocytoma, fibrosarcoma, pleomorphic rhabdomyosarcoma, acinar soft tissue sarcoma, clear cell sarcoma, angiosarcoma, epithelioid sarcoma, malignant peripheral nerve sheath tumor, undifferentiated sarcoma, sarcoma after radiotherapy, etc. 4. Patients who have used at least one chemotherapy regimen (including anthracyclines) in the past (except for acinar soft tissue sarcoma and clear cell sarcoma) and are evaluated as disease progression according to the efficacy evaluation criteria of solid tumors within 6 months. 5. According to RECIST 1.1, there was at least one measurable tumor lesion. 6. ECoG score 0 or 1. 7. The expected survival was ≥ 3 months. 8. The main organs function well: a) Hematology (no blood components and cell growth factors were used to support treatment within 7 days before starting the study treatment): i. The absolute value of neutrophils ANC ≥ 1.5 × 109/l (1500/mm3). Ii Platelet count ≥ 100 × 109/l (100000/mm3). III. hemoglobin ≥ 90 g/l. b) Kidney: i. Creatinine clearance \* (CrCl) calculated value ≥ 50 ml/min. \*The Cockcroft Gault formula will be used to calculate CrCl (Cockcroft Gault formula) CrCl (ml/min) = \[(140 - age) × Weight (kg) × F\] / (SCR (mg/dl) × 72) Among them, f=1 for men and f=0.85 for women; SCR = serum creatinine. Ii Urine protein \< 2+ or 24-hour (H) urine protein quantification \<1.0 G. c) Liver: i. Total serum bilirubin (TBIL) ≤ 1.5 × ULN. II. AST and alt ≤ 2.5 × ULN. III. for subjects with liver metastasis, serum total bilirubin (TBIL) ≤ 3 × ULN; ALT and AST ≤ 5 × ULN; d) Coagulation function: i. International normalized ratio (INR) and activated partial thromboplastin time (APTT) ≤ 1.5 × ULN. 9. Female subjects with fertility must have a serum pregnancy test within 3 days before the first medication and the result is negative. If a female issue with fertility has sex with a male partner who has not been sterilized, the subject must take an acceptable contraceptive method since the screening, and must agree to continue using the contraceptive method within 6 months after the last administration of the study drug; Whether to stop contraception after this time point should be discussed with the investigator. 10. The subject is willing and able to comply with the visit, treatment plan, laboratory test, and other study requirements as stipulated in the schedule. Exclusion Criteria: 1. Participated in the treatment of experimental drugs or used experimental devices within 4 weeks before the first administration of candonilimab. 2. Had other active malignancies within 3 years before enrollment. Except for locally curable malignant tumors (manifested as cured), such as basal or cutaneous squamous cell carcinoma, superficial bladder cancer, endometrial, cervical or breast cancer in situ. 3. Another clinical study is enrolled at the same time, unless it is an observational (non interventional) clinical study or the follow-up period of an interventional study (defined as the time from the first medication to the last medication of the previous clinical study is more than 4 weeks or the five half lives of the study drug are more than 5, whichever is the longest). 4. Active autoimmune diseases requiring systemic treatment within two years before the start of study treatment, or autoimmune diseases that may recur or are planned to be treated according to the judgment of the investigator; The following exceptions: skin diseases that do not need systematic treatment (such as vitiligo, alopecia, psoriasis or eczema); Hypothyroidism caused by autoimmune thyroiditis only requires a stable dose of hormone replacement therapy; Well controlled type I diabetes; Subjects whose asthma in childhood has been completely relieved and who do not need any intervention after adulthood; The investigator judged that the disease would not recur without external triggers. 5. Inflammatory bowel disease (such as Crohn's disease, ulcerative colitis, or chronic diarrhea) with active or requiring clinical treatment. 6. The subject required systemic treatment with corticosteroids (\>10mg daily prednisone equivalent) or other immunosuppressive drugs within 14 days after taking the study drug. In the absence of active autoimmune disease, inhaled or topical steroids and adrenal gland replacement doses of \>10mg daily prednisone equivalent were allowed. Subjects were allowed to use topical, ocular, intra-articular, intranasal, and inhaled corticosteroids (with minimal systemic absorption). Physiological alternative doses of systemic corticosteroids are allowed, even if \>10 mg / day of prednisone equivalent. Short term use of corticosteroids is allowed to prevent (such as contrast allergy) or treat non autoimmune diseases (such as delayed type hypersensitivity caused by contact allergens). 7. He has previously received immune checkpoint inhibitors (such as anti-PD-1 antibody, anti-PD-L1 antibody, anti-CTLA-4 antibody, etc.), immune checkpoint agonists (such as antibodies against ICOS, CD40, CD137, GITR, OX40 targets, etc.), immune cell therapy and other treatments targeting tumor immune mechanism. 8. The best swelling evaluation result of patients who had received previous treatment with anlotinib was PD, or SD ≤ 12 weeks. 9. History of a known positive test for human immunodeficiency virus or known acquired immune deficiency syndrome. 10. Known history of allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation. 11. Known presence or history of interstitial lung disease. 12. Necrotic lesions were found within 4 weeks before the subjects were enrolled, and the investigator judged that there was a ri