• signed informed consent obtained,can be followed upon protocol;

• age ≥ 10 years;

• histopathologically confirmed diagnosis of advanced metastatic osteosarcoma or non-specific soft tissue sarcoma;

• Subjects for dose-escalation studies: failed to at least one chemotherapy regimen and undergoing disease progression or untolerable drug toxicity before enrollment;Subjects for postoperative adjuvant therapy study: radical surgery within 3 months before the first infusion of NK510 and no local recurrence or distant metastasis;

• according to RECIST 1.1,Recurrent and refractory patients have at least one measurable lesion at baseline. Patients receiving adjuvant treatment after radical surgery have no measurable lesions on imaging examination;

• ECOG physical status score of 0 or 1;

• Expected survival \>=12 weeks;

• Female subjects of childbearing age or male subjects whose sexual partners are female subjects of childbearing age are required to take effective contraceptive measures throughout the entire treatment period and 6 months after the treatment period;

• good organ and bone marrow hematopoietic function, the laboratory test values within 7 days before enrollment meet the following requirements (no medication for blood components, cell growth factors, or albumin correction treatment is allowed within the first 14 days of obtaining laboratory test), as follows:

‣ Hematological:Neutrophil count ≥1.5×10\^9/L; Platelet count ≥ 75×10\^9/L; Hemoglobin ≥ 9 g/dL;

⁃ Hepatic:Total bilirubin ≤1.5 x ULN;ALT and AST≤2.5×ULN;Albumin ≥ 28 g/L; Alkaline phosphatase ≤ 5 × ULN;

⁃ Renal:Serum creatinine ≤ 1.25 × ULN or creatinine clearance ≥ 50mL/min (Cockcroft Fault formula);Patients whose urine routine results show urinary protein\<2+or whose baseline urine routine test shows urinary protein ≥ 2+will undergo 24-hour urine collection with a 24-hour urine protein quantification of\<1g.

⁃ Coagulation:International standardized ratio (INR) ≤ 2, and activated partial thromboplastin time ≤ 1.5 × ULN.