• Age .12 years old

• Histologically-confirmed locally advanced or metastatic soft tissue or bone sarcoma

• Osteosarcoma expansion cohort: histologically confirmed unresectable recurrent/metastatic osteosarcoma

• Evaluable disease.

• Patients must have received at least 1 prior line of systemic therapy for the treatment of sarcoma, unless no standard therapy exists for a specific sarcoma subtype

• Prior Cancer Therapy . At least 3 weeks must have elapsed since the last cytotoxic chemotherapy or immunotherapy prior to leukapheresis/PBMC collection.

‣ For targeted therapies, at least 4 half-lives or 3 weeks must have elapsed prior to leukapheresis (whichever is shorter).

• Standard of care anti-cancer therapy will be permitted following leukapheresis but prior to initiation of cyclophosphamide such that:

• . At least 3 weeks must have elapsed since last cytotoxic chemotherapy or immunotherapy prior to starting treatment with cyclophosphamide.

• . For targeted therapies, at least 4 half-lives or 3 weeks must have elapsed prior to initiation of treatment with cyclophosphamide (whichever is shorter).

• . At least 2 weeks must have elapsed since last radiation therapy prior to cyclophosphamide.

• . Investigational anti-cancer therapy will not be permitted.

• ECOG performance status of 0 or 1 (Performance level as measured by Karnofsky for patients . 16 years of age or Lansky for patients \< 16 years of age, see Appendix B)

• Participants must be willing to undergo tumor biopsy

• . Patients in whom biopsy is medically contraindicated or otherwise high risk will not be excluded and may forego research tumor biopsies

⁃ Patients must have organ and marrow function as defined below

⁃ Absolute neutrophil count (ANC) . 1 K/uL, Hemoglobin . 9 g/dL, Platelets.100 K/mm3

⁃ Serum creatinine . 2 mg/dL OR creatinine clearance \> 50 mL/min

⁃ Aspartic transaminase (AST) . 1.5 x upper limit of normal (ULN), Alanine transaminase (ALT) . 1.5 x ULN, Bilirubin . 1.5 x ULN

⁃ Cardiac function . LVEF \>50%

⁃ Pulmonary function

⁃ . Oxygen saturation \>92% on room air

‣ Total lung capacity \>70% of predicted

‣ DLCO \>60% of predicted

⁃ Women of childbearing potential (WOCBP) must agree to use method(s) of contraception: at least one highly effective or two effective accepted methods of contraception to avoid conception throughout the study in such a manner that the risk of pregnancy is minimized. Suggested precautions should be used to minimize the risk or pregnancy for at least 1 month before start of therapy, and while women are on study for up to 3 months after T cell infusion. WOCBP include any female who has experienced menarche and who has not undergone successful surgical sterilization (hysterectomy, bilateral tubal ligation or bilateral oophorectomy) or is not postmenopausal

⁃ Men must be willing and able to use an acceptable method of birth control such as latex condom during the dosing period and for at least 3 months after completion of the study agent administration (T cell infusion) if their sexual partners are WOCBP.

⁃ Signed Informed Consent and if applicable, pediatric assent