SPEARHEAD-3 Pediatric Study

Inclusion Criteria:

• Subject has histologically confirmed diagnosis of any one of the following cancers: (A) Synovial Sarcoma (SS), (B) MPNST, (C) Neuroblastoma, or (D) Osteosarcoma (OS).

• Age:

(A) Synovial Sarcoma: 2 to 17 years (B) MPNST, Neuroblastoma and Osteosarcoma: 2 to 21 years

• Body weight ≥ 10 kg

• Must have previously received a systemic chemotherapy

• Measurable disease prior to lymphodepletion according to RECIST v1.1 (or INCR, 2017Neuroblastoma only).

• HLA-A*02 positive

• Tumor shows MAGE-A4 expression confirmed by central laboratory.

• Performance Status:

(A) Subjects ≥16: Eastern Cooperative Oncology Group (ECOG) 0 or 1 (B) Subjects 2 to 16: Lansky score ≥ 80

• Subject has anticipated life expectancy of greater than 3 months in the opinion of the investigator.

Exclusion Criteria:

• Positive for HLA-A02:05 in either allele; or any A02 having same protein sequenceas HLA-A*02:05

• History of allergic reactions attributed to compounds of similar chemical orbiologic composition to fludarabine, cyclophosphamide.

• History of autoimmune or immune mediated disease

• Known central nervous system (CNS) metastases.

• Other prior malignancy that is not considered by the Investigator to be in completeremission

• Clinically significant cardiovascular disease

• Active infection with human immunodeficiency virus, hepatitis B virus, hepatitis Cvirus, or human T cell leukemia virus

• Pregnant or breastfeeding

• Experiencing ongoing rapid disease progression that in the opinion of theInvestigator significantly increases the subjects risk associated with treatment.