SPEARHEAD-3 Pediatric Study

Inclusion Criteria:

• Age 2-21 years

• Body weight ≥ 10 kg

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

• Must have previously received a systemic chemotherapy

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

• HLA-A*02 positive

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

• Performance Status: ECOG 0-1 or Lansky Score ≥ 80

Exclusion Criteria:

• HLA-A02:05 in either allele; or any A02 having same protein sequence asHLA-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