Hypofractionated Radiation in Combination With B7-H3-CAR T Cells for Pediatric Patients With Relapsed/Refractory Sarcomas

INCLUSION CRITERIA \*a previously collected, autologous leukapheresis product can be used for T cell production Collection and manufacturing eligibility * Age ≤ 21 years old * B7-H3+ sarcoma; B7-H3 expression will be evaluated by standard immunohistochemistry (IHC) using any previously obtained biopsy; a tumor is considered B7-H3 positive with a H score greater than or equal to 100 * Osteosarcoma * Ewing Sarcoma * Rhabdomyosarcoma Non-rhabdomyosarcoma soft tissue sarcomas * Evidence of relapsed (cancer that has completely responded \[i.e., no evidence of disease using standard imaging modalities\] to first-line therapy but has recurred for the first or subsequent time); or refractory (cancer that does not respond completely to treatment; cancer may be resistant at the beginning or may become resistant during treatment) disease after standard first-line therapy * Evaluable disease with presence of at least one lesion amenable to hypofractionated radiation therapy * For dose expansion cohort: participants must also have additional evaluable disease beyond planned radiation field * Estimated life expectancy of \> 12 weeks * Karnofsky or Lansky (age-dependent) performance score ≥ 60 * Participants with mobility limitations due to prior surgical intervention (i.e., amputation) but who are up in wheelchair or with other assistive devices will be considered ambulatory for the purpose of performance score determination * For females of child-bearing age: * Not preg…