Genetically Engineered Cells (BAFFR-CAR T Cells) for the Treatment of Relapsed or Refractory B-cell Acute Lymphoblastic Leukemia and B-cell Lymphoblastic Lymphoma

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative * Agreement to allow the use of archival tissue from diagnostic tumor biopsies * If unavailable, exceptions may be granted with study principal investigator (PI) approval * Age ≥ 18 years * Eastern Cooperative Oncology Group (ECOG) ≤ 2 * Life expectancy ≥ 16 weeks * Histologically confirmed B-ALL or B-cell lymphoblastic lymphoma * Relapsed/refractory disease. Minimal residual disease (MRD) relapse is allowed * Evidence of tumor expressing BAFF-R at any level either by flow or immunohistochemistry * Recovered to ≤ grade 1 from the acute toxic effects (except alopecia and peripheral neuropathy) of prior anti-cancer therapy * No known contraindications to leukapheresis, steroids or tocilizumab * Ineligible for or failed prior CD19-targeted immunotherapy (e.g., blinatumomab or CD19-CAR T cells) * For participants who had prior CD19-CAR T cell therapy: * At least 90-days has elapsed since participant received last CD19-CAR T cell therapy AND * Persistence of prior CD19-CAR T cells must be evaluated and found to be \< 5% prior to leukapheresis procedure * Note: Participants who have undergone stem cell transplantation (at least 100 days prior to enrollment) after the last CD19-CAR T cell therapy, are considered eligible and do not need to meet the above criteria * Participants with central nervous system (CNS) involvement by leukemia (CNS2 and asymptomat…