CARPALL: Immunotherapy with CD19+CD22 CAR T-cells for CD19+ and CD22+ Acute Lymphoblastic Leukaemia

Patients will undergo an unstimulated leukapheresis to isolate the required immune cells to produce the CD19+CD22 CAR T-cells

Participants will receive total body irradiation delivered as a single fraction (2Gy) on day -7 prior to CD19+CD22CAR T-cell infusion.

Patients will receive lymphodepleting chemotherapy with iv fludarabine 30 mg/m2 on days -6 to -3 prior to CD19+CD22CAR T-cell infusion.

Patients will receive lymphodepleting chemotherapy with iv cyclophosphamide 0.5 g/m2 on days -6 to -5 prior to CD19+CD22CAR T-cell infusion.

Dose level 1: 2 doses of 4 x 10\^5 CD19+CD22 CAR T-cells/kg Dose level 2: 2 doses of 1 x 10\^6 CD19+CD22 CAR T-cells/kg given as a split dose as an intravenous injection through a Hickman line or PICC line (peripherally inserted central catheter) on day 0 and day 14.