Eligible patients will receive escalating doses of 4G7-CARD T-cells paralleling clinical standard of care with unmanipulated donor lymphocytes. There are 3 intra-patient dose levels planned.

Patients will be followed up regularly during the interventional phase of the study until 12 months post-final 4G7-CARD T-cell infusion. Thereafter patients will be followed up annually for years 2 and 3.

Patients will receive escalating doses of 4G7-CARD T-cells (after pre-conditioning with Fludarabine and Cyclophosphamide), paralleling clinical standard of care with unmanipulated donor lymphocytes. Intra-patient dose escalation will proceed at intervals of not less than 8 weeks, dependent on development of toxicity or evidence of efficacy and confirmation by the Trial Management Group.

Three dose cohorts levels are planned, and dosing will be according to total CD3+ T- cell dose as this correlates with toxicity in the unmanipualated donor lymphocyte setting:

• Dose Level 1: 1x10^6 CD3+ T-cells/kg (starting dose for all patients)
• Dose Level 2: 3x10^6 CD3+ T-cells/kg
• Dose Level 3: 1x10^7 CD3+ T-cells/kg

The inter-patient dosing for the first 3 patients was at least 28 days, following TMG confirmation.

Patients will be followed up regularly during the interventional phase of the study until 12 months post-final 4G7-CARD T-cell infusion. During the long term follow up phase of the study (years 2-3 post-final 4G7-CARD T-cell infusion) patients will be followed-up annually for overall survival, disease status and safety.

All patients will enter long term follow up until 3 years post-final 4G7-CARD T-cell infusion.

Inclusion Criteria:

1. Age 16-70 years
2. Confirmed diagnosis of CD19+ malignancy relapsing following allogeneic transplantation
3. Agreement to have a pregnancy test, use adequate contraception for 12 months post-final 4G7-CARD T-cell infusion
4. Karnofsky performance status >60
5. Written informed consent

Exclusion Criteria:

1. Women who are pregnant or lactating
2. Prior history of ischaemic heart disease, dysrhythmias, abnormal ECG (LBBB), Multi Gated Acquisition Scan (MUGA) left ventricular ejection fraction (LVEF<40%) (if performed)
3. Known involvement of the central nervous system or cerebral vascular accident within prior 3 months
4. Patients receiving corticosteroids at a dose of > 10mg prednisolone per day (or equivalent)
5. Active graft versus host disease requiring immunosuppression
6. Use of rituximab within the last 2 months prior to ATIMP infusion
7. Known allergy to albumin or dimethyl sulfoxide (DMSO)
8. Patients who have experienced significant neurotoxicity following blinatumomab treatment