Donor Regulatory T Cells Infusion in Patients With Chronic Graft-versus-host Disease (GVHD)

TREATMENT PLAN

1 Immunosuppressive drugs (DTI and control arms)

• Rapa will be started within 2 weeks after inclusion. Rapa will be given at 2-6 mg loading dose for one day, followed by approximately 1mg daily to achieve a target trough level of 5 to 10 ng/mL. The frequency of trough level measurements will be done according to the investigator choice;
• Rapa may be discontinued in case of resolution of chronic GVHD ≥ 3 months or in case of un-manageable side effects or progression of chronic GVHD.
• Calcineurin inhibitor discontinuation within 2 weeks after rapa initiation. No other modification of immunosuppressive drugs and in particular no decrease in the dose of steroids (unless necessary for side effects).
• Evaluation of chronic GVHD 60 days after rapa initiation. DTI will not be given in patients who had progression of their GVHD on day 60 nor in those who are in CR of their GVHD.

1. Collection of donor lymphocytes (DTI arm)

• Apheresis of the donor will be performed 60-90 days after first day of rapa administration to the patient.There will be no particular preparation of the donor prior to leukapheresis. After written informed consent, the donor will undergo leukaphereses on 1 day. Leukapheresis will be performed using a continuous flow blood cell separator and following a mononuclear cell collection protocol. The volume of blood processed will be 20 liters. Anticoagulation will be performed with the ACD-A / heparin solution.

1. Tregselection and infusion (DTI arm)

• Treg will be isolated at the LTCG of the CHU of Liège from apheresis product with the CliniMACS separation system (MiltenyiBiotec) following a two-step procedure (CD8 and CD19 depletion followed by CD25 positive selection)according to the manufacturer's recommendation. Aliquots (≈ 3 mL) of the Treg product will be saved for analyses.
• Treg will be infused i.v.60-90 days after first day of rapa administration and after calcineurin inhibitor discontinuation. No DTI will be performed in the control arm.
• Low-dose Il-2 (1x106 IU/day) will be started the day of DTI and will be continued for a period of 2months in order to expand infused donor Tregs.

PATIENTS' FOLLOW-UP

1. Quality controls of cell products 1.1 Peripheral blood. The following laboratory analyses will be performed in the peripheral blood of the donor on the days of lymphocyte collections :

• Nucleated cell count and differential in an automated cell counter; 1.1.2 Leukapheresis product as well as start, intermediate, and final fractions of Treg selection. The following laboratory analyses will be performed in the lymphocyte collection as well as start, intermediate and final fractions of the Treg selection:
• Nucleated cell count and differential on an automated cell counter;
• FACS analysis with determination of the % cells (on total WBC) with the markers: CD20-FITC (Miltenyi #130-091-110), CD14-PE (Miltenyi #130-091-412), CD15-PE (Miltenyi #130-091-390), CD56-PE (Miltenyi #130-090-910), CD45-VioBlue (Miltenyi #130-092-497), CD8-APC (Miltenyi #130-091-083), PropidiumIodid(Miltenyi #130-093-233), T reg Detection Kit (CD4/Cd25/CD127) (Miltenyi #130-096-076), and Treg Detection Kit#2 (CD4/CD25/Foxp3)-APC (Miltenyi #130-094-158).
• Treg phenotype using the following markers: CD127, CD45RA, CCR4, CCR7 and KI67.
• Estimation of Treg function42.
• Methylation status of CpG dinucleotides located in a conserved region of FoxP3 intron
• Cell viability by trypan blue exclusion.
• Microbiology testing including standard virology and bacterial culture. 1.1.3Release criteria. The following criteria should be met for release:
• ≥ 0.5 x106 cells/kg recipient;
• ≥ 55% CD4+FoxP3+;
• Viability > 80%;
• <0.05 x 106 CD45+CD8+ cells/kg.

1. Toxicities of cell infusions Potential toxicities associated with Treg infusions will be carefully monitored per standard procedures.
2. Clinical data Patient will be carefully observed and the following clinical parameters will be recorded:

• Incidence, timing and severity of acute GVHD following DTI, its treatment and outcome;
• Evolution of chronic GVHD, its treatment and outcome. More specifically, chronic GVHD (including current immunosuppressive therapy) will be assessed for each organ according to the revised NIH consensus:
• Incidence, timing and severity of secondary cytopenia, its treatment and outcome;
• Incidence, timing and severity of bacterial, viral, fungal and protozoal infections
• Duration of hospitalization if any;
• Evolution of the primary malignant disease: response if not in CR at the time of inclusion, relapse, its treatment and outcome;
• Any other serious complication associated with the transplant procedure;
• Death and survival.

1. Immunological data(performed in the GIGA at the ULG for all but the analyses of methylation status of CpG dinucleotides located in a conserved region of FoxP3 intron 1 that will be performed at the UCL).
2. Immune recovery I (flow cytometry). The following analyses will be performed (starting with 5 mL of blood).
3. Immune recovery II. Isolation of T-cell subsets for analyses of repertoire diversity through next-generation sequencing (NGS; starting from 50 mL of blood). The following subsets will be isolated (~50,000 cells each) and then cryopreserved:

• CD4+ CD25+ regulatory T cells (naïve, activated and memory),
• CD4+ CD25- non-regulatory T cells (naïve/memory), and
• CD8+ cytotoxic T cells (naïve/memory).