Multiple Donor Treg DLI for Severe Refractory Chronic GVHD

The procedure under study is the infusion of patients with chronic GVHD with purified Treg cells obtained from the original HSC donor (T reg DLI).

T reg cells are PURIFIED utilizing the CliniMACS Plus Systems for depletion of CD8 and CD19 positive cells and enrichment for CD25high expressing. Treg purification will be performed according to GMP procedure by using the clinical grade CLINI-MACS® device. The protocol is detailed in chapter 3.5

The entire manufacturing process including cell harvesting, transport and Treg purification has been validated.

The feasibility of the selection of nTreg from human peripheral blood using the CliniMACS® System has been previously documented. In these studies, CD8+ and CD19+ cells were undetectable in the final blood products. Final content of CD4+CD25+CD127lo-expressing cells was in mean 79% (range 52-82%) with the improved CD25 enrichment procedure. This protocol has also been validated by two partner Centres in the Treg GENERATION CONSORTIUM, Liège and Boston, with results that meet the release criteria for infusion. These purification procedures provided between 0.98 and 2.93x10e6 Treg per kg. It is noteworthy that the degree of purity in terms of CD4+CD25+CD127- cells ranged between 72.80% and 93.90%.

According to the "Reflection paper on classification of advanced therapy medicinal therapy", published by the Committee for Advanced Therapies (CAT) of the European Medicine Agency on June 20th 2014 [EMA/CAT/600280/2010 Rev.1 lines 118-131] the Treg DLI SHOULD NOT BE CONSIDERED CELL THERAPY MEDICINAL PRODUCTS. Indeed somatic cell therapy medicinal product means a biological medicinal product which fulfils BOTH following two characteristics: (a) contains or consists of cells or tissues that have been subject to substantial manipulation so that biological characteristics, physiological functions or structural properties relevant for the intended clinical use have been altered, or of cells or tissues that are not intended to be used for the same essential function(s) in the recipient and the donor; (b) is presented as having properties for, or is used in or administered to human beings with a view to treating, preventing or diagnosing a disease through the pharmacological, immunological or metabolic action of its cells or tissues. For the purposes of point (a), the manipulations listed in Annex I to Regulation (EC) No 1394/2007, including cutting, grinding, shaping, centrifugation, soaking in antibiotic or antimicrobial solutions, sterilization, irradiation, cell separation, concentration or purification, filtering, lyophilization, freezing, cryopreservation, and vitrification, shall not be considered as substantial manipulations. The procedures listed above for the preparation of the purified T reg product DO NOT FULFILL the definition of substantial manipulation.

Moreover, according to the same document [lines 286-306] T reg DLI SHOULD BE REGARDED as administered for HOMOLOGOUS USE. Indeed, as outlined in "Reflection paper on classification of advanced therapy medicinal therapy" the cells harvested and separated by a simple selection method, and re-administered to fulfil their same essential function will generally be regarded as homologous use. The same essential function for a cell population means that the cells when removed from their original environment in the human body are used to maintain the original function in the same anatomical or histological environment.

Therefore the INFUSION of donor purified T reg cells in TRANSPLANTED PATIENTS (T reg DLI) SHOULD be considered as TRANSPLANTATION rather than the administration of ADVANCED THERAPY MEDICINAL PRODUCT.

The aim of the study is to assess whether multiple infusions of donor-derived purified T regulatory cells (T reg DLI) in patients with steroid-refractory chronic GVHD is safe and whether it may induce clinical remission of GVHD. Based on the observation of the pathophysiological involvement of T regulatory cells in chronic GVHD, the adoptive transfer of donor T regulatory cells appears more reproducible and effective than their in vivo expansion following the administration of drugs.

We will determine feasibility, toxicity and MTD; assess clinical impact and effect on Treg and Tcon homeostasis; and determine whether these effects can be maintained and the extent to which they persist. We will also assess for predictors of response to therapy, both clinical (e.g., patient, disease, concurrent agents) and biological (e.g., degree of Treg expansion; Treg:Tcon ratio; Treg function).

As of 1/1/2015, the current TRIAL PROPOSAL has received funding by the European Union Framework Program on Research and Innovation as a part of a project titled "Repair of tissue and organ damage in refractory chronic graft versus host disease after hematopoietic stem cell transplantation by the infusion of purified allogeneic donor regulatoryT lymphocytes" (acronym TREGeneration, code 643776). The project includes a set of proposals by different European institutions (University of Lisbona, University of Liege, University of Regensburg and the University of Bologna) all investigating the role of Treg DLI in the treatment of chronic GVHD. The GRANT AGREEMENT signed with the EUROPEAN COMMISSION is attached to the proposal.