Immune therapy for EBV infections after hemopoietic stem-cell transplant

Clinical-grade generation of peptide-stimulated CMV/EBV-specific T cells from G-CSF mobilized stem cell grafts

Background

A major complication after allogeneic hematopoietic stem cell transplantation (aSCT) is the reactivation of herpesviruses such as cytomegalovirus (CMV) and Epstein–Barr virus (EBV). Both viruses cause significant mortality and compromise quality of life after aSCT. Preventive transfer of virus-specific T cells can suppress reactivation by re-establishing functional antiviral immune responses in immunocompromised hosts.

Methods

We have developed a good manufacturing practice protocol to generate CMV/EBV-peptide-stimulated T cells from leukapheresis products of G-CSF mobilized and non-mobilized donors. Our procedure selectively expands virus-specific CD8+ und CD4+ T cells over 9 days using a generic pool of 34 CMV and EBV peptides that represent well-defined dominant T-cell epitopes with various HLA restrictions. For HLA class I, this set of peptides covers at least 80% of the European population.

Results

CMV/EBV-specific T cells were successfully expanded from leukapheresis material of both G-CSF mobilized and non-mobilized donors. The protocol allows administration shortly after stem cell transplantation (d30+), storage over liquid nitrogen for iterated applications, and protection of the stem cell donor by avoiding a second leukapheresis.

Conclusion

Our protocol allows for rapid and cost-efficient production of T cells for early transfusion after aSCT as a preventive approach. It is currently evaluated in a phase I/IIa clinical trial.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1498-3) contains supplementary material, which is available to authorized users.

Preservation of Antigen-Specific Functions of αβ T Cells and B Cells Removed from Hematopoietic Stem Cell Transplants Suggests Their Use As an Alternative Cell Source for Advanced Manipulation and Adoptive Immunotherapy

Hematopoietic stem cell transplantation is standard therapy for numerous hematological diseases. The use of haploidentical donors, sharing half of the HLA alleles with the recipient, has facilitated the use of this procedure as patients can rely on availability of a haploidentical donor within their family. Since HLA disparity increases the risk of graft-versus-host disease, T-cell depletion has been used to remove alloreactive lymphocytes from the graft. Selective removal of αβ T cells, which encompass the alloreactive repertoire, combined with removal of B cells to prevent EBV-related lymphoproliferative disease, proved safe and effective in clinical studies. Depleted αβ T cells and B cells are generally discarded as by-products. Considering the possible use of donor T cells for donor lymphocyte infusions or for generation of pathogen-specific T cells as mediators of graft-versus-infection effect, we tested whether cells in the discarded fractions were functionally intact. Response to alloantigens and to viral antigens comparable to that of unmanipulated cells indicated a functional integrity of αβ T cells, in spite of the manipulation used for their depletion. Furthermore, B cells proved to be efficient antigen-presenting cells, indicating that antigen uptake, processing, and presentation were fully preserved. Therefore, we propose that separated αβ T lymphocytes could be employed for obtaining pathogen-specific T cells, applying available methods for positive selection, which eventually leads to indirect allodepletion. In addition, these functional T cells could undergo additional manipulation, such as direct allodepletion or genetic modification.

Strategies to prevent EBV reactivation and posttransplant lymphoproliferative disorders (PTLD) after allogeneic stem cell transplantation in high-risk patients

Epstein-Barr virus (EBV)-associated postallogeneic stem cell transplantation (SCT) lymphoproliferative disorder (PTLD) is often life threatening. The risk of EBV reactivation is highest in older patients, T cell-depleted SCT (in vivo or vitro), and in unrelated or mismatched SCT. Cumulative numbers of patients with EBV reactivation and PTLD are rising as more patients at high risk for EBV reactivation and PTLD are receiving allo-SCT. Novel but easily applicable strategies are needed to prevent EBV reactivation and PTLD to serve the needs of the increasingly enlarging population of high-risk SCT recipients across the globe.

Preparation of Genetically Homogeneous Antigen-Specific Thymidine Kinase Positive T-Lymphocyte Clones for the Control of Alloreactivity Post-Bone Marrow Transplantation

We have previously proposed the use of HLA-specific T-cell clones transduced with a suicide gene to produce an allogeneic effect that can be controlled after allogeneic bone marrow transplantation. Procedures described so far to obtain specific T-cells transduced with a suicide gene have led to the recovery of heterogeneous polyclonal T-cells with a limited level of purity. We have therefore developed an approach to select specific T-cell clones in which the suicide transgene is inserted at a unique site of the genome, and used it to produce CD(+)-cytotoxic HLA-DP-specific T-cell clones. Immunization was performed by a one-way mixed lymphocyte culture and responder T lymphocytes were transduced at day 16, 6 days after the second stimulation. Transductions were carried out using gibbon ape leukemia virus (GALV)-pseudotyped retroviral particles harboring a bicistronic Thy-1/TK vector produced by TEFLY GA16-pKM4 clone 34 packaging cells. Three to 5 days later, CD90 immunomagnetic selection and cloning were performed on the transduced T cells. Our results demonstrate that this procedure led to the recovery of T-cell clones, the majority of which had the expected specificity and a single site of transgene insertion. Such clonotransgenic T-cell populations represent suitable tools to drive a defined alloreaction that can be controlled after bone marrow transplantation.

Genetic, cellular and immune approaches to disease therapy: past and future

Advances in immunology and molecular genetics have accelerated our understanding of the genetic and cellular basis of many diseases. At the same time, remarkable progress in recombinant DNA technology has enabled the development of molecular and cellular treatments for infectious diseases, inherited disorders and cancer. This Perspective is intended to give a sample of the progress over the past ten years in cellular, genetic and immune therapy of disease. During this time, monoclonal antibody technology and cellular transplantation have begun to come of age in biomedicine. Innovations in gene delivery have not only catalyzed the nascent field of human gene therapy, but may also ultimately impact human health by advancing recombinant vaccine technology.