Clinical Grade Generation of Hexon-specific T Cells for Adoptive T-cell Transfer as a Treatment of Adenovirus Infection After Allogeneic Stem Cell Transplantation

Abstract

Adenovirus infection after allogeneic hematopoietic stem cell transplantation is still causing significant morbidity and mortality, especially in children. It has been demonstrated that a sufficient host T-cell response is essential to clear the virus. Adoptive transfer of specific T-cell immunity from the donor to the recipient has become a new treatment option for patients with systemic adenoviral infection who lack specific T-cell responses. The adenoviral hexon protein was shown to be an immunodominant T-cell target. We describe here a Good Manufacturing Practice-compatible generation of hexon-specific T cells developed by isolating interferon-gamma-secreting T cells after stimulation of mononuclear cells ex vivo with hexon protein. Phenotypical and functional characterization of the generated, specific T-cell product resulted in a mixed population of CD4 and CD8-positive T cells with an intermediate effector memory phenotype. Isolated hexon-specific T cells showed high expansion potential in vitro and specific cytotoxicity. T-cell lines, directed against type 5 hexon protein showed good crossreactivity against viral strains from other adenovirus species. The availability for isolation of hexon-specific T cells among 76 hematopoietic stem cell transplantation donors showed in > 72% a sufficient T-cell response (0.05% of T cells). In conclusion, Good Manufacturing Practice-grade selection of adenovirus-specific T cells for adoptive immunotherapy by hexon-induced secretion of interferon-gamma has been established. Adoptive T-cell transfer could potentially restore T-cell immunity against adenovirus after allogeneic stem cell transplantation.

Monitoring of adenovirus load in stool by real-time PCR permits early detection of impending invasive infection in patients after allogeneic stem cell transplantation

“…1,11,17,18 It has been shown that the adoptive transfer of donor-derived AdV-specific T-lymphocytes may provide an attractive treatment option in patients with invasive AdV infection, but the favorable outcome observed upon in vivo expansion of the transferred T cells appeared to be related to the early onset of adoptive T-cell transfer during the course of infection. 19,20 These observations suggested that timely initiation of antiviral treatment, possibly before the occurrence of invasive infection, might be beneficial.…”

Generation of cytotoxic T-cell lines using overlapping pentadecapeptides derived from conserved regions of the adenovirus hexon protein

“…In this regard, using products that are antigen-expanded ex vivo has advantages, as such lines contain few or no alloreactive T cells (reviewed by . More recent preclinical studies used purified Ad5 hexon protein as the stimulus for IFN-c capture, but this resulted in low cell recovery and purity and even fewer Ad-specific CD8 + cells (Feuchtinger et al, 2008). …”

Immunotherapy for viral and fungal infections

“…Until now 4100 patients after allo-SCT have been treated against single pathogens all over Europe with Ag-specific T cells. 37,38 However, in vivo persistence of transferred T cells in the recipient remains a problem of T-cell transfer either due to inherent properties of the T-cell product or due to immunosuppressive drugs in the recipient. Especially, third-party T-cell transfer from HLA-partially matched donors has been shown safe and feasible 38,39 but in vivo persistence of T cells is limited.…”