Multicenter phase 1/2 application of adenovirus-specific T cells in high-risk pediatric patients after allogeneic stem cell transplantation.

BACKGROUND: Adenovirus (ADV) reactivation can cause significant morbidity and mortality in children after allogeneic stem cell transplantation. Antiviral drugs can control viremia, but viral clearance requires recovery of cell-mediated immunity. METHOD: This study was an open-label phase 1/2 study to investigate the feasibility of generating donor-derived ADV-specific T cells (Cytovir ADV, Cell Medica) and to assess the safety of pre-emptive administration of ADV-specific T cells in high-risk pediatric patients after allogeneic hematopoietic stem cell transplantation (HSCT) to treat adenoviremia. Primary safety endpoints included graft-versus-host disease (GvHD), and secondary endpoints determined antiviral responses and use of antiviral drugs. RESULTS: Between January 2013 and May 2016, 92 donors were enrolled for the production of ADV T cells at three centers in the United Kingdom (UK), and 83 products were generated from 72 mobilized peripheral blood harvests and 20 steady-state whole blood donations. Eight children received Cytovir ADV T cells after standard therapy and all resolved ADV viremia between 15 and 127 days later. ADV-specific T cells were detectable using enzyme-linked immunospot assay (ELISpot) in the peripheral blood of all patients analyzed. Serious adverse events included Grade II GvHD, Astrovirus encephalitis and pancreatitis. CONCLUSION: The study demonstrates the safety and feasibility of pre-emptively manufacturing peptide pulsed ADV-specific cells for high-risk pediatric patients after transplantation and provides early evidence of clinical efficacy.

Manufacture of GMP-compliant functional adenovirus-specific T-cell therapy for treatment of post-transplant infectious complications.

BACKGROUND AIMS: In pediatric patients, adenovirus (ADV) reactivation after allogeneic hematopoietic stem cell transplantation (allo HSCT) is a major cause of morbidity and mortality. For patients who do not respond to antiviral drug therapy, a new treatment approach using ADV-specific T cells can present a promising alternative. Here we describe the clinical scale Good Manufacturing Practice (GMP)-compliant manufacture and characterization of 40 ADV-specific T-cell products, Cytovir ADV, which are currently being tested in a multi-center phase I/IIa clinical trial. This process requires minimal intervention, is high yield, and results in a pure T-cell product that is functional. METHODS: Mononuclear cells (2 × 10(7)) were cultured in a closed system in the presence of GMP-grade ADV peptide pool and cytokines for 10 days. On day 10, the T-cell product was harvested, washed in a closed system, counted and assessed for purity and potency. Additional characterization was carried out where cell numbers allowed. RESULTS: Thirty-eight of 40 products (95%) met all release criteria. Median purity of the cell product was 88.3% CD3+ cells with a median yield of 2.9 × 10(7) CD3+ cells. Potency analyses showed a median ADV-specific interferon (IFN)γ response of 5.9% of CD3+ and 2345 IFNγ spot-forming cells/million. CD4 and CD8 T cells were capable of proliferating in response to ADV (63.3 and 56.3%, respectively). These virus-specific T cells (VST) were heterogenous, containing both effector memory and central memory T cells. In an exemplar patient with ADV viremia treated in the open ASPIRE trial, ADV-specific T-cell response was detected by IFNγ enzyme-linked immunospot from 13 days post-infusion. ADV DNA levels declined following cellular therapy and were below level of detection from day 64 post-infusion onward. CONCLUSIONS: The clinical-scale GMP-compliant One Touch manufacturing system is feasible and yields functional ADV-specific T cells at clinically relevant doses.

Structural insights into the catalytic mechanism of Trypanosoma cruzi GPXI (glutathione peroxidase-like enzyme I).

Current drug therapies against Trypanosoma cruzi, the causative agent of Chagas disease, have limited effectiveness and are highly toxic. T. cruzi-specific metabolic pathways that utilize trypanothione for the reduction of peroxides are being explored as potential novel therapeutic targets. In the present study we solved the X-ray crystal structure of one of the T. cruzi enzymes involved in peroxide reduction, the glutathione peroxidase-like enzyme TcGPXI (T. cruzi glutathione peroxidase-like enzyme I). We also characterized the wild-type, C48G and C96G variants of TcGPXI by NMR spectroscopy and biochemical assays. Our results show that residues Cys48 and Cys96 are required for catalytic activity. In solution, the TcGPXI molecule readily forms a Cys48-Cys96 disulfide bridge and the polypeptide segment containing Cys96 lacks regular secondary structure. NMR spectra of the reduced TcGPXI are indicative of a protein that undergoes widespread conformational exchange on an intermediate time scale. Despite the absence of the disulfide bond, the active site mutant proteins acquired an oxidized-like conformation as judged from their NMR spectra. The protein that was used for crystallization was pre-oxidized by t-butyl hydroperoxide; however, the electron density maps clearly showed that the active site cysteine residues are in the reduced thiol form, indicative of X-ray-induced reduction. Our crystallographic and solution studies suggest a level of structural plasticity in TcGPXI consistent with the requirement of the atypical two-cysteine (2-Cys) peroxiredoxin-like mechanism implied by the behaviour of the Cys48 and Cys96 mutant proteins.