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Background: Interleukin 6 mediates graft-versus-host disease (GVHD) in experimental allogeneic stem-cell transplantation (allogeneic SCT) and represents an attractive therapeutic target. We aimed to assess whether the humanised anti-interleukin-6 receptor monoclonal antibody, tocilizumab, could attenuate the incidence of acute GVHD., Methods: We undertook a single-group, single-institution phase 1/2 study at the Royal Brisbane and Women's Hospital Bone Marrow Transplantation unit, QLD, Australia. Eligible patients were 18-65 years old and underwent T-replete HLA-matched allogeneic SCT with either total body irradiation-based myeloablative or reduced-intensity conditioning from unrelated or sibling donors. One intravenous dose of tocilizumab (8 mg/kg, capped at 800 mg, over 60 mins' infusion) was given the day before allogeneic SCT along with standard GVHD prophylaxis (cyclosporin [5 mg/kg per day on days -1 to +1, then 3 mg/kg per day to maintain therapeutic levels (trough levels of 140-300 ng/mL) for 100 days plus methotrexate [15 mg/m(2) on day 1, then 10 mg/m(2) on days 3, 6, and 11]). The primary endpoint was incidence of grade 2-4 acute GVHD at day 100, assessed and graded as per the Seattle criteria. Immunological profiles were compared with a non-randomised group of patients receiving allogeneic SCT, but not treated with tocilizumab. This trial is registered with the Australian and New Zealand Clinical Trials Registry, number ACTRN12612000726853., Findings: Between Jan 19, 2012, and Aug 27, 2013, 48 eligible patients receiving cyclosporin and methotrexate as GVHD prophylaxis were enrolled into the study. The incidence of grade 2-4 acute GVHD in patients treated with tocilizumab at day 100 was 12% (95% CI 5-24), and the incidence of grade 3-4 acute GVHD was 4% (1-13). Grade 2-4 acute GVHD involving the skin developed in five (10%) patients of 48 treated with tocilizumab, involving the gastrointestinal tract in four (8%) patients; there were no reported cases involving the liver. Low incidences of grade 2-4 acute GVHD were noted in patients receiving both myeloablative total body irradiation-based conditioning (12% [95% CI 2-34) and fludarabine and melphalan reduced-intensity conditioning (12% [4-27]). Immune reconstitution was preserved in recipients of interleukin-6 receptor inhibition, but qualitatively modified with suppression of known pathogenic STAT3-dependent pathways., Interpretation: Interleukin 6 is the main detectable and dysregulated cytokine secreted after allogeneic SCT and its inhibition is a potential new and simple strategy to protect from acute GVHD despite robust immune reconstitution; a randomised, controlled trial assessing tocilizumab in addition to standard GVHD prophylaxis in these patients is warranted., Funding: National Health and Medical Research Council and Queensland Health., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The reconstitution of anti-viral cellular immunity following hematopoietic stem cell transplantation (HSCT) is crucial in preventing cytomegalovirus (CMV)-associated complications. Thus immunological monitoring has emerged as an important tool to better target pre-emptive anti-viral therapies. However, traditional laboratory-based assays are too cumbersome and complicated to implement in a clinical setting. Here we conducted a prospective study of a new whole blood assay (referred to as QuantiFERON-CMV®) to determine the clinical utility of measuring CMV-specific CD8+ T-cell responses as a prognostic tool. Forty-one evaluable allogeneic HSCT recipients underwent weekly immunological monitoring from day 21 post-transplant and of these 21 (51.2%) showed CMV reactivation and 29 (70.7%) developed acute graft-versus-host disease (GvHD). Patients with acute GvHD (grade ≥ 2) within 6 weeks of transplant showed delayed reconstitution of CMV-specific T-cell immunity (p = 0.013) and a higher risk of CMV viremia (p = 0.026). The median time to stable CMV-specific immune reconstitution was 59 days and the incidence of CMV reactivation was lower in patients who developed this than those who did not (27% versus 65%; p = 0.031). Furthermore, a failure to reconstitute CMV-specific immunity soon after the onset of CMV viraemia was associated with higher peak viral loads (5685 copies/ml versus 875 copies/ml; p = 0.002). Hence, QuantiFERON-CMV® testing in the week following CMV viremia can be useful in identifying HSCT recipients at risk of complicated reactivation.