A Prospective Observational Study to Evaluate a Cytomegalovirus(CMV)–specific T-SPOT® Assay in Hematopoietic Stem Cell Transplant Recipients: The REACT Study Interim Data Review

Background. Cytomegalovirus (CMV) infection causes significant morbidity and mortality after allogeneic hematopoietic cell transplantation (allo-HCT). CMV management after HCT includes risk stratification and mainly a preemptive strategy with CMV viral load serial monitoring. Cell mediated immunity (CMI) plays a role in CMV reactivation and can be assessed by cytokine responses such as T cell production of interferon gamma (IFN-γ). Quantification of CMV CMI may have value in CMV management. This study evaluated the potential of a CMV-specific ELISPOT assay to determine CMI against CMV reactivation in allo-HCT recipients ≤26 weeks post-HCT. Methods. This is an ongoing, multi-center, prospective, observational study of ≥150 adult CMV seropositive allo-HCT recipients. CMV management was according to institutional protocols. Date of CMV reactivation, as defined by each institution, was recorded. T cell responses were serially monitored pre-, and every 2 weeks post-transplantation up to 26 weeks with an ELISPOT assay that uses CMV-specific antigens IE-1 and pp65 (T-SPOT.CMV, Oxford Diagnostics Laboratories®, Memphis, TN). Data reviewed include patients reaching ≥12 weeks post-HCT by March 2016. Results. Thirty-five patients across 6 sites reached ≥12 weeks post-HCT, and 15 reached ≥22 weeks. Majority of the patients were white (54%), males (77%), with a median age of 57 (25–80) years, and had unrelated (43%) or matched related (46%) HCT. CMV reactivation occurred in 13 patients (37%) and time to first reactivation occurred ≤10 weeks post-HCT (figure 1). Average immune response as measured by CMV-specific IE-1 and pp65 spot counts (SPC) increased over time post-transplantation (Figure 2). Conclusion. The preliminary analysis of the REACT study showed CMV reactivation occurred early during transplantation when the CMV immune response (measured by a CMV-specific ELISPOT assay) was lower. In contrast, no reactivation was seen later on when immune response was higher. This study may provide insights into the CMV immune response which may guide personalized decisions regarding CMV management. Disclosures. E. Ariza-Heredia, Oxford Immunotec: Investigator, Research support; K. Mullane, Oxford Immunotec: Investigator, Research support; S. Rowley, Oxford Immunotec: Investigator, Research support; P. Chandrasekar, Oxford Immunotec: Investigator, Research support; D. J. Winston, Oxford Immunotec: Investigator, Research support; P. Hari, Oxford Immunotec: Investigator, Research support; H. Gillis, Oxford Immunotec: Employee, Salary; R. Nath, Oxford Immunotec: Investigator, Research support; D. Kumar, Oxford Immunotec: Investigator, Research support; S. Mossad, Oxford Immunotec: Investigator, Research support; P. Ljungman, Oxford Immunotec: Consultant and Investigator, Consulting fee and Research support; R. F. Chemaly, Oxford Immunotec: Consultant, Grant Investigator and Investigator, Consulting fee, Research support and Speaker honorarium

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