Clinical Validation of an Improved T-Track® CMV Assay to Assess the Functionality of CMV Protein-reactive Cell-mediated Immunity (CMI) and Its Suitability to Determine a Protective Cut-off Value for Recurrent CMV Reactivations in Allo-HSCT Recipients

CMV reactivation after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with significant morbidity and increased overall mortality. Patients are generally pre-emptively treated with antiviral medication after elevated levels of CMV copies in peripheral blood or plasma have been detected by quantitative PCR. However, these CMV reactivations are often subclinical and do not lead to complications or CMV disease. In these cases functional CMV- specific effector cells have been shown to mediate protection from clinical symptoms. Monitoring of CMV- specific effector cells after allo-HSCT could help to prevent severe side effects due to unnecessary antiviral treatment.

Since the majority of patients develops more than one episode of CMV reactivation, determination of functional CMV-reactive effector cells of cell mediated immunity (CMI) could also help to predict the likelihood of relapsing CMV reactivations and thereby adjust the need for and duration of secondary prophylaxis.

Currently available techniques to measure CMV-specific effector cells lack either a functional read out (multimer stain) or are time consuming and difficult to standardize (detection of intracellular interferon gamma (IFN-ᵞ) after in vitro stimulation using flow cytometry). The improved T-Track® CMV assay has the advantage of combining a standardized and highly sensitive test system with a functional read out (IFN-ᵞ production) considering the function of antigen presenting cells (APC) and different populations of clinically relevant effector cells (CTL, T helper-, NK-, NKT cells). Based on experiences of the performance of this assay system in healthy individuals and hemodialysis patients (the latter as part of a performance evaluation - EUDAMED number 00015561) the presented trial aims to validate an improved variant of this test (including optimized, LPS-depleted IE-1 protein) with regard to its suitability to predict freedom from relapse of CMV-reactivation following treatment of CMV reactivation in a cohort of 120-150 patients after allo-HSCT. Moreover, the results will be compared to (i) analysis of leukocyte subpopulations and (ii) multimer techniques detecting CMV-specific CD8 positive T lymphocytes (CTL) (optional).

Demonstrating the suitability of the improved T-Track® CMV assay to identify patients at reduced risk for recurrent CMV-reactivation, CMV disease or GvHD would highly improve and optimize follow-up care after allo-HSCT regarding therapy success as well as reduced public health care costs.