Standardized monitoring of cytomegalovirus-specific immunity can improve risk stratification of recurrent cytomegalovirus reactivation after hematopoietic stem cell transplantation

Abstract

Recurrence of cytomegalovirus reactivation remains a major cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation. Monitoring cytomegalovirus-specific cellular immunity using a standardized assay might improve the risk stratification of patients. A prospective multicenter study was conducted in 175 intermediate- and high-risk allogeneic hematopoietic stem cell transplant recipients under preemptive antiviral therapy. Cytomegalovirus-specific cellular immunity was measured using a standardized IFN-γ ELISpot assay (T-Track® CMV). Primary aim was to evaluate the suitability of measuring cytomegalovirus-specific immunity after end of treatment for a first cytomegalovirus reactivation to predict recurrent reactivation. 40/101 (39.6%) patients with a first cytomegalovirus reactivation experienced recurrent reactivations, mainly in the high-risk group (cytomegalovirus-seronegative donor/cytomegalovirus-seropositive recipient). The positive predictive value of T-Track® CMV (patients with a negative test after the first reactivation experienced at least one recurrent reactivation) was 84.2% in high-risk patients. Kaplan-Meier analysis revealed a higher probability of recurrent cytomegalovirus reactivation in high-risk patients with a negative test after the first reactivation (hazard ratio 2.73; p=0.007). Interestingly, a post-hoc analysis considering T-Track® CMV measurements at day 100 post-transplantation, a time point highly relevant for outpatient care, showed a positive predictive value of 90.0% in high-risk patients. Our results indicate that standardized cytomegalovirus-specific cellular immunity monitoring may allow improved risk stratification and management of recurrent cytomegalovirus reactivation after hematopoietic stem cell transplantation. This study was registered at www.clinicaltrials.gov as #NCT02156479.

T-Cell Immune Surveillance in Allogenic Stem Cell Transplant Recipients: Are Whole Blood–Based Assays Ready to Challenge ELISPOT?

“…In line with prior reports [ 6 , 15 ], ELISPOT produced few nonevaluable results (7%) ( Figure 1A ), mainly due to elevated unspecific background. WB-ELISA performed comparably to CD154 + IFN-γ + WB flow cytometry, with 74% successful measurements.…”

“…Plausible CMV-induced IFN-γ kinetics, especially for ELISPOT and WB-ELISA, were seen in a patient with an asymptomatic primary CMV infection before the first T-cell measurement ( Figure 2B ). Importantly, poor IFN-γ response to CMV antigens in seropositive patients (with reactive positive controls) does not indicate technical failure, but is considered a prognostic indicator of an increased risk of CMV reactivation or disease in allo-HSCT recipients [ 6 , 15 ]. Although data are limited, the IFN-γ responses of 2 patients who experienced PCR-documented CMV reactivation clustered at the bottom of the range for seropositive patients in both WB-based assays but not ELISPOT ( Figure 2A and C ).…”

Comparison of Cytomegalovirus-Specific Immune Cell Response to Proteins versus Peptides Using an IFN-γ ELISpot Assay after Hematopoietic Stem Cell Transplantation

“…This study was performed as part of the registered and reported AlloProtectCMV study (clinicaltrials.gov identifier: NCT02156479; [4]). Spare peripheral blood mononuclear cells (PBMC) were used to conduct additional T-cell-based assays for research purposes only, in accordance with the study protocol.…”

“…Cytomegalovirus (CMV) infection is a serious cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT) [1]. We and others have proposed that measuring CMV-specific cellular immunity might help identify patients at risk for CMV infection and reactivation following HSCT [2][3][4][5][6][7][8][9]. Existing CMV-specific immune monitoring assays are based on the quantification of the number and/or functionality of CMV-specific immune cells using various detection technologies: flow cytometry (following intracellular or tetramer staining), enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISpot) [10][11][12].…”

“…Existing CMV-specific immune monitoring assays are based on the quantification of the number and/or functionality of CMV-specific immune cells using various detection technologies: flow cytometry (following intracellular or tetramer staining), enzyme-linked immunosorbent assay (ELISA) or enzyme-linked immunospot (ELISpot) [10][11][12]. Two standardized CMVspecific IFN-γ ELISpot assays, based on the in vitro stimulation of peripheral blood mononuclear cells (PBMC) with pp65 and IE-1 peptides (T-SPOT ® .CMV) or T-activated ® proteins (T-Track ® CMV), recently demonstrated their suitability to measure CMVspecific cellular immunity in clinical settings [4,5,8,9,[13][14][15][16][17][18].…”