Clinical Usefulness of Monitoring Cytomegalovirus-Specific Immunity by Quantiferon-CMV in Pediatric Allogeneic Hematopoietic Stem Cell Transplantation Recipients

Predicting cytomegalovirus infection and graft-versus-host disease using QuantiFERON-CMV and Monitor in pediatric transplants: a proof-of-concept study

Background

Cytomegalovirus (CMV) infection can lead to significant morbidity and mortality in pediatric hematopoietic stem cell transplant recipients. Early detection of CMV infection is crucial for managing its impact.

Aim

This study aims to evaluate the effectiveness of QuantiFERON-CMV® (QF-CMV) and QuantiFERON-Monitor® (QFM) tests in predicting CMV infection and graft-versus-host disease (GvHD) in pediatric hematopoietic stem cell transplant recipients to enhance patient outcomes and support personalized prevention strategies.

Methods

The QF-CMV and QFM tests were used to predict CMV pp65 antigen and GvHD in 24 pediatric hematopoietic stem cell transplant recipients.

Results

Data showed that positive CMV antigenemia (CMV-Ag) increased the risk of GvHD by 21.2%. QF-CMV and QFM were associated with CMV-Ag, with QF-CMV inversely predicting GvHD. Lymphocyte and neutrophil counts were positively linked to both tests.

Conclusion

The findings suggest that QF-CMV and QFM tests could predict GvHD and CMV infection risk and help identify high-risk patients, contributing to personalized prevention strategies and improving CMV treatment. Despite the small sample size, this study is an essential proof of concept due to the unique patient population of pediatric bone marrow stem cell transplant recipients. Further multicenter studies are needed to validate these results.

Cytomegalovirus Infections in Hematopoietic Stem Cell Transplant: Moving Beyond Molecular Diagnostics to Immunodiagnostics

Human CMV, regularly reactivated by simple triggers, results in asymptomatic viral shedding, powerful cellular immune responses, and memory inflation. Immunocompetent individuals benefit from a robust immune response, which aids in viral management without causing clinically significant illness; however, immunodeficient individuals are always at a higher risk of CMV reactivation and disease. Hematopoietic stem cell transplant (HSCT) recipients are consistently at higher risk of CMV reactivation and clinically significant CMV illness due to primary disease, immunosuppression, and graft vs. host disease. Early recovery of CMV-CMI responses may mitigate effects of viral reactivation in HSCT recipients. Immune reconstitution following transplantation occurs spontaneously and is mediated initially by donor-derived T cells, followed by clonal growth of T cells produced from graft progenitors. CMV-specific immune reconstitution post-transplant is related to spontaneous clearance of CMV reactivation and may eliminate the need for prophylactic or pre-emptive medication, making it a potential predictive marker for monitoring CMV reactivation. This review highlights current thoughts and therapeutic options for CMV reactivation in HSCT, with focus on CMV immune reconstitution and post-HSCT monitoring. Immune monitoring aids in risk stratification of transplant recipients who may progress from CMV reactivation to clinically significant CMV infection. Implementing this approach in clinical practice reduces the need for periodic viral surveillance and antiviral therapy in recipients who have a high CMV-CMI and thus may experience self-limited reactivation. Therefore, in the age of precision medicine, it is critical to incorporate CMV-specific cellular immune surveillance into conventional procedures and algorithms for the management of transplant recipients.

QuantiFERON monitor predicts early cytomegalovirus infection and viral burden in allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Cytomegalovirus (CMV) infection is a major cause of transplantation-related morbidity and mortality. This study assessed the utility of the QuantiFERON monitor (QFM; Qiagen) for the prediction of early CMV infection and viral burden.

METHODS

QuantiFERON-CMV (QF-CMV; Qiagen) and QFM were measured at the post-allogeneic hematopoietic stem cell transplantation (HSCT) week 4. CMV DNA was measured at every visit until post-HSCT week 24. The QFM cutoff specific to CMV infection was established.

RESULT

At the post-HSCT week 4, the QFM cutoff predicting CMV infection was 86.95 IU/mL. While QF-CMV results at the post-HSCT week 4 were associated with high-level CMV infection (CMV DNA ≥ 5,000 IU/mL) but not with CMV infection (CMV DNA ≥ 500 IU/mL), QFM was associated with both CMV infection and high-level CMV infection. Both indeterminate QF-CMV and nonreactive QFM were associated with increased peak CMV DNA.

CONCLUSION

Low QFM is a risk factor for CMV infection and increased CMV viral loads. QFM at post-HSCT week 4 can be utilized as an assay to predict the risk and burden of early CMV infection in HSCT recipients, in conjunction with other risk factors.

Impaired T cells and "memory-like" NK-cell reconstitution is linked to late-onset HCMV reactivation after letermovir cessation

ABSTRACT

Allogeneic hematopoietic stem cell transplantation (alloSCT) is the only cure for many hematologic malignancies. However, alloSCT recipients are susceptible to opportunistic pathogens, such as human cytomegalovirus (HCMV). Letermovir prophylaxis has revolutionized HCMV management, but the challenge of late HCMV reactivations has emerged. Immunological surrogates of clinically significant HCMV infection (csCMVi) after discontinuation of letermovir remain to be defined. Therefore, we studied natural killer (NK)-cell reconstitution along with the global and HCMV pp65-specific T-cell repertoire of 24 alloSCT recipients at 7 time points before (day +90) and after (days +120-270) cessation of letermovir prophylaxis. Patients who experienced csCMVi had lower counts of IFN-γ+ HCMV-specific CD4+ and CD8+ T cells than HCMV controllers. Furthermore, patients with csCMVi displayed late impairment of NK-cell reconstitution, especially suppression of "memory-like" CD159c+CD56dim NK-cell counts that preceded csCMVi events in most patients. Moreover, several surrogates of immune reconstitution were associated with the severity of HCMV manifestation, with patients suffering from HCMV end-organ disease and/or refractory HCMV infection harboring least HCMV-specific T cells and "memory-like" NK cells. Altogether, our findings establish an association of delayed or insufficient proliferation of both HCMV-specific T cells and "memory-like" NK cells with csCMVi and the severity of HCMV manifestations after discontinuation of letermovir prophylaxis.

Cytomegalovirus Cell-mediated Immunity Assays in Pediatric Transplantation

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality in pediatric transplantation. However, currently utilized CMV prevention paradigms have limitations, leading to research aimed at novel strategies for mitigation of CMV infection. Cell-mediated immunity (CMI) is crucial in controlling CMV infection and the use of CMV-specific CMI assays to guide prevention and treatment of CMV infection in both solid organ transplant and hematopoietic cell transplant recipients shows great promise. In this article, we review the immune response to CMV infection to highlight the rationale for CMI assays, describe available commercial assays and strategies for their use, and summarize relevant literature regarding the use of CMI assays in transplant recipients.

QuantiFERON-CMV and monitor predict cytomegalovirus, mortality, and graft-versus-host disease in transplant recipients

Cytomegalovirus (CMV) is the most prevalent infection in recipients of hematopoietic stem cell transplant (HSCT). QuantiFERON-CMV (QF-CMV) and QuantiFERON-Monitor (QFM) assays were used to test whether immune-competent adult allogeneic HSCT recipients with CMV-specific T cells can control CMV infection or reactivation. Our data demonstrated a significant correlation between CMV infection measured by CMV-antigenemia test and QF-CMV results, graft versus host disease (GvHD), and mortality rates. The QF-CMV test revealed that CMV-specific T cells with higher interferon-γ (IFN-γ) release were correlated with lower CMV infection rates. There was a significant negative association between QF-CMV results, GvHD, and mortality rates. Data showed that a one-unit rise in IFN-γ was linked with a 12.7% reduction in GvHD and a 20.7% reduction in the mortality odds ratio. In addition, a negative correlation was found between QF-M results and CMV infection, with the QFM test predicting protection against CMV infection by 1.9%. This is one of the few studies establishing the QF-CMV test's predictive value for GvHD and mortality, its use to monitor HSCT patients for pre-emptive therapy, and the use of the QFM test to predict CMV infection and mortality in HSCT patients. Thus, these assays could be utilized to optimize preventive and pre-emptive therapy procedures to reduce transplant recipient adverse effects and posttransplant therapy costs.

CMV-IgG pre-allogeneic hematopoietic stem cell transplantation and the risk for CMV reactivation and mortality

Cytomegalovirus (CMV) represents one of the most common infectious complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Currently, a common diagnostic test used to stratify the risk for CMV infection in allo-HSCT recipients is the qualitative CMV serology of donor and recipient. A positive serostatus of the recipient is the most important risk factor for CMV reactivation and associated with reduced overall survival post-transplantation (TX). Direct and indirect effects of CMV are involved in the poorer survival outcome. The present study investigated if the quantitative interpretation of anti-CMV IgG before allo-HSCT might serve as a novel parameter for the identification of patients at risk for CMV reactivation and worse outcome post-TX. For this purpose, a cohort of 440 allo-HSCT recipients over a period of 10 years was retrospectively analyzed. Our findings indicated that patients with high CMV IgG pre-allo-HSCT had a higher risk to develop CMV reactivation, including clinically relevant infections, and a worse prognosis 36 months post-allo-HSCT as compared to recipients with low CMV IgG values. In the letermovir (LMV) era, this group of patients might benefit from a closer CMV monitoring, and hence, earlier intervention if needed, especially after discontinuation of prophylaxis.

CD4+ T cells are the major predictor of HCMV control in allogeneic stem cell transplant recipients on letermovir prophylaxis

Introduction

Human cytomegalovirus (HCMV) causes significant morbidity and mortality in allogeneic stem cell transplant (alloSCT) recipients. Recently, antiviral letermovir prophylaxis during the first 100 days after alloSCT replaced PCR-guided preemptive therapy as the primary standard of care for HCMV reactivations. Here, we compared NK-cell and T-cell reconstitution in alloSCT recipients receiving preemptive therapy or letermovir prophylaxis in order to identify potential biomarkers predicting prolonged and symptomatic HCMV reactivation.

Methods

To that end, the NK-cell and T-cell repertoire of alloSCT recipients managed with preemptive therapy (n=32) or letermovir prophylaxis (n=24) was characterized by flow cytometry on days +30, +60, +90 and +120 after alloSCT. Additionally, background-corrected HCMV-specific T-helper (CD4+IFNγ+) and cytotoxic (CD8+IFNγ+CD107a+) T cells were quantified after pp65 stimulation.

Results

Compared to preemptive therapy, letermovir prophylaxis prevented HCMV reactivation and decreased HCMV peak viral loads until days +120 and +365. Letermovir prophylaxis resulted in decreased T-cell numbers but increased NK-cell numbers. Interestingly, despite the inhibition of HCMV, we found high numbers of "memory-like" (CD56dimFcεRIγ- and/or CD159c+) NK cells and an expansion of HCMV-specific CD4+ and CD8+ T cells in letermovir recipients. We further compared immunological readouts in patients on letermovir prophylaxis with non/short-term HCMV reactivation (NSTR) and prolonged/symptomatic HCMV reactivation (long-term HCMV reactivation, LTR). Median HCMV-specific CD4+ T-cell frequencies were significantly higher in NSTR patients (day +60, 0.35 % vs. 0.00 % CD4+IFNγ+/CD4+ cells, p=0.018) than in patients with LTR, whereas patients with LTR had significantly higher median regulatory T-cell (Treg) frequencies (day +90, 2.2 % vs. 6.2 % CD4+CD25+CD127dim/CD4+ cells, p=0.019). ROC analysis confirmed low HCMV specific CD4+ (AUC on day +60: 0.813, p=0.019) and high Treg frequencies (AUC on day +90: 0.847, p=0.021) as significant predictors of prolonged and symptomatic HCMV reactivation.

Discussion

Taken together, letermovir prophylaxis delays HCMV reactivation and alters NK- and T-cell reconstitution. High numbers of HCMV-specific CD4+ T cells and low numbers of Tregs seem to be pivotal to suppress post-alloSCT HCMV reactivation during letermovir prophylaxis. Administration of more advanced immunoassays that include Treg signature cytokines might contribute to the identification of patients at high-risk for long-term and symptomatic HCMV reactivation who might benefit from prolonged administration of letermovir.

Immunological monitoring after allogeneic stem cell transplantation: T-SPOT.CMV and QuantiFERON-CMV, are they the same?

BACKGROUND

CMV-reactivation and -disease is still a major concern after allogeneic stem cell transplantation [allo-HSCT], despite prophylactic and pre-emptive strategies. In recent years, immunologic monitoring using CMV-IGRA has gained interest to better risk stratify immunocompromised patients or to guide prophylactic therapies. CMV-IGRA can quantify CMV cell-mediated immunity by measuring the interferon-gamma that is released by CD4+ and CD8+ T-lymphocytes in the presence of CMV-antigens. However, the two most widely used CMV-IGRAs, T-SPOT.CMV and QuantiFERON-CMV, have not yet been compared in the setting of an allo-HSCT.

OBJECTIVE

To perform a method comparison between the T-SPOT.CMV and QuantiFERON-CMV 28 and 100 days after allo-HSCT, and to assess predictive values of both tests for CMV-reactivation.

STUDY DESIGN

In a bicentric prospective trial, 27 patients were included. Samples were taken on day +28 and day +100 after allo-HSCT. Patients' clinical information was collected up to 270 days after the transplant. Method comparison was performed using Cohen's kappa.

RESULTS

On day +28 (n=26) after allo-HSCT T-SPOT.CMV gave three positive test results, and QuantiFERON-CMV only two. On day +100 (n=24) T-SPOT.CMV gave seven positive test results, and QuantiFERON-CMV nine. One discordant result was obtained at day +28 (n=26), while six results were discordant at day +100 (n=24). Method comparison showed a strong agreement on day +28 (κ = 0.780 [95% CI: 0.366-1.000]), but only a moderate agreement on day +100 (κ = 0.442 [95% CI: 0.070-0.814]) and on pooled data from both time points (κ = 0.578 [95% CI: 0.300-0.856]). Four clinically significant CMV infections, (CS-CMVi) were observed, all occurring after discontinuation of letermovir-prophylaxis. None of those four patients had a positive result with either test at day +100 (or day +28). Negative predictive values (NPV) and sensitivity are therefore very high at 100% (for both tests, for NPV and sensitivity, measured at day +100). At day+100, positive predictive values (PPV) and specificity were considerably lower (T-SPOT.CMV: PPV 23.5% and specificity 35% - QuantiFERON-CMV: PPV 26.7% and specificity 45%).

CONCLUSION

T-SPOT.CMV and QuantiFERON-CMV only have a moderate agreement (at day +100) after allo-HSCT. Although these IGRAs are very promising, as shown by their very high negative predictive values for protection against CS-CMVi, they are not interchangeable. Future research should stipulate which IGRA was used, and future guidelines should preferably be assay-specific. As the QuantiFERON-CMV to date still lacks a large validation study after allo-HSCT, the moderate agreement with the T-SPOT.CMV poses a significant hurdle in the routine implementation of this test.

Immune Monitoring Using QuantiFERON®-CMV Assay in Congenital Cytomegalovirus Infection: Correlation With Clinical Presentation and CMV DNA Load

BACKGROUND

Cytomegalovirus (CMV)-specific CD8 + T-cell responses can be detected early in fetal life, but their role in the manifestations of congenital CMV (cCMV) infection remains largely unknown.

METHODS

CMV-specific CD8 + T-cell responses were assessed in neonates with cCMV using QuantiFERON®-CMV assay, within day 14 of life (T0) and during the second month of life (T1). Detection and quantification of CMV DNA in whole blood and urine samples were performed at both time points. QuantiFERON®-CMV results were evaluated in relation to timing of maternal infection, clinical manifestations of cCMV and CMV DNA levels.

RESULTS

Thirty neonates were enrolled (10/30 [33%] symptomatic; 20/30 [67%] asymptomatic). At T0 16/30 (53%) subjects had a reactive QuantiFERON®-CMV result and 16/16 (100%) were asymptomatic, whereas 14/30 (47%) had a nonreactive or indeterminate QuantiFERON®-CMV result and 4/14 (29%) were asymptomatic. At T1, 17/29 (59%) subjects had a reactive QuantiFERON®-CMV result, and 17/17 (100%) were asymptomatic, whereas 12/29 (41%) had a nonreactive or indeterminate result and 3/12 (25%) were asymptomatic. At both T0 and T1 reactive QuantiFERON®-CMV results correlated with lack of symptoms (P = .0001). At T1 median CMV DNAemia was lower in subjects with reactive QuantiFERON®-CMV results as compared with subjects with nonreactive or indeterminate results (1.82 log IU/mL [1.82-2.89] vs 2.55 log IU/mL [1.82-4.42], P = .009). No correlation was found between QuantiFERON®-CMV results and gestational age at maternal infection nor with urine CMV DNA levels.

CONCLUSIONS

A detectable CMV-specific CD8 + T-cell response, evaluated using the QuantiFERON®-CMV assay, correlates with the lack of CMV-related symptoms and the control of CMV DNAemia.

Patient risk stratification and tailored clinical management of post-transplant CMV-, EBV-, and BKV-infections by monitoring virus-specific T-cell immunity

Background

Despite routine post-transplant viral monitoring and pre-emptive therapy, viral infections remain a major cause of allogeneic hematopoietic cell transplantation-related morbidity and mortality.

Objective

We here aimed to prospectively assess the kinetics and the magnitude of cytomegalovirus-(CMV), Epstein Barr virus-(EBV), and BK virus-(BKV)-specific T cell responses post-transplant and evaluate their role in guiding therapeutic decisions by patient risk-stratification.

Study design

The tri-virus-specific immune recovery was assessed by Elispot, in 50 consecutively transplanted patients, on days +20, +30, +60, +100, +150, +200 post-transplant and in case of reactivation, weekly for 1 month.

Results

The great majority of the patients experienced at least one reactivation, while over 40% of them developed multiple reactivations from more than one of the tested viruses, especially those transplanted from matched or mismatched unrelated donors. The early reconstitution of virus-specific immunity (day +20), favorably correlated with transplant outcomes. Εxpanding levels of CMV-, EBV-, and BKV-specific T cells (VSTs) post-reactivation coincided with decreasing viral load and control of infection. Certain cut-offs of absolute VST numbers or net VST cell expansion post-reactivation were determined, above which, patients with CMV or BKV reactivation had >90% probability of complete response (CR).

Conclusion

Immune monitoring of virus-specific T-cell reconstitution post-transplant may allow risk-stratification of virus reactivating patients and enable patient-tailored treatment. The identification of individuals with high probability of CR will minimize unnecessary overtreatment and drug-associated toxicity while allowing candidates for pre-emptive intervention with adoptive transfer of VSTs to be appropriately selected.

CMV-Specific Cell-Mediated Immunity in Immunocompetent Adults with Primary CMV Infection: A Case Series and Review of the Literature

Cytomegalovirus-specific cell-mediated immunity (CMV-CMI) in actively infected healthy immunocompetent hosts has been poorly investigated. Conversely, correlates of maternal protective immunity for the fetus after primary infection in pregnancy continue to be studied. The kinetics and magnitude of CMV-specific CMI in immunocompetent primary CMV-infected adults are described. A literature review on CMV-CMI in primarily infected pregnant women and its correlation to the risk of vertical virus transmission is included. Immunological measurements after infection were performed by enzyme-linked ImmunoSPOT assay enumerating IFN-γ secreting CMV-specific T cells, at a single cell level, upon in vitro stimulation with viral antigens. Simultaneously, serological and virological profiles of infected patients were investigated. Patients displayed mild-to-moderate clinical and laboratory profiles for infection, and all showed positive EliSpot results in the early stage of infection (<20 days after onset). The virus-CMI was strong in the majority of patients (58.8%) in which the lowest CMV-DNAemia levels (<300 copies/mL) were detected. Significantly higher viral loads were observed in patients with weak CMV-CMI at the same time-point post-infection (up to 15,104 copies/mL; p < 0.001). T cell response magnitudes to IE-1 and pp65-UL83 peptides were overlapping and stable over time. In these case series, the early presence of CMV-CMI was probably pivotal in controlling viral replication and led to spontaneous viral clearance.

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

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.

Usefulness of BK virus-specific interferon-γ enzyme-linked immunospot assay for predicting the outcome of BK virus infection in kidney transplant recipients

BACKGROUND/AIMS

To investigate if BK virus (BKV)-specific T cell immunity measured by an interferon-γ enzyme-linked immunospot (ELISPOT) assay can predict the outcome of BK virus infection in kidney transplant recipients (KTRs).

METHODS

We included 68 KTRs with different viremia status (no viremia [n = 17], BK viremia [n = 27], and cleared viremia [n = 24]) and 44 healthy controls (HCs). The BK viremia group was divided into controller (< 3 months) and noncontroller (> 3 months) according to sustained duration of BKV infection. We compared BKV-ELISPOT results against five BKV peptides (large tumor antigen [LT], St, VP1-3).

RESULTS

BKV-ELISPOT results were higher in three KTRs groups with different BKV infection status than the HCs group (p < 0.05). In KTR groups, they were higher in cleared viremia group than no viremia or BK viremia group. Within the BK viremia group, controller group had higher LT-ELISPOT results compared to noncontroller group (p = 0.032). Also, KTRs without BK virus-associated nephropathy (BKVN) had higher LT, St, VP1, and VP2-ELISPOT results than those with BKVN (p < 0.05).

CONCLUSION

BKV-ELISPOT assay may be effective in predicting clinical outcomes of BKV infection in terms of clearance of BK virus and development of BKVN.

Virus-specific T cells in pediatric renal transplantation

After pediatric kidney transplantation, immunosuppressive therapy causes an increased risk of severe viral complications, especially from cytomegalovirus (CMV), BK polyomavirus (BKPyV) or Epstein-Barr virus (EBV), and less frequent from adenovirus (ADV). However, suitable predictive markers for the individual outcome of viral infections are missing and the therapeutic management remains a challenge to the success of pediatric kidney transplantation. Virus-specific T cells are known for controlling viral replication and there is growing evidence that virus-specific T cells may serve as a prognostic marker to identify patients at risk for viral complications. This review provides an overview of the usability of virus-specific T cells for improving diagnostic and therapeutic management of viral infections with reference to the necessity of antiviral prophylaxis, timing of pre-emptive therapy, and dosing of immunosuppressive medication after pediatric kidney transplantation. Several studies demonstrated that high levels of virus-specific T cells are associated with decrease of virus load and favorable outcome, whereas lack of virus-specific T cells coincided with virus-induced complications. Accordingly, the additional monitoring of virus-specific T cells aims to personalize the management of antiviral therapy, identify overimmunosuppression, and avoid unnecessary therapeutic interventions. Prospective randomized trials in pediatric kidney recipients comparing standard antiviral and immunosuppressive regimens with T cell-guided therapeutic interventions are needed, before monitoring of virus-specific T cells is implemented in the routine care of pediatric kidney graft recipients.

How I treat CMV reactivation after allogeneic hematopoietic stem cell transplantation

Cytomegalovirus (CMV) reactivation remains one of the most common and life-threatening infectious complications following allogeneic hematopoietic stem cell transplantation, despite novel diagnostic technologies, several novel prophylactic agents, and further improvements in preemptive therapy and treatment of established CMV disease. Treatment decisions for CMV reactivation are becoming increasingly difficult and must take into account whether the patient has received antiviral prophylaxis, the patient's individual risk profile for CMV disease, CMV-specific T-cell reconstitution, CMV viral load, and the potential drug resistance detected at the time of initiation of antiviral therapy. Thus, we increasingly use personalized treatment strategies for the recipient of an allograft with CMV reactivation based on prior use of anti-CMV prophylaxis, viral load, the assessment of CMV-specific T-cell immunity, and the molecular assessment of resistance to antiviral drugs.

Update on prevention of cytomegalovirus in hematopoietic cell transplantation

PURPOSE OF REVIEW

Cytomegalovirus infection (CMVi) has been the troll of allogeneic hematopoietic cell transplantation (allo-HCT). Over the last 4 decades various approaches have been adopted to minimize the burden from CMVi. There has been major advancement in the management of CMVi in HCT within the last few years that is poised to change the approaches employed in preventing and managing CMVi. This review will summarize recent advances and potential future development in the management of CMV in HCT.

RECENT FINDING

The major development has been the approval of letermovir for the prevention of CMVi in allo-HCT recipients. Also, with the potential availability of tests that can determine host CMV immunity a risk adapted approach to CMV prevention may become a possibility.

SUMMARY

The landscape of CMV prevention is about to change with the approval of a new anti-CMV antiviral that is safe and effective. However, the prophylaxis may lead to late onset CMVi in the context of ongoing risk factors after stopping prophylaxis and measures to counter this shifting epidemiology will need further research; such as extending the prophylaxis in high-risk patients vs. immunotherapy with vaccination and T-cell therapy.

Quantiferon-Cytomegalovirus assay: A potentially useful tool in the evaluation of CMV-specific CD8+ T-cell reconstitution in pediatric hematopoietic stem cell transplant patients

Pediatric HSCT recipients are at high risk for CMV reactivation due to their immature immune system and therapy following transplantation. Reconstitution of CMV-specific T-cell immunity is associated with control and protection against CMV. The clinical utility of monitoring CMV-specific CMI to predict CMV viremia in pediatric HSCT patients using the Quantiferon-CMV (QIAGEN^® ) test was investigated prospectively. Thirty-seven pediatric allogeneic HSCT recipients were enrolled from 3/2010-6/2012. CMV viremia was detected via weekly real-time PCR. The Quantiferon-CMV test was conducted pretransplant, early after transplantation, 30, 90, 180, 270, and 360 days post-transplantation. The incidence of CMV viremia was 51% (19/37) with half of the episodes within ≤30 days post-transplant. Fifteen patients showed CMV-specific immunity (average of 82 days). The cumulative incidence of CMV reactivation in patients who developed CMV-specific immunity was lower than those who did not (15% vs 53%; P = .023). The ROC statistical analysis showed that the AUC was 0.725 in predicting viremia, for Quantiferon-CMV test. In this cohort, the Quantiferon-CMV assay was a valuable method for identifying pediatric HSCT patients at high risk for CMV viremia, suggesting potential clinical utility to individualize patient's management post-transplant.

Immune Monitoring for CMV in Transplantation

PURPOSE OF REVIEW

Immune monitoring to determine when and how the recovery of cytomegalovirus (CMV)-specific T-cells occurs post-transplantation may help clinicians to risk stratify individuals at risk of complications from CMV. We aimed to review all recent clinical studies using CMV immune monitoring in the pre- and post-transplant setting including the use of recently developed standardized assays (Quantiferon-CMV and the CMV ELISPOT) to better understand in whom, when, and how immune monitoring is best used.

RECENT FINDINGS

Pre-transplant assessment of CMV immunity in solid-organ transplant recipients where CMV seropositive recipients had undetectable cell-mediated responses despite past immunity has shown that they are at a much higher risk of developing CMV reactivation. Post-transplant CMV immune monitoring can guide (shorten or prolong) the duration of antiviral prophylaxis, identify recipients at risk of post-prophylaxis CMV disease, and predict recurrent CMV reactivation. Thus, CMV immune monitoring, in addition to current clinical and DNA-based monitoring for CMV, has the potential to be incorporated into routine clinical care to better improve CMV management in both the stem and solid-organ transplant population.

Betaherpesvirus Complications and Management During Hematopoietic Stem Cell Transplantation

Two of the four betaherpesviruses, Cytomegalovirus (CMV) and human herpesvirus 6B (HHV-6B), play an important role in opportunistic infections in hematopoietic stem cell transplant (HSCT) recipients. These viruses are ubiquitous in humans and can latently infect mononuclear lymphocytes, complicating the diagnosis of the diseases they cause. Although the detection of viral DNA in a patient's peripheral blood by real-time PCR is widely used for monitoring viral infection, it is insufficient for the diagnosis of virus-associated disease. Theoretically, end-organ disease should be confirmed by detecting either viral antigen or significant amounts of viral DNA in a tissue sample obtained from the involved organ; however, this is often difficult to perform in clinical practice. The frequency of CMV-associated diseases has decreased gradually as a result of the introduction of preemptive or prophylactic treatments; however, CMV and HHV-6B infections remain a major problem in HSCT recipients. Measurement of viral DNA load in peripheral blood or plasma using real-time PCR is commonly used for monitoring these infections. Additionally, recent data suggest that an assessment of host immune response, particularly cytotoxic T-cell response, may be a reliable tool for predicting these viral infections. The antiviral drugs ganciclovir and foscarnet are used as first-line treatments; however, it is well known that these drugs have side effects, such as bone marrow suppression and nephrotoxicity. Further research is required to develop less-toxic antiviral drugs.

Low T-Cell Responses to Mitogen Stimulation Predicts Poor Survival in Recipients of Allogeneic Hematopoietic Stem Cell Transplantation

Background

Successful engraftment and reconstitution of the innate and adaptive immune system are associated with improved outcomes in recipients of allogeneic hematopoietic stem cell transplantation (HSCT). A clinically meaningful and simple biomarker of immunosuppression could potentially assist clinicians in their decision-making. We aimed to determine the relationship between T-cell production of interferon gamma (IFN-γ) in response to phytohemagglutinin (PHA) to clinical outcomes in HSCT recipients.

Methods

A prospective observational multicenter study of 73 adult allogeneic HSCT recipients was conducted in Melbourne, Australia. Eligible participants were >18 years and at risk of cytomegalovirus disease. T-cell responses to PHA were assessed at 3, 6, 9, and 12 months post-HSCT using the commercial quantiferon-cytomegalovirus assay, which quantifies IFN-γ production by ELISA following stimulation with PHA. A low response was defined as IFN-γ <0.5 IU/ml following stimulation with PHA.

Results

At 3 months post-HSCT, high responses to PHA (median IFN-γ 7.68 IU/ml) were seen in 63% of participants and low responses to PHA (median IFN-γ 0.06 IU/ml) in 37%. IFN-γ responses to PHA were significantly associated with the severity of acute graft versus host disease (AGVHD) (spearman r = −0.53, p < 0.001) and correlated with blood lymphocyte count (spearman r = 0.52, p < 0.001). Twelve month overall survival was greater in individuals with high compared to low IFN-γ response to PHA at 3 months [92 vs. 62%, respectively, Cox proportional hazard ratio (HR): 4.12 95% CI: 1.2–13.7, p = 0.02]. Non-relapse mortality (NRM) was higher in individuals with low IFN-γ response to PHA (competing risk regression HR 11.6 p = 0.02). In individuals with no AGVHD compared to AGVHD and high IFN-γ response to PHA compared to AGVHD and low IFN-γ response to PHA, 12-month survival was 100 vs. 80 vs. 52%, respectively (log rank test p < 0.0001).

Conclusion

Low IFN-γ response to PHA at the 3-month time-point following allogeneic HSCT was predictive of reduced 12-month overall survival, increased NRM, and reduced survival in recipients with AGVHD. Assessing IFN-γ response to PHA post-HSCT may be a clinically useful immune biomarker.