Recent advances in cytomegalovirus: an update on pharmacologic and cellular therapies

Cytomegalovirus Pneumonia in a Patient with Down Syndrome

Down syndrome (DS) is a chromosomal disorder due to the presence of an additional chromosome 21 that causes intellectual deficit and physical anomalies and predisposes patients to develop infections throughout their lives. Pneumonias are more serious in patients with DS, requiring hospitalization, and they represent an important cause of mortality in this population. Cytomegalovirus (CMV) causes widespread and serious infections in immunocompromised individuals, affecting the respiratory tract and, when causing interstitial pneumonia, associated with a high mortality rate. However, CMV-induced pneumonia is not reported in DS patients. The prevalence and severity of CMV respiratory infections in subjects with DS is unknown. This case describes a 50-year-old female patient with DS who developed extensive bilateral pneumonia with severe respiratory failure which required hospitalization in intensive care, intubation, and mechanical ventilation after approximately 10 days of empiric antibiotic and anitimycotic therapy for fever, cough, and dyspnea. The patient was diagnosed with CMV pneumonia and recovered after treatment with ganciclovir. To the best of our knowledge, this is the first reported case of CMV pneumonia in a patient with DS. This case aims to highlight that CMV pneumonia in individuals with DS can be a life-threatening condition. It also clarifies the importance of early diagnosis of infections from opportunistic pathogens such as CMV to ensure timely and efficient treatment.

Outcomes of allogeneic hematopoietic cell transplantation under letermovir prophylaxis for cytomegalovirus infection

Cytomegalovirus (CMV) infection is a major infectious complication following allogeneic hematopoietic cell transplantation (allo-HCT). Although letermovir (LMV) prophylaxis dramatically reduces the incidence of early clinically significant CMV (csCMV) infection, it remains unclear whether it has a beneficial effect on nonrelapse mortality (NRM) and overall survival (OS). Herein, we evaluated the impact of LMV prophylaxis on posttransplant outcomes using the registry database of the Japanese Society for Transplantation and Cellular Therapy. Adult patients who underwent allo-HCT between 2017 and 2019 were analyzed (n = 6004). LMV prophylaxis was administered to 1640 patients (LMV group) and it significantly reduced the incidence of csCMV infection compared with those not administered LMV prophylaxis (15.4% vs 54.1%; p < 0.01). However, it did not improve the 1-year NRM (hazard ratio [HR], 0.93; p = 0.40) and OS (HR, 0.96; p = 0.49). In the LMV group, 74 patients had breakthrough csCMV infection and showed inferior NRM (HR, 3.44; p < 0.01) and OS (HR, 1.93; p = 0.02) compared with those without infection. After completing LMV prophylaxis, 252 patients had late csCMV infection and showed inferior NRM (HR, 1.83; p < 0.01) and OS (HR, 1.58; p < 0.01). Our findings suggest that managing breakthrough and late csCMV infections is important for improving long-term outcomes.

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.

Herpesviruses in Critically Ill Patients With ARDS

Reactivation of herpsviruses, mainly HSV, CMV and EBV, are frequent among critically ill patients. Although they are not immunocompromised from a classical point of view, these patients often present an alteration of their immune system favoring viral reactivation. Seropositive patients with sepsis and under mechanical ventilation are particularly at risk. Herpesviruses have a pulmonary tropism and can be responsible for non-resolving forms of acute respiratory distress syndrome with high mortality. However, the direct causality between herpesviruses reactivation and impaired outcomes among severely ill patients remains under debate.

Incidence of refractory cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation

Post-transplant cytomegalovirus (CMV) disease can be almost completely avoided by current infection control procedures. However, CMV reactivation occurs in more than half of patients, and some patients can develop clinically resistant CMV infections. Whether resistance is due to the host's immune status or a viral resistance mutation is challenging to confirm. Therefore, a prospective observational analysis of refractory CMV infection was conducted in 199 consecutive patients who received allogeneic hematopoietic stem cell transplantation at a single institution. Among them, 143 (72%) patients received anti-CMV drugs due to CMV reactivation, and only 17 (8.5%) exhibited refractory CMV infection. These patients had clinically refractory infection. However, viral genome analysis revealed that only one patient exhibited a mutation associated with the anti-CMV drug resistance. Clinical resistance was mainly correlated with host immune factors, and the incidence of resistance caused by gene mutations was low at the early stage after a transplantation.

In-depth summary over cytomegalovirus infection in allogeneic hematopoietic stem cell transplantation recipients

In this study, we reviewed various aspects of cytomegalovirus infection, including pathophysiology, diagnosis methods, and antiviral treatments. Background: Infections continue to be a major reason of complications like high non-relapse morbidity and mortality rate after allogenic hematopoietic stem cell transplantation. Cytomegalovirus is the most common infection in immunocompromised patients or those with graft-versus-host disease. The Latent-cytomegalovirus disease could increase the risk of reactivation in allogenic hematopoietic stem cell transplantation patients and lead to profound adverse effects on transplantation outcomes. Cytomegalovirus-specific CD4 + and CD8 + T cells reconstitution is crucial for protection against the virus reactivation. Different prophylactic, pre-emptive, and therapeutic anti-viral drugs are available to prevent cytomegalovirus infection/reactivation and treat resistant infections. Conclusion: Although there has been introduced various CMV antiviral treatment strategies like antiviral drugs, Vaccination, passive immunotherapies and adoptive transfer of CMV-specific T cells, further clinical trials are required to approve current therapies.

Update in Viral Infections in the Intensive Care Unit

The advent of highly sensitive molecular diagnostic techniques has improved our ability to detect viral pathogens leading to severe and often fatal infections that require admission to the Intensive Care Unit (ICU). Viral infections in the ICU have pleomorphic clinical presentations including pneumonia, acute respiratory distress syndrome, respiratory failure, central or peripheral nervous system manifestations, and viral-induced shock. Besides de novo infections, certain viruses fall into latency and can be reactivated in both immunosuppressed and immunocompetent critically ill patients. Depending on the viral strain, transmission occurs either directly through contact with infectious materials and large droplets, or indirectly through suspended air particles (airborne transmission of droplet nuclei). Many viruses can efficiently spread within hospital environment leading to in-hospital outbreaks, sometimes with high rates of mortality and morbidity, thus infection control measures are of paramount importance. Despite the advances in detecting viral pathogens, limited progress has been made in antiviral treatments, contributing to unexpectedly high rates of unfavorable outcomes. Herein, we review the most updated data on epidemiology, common clinical features, diagnosis, pathogenesis, treatment and prevention of severe community- and hospital-acquired viral infections in the ICU settings.

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.

Progress and Challenges in the Prevention, Diagnosis, and Management of Cytomegalovirus Infection in Transplantation

Hosts with compromised or naive immune systems, such as individuals living with HIV/AIDS, transplant recipients, and fetuses, are at the highest risk for complications from cytomegalovirus (CMV) infection. Despite substantial progress in prevention, diagnostics, and treatment, CMV continues to negatively impact both solid-organ transplant (SOT) and hematologic cell transplant (HCT) recipients. In this article, we summarize important developments in the field over the past 10 years and highlight new approaches and remaining challenges to the optimal control of CMV infection and disease in transplant settings.

High-efficient generation of natural killer cells from peripheral blood with preferable cell vitality and enhanced cytotoxicity by combination of IL-2, IL-15 and IL-18

Natural killer (NK) cells are pivotal effector lymphocytes characterized for the innate immune response to pathogenic microorganism and tumor cells without priming and sensitization. Despite emerging knowledge has highlighted the rosy prospects in tumor immunosurveillance, yet the large-scale clinical application of NK cell-based therapy is hindered largely attributes to the defects in generating sufficient and high-quality cellular products. Herein, on the basis of 16 kinds of candidate combinations, we investigated the feasibility of cytokine cocktail-based strategy for convenient and standardized NK cell cultivation as well as the multifaceted characteristics and cytotoxicity against tumor cells. Our results revealed that joint utilization of Interleukin (IL)-2, IL-15, IL-18 manifested the optimal facilitation upon the ex vivo expansion and proportion of NK cells in peripheral blood mononuclear cells (PBMCs). Meanwhile, the obtained NK cell population expressed high levels of activating molecules (CD16 and NKG2D) and exhibited splendid cytotoxicity against K562 cell line. Collectively, with the aid of cytokine-based programming, we established an alternative strategy for facilitating the large-scale persistence and activation of NK cells from peripheral blood, which would benefit the NK cell- and chimeric antigen receptor-modified NK (CAR-NK) cell-based autologous or allogeneic tumor immunotherapy.

Cost-effectiveness of letermovir as cytomegalovirus prophylaxis in adult recipients of allogeneic hematopoietic stem cell transplantation in Hong Kong

BACKGROUND

The cost-effectiveness of letermovir as cytomegalovirus (CMV) prophylaxis in adult seropositive patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT), compared with the conventional strategy of preemptive treatment, has not been evaluated in Asia.

METHODS

A decision analytical model, simulating the clinical progression of CMV infection on a lifetime horizon, was developed to compare prophylactic strategy with letermovir with preemptive therapy alone as anti-CMV strategies. Prophylaxis comprised administering letermovir for 14 weeks, with clinical outcomes measured at 24 weeks, followed by preemptive therapy if CMV infection occurred. This approach was modeled on outcomes of the letermovir phase 3 clinical study. The model enumerated the cost of letermovir prophylaxis, quality-adjusted life years (QALYs), and incremental cost per QALYs gained with prophylaxis. The opposite arm involved regular monitoring and preemptive therapy for CMV reactivation. Real-world costs from the adult HSCT center at Queen Mary Hospital, Hong Kong, were adopted for analysis. Costs and clinical benefits, expressed as QALYs, were discounted at 3% per year.

RESULTS

Letermovir prophylaxis compared with preemptive therapy only would lead to an increase of life-year and QALYs at increased costs. Incremental cost-effectiveness analysis showed that letermovir prophylaxis had an associated cost of HKD 193,580 for each life-year gained, and HKD 234,675 for each QALY gained. Probabilistic sensitivity analysis showed that the majority of incremental cost-effectiveness ratio fell below the cost-effectiveness threshold of HKD 382,046 (one gross domestic product per capita) per QALY gained.

CONCLUSIONS

Letermovir prophylaxis would be cost-effective for preventing CMV infection in adult seropositive allogeneic HSCT recipients in Hong Kong.

Negative Impact of Cytomegalovirus Reactivation on Survival in Adult Patients with Aplastic Anemia after an Allogeneic Hematopoietic Stem Cell Transplantation: A Report from Transplantation-Related Complication and Adult Aplastic Anemia Working Groups of the Japan Society for Hematopoietic Cell Transplantation

Cytomegalovirus (CMV) infection is a major infectious complication following an allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recent large-scale retrospective studies reported that CMV reactivation is an independent risk factor for poor post-transplant outcomes, although the development of CMV end-organ disease is suppressed by the CMV antiviral preemptive therapy, which has been mainly analyzed for hematopoietic malignancies, such as acute leukemia. However, it remains unclear whether CMV reactivation also has a negative effect on post-transplant outcomes in aplastic anemia (AA). Therefore, we evaluated the clinical relevance of CMV reactivation in patients with AA using the registry database of the Japan Society for Hematopoietic Cell Transplantation. Adult patients with AA who underwent their first allo-HSCT between 2005 and 2017 and who survived with neutrophil engraftment until 100 days post-transplantation were analyzed (n = 672). Patients were monitored using pp65 antigenemia since the time of engraftment, and CMV reactivation in the analysis of this study was defined as the beginning of CMV preemptive or definitive therapy within 100 days post-transplantation. CMV reactivation occurred in 372 (55%) patients, including 19 with CMV end-organ disease. In time-dependent multivariate analysis, patients aged ≥40 years (hazard ratio [HR], 1.89; P = .003) who underwent transplantation from HLA-matched related peripheral blood stem cells (HR, 2.85; P = .008), HLA-matched unrelated bone marrow (BM) (HR, 2.01; P = .036), and other stem cell sources (HR, 2.32; P = .007) compared to HLA-matched related BM, CMV reactivation (HR 1.65; P = .042), grade II to IV acute graft-versus-host disease (HR 1.73; P = .013), and secondary graft failure (HR 7.09; P < .001) had independent risk factors that significantly decreased overall survival, indicating that CMV reactivation, one of the early events at post-transplantation, had a significant negative impact on the long-term prognosis at post-transplantation. This effect was more pronounced in patients aged ≥40 years who received a graft from other than HLA-matched related BM. Comparing the causes of death with and without CMV reactivation, no significant difference in the frequency of each cause of death was observed between the 2 groups (P = .453). Improvement of post-transplant CMV management that effectively suppresses CMV reactivation in the early stage at post-transplantation will be required to improve post-transplant outcomes, especially in high-risk patients.

Cellular Therapeutic Approaches to Cytomegalovirus Infection Following Allogeneic Stem Cell Transplantation

Cytomegalovirus (CMV) infection is common following allogeneic hematopoietic stem cell transplant (HSCT) and is a major cause of morbidity and increased mortality. Whilst pharmacotherapy can be effective in the prevention and treatment of CMV, these agents are often expensive, toxic and in some cases ineffective due to viral resistance mechanisms. Immunotherapeutic approaches are compelling and early clinical trials of adoptively transferred donor-derived virus-specific T (VST) cells against CMV have demonstrated efficacy. However, significant logistical challenges limit their broad application. Strategies to optimize VST manufacture and cell banking alongside scientific developments to enhance efficacy whilst minimizing toxicity are ongoing. This review will discuss the development of CMV-specific T-cell therapies, the challenges of widespread delivery of VSTs for CMV and explore how VST therapy can change outcomes in CMV infection following HSCT.

Definitions of Resistant and Refractory Cytomegalovirus Infection and Disease in Transplant Recipients for Use in Clinical Trials

Despite advances in preventive strategies, cytomegalovirus (CMV) infection remains a major complication in solid organ and hematopoietic cell transplant recipients. CMV infection may fail to respond to commercially available antiviral therapies, with or without demonstrating genotypic mutation(s) known to be associated with resistance to these therapies. This lack of response has been termed "resistant/refractory CMV" and is a key focus of clinical trials of some investigational antiviral agents. To provide consistent criteria for future clinical trials and outcomes research, the CMV Resistance Working Group of the CMV Drug Development Forum (consisting of scientists, clinicians, regulatory officials, and industry representatives from the United States, Canada, and Europe) has undertaken establishing standardized consensus definitions of "resistant" and "refractory" CMV. These definitions have emerged from the Working Group's review of the available virologic and clinical literature and will be subject to reassessment and modification based on results of future studies.

Implementation and Validation of the Roche Light Cycler 480 96-Well Plate Platform as a Real-Time PCR Assay for the Quantitative Detection of Cytomegalovirus (CMV) in Clinical Specimens Using the Luminex MultiCode ASRs System

Allogenic stem-cell therapies benefit patients in the treatment of multiple diseases; however, the side effects of stem-cell therapies (SCT) derived from the concomitant use of immune suppression agents often include triggering infection diseases. Thus, analysis is required to improve the detection of pathogen infections in SCT. We develop a polymerase chain reaction (PCR)-based methodology for the qualitative real-time DNA detection of cytomegalovirus (CMV), with reference to herpes simplex virus types 1 (HSVI), Epstein–Barr virus (EBV), and varicella-zoster virus (VZV) in blood, urine, solid tissues, and cerebrospinal fluid. This real-time PCR of 96-well plate format provides a rapid framework as required by the Food and Drug Administration (FDA) for clinical settings, including the processing of specimens, reagent handling, special safety precautions, quality control criteria and analytical accuracy, precisely reportable range (analyst measurement range), reference range, limit of detection (LOD), analytical specificity established by interference study, and analyte stability. Specifically, we determined the reportable range (analyst measurement range) with the following criteria: CMV copies ≥200 copies/mL; report copy/mL value; CMV copies ≤199 copies/mL; report detected but below quantitative range; CMV copies = 0 with report <200 copies/mL. That is, with reference range, copy numbers (CN) per milliliter (mL) of the LOD were determined by standard curves that correlated Ct value and calibrated standard DNA panels. The three repeats determined that the measuring range was 1E2~1E6 copies/mL. The standard curves show the slopes were within the range −2.99 to −3.65 with R² ≥ 0.98. High copy (HC) controls were within 0.17–0.18 log differences of DNA copy numbers; (2) low copy (LC) controls were within 0.17–0.18 log differences; (3) LOD was within 0.14–0.15 log differences. As such, we set up a fast, simple, inexpensive, sensitive, and reliable molecular approach for the qualitative detection of CMV pathogens. Conclusion: This real-time PCR of the 96-well plate format provides a rapid framework as required by the FDA for clinical settings.

Cytomegalovirus infection and associated hospitalization and costs among individuals undergoing allogeneic hematopoietic stem cell transplant

Objective: This study utilized a large, national US database to explore the impact of Cytomegalovirus (CMV) infection on hospital services utilization and costs during the first 100 days following allogeneic hematopoietic stem cell transplant (allo-HSCT).Methods: This retrospective, observational cohort study used data from the Premier Healthcare database to identify patients undergoing their first (index) allo-HSCT procedure between 1 January 2006 and 31 March 2015. Three subgroups were analyzed according to CMV-related readmissions during the 100-day follow-up (0, 1, or 2+ readmissions) to compare healthcare utilization and costs.Results: A total of 1610 patients (mean age, 50.5 years; 56.9% male) from 52 US hospitals met the inclusion criteria. During follow-up, 212 (13.2%) patients had 1 (n = 161; 10.0%) or 2+ (n = 51; 3.2%) CMV-related readmissions. The mean ± SD number of all follow-up encounters (inpatient admissions and hospital-based outpatient visits) was similar for the no CMV (3.9 ± 3.9), 1 CMV (3.7 ± 3.9), and 2+ CMV (4.5 ± 3.8) readmission groups (p = .439). Mean total costs of hospital-based healthcare encounters (inpatient admissions and hospital-based outpatient visits) during follow-up were significantly greater in patients who had a CMV readmission ($111,729 [1 CMV readmission]; $184,021 [2+ CMV readmissions]) compared to those without a CMV readmission ($46,064; p < .001]. 100-day follow-up mortality was higher in the CMV vs. non-CMV readmission groups (30.2 vs. 8.2%; p < .001).Conclusions: This large, national database study revealed significantly higher healthcare utilization and costs, as well as mortality, among patients with CMV-related re-hospitalization during the first 100 days post-transplant as compared to patients without CMV-related hospitalization.

Immunological and Clinical Impact of Manipulated and Unmanipulated DLI after Allogeneic Stem Cell Transplantation of AML Patients

Allogeneic stem cell transplantation (allo-SCT) is the preferred curative treatment for several hematological malignancies. The efficacy of allo-SCT depends on the graft-versus-leukemia (GvL) effect. However, the prognosis of patients with relapsed acute myeloid leukemia (AML) following allo-SCT is poor. Donor lymphocyte infusion (DLI) is utilized after allo-SCT in this setting to prevent relapse, to prolong progression free survival, to establish full donor chimerism and to restore the GvL effect in patients with hematological malignancies. Thus, there are different options for the administration of DLI in AML patients. DLI is currently used prophylactically and in the setting of an overt relapse. In addition, in the minimal residual disease (MRD) setting, DLI may be a possibility to improve overall survival. However, DLI might increase the risk of severe life-threatening complications such as graft-versus-host disease (GvHD) as well as severe infections. The transfusion of lymphocytes has been tested not only for the treatment of hematological malignancies but also chronic infections. In this context, manipulated DLI in a prophylactic or therapeutic approach are an option, e.g., virus-specific DLI using different selection methods or antigen-specific DLI such as peptide-specific CD8+ cytotoxic T lymphocytes (CTLs). In addition, T cells are also genetically engineered, using both chimeric antigen receptor (CAR) genetically modified T cells and T cell receptor (TCR) genetically modified T cells. T cell therapies in general have the potential to enhance antitumor immunity, augment vaccine efficacy, and limit graft-versus-host disease after allo-SCT. The focus of this review is to discuss the different strategies to use donor lymphocytes after allo-SCT. Our objective is to give an insight into the functional effects of DLI on immunogenic antigen recognition for a better understanding of the mechanisms of DLI. To ultimately increase the GvL potency without raising the risk of GvHD at the same time.

Clinical and economic burden of pre-emptive therapy of cytomegalovirus infection in hospitalized allogeneic hematopoietic cell transplant recipients

Cytomegalovirus (CMV) infection remains a major complication after allogeneic hematopoietic cell transplantation (allo-HCT). We conducted a retrospective study to determine the clinical and economic burden of pre-emptive therapy (PET) for CMV infection in 100 consecutive hospitalized adult CMV positive serostatus allo-HCT recipients and compared their hospitalization cost with allo-HCT recipients hospitalized with graft vs host disease without CMV infection (control group) and across 19 US cancer centers for hospitalized patients with CMV infection between 2012 and 2015 (Vizient database). A total of 192 CMV episodes of PET for CMV infection occurred within 1 year post-HCT. PET consisted of ganciclovir (41% of episodes), foscarnet (40%), and valganciclovir (38%) with the longest average length of stay in foscarnet-treated patients (41 days). The average direct cost per patient admitted for PET was $116 976 (range: $7866-$641 841) compared with $12 496 (range: $2004-$43 069) in the control group (P < .0001). The total direct cost per encounter was significantly higher in patients treated with foscarnet and had nephrotoxicity ($284 006) compared with those who did not ($112 195). The average cost amongst the 19 US cancer centers, including our institution, was $42 327 with major disparities in cost and clinical outcomes. PET for CMV infection is associated with high economic burden in allo-HCT recipients.

DNAM-1 Activating Receptor and Its Ligands: How Do Viruses Affect the NK Cell-Mediated Immune Surveillance during the Various Phases of Infection?

Natural Killer (NK) cells play a critical role in host defense against viral infections. The mechanisms of recognition and killing of virus-infected cells mediated by NK cells are still only partially defined. Several viruses induce, on the surface of target cells, the expression of molecules that are specifically recognized by NK cell-activating receptors. The main NK cell-activating receptors involved in the recognition and killing of virus-infected cells are NKG2D and DNAM-1. In particular, ligands for DNAM-1 are nectin/nectin-like molecules involved also in mechanisms allowing viral infection. Viruses adopt several immune evasion strategies, including those affecting NK cell-mediated immune surveillance, causing persistent viral infection and the development of virus-associated diseases. The virus's immune evasion efficacy depends on molecules differently expressed during the various phases of infection. In this review, we overview the molecular strategies adopted by viruses, specifically cytomegalovirus (CMV), human immunodeficiency virus (HIV-1), herpes virus (HSV), Epstein-Barr virus (EBV) and hepatitis C virus (HCV), aiming to evade NK cell-mediated surveillance, with a special focus on the modulation of DNAM-1 activating receptor and its ligands in various phases of the viral life cycle. The increasing understanding of mechanisms involved in the modulation of activating ligands, together with those mediating the viral immune evasion strategies, would provide critical tools leading to design novel NK cell-based immunotherapies aiming at viral infection control, thus improving cure strategies of virus-associated diseases.

Strain-specific antibody therapy prevents cytomegalovirus reactivation after transplantation

Cytomegalovirus infection is a frequent and life-threatening complication that significantly limits positive transplantation outcomes. We developed preclinical mouse models of cytomegalovirus reactivation after transplantation and found that humoral immunity is essential for preventing viral recrudescence. Preexisting antiviral antibodies decreased after transplant in the presence of graft-versus-host disease and were not replaced, owing to poor reconstitution of donor B cells and elimination of recipient plasma cells. Viral reactivation was prevented by the transfer of immune serum, without a need to identify and target specific antigenic determinants. Notably, serotherapy afforded complete protection, provided that the serum was matched to the infecting viral strain. Thus, we define the mechanisms for cytomegalovirus reactivation after transplantation and identify a readily translatable strategy of exceptional potency, which avoids the constraints of cellular therapies.

Cytomegalovirus Infections after Hematopoietic Stem Cell Transplantation: Current Status and Future Immunotherapy

Cytomegalovirus (CMV) infection after hematopoietic stem cell transplantation (HSCT) is one of the critical infectious complications related to host immune recovery. The spectrum of CMV infection is quite extensive, from asymptomatic CMV reactivation presenting mainly as CMV DNAemia to fatal CMV diseases involving gut, liver, lungs, or brain. In addition to organ involvement, CMV reactivation can exert indirect effects such as immunosuppression or graft failure that may result in the development of concurrent infectious complications. Currently, preemptive therapy, which is based on PCR-based monitoring of CMV from blood, is a mainstay enabling improvement in CMV-related outcomes. During the past decades, new antiviral drugs, clinical trials for prophylaxis in high-risk groups, and vaccines for preventing CMV infection have been introduced. In addition, data for immunologic monitoring and adoptive immunotherapy have also been accumulated. Here, we review the current status and recent updates in this field, with future perspectives including immunotherapy in HSCT recipients.

PTX3 Polymorphisms Influence Cytomegalovirus Reactivation After Stem-Cell Transplantation

Background: Reactivation of latent human cytomegalovirus (CMV) in patients undergoing allogeneic stem-cell transplantation (HSCT) predisposes to several clinical complications and is therefore a major cause of morbidity and mortality. Although pentraxin-3 (PTX3) has been previously described to bind both human and murine CMV and mediate several host antiviral mechanisms, whether genetic variation in the PTX3 locus influences the risk of CMV infection is currently unknown.

Methods: To dissect the contribution of genetic variation within PTX3 to the development of CMV infection, we analyzed described loss-of-function variants at the PTX3 locus in 394 recipients of HSCT and their corresponding donors and assessed the associated risk of CMV reactivation.

Results: We report that the donor, but not recipient, h2/h2 haplotype in PTX3 increased the risk of CMV reactivation after 24 months following transplantation, with a significant effect on survival. Among recipients with h2/h2 donors, CMV seropositive patients as well as those receiving grafts from unrelated donors, regardless of the CMV serostatus, were more prone to develop viral reactivation after transplantation. Most importantly, the h2/h2 haplotype was demonstrated to display an influence toward risk of CMV reactivation comparable to that conferred by the unrelated status of the donor alone.

Conclusions: Our findings demonstrate the important contribution of genetic variation in donor PTX3 to the risk of CMV reactivation in patients undergoing HSCT, highlighting a promising prognostic value of donor PTX3 to predict risk of CMV reactivation in this clinical setting.

Adoptive T Cell Therapy Strategies for Viral Infections in Patients Receiving Haematopoietic Stem Cell Transplantation

Adverse outcomes following virus-associated disease in patients receiving allogeneic haematopoietic stem cell transplantation (HSCT) have encouraged strategies to control viral reactivation in immunosuppressed patients. However, despite timely treatment with antiviral medication, some viral infections remain refractory to treatment, which hampers outcomes after HSCT, and are responsible for a high proportion of transplant-related morbidity and mortality. Adoptive transfer of donor-derived lymphocytes aims to improve cellular immunity and to prevent or treat viral diseases after HSCT. Early reports described the feasibility of transferring nonspecific lymphocytes from donors, which led to the development of cell therapy approaches based on virus-specific T cells, allowing a targeted treatment of infections, while limiting adverse events such as graft versus host disease (GvHD). Both expansion and direct selection techniques have yielded comparable results in terms of efficacy (around 70–80%), but efficacy is difficult to predict for individual cases. Generating bespoke products for each donor–recipient pair can be expensive, and there remains the major obstacle of generating products from seronegative or poorly responsive donors. More recent studies have focused on the feasibility of collecting and infusing partially matched third-party virus-specific T cells, reporting response rates of 60–70%. Future development of this approach will involve the broadening of applicability to multiple viruses, the optimization and cost-control of manufacturing, larger multicentred efficacy trials, and finally the creation of cell banks that can provide prompt access to virus-specific cellular product. The aim of this review is to summarise present knowledge on adoptive T cell manufacturing, efficacy and potential future developments.

Acute Respiratory Failure and Management

Acute respiratory failure is a common reason for admission to the pediatric intensive care unit in oncology patients. Acute respiratory complications are also common after pediatric hematopoietic stem cell transplant (HSCT), accounting for a high proportion of HSCT-related morbidity and mortality. Evaluation of these patients requires a thorough workup that includes identification and treatment of infectious etiologies, and treatment for noninfectious causes once infectious causes are ruled out. These patients should be closely monitored for development of pediatric acute respiratory distress syndrome (PARDS) with early escalation of respiratory support. Patients undergoing a trial of noninvasive ventilation (NIV) should be continuously monitored to ensure they are responding. Prolonged delay of endotracheal intubation in patients who do not improve or worsen on NIV could worsen their outcome. Optimal treatment of immunocompromised patients with acute lung failure requires early and aggressive lung protective ventilation, prevention of fluid overload, and rapid diagnosis of underlying causes to facilitate prompt disease-directed therapy.

Factors associated with cytomegalovirus infection in children undergoing allogeneic hematopoietic stem-cell transplantation

While preemptive therapy with ganciclovir (GCV) for cytomegalovirus (CMV) infection is used following allogeneic hematopoietic stem-cell transplantation (HSCT), risk factors for CMV infection in children undergoing HSCT are poorly understood.We studied CMV reactivation following allogeneic HSCT by retrospectively analyzing pediatric patients who received allogeneic HSCT and preemptive GCV therapy between 1998 and 2016. The level of viremia requiring preemptive GCV therapy was >1 CMV antigen-positive cells per 5 × 10 leukocytes during the antigenemia assay era and >1000 copies/mL in the polymerase chain reaction era. Among 290 at-risk patients, 54 (18.6%) patients had primary CMV infection or CMV reactivation occurring at a median of 76 days (range, 7-234) following HSCT. CMV reactivation occurred in 28.2% (44/156) of CMV-seropositive transplant recipients at a median of 26 days posttransplant.Univariate and multivariate analyses revealed statistically significant relationships between CMV infection and grade III-IV acute graft-vs-host disease, seronegative donor/seropositive recipient combination, and unrelated/mismatched donors. The remaining demographic factors were not predictive of CMV infection.The seronegative donor/seropositive recipient combination for HSCT was associated with an incomplete response to antiviral therapy. Human leukocyte antigen identical donors were the best choice for patients undergoing allogeneic HSCT to reduce the incidence of CMV disease and mortality.

Signatures of T and B Cell Development, Functional Responses and PD-1 Upregulation After HCMV Latent Infections and Reactivations in Nod.Rag.Gamma Mice Humanized With Cord Blood CD34+ Cells

Human cytomegalovirus (HCMV) latency is typically harmless but reactivation can be largely detrimental to immune compromised hosts. We modeled latency and reactivation using a traceable HCMV laboratory strain expressing the Gaussia luciferase reporter gene (HCMV/GLuc) in order to interrogate the viral modulatory effects on the human adaptive immunity. Humanized mice with long-term (more than 17 weeks) steady human T and B cell immune reconstitutions were infected with HCMV/GLuc and 7 weeks later were further treated with granulocyte-colony stimulating factor (G-CSF) to induce viral reactivations. Whole body bio-luminescence imaging analyses clearly differentiated mice with latent viral infections vs. reactivations. Foci of vigorous viral reactivations were detectable in liver, lymph nodes and salivary glands. The number of viral genome copies in various tissues increased upon reactivations and were detectable in sorted human CD14⁺, CD169⁺, and CD34⁺ cells. Compared with non-infected controls, mice after infections and reactivations showed higher thymopoiesis, systemic expansion of Th, CTL, Treg, and Tfh cells and functional antiviral T cell responses. Latent infections promoted vast development of memory CD4⁺ T cells while reactivations triggered a shift toward effector T cells expressing PD-1. Further, reactivations prompted a marked development of B cells, maturation of IgG⁺ plasma cells, and HCMV-specific antibody responses. Multivariate statistical methods were employed using T and B cell immune phenotypic profiles obtained with cells from several tissues of individual mice. The data was used to identify combinations of markers that could predict an HCMV infection vs. reactivation status. In spleen, but not in lymph nodes, higher frequencies of effector CD4⁺ T cells expressing PD-1 were among the factors most suited to distinguish HCMV reactivations from infections. These results suggest a shift from a T cell dominated immune response during latent infections toward an exhausted T cell phenotype and active humoral immune response upon reactivations. In sum, this novel in vivo humanized model combined with advanced analyses highlights a dynamic system clearly specifying the immunological spatial signatures of HCMV latency and reactivations. These signatures can be merged as predictive biomarker clusters that can be applied in the clinical translation of new therapies for the control of HCMV reactivation.

Acquired sensorineural hearing loss in children: current research and therapeutic perspectives

The knowledge of mechanisms responsible for acquired sensorineural hearing loss in children, such as viral and bacterial infections, noise exposure, aminoglycoside and cisplatin ototoxicity, is increasing and progressively changing the clinical management of affected patients. Viral infections are by far the most relevant cause of acquired hearing loss, followed by aminoglycoside and platinum derivative ototoxicity; moreover, cochlear damage induced by noise overexposure, mainly in adolescents, is an emerging topic. Pharmacological approaches are still challenging to develop a truly effective cochlear protection; however, the use of steroids, antioxidants, antiviral drugs and other small molecules is encouraging for clinical practice. Most of evidence on the effectiveness of antioxidants is still limited to experimental models, while the use of corticosteroids and antiviral drugs has a wide correspondence in literature but with controversial safety. Future therapeutic perspectives include innovative strategies to transport drugs into the cochlea, such as molecules incorporated in nanoparticles that can be delivered to a specific target. Innovative approaches also include the gene therapy designed to compensate for abnormal genes or to make proteins by introducing genetic material into cells; finally, regenerative medicine (including stem cell approaches) may play a central role in the upcoming years in hearing preservation and restoration even if its role in the inner ear is still debated.

A fifty-year odyssey: prospects for a cytomegalovirus vaccine in transplant and congenital infection

INTRODUCTION

It has been almost fifty years since the Towne strain was used by Plotkin and collaborators as the first vaccine candidate for cytomegalovirus (CMV). While that approach showed partial efficacy, there have been a multitude of challenges to improve on the promise of a CMV vaccine. Efforts have been dichotomized into a therapeutic vaccine for patients with CMV-infected allografts, either stem cells or solid organ, and a prophylactic vaccine for congenital infection.

AREAS COVERED

This review will evaluate research prospects for a therapeutic vaccine for transplant recipients that recognizes CMV utilizing primarily T cell responses. Similarly, we will provide an extensive discussion on attempts to develop a vaccine to prevent the manifestations of congenital infection, based on eliciting a humoral anti-CMV protective response. The review will also describe newer developments that have upended the efforts toward such a vaccine through the discovery of a second pathway of CMV infection that utilizes an alternative receptor for entry using a series of antigens that have been determined to be important for prevention of infection.

EXPERT COMMENTARY

There is a concerted effort to unify separate therapeutic and prophylactic vaccine strategies into a single delivery agent that would be effective for both transplant-related and congenital infection.

Letermovir for the prevention of cytomegalovirus infection in adult cytomegalovirus-seropositive hematopoietic stem cell transplant recipients

INTRODUCTION

Allogeneic hematopoietic cell transplants (allo-HCT) recipients are at the high-risk of reactivation of cytomegalovirus (CMV), and reactivation is associated with significant morbidity and mortality. Although available anti-CMV therapies may be effective for the prevention of CMV, they are plagued by unacceptable toxicities that prohibit their use in the post-transplant period. Recently studied CMV-active agents, such as maribavir and brincidofovir, failed to reduce the incidence of CMV infection in HCT recipients. Letermovir represents the first agent in the non-nucleoside 3,4 dihydro-quinazoline class of CMV viral terminase complex inhibitors, with activity solely against CMV. The positive results from the recently published Phase III study of letermovir for prevention of CMV infection in CMV-seropositive allo-HCT recipients led to its approval as a prophylactic agent for CMV in multiple countries. Areas covered: In this review, we will evaluate this novel agent with a focus on letermovir mechanism of action, pharmacokinetics and metabolism, clinical efficacy, and safety and toxicities. Expert commentary: With the introduction of letermovir, prevention of CMV infection in allo-HCT recipients may shift considerably, from a predominantly preemptive strategy to one that utilizes this novel therapy for prophylaxis.

Leflunomide therapy for refractory cytomegalovirus infections in hematopoietic stem cell transplant recipients

BACKGROUND

Currently, there are no prospective, randomized trials analyzing leflunomide for the treatment of cytomegalovirus infection or disease in allogeneic stem cell transplant patients.

OBJECTIVE

The primary objective of this case series was to determine the clinical and virological responses of utilizing leflunomide as therapy for refractory cytomegalovirus infections, unresponsive to first-line therapy in allogeneic stem cell transplant patients. Additionally, patient and leflunomide specific characteristics were identified and determined in this descriptive case series.

METHODS

This is a single-center, case series of adult allogeneic stem cell transplant patients with refractory cytomegalovirus infections receiving leflunomide between 1 January 2005 and 31 March 2015.

RESULTS

A total of 14 patients with refractory cytomegalovirus infections received leflunomide. All patients received concurrent anti-cytomegalovirus therapy. Nine of 13 patients tested positive for phosphotransferase UL97 and/or viral DNA polymerase UL54 genotype mutations. Nine patients achieved a virological response with undetectable cytomegalovirus titers. Of the 13 patients with teriflunomide serum levels, eight patients maintained levels >40 micrograms/milliliter (mcg/mL). Common adverse effects were pancytopenia (n = 8) and elevated liver function tests (n = 4).

CONCLUSIONS

Despite current strategies, refractory or recurrent cytomegalovirus infection and disease remain a clinical challenge to treat in the stem cell transplant patient population. Leflunomide used in combination with other concomitant therapies use for refractory cytomegalovirus infection in clinical practice may be a safe and effective option in the allogeneic stem cell transplant patient population.

Cytomegalovirus infection in immunocompetent adults: Is observation still the best strategy?

Cytomegalovirus (CMV) infection in immunocompetent patients generally resolves with few sequelae. However, it can cause severe and relapsing symptoms that can last for several weeks. Due to the self-limiting nature of CMV disease in immunocompetent individuals, criteria for specific antiviral therapy in this cohort are not well established. Additionally the adverse effect profile of currently available anti-CMV therapy limits its use in specific patient populations .We describe 3 immunocompetent adults who developed symptomatic CMV infection and were ill for several weeks. All patients had positive CMV viral assays and ultimately received anti-CMV therapy with significant improvement in symptoms within a few days of starting therapy. Choosing appropriate candidates for anti-CMV therapy, among mmunocompetent individuals, requires further research.

The prognostic benefit of tumour-infiltrating Natural Killer cells in endometrial cancer is dependent on concurrent overexpression of Human Leucocyte Antigen-E in the tumour microenvironment

BACKGROUND

Human Leucocyte Antigen- E (HLA-E) has been reported as both a positive and negative prognostic marker in cancer. This apparent discrepancy may be due to opposing actions of HLA-E on tumour-infiltrating immune cells. Therefore, we evaluated HLA-E expression and survival in relation to the presence of intratumoural natural killer (NK) cells and cytotoxic T cells (CTLs).

METHODS

Tissue microarrays (TMAs) of endometrial tumours were used for immunohistochemical staining of parameters of interest. The combined impact of clinical, pathological and immune parameters on survival was analysed using log rank testing and Cox regression analyses.

RESULTS

Upregulation of HLA-E was associated with an improved disease-free and disease-specific survival in univariate analysis (HR 0.58 95% CI 0.37-0.89; HR 0.42 95% CI 0.25-0.73, respectively). In multivariate analysis, the presence of NK cells predicts survival with a hazard ratio (HR) 0.28 (95% confidence interval (CI) 0.09-0.91) when HLA-E expression is upregulated; but it is associated with a worse prognosis when HLA-E expression is normal (HR 13.43, 95% CI 1.70-106.14). By contrast, the prognostic benefit of T cells was not modulated by HLA-E expression.

CONCLUSIONS

Taken together, we demonstrate that the prognostic benefit of NK cells, but not T-cells, is influenced by HLA-E expression in endometrial cancer (EC) and propose a model to explain our observations.

BK Polyomavirus and the Transplanted Kidney: Immunopathology and Therapeutic Approaches

BK polyomavirus is ubiquitous, with a seropositivity rate of over 75% in the adult population. Primary infection is thought to occur in the respiratory tract, but asymptomatic BK virus latency is established in the urothelium. In immunocompromised host, the virus can reactivate but rarely compromises kidney function except in renal grafts, where it causes a tubulointerstitial inflammatory response similar to acute rejection. Restoring host immunity against the virus is the cornerstone of treatment. This review covers the virus-intrinsic features, the posttransplant microenvironment as well as the host immune factors that underlie the pathophysiology of polyomavirus-associated nephropathy. Current and promising therapeutic approaches to treat or prevent this complication are discussed in relation to the complex immunopathology of this condition.

Cytomegalovirus Treatment in Pediatric Hematopoietic Stem Cell Transplant Patients

Cytomegalovirus (CMV) is a frequent complication of hematopoietic stem cell transplant in pediatric patients, with significant morbidity and mortality. Antiviral drugs are used as prophylactic, preemptive or therapeutic medicines; however, no uniform guidelines exist for the best strategy to prevent CMV disease. Resistance to standard antiviral therapies can lead to further difficulty in managing CMV disease. Studies for investigational therapies are underway and could provide options for treatment of resistant CMV, while limiting toxicities associated with currently used antiviral therapies.

Peptide vaccination in the presence of adjuvants in patients after hematopoietic stem cell transplantation with CD4+ T cell reconstitution elicits consistent CD8+ T cell responses

Rationale: Patients receiving an allogeneic stem cell graft from cytomegalovirus (CMV) seronegative donors are particularly prone to CMV reactivation with a high risk of disease and mortality. Therefore we developed and manufactured a novel vaccine and initiated a clinical phase I trial with a CMV phosphoprotein 65 (CMVpp65)-derived peptide. Methods: Ten patients after allogeneic stem cell transplantation received four vaccinations at a biweekly interval. All patients were monitored for CMVpp65 antigenemia. Flow cytometry for CMV-specific CD8+ and γδ T cells as well as neutralizing anti-CMV antibodies were correlated to clinical parameters. Results: The vaccination was well tolerated. Seven of nine patients cleared CMVpp65 antigenemia after four vaccinations and are still free from antigenemia to this day. Two patients with CMV reactivation showed persisting CMV antigenemia. One patient received prophylactic vaccination and did not develop antigenemia. An increase of up to six-fold in frequency of both CMV-specific CD8+ T cells and/or Vδ2negative γδ T cells was detected. Titers of neutralizing antibodies increased up to the tenfold. Humoral and cellular immune responses correlated with clearance of CMV. Conclusion: In summary, CMVpp65 peptide vaccination for patients after allogeneic stem cell transplantation at high risk for CMV reactivation was safe, well tolerated and clinically encouraging. A study in solid-organ transplant patients is ongoing.

Allogeneic hematopoietic stem cell transplantation for non-Hodgkin's lymphomas: a retrospective analysis of 77 cases

Allogeneic hematopoietic stem cell transplantation (allo-SCT) is a therapeutic option for relapsed, advanced, and otherwise incurable non-Hodgkin's lymphomas (NHL) suggested by the existence of a graft-versus-lymphoma effect. The main complications are graft-versus-host disease and infections. We performed a retrospective analysis of patients with NHL, who received an allo-SCT between January 1995 and December 2014. The parameters that had an impact on overall survival were age ≤60 years old, chemosensitive disease pre-allo-SCT, and indolent NHL histology. The parameters that had an impact on progression-free survival were age ≤60 years old and chemosensitive disease pre-allo-SCT. Only aggressive NHL histology and refractory disease pre-allo-SCT showed an increased risk of death in the multivariate model. The use of allo-SCT for young patients with multiple relapsed chemosensitive indolent NHL is a suitable option. Despite poor prognosis, young aggressive NHL patients can be considered for allo-SCT provided they have chemosensitive disease.

Case report: Brincidofovir-induced reversible severe acute kidney injury in 2 solid-organ transplant for treatment of cytomegalovirus infection

RATIONALE

Resistant cytomegalovirus-mediated infections are increasing in solid organ recipient with few available alternative treatments. Brincidofovir is an oral broad-spectrum antiviral in development for prevention and treatment of viral infection, particularly cytomegalovirus.

PATIENTS CONCERNS

Although brincidofovir is an analogue of cidofovir, previous studies reported no renal toxicity.

DIAGNOSES

Here, we report 2 cases of severe tubular necrosis in solid organ recipients, 1 heart and 1 kidney transplant.

INTERVENTIONS

Both patients received brincidofovir for the treatment of cytomegalovirus infection with mutation of UL-97. They presented an acute kidney injury without any occurrence of other clinical event such as introduction of nephrotoxic drug, graft rejection, urinary tract obstruction or infection, and calcineurin inhibitor overdosage. In each case, renal biopsy showed extended tubular necrosis.

OUTCOMES

The discontinuation of brincidofovir led to improve renal function without other any intervention. Reintroduction of brincidofovir in case 1, due to the absence of other medical alternative, led to a new episode of acute kidney injury. One more time, renal biopsy showed tubular necrosis and patient recovered renal function after discontinuation.

LESSONS

To our knowledge, this is the first report of brincidofovir-mediated renal adverse event. Clinicians may be aware of this severe complication in this specific population.

Distinct Roles for Human Cytomegalovirus Immediate Early Proteins IE1 and IE2 in the Transcriptional Regulation of MICA and PVR/CD155 Expression

Elimination of virus-infected cells by cytotoxic lymphocytes is triggered by activating receptors, among which NKG2D and DNAM-1/CD226 play an important role. Their ligands, that is, MHC class I-related chain (MIC) A/B and UL16-binding proteins (ULBP)1-6 (NKG2D ligand), Nectin-2/CD112, and poliovirus receptor (PVR)/CD155 (DNAM-1 ligand), are often induced on virus-infected cells, although some viruses, including human CMV (HCMV), can block their expression. In this study, we report that infection of different cell types with laboratory or low-passage HCMV strains upregulated MICA, ULBP3, and PVR, with NKG2D and DNAM-1 playing a role in NK cell-mediated lysis of infected cells. Inhibition of viral DNA replication with phosphonoformic acid did not prevent ligand upregulation, thus indicating that early phases of HCMV infection are involved in ligand increase. Indeed, the major immediate early (IE) proteins IE1 and IE2 stimulated the expression of MICA and PVR, but not ULBP3. IE2 directly activated MICA promoter via its binding to an IE2-responsive element that we identified within the promoter and that is conserved among different alleles of MICA. Both IE proteins were instead required for PVR upregulation via a mechanism independent of IE DNA binding activity. Finally, inhibiting IE protein expression during HCMV infection confirmed their involvement in ligand increase. We also investigated the contribution of the DNA damage response, a pathway activated by HCMV and implicated in ligand regulation. However, silencing of ataxia telangiectasia mutated, ataxia telangiectasia and Rad3-related protein, and DNA-dependent protein kinase did not influence ligand expression. Overall, these data reveal that MICA and PVR are directly regulated by HCMV IE proteins, and this may be crucial for the onset of an early host antiviral response.

Cytomegalovirus in hematopoietic stem cell transplant recipients - management of infection

INTRODUCTION

Cytomegalovirus (CMV) still causes significant morbidity and mortality in patients given allogeneic hematopoietic stem cell transplantation (HSCT). Despite effective pharmacotherapy, potentially life-threatening CMV disease occurs nowadays in up to 10% of HSCT recipients; moreover, routinely used anti-CMV agents have been shown to be associated with morbidity. Areas covered: This review examines different issues related to diagnosis and management of CMV infection in HSCT recipients, paying particular attention to the monitoring of CMV-specific immune recovery, approaches of adoptive cell therapy and new antiviral drugs. Expert commentary: Despite advances in diagnostic tests and treatment, there is still room for refining management of CMV in HSCT recipients. Immunological monitoring should be associated in the future to virological monitoring. The safety profile and efficacy of new anti-CMV agents should be compared with that of standard-of-care drugs. Donor-derived, pathogen-specific T cells adoptively transferred after transplantation could contribute to reduce the impact of CMV infection on patient's outcome.

Immunotherapy for opportunistic infections: Current status and future perspectives

The outcome after allogeneic haematopoietic stem cell transplantation (allo-HSCT) has significantly improved during the last decades. However, opportunistic infections such as viral and mold infections are still a major obstacle for cure. Within this field, adoptive T cell therapy against pathogens is a promising treatment approach. Recently, the techniques to develop T cell products including pathogen-specific T cells have been sophisticated and are now available in accordance to good manufacturing practice (GMP). Here, we aim to summarize current knowledge about adoptive T cell therapy against viral and mold infections.

Xenotransplantation and porcine cytomegalovirus

Porcine microorganisms may be transmitted to the human recipient when xenotransplantation with pig cells, tissues, and organs will be performed. Most of such microorganisms can be eliminated from the donor pig by specified or designated pathogen-free production of the animals. As human cytomegalovirus causes severe transplant rejection in allotransplantation, considerable concern is warranted on the potential pathogenicity of porcine cytomegalovirus (PCMV) in the setting of xenotransplantation. On the other hand, despite having a similar name, PCMV is different from HCMV. The impact of PCMV infection on pigs is known; however, the influence of PCMV on the human transplant recipient is unclear. However, first transplantations of pig organs infected with PCMV into non-human primates were associated with a significant reduction of the survival time of the transplants. Sensitive detection methods and strategies for elimination of PCMV from donor herds are required.

CMV in Hematopoietic Stem Cell Transplantation

Due to its negative impact on the outcome of stem cell transplant (SCT) and solid organ transplant patients (SOT) CMV has been called “the troll of transplantation”. One of the greatest advances in the management of SCT has been the introduction of the preemptive strategy. Since its introduction, the incidence of the viremia, as expected, remains unchanged but there has been a marked decline in the incidence of early CMV disease. However, in spite of the advances in prevention of CMV disease, CMV is still today an important cause of morbidity and mortality. Late CMV disease is still occurring in a significant proportion of patients and the so-called indirect effects of CMV are causing significant morbidity and mortality. Fortunately there have been several advances in the development of new antivirals, adoptive immunotherapy and DNA-CMV vaccines that might transform the management of CMV in the near future.

Plasma metabolomics profiling for the prediction of cytomegalovirus DNAemia and analysis of virus–host interaction in allogeneic stem cell transplant recipients

Metabolomics analysis of biofluids is increasingly being recognized as a useful tool for the diagnosis and management of a number of infectious diseases. Here we showed that plasma metabolomics profiling by untargeted 1H nuclear magnetic resonance may allow the anticipation of the occurrence of cytomegalovirus (CMV) DNAemia in allogeneic stem cell transplant. For this purpose, key discriminatory metabolites were total glutathione, taurine, methylamine, trimethylamine N-oxide and lactate, all of which were upregulated in patients eventually developing CMV DNAemia. The overall classification accuracy (predictability) of the projection to latent structure discriminant analysis (PLS-DA) model in cross-validation technical replicates was 73 %. Increased levels of alanine, lactate and total fatty acids, and a shift in the fatty acid profile towards unsaturated species, were observed in patients with detectable CMV DNA in plasma. The classification accuracy of this PLS-DA model in cross-validation technical replicates was 81 %. Plasma metabolomics profiling may prove useful for identifying patients at highest risk for CMV DNAemia thus allowing early inception of antiviral therapy.

Cytomegalovirus Infection after CD34(+)-Selected Hematopoietic Cell Transplantation

The effectiveness of preemptive treatment (PET) for cytomegalovirus (CMV) in recipients of ex vivo T cell-depleted (TCD) hematopoietic cell transplantation (HCT) by CD34(+) selection is not well defined. We analyzed 213 adults who received TCD-HCT at our institution from June 2010 through May 2014. Patients were monitored by a CMV quantitative PCR assay if recipient (R) or donor (D) were CMV seropositive. CMV viremia occurred early (median, 27 days after HCT) in 91 of 213 (42.7%) patients for a 180-day cumulative incidence of 84.5%, 61.8%, and 0 for R+/D+, R+/D-, and R-/D+ patients, respectively. CMV disease occurred in 5% of patients. In Cox regression analysis, R+/D+ status was associated with increased risk for CMV viremia compared with R+/D- (hazard ratio [HR], 1.79, 95% confidence interval [CI], 1.16 to 2.76, P = .01), whereas matched unrelated donor allograft was associated with decreased risk (HR, .62; 95% CI, .39 to .97, P = .04). Of 91 patients with CMV viremia, 52 (57%) had persistent viremia (>28 days duration). Time lag from detection of CMV viremia to PET was associated with incremental risk for persistent viremia (HR, 1.09; 95% CI, 1.01 to 1.18; P = .03). Overall, 166 of 213 (77.9%) patients were alive 1 year after HCT, with no difference between patients with and without CMV viremia or among the different CMV serostatus pairs (P = not significant). CMV viremia occurred in 70% of R + TCD-HCT. Delay in PET initiation was associated with persistent viremia. With PET, CMV R/D serostatus did not adversely impact survival in TCD-HCT on 1-year survival in the present cohort.