Cytomegalovirus in hematopoietic stem cell transplant recipients

Donor cytomegalovirus status influences the outcome of allogeneic stem cell transplant: a study by the European group for blood and marrow transplantation

BACKGROUND

The use of a cytomegalovirus (CMV)-seronegative donor for a CMV-seronegative allogeneic hematopoietic stem cell transplant (HSCT) recipient is generally accepted. However, the importance of donor serostatus in CMV-seropositive patients is controversial.

METHODS

A total of 49 542 HSCT patients, 29 349 seropositive and 20 193 seronegative, were identified from the European Group for Blood and Marrow Transplantation database. Cox multivariate models were fitted to estimate the effect of donor CMV serological status on outcome.

RESULTS

Seronegative patients receiving seropositive unrelated-donor grafts had decreased overall survival (hazard ratio [HR], 1.13; 95% confidence interval [CI], 1.06-1.21; P < .0001) compared with seronegative donors, whereas no difference was seen in patients receiving HLA-matched sibling grafts. Seropositive patients receiving grafts from seropositive unrelated donors had improved overall survival (HR, 0.92; 95% CI, .86-.98; P < .01) compared with seronegative donors, if they had received myeloablative conditioning. This effect was absent when they received reduced-intensity conditioning. No effect was seen in patients grafted from HLA-identical sibling donors. The same association was found if the study was limited to patients receiving transplants from the year 2000 onward.

CONCLUSIONS

We confirm the negative impact on overall survival if a CMV-seropositive unrelated donor is selected for a CMV-seronegative patient. For a CMV-seropositive patient, our data support selecting a CMV-seropositive donor if the patient receives a myeloablative conditioning regimen.

Cytomegalovirus pp65 limits dissemination but is dispensable for persistence

The most abundantly produced virion protein in human cytomegalovirus (HCMV) is the immunodominant phosphoprotein 65 (pp65), which is frequently included in CMV vaccines. Although it is nonessential for in vitro CMV growth, pp65 displays immunomodulatory functions that support a potential role in primary and/or persistent infection. To determine the contribution of pp65 to CMV infection and immunity, we generated a rhesus CMV lacking both pp65 orthologs (RhCMVΔpp65ab). While deletion of pp65ab slightly reduced growth in vitro and increased defective particle formation, the protein composition of secreted virions was largely unchanged. Interestingly, pp65 was not required for primary and persistent infection in animals. Immune responses induced by RhCMVΔpp65ab did not prevent reinfection with rhesus CMV; however, reinfection with RhCMVΔUS2-11, which lacks viral-encoded MHC-I antigen presentation inhibitors, was prevented. Unexpectedly, induction of pp65b-specific T cells alone did not protect against RhCMVΔUS2-11 challenge, suggesting that T cells targeting multiple CMV antigens are required for protection. However, pp65-specific immunity was crucial for controlling viral dissemination during primary infection, as indicated by the marked increase of RhCMVΔpp65ab genome copies in CMV-naive, but not CMV-immune, animals. Our data provide rationale for inclusion of pp65 into CMV vaccines but also demonstrate that pp65-induced T cell responses alone do not recapitulate the protective effect of natural infection.

Cytomegalovirus diseases after hematopoietic stem cell transplantation: a mini-review

Cytomegalovirus (CMV) infection remains a significant complication after hematopoietic stem cell transplantation (HSCT) and may have a deleterious impact on the overall outcome after transplantation. In addition to the direct effects of CMV infection, tissue-invasive CMV diseases may be associated with increased risk of graft versus host disease, myelosuppression, and invasive bacterial and fungal infections. Because of these direct and indirect adverse effects, prevention of CMV infection, mostly through pre-emptive therapy, is one of the essential strategies that may improve outcomes of HSCT recipients. Management of CMV infection relies mainly on intravenous (IV) antiviral therapy with ganciclovir and foscarnet, with or without IV polyclonal immunoglobulins. Although viral resistance remains rare, better tolerated antiviral agents with less serious side effects are needed, and a few will be evaluated in phase III clinical trials in the near future.

Overview of human cytomegalovirus pathogenesis

Human cytomegalovirus (HCMV) is a human pathogen that infects greater than 50 % of the human population. HCMV infection is usually asymptomatic in most individuals. That is, primary infection or reactivation of latent virus is generally clinically silent. HCMV infection, however, is associated with significant morbidity and mortality in the immunocompromised and chronic inflammatory diseases in the immunocompetent. In immunocompromised individuals (acquired immune deficiency syndrome and transplant patients, developing children (in utero), and cancer patients undergoing chemotherapy), HCMV infection increases morbidity and mortality. In those individuals with a normal immune system, HCMV infection is also associated with a risk of serious disease, as viral infection is now considered to be a strong risk factor for the development of various vascular diseases and to be associated with some types of tumor development. Intense research is currently being undertaken to better understand the mechanisms of viral pathogenesis that are briefly discussed in this chapter.

The prevalence and prognostic value of concomitant eosinophilia in chronic graft-versus-host disease after allogeneic stem cell transplantation

The prognostic significance of eosinophilia after myeloablative allogeneic stem cell transplantation (ASCT) remains to be established. Patients, whom developed chronic graft-versus-host disease (cGVHD) after ASCT, were included (n = 142). Eosinophil count was analyzed at cGVHD onset. We observed no significant association between EO and the grade of cGVHD, thrombocytopenia, nor extensive skin involvement. Importantly, we observed no significant association between cGVHD with concomitant eosinophilia and long-term clinical outcomes, and subgroup analyses revealed a considerable confounding effect of ongoing steroid treatment. In conclusion, we advocate that prognostic conclusions regarding cGVHD with concomitant eosinophilia after ASCT should be interpreted with caution.

Human cytomegalovirus manipulation of latently infected cells

Primary infection with human cytomegalovirus (HCMV) results in the establishment of a lifelong infection of the host which is aided by the ability of HCMV to undergo a latent infection. One site of HCMV latency in vivo is in haematopoietic progenitor cells, resident in the bone marrow, with genome carriage and reactivation being restricted to the cells of the myeloid lineage. Until recently, HCMV latency has been considered to be relatively quiescent with the virus being maintained essentially as a “silent partner” until conditions are met that trigger reactivation. However, advances in techniques to study global changes in gene expression have begun to show that HCMV latency is a highly active process which involves expression of specific latency-associated viral gene products which orchestrate major changes in the latently infected cell. These changes are argued to help maintain latent infection and to modulate the cellular environment to the benefit of latent virus. In this review, we will discuss these new findings and how they impact not only on our understanding of the biology of HCMV latency but also how they could provide tantalising glimpses into mechanisms that could become targets for the clearance of latent HCMV.

Asymptomatic DNAemia heralds CMV-associated NEC: case report, review, and rationale for preemption

Human cytomegalovirus (CMV) infection may be acquired in very low birth weight and extremely low birth weight (ELBW) infants from breast milk. The clinical relevance of such infections is uncertain. There is no consensus on whether screening breast milk for CMV, freezing/pasteurizing milk before feeding, or performing virological monitoring on at-risk infants is warranted. We describe an ELBW infant who acquired CMV postnatally from breast milk and developed CMV sepsis syndrome and clinical evidence of necrotizing enterocolitis (NEC) at ≈ 5 weeks of age. The availability of serial dried blood spots from day of life (DOL) 4 to 21, coincidentally obtained for a metabolic study, provided the novel opportunity to retrospectively test for and quantify the magnitude of CMV DNAemia. DNAemia was present for several weeks before the onset of severe CMV disease, first being noted on DOL 18 and increasing in magnitude daily to 4.8 log10 genomes/mL on DOL 21, approximately 8 days before the onset of abdominal distension and 15 days before the onset of CMV sepsis syndrome and NEC. After surgical resection, supportive care, and ganciclovir therapy, the infant recovered. This case underscores the importance of including CMV infection in the differential diagnosis of sepsis and NEC in premature infants. This case also suggests the value of prospective virological monitoring in at-risk low birth weight and ELBW infants. Future studies should examine the potential utility of preemptive monitoring for, and possibly treatment of, CMV DNAemia in premature infants, which may herald the onset of serious disease.

Protective effect of cytomegalovirus reactivation on relapse after allogeneic hematopoietic cell transplantation in acute myeloid leukemia patients is influenced by conditioning regimen

Cytomegalovirus (CMV) reactivation after allogeneic hematopoietic cell transplant (allo-HCT) has been associated with a reduced risk of relapse in patients with acute myeloid leukemia (AML). However, the influence of the conditioning regimen on this protective effect of CMV reactivation after allo-HCT is relatively unexplored. To address this, we evaluated the risk of relapse in 264 AML patients who received T cell-replete, 6/6 HLA matched sibling or 10/10 HLA matched unrelated donor transplantation at a single institution between 2006 and 2011. Of these 264 patients, 206 received myeloablative (MA) and 58 received reduced-intensity conditioning (RIC) regimens. CMV reactivation was observed in 88 patients with MA conditioning and 37 patients with RIC. At a median follow-up of 299 days, CMV reactivation was associated with significantly lower risk of relapse in patients who received MA conditioning both in univariate (P = .01) and multivariate analyses (hazard ratio, .5246; P = .006); however, CMV reactivation did not significantly affect the risk of relapse in our RIC cohort. These results confirm the protective effect of CMV reactivation on relapse in AML patients after allo-HCT reported by previous studies but suggest this protective effect of CMV reactivation on relapse is influenced by the conditioning regimen used with the transplant.

Can low-dose preemptive valganciclovir replace standard intravenous ganciclovir treatment in recipients of allogeneic stem cell transplantation?

The aim of this retrospective study was to compare the efficacy and safety of standard intravenous ganciclovir (GCV) with low-dose oral valganciclovir (VGC) in preemptive treatment of cytomegalovirus (CMV) infection in patients who received allogeneic stem cell transplantation (ASCT). Fifty-nine adult ASCT patients with asymptomatic 68 CMV reactivations were included. For preemptive CMV treatment, VGC (900 mg/day) in 44 reactivations or GCV (5 mg/kg twice daily during the first week and once daily afterwards) in 24 CMV reactivations were administered for 21 days. Two consecutive negative results for PCR and/or CMV antigenemia were considered as treatment success. All patients with CMV reactivations were on immunosuppressive treatment. While no positivity was identified in any of the patients who received GCV on day 21, low-titer CMV positivity was noted in three of the patients in the VGC group (P = 0·264). In all three patients, VGC was continued at same dose and no positivity result was detected after 2-3 weeks. Low-grade neutropenia and high grade thrombocytopenia were significantly higher in the GCV group than in the VGC group (P = 0·018 and P = 0·04 respectively). Preemptive strategy of oral low-dose VGC appears preferable to the prevention of CMV disease in ASCT. These results require confirmation in prospective larger clinical studies.

Cytomegalovirus DNAemia detected with real-time polymerase chain reaction in hematopoietic stem cell transplant patients

INTRODUCTION

Cytomegalovirus (CMV) infections continue to cause significant morbidity and mortality in hematopoietic stem cell transplant (HSCT) recipients. Successful pre-emptive therapy in transplant patients depends on the availability of reliable diagnostic tests for CMV infections. The purpose of this retrospective study was to evaluate CMV DNA viral load, incidence of CMV disease and CMV seropositivity, risk factors and correlation between CMV DNA positivity and clinical course in HSCT patients.

METHODS

Two hundred and twenty-five patients who underwent peripheral blood stem cell or bone marrow transplantation between June 2003 and April 2010 were included. A real-time polymerase chain reaction (RT-PCR) assay was used for CMV monitoring.

RESULTS

Recipient median age was 42.5 years. CMV seropositivity was 95.6%. CMV DNA positivity determined by RT-PCR was 24.9% among the entire patient group. CMV DNA positivity with RT-PCR was found to be significantly higher in allogeneic transplant recipients than autologous transplant recipients (46.7% vs 14.0%; P < 0.0001). Gender, age, conditioning regimen, stem cell source, underlying disease and recipient and donor seropositivity (alone or paired) were not significant risk factors for CMV DNAemia. We did not observe any CMV end-organ disease.

CONCLUSION

CMV DNAemia was significantly higher in allogeneic transplant recipients than in autologous transplant patients. End-organ disease could be prevented with appropriate pre-emptive therapy.

Fully automated quantification of cytomegalovirus (CMV) in whole blood with the new sensitive Abbott RealTime CMV assay in the era of the CMV international standard

Fully standardized reproducible and sensitive quantification assays for cytomegalovirus (CMV) are needed to better define thresholds for antiviral therapy initiation and interruption. We evaluated the newly released Abbott RealTime CMV assay for CMV quantification in whole blood (WB) that includes automated extraction and amplification (m2000 RealTime system). Sensitivity, accuracy, linearity, and intra- and interassay variability were validated in a WB matrix using Quality Control for Molecular Diagnostics (QCMD) panels and the WHO international standard (IS). The intra- and interassay coefficients of variation were 1.37% and 2.09% at 5 log10 copies/ml and 2.41% and 3.80% at 3 log10 copies/ml, respectively. According to expected values for the QCMD and Abbott RealTime CMV methods, the lower limits of quantification were 104 and <50 copies/ml, respectively. The conversion factor between international units and copies (2.18), determined from serial dilutions of the WHO IS in WB, was significantly different from the factor provided by the manufacturer (1.56) (P = 0.001). Results from 302 clinical samples were compared with those from the Qiagen artus CMV assay on the same m2000 RealTime system. The two assays provided highly concordant results (concordance correlation coefficient, 0.92), but the Abbott RealTime CMV assay detected and quantified, respectively, 20.6% and 47.8% more samples than the Qiagen/artus CMV assay. The sensitivity and reproducibility of the results, along with the automation, fulfilled the quality requirements for implementation of the Abbott RealTime CMV assay in clinical settings. Our results highlight the need for careful validation of conversion factors provided by the manufacturers for the WHO IS in WB to allow future comparison of results obtained with different assays.

Factors with an impact on chimerism development and long-term survival after umbilical cord blood transplantation

BACKGROUND

Umbilical cord blood transplantation (UCBT) is increasingly used and produces similar results to matched unrelated donor transplantation.

METHODS

We performed a retrospective single-center analysis of 50 umbilical cord blood transplantations UCBTs performed from 2001 to 2010, including 37 single and 13 double umbilical cord blood transplantations UCBTs.

RESULTS

The rate of engraftment of neutrophils was 88% at a median time of 29 days (range, 3-79). Complete donor chimerism (DC) within the CD19, CD3, and CD33 cell lineages was seen in 74%, 72%, and 76% of the patients, respectively. DC was associated with acute graft-versus-host disease (GVHD) grades II to IV for the CD3 cell lineage (P=0.01) and, in multivariate analysis, with total body irradiation for all lineages (P<0.01). Overall survival (OS) at 1 and 5 years was 55% and 43%. Nonmalignant diseases were associated with better 5-year OS (72%) than malignancies (28%; P=0.026). In multivariate analysis, a negative correlation was seen between OS and age (hazard ratio [HR], 1.04; 95% confidence interval [95% CI], 1.02-1.06; P<0.001), acute GVHD grades III and IV (HR, 3.43; 95% CI, 1.95-6.02; P<0.001), and mesenchymal stem cell treatment (HR, 2.66; 95% CI, 1.11-6.35; P=0.027). Transplant-related mortality at 100 days and 1 year was 16% and 30%. The incidence of acute GVHD grades II to IV was 34%. Acute GVHD grades III and IV was associated with ABO incompatibility (HR, 2.61; P=0.05) and myeloablative conditioning (HR, 4.17; P=0.047).

CONCLUSIONS

The outcome in patients with nonmalignant diseases was acceptable, but transplant-related mortality in the whole group remains high. A significantly higher rate of DC was associated with total body irradiation-based conditioning and with acute GVHD grades II and IV.

Detection of cytomegalovirus infection by quantitative polymerase chain reaction

Human cytomegalovirus (CMV), also known as human herpes virus-5 (HHV-5), is a common human pathogen acquired early in life in the majority of immunocompetent individuals. Primary infection establishes a state of latency and the virus can be reactivated during immunosuppression. CMV is a significant cause of morbidity and mortality in newborns and patients with impaired immune system. Prenatal infection can result in intrauterine growth retardation, hepatitis, myocarditis, pneumonitis, and neurologic abnormalities. Individuals with congenital or acquired immunosuppression can develop a primary CMV infection, infection with another CMV strain or experience reactivation of the latent virus. The hematopoietic stem cell and solid organ transplant recipients are at high risk of developing CMV infection, especially early in a post-transplant period. The definition of CMV disease includes the evidence of end-organ involvement in the presence of CMV detected by a validated laboratory assay. The selection of a laboratory method is highly dependent on the type of sample to be tested and the clinical presentation. In the clinical practice, the quantitative PCR-based assays are most helpful, since they can measure the level of CMV DNA in whole blood, plasma, cerebrospinal fluid, amniotic fluid, tissue, and urine, and follow the kinetics of infection. In this chapter we describe the PCR assay designed to quantify CMV DNA in human plasma by amplifying a 105 base-pair (bp) fragment of the CMV immediate-early DNA polymerase gene.

Comparison of droplet digital PCR to real-time PCR for quantitative detection of cytomegalovirus

Quantitative real-time PCR (QRT-PCR) has been widely implemented for clinical viral load testing, but a lack of standardization and relatively poor precision have hindered its usefulness. Digital PCR offers highly precise, direct quantification without requiring a calibration curve. Performance characteristics of real-time PCR were compared to those of droplet digital PCR (ddPCR) for cytomegalovirus (CMV) load testing. Tenfold serial dilutions of the World Health Organization (WHO) and the National Institute of Standards and Technology (NIST) CMV quantitative standards were tested, together with the AcroMetrix CMV tc panel (Life Technologies, Carlsbad, CA) and 50 human plasma specimens. Each method was evaluated using all three standards for quantitative linearity, lower limit of detection (LOD), and accuracy. Quantitative correlation, mean viral load, and variability were compared. Real-time PCR showed somewhat higher sensitivity than ddPCR (LODs, 3 log(10) versus 4 log(10) copies/ml and IU/ml for NIST and WHO standards, respectively). Both methods showed a high degree of linearity and quantitative correlation for standards (R(2) ≥ 0.98 in each of 6 regression models) and clinical samples (R(2) = 0.93) across their detectable ranges. For higher concentrations, ddPCR showed less variability than QRT-PCR for the WHO standards and AcroMetrix standards (P < 0.05). QRT-PCR showed less variability and greater sensitivity than did ddPCR in clinical samples. Both digital and real-time PCR provide accurate CMV load data over a wide linear dynamic range. Digital PCR may provide an opportunity to reduce the quantitative variability currently seen using real-time PCR, but methods need to be further optimized to match the sensitivity of real-time PCR.

Humoral immunity to cytomegalovirus and chronic graft-versus-host disease

Human cytomegalovirus (HCMV) is an important cause of morbidity and mortality in patients with chronic graft-versus-host disease (cGVHD), but the underlying mechanisms are not understood. The aim of this investigation was to determine whether humoral immune responses to the HCMV antigens were quantitatively different in hematopoietic cell transplant (HCT) recipients who developed cGVHD from those who did not. Antibodies to HCMV and its proteins UL94 and UL70 were quantitated in 79 cGVHD and 30 non-cGVHD patients by enzyme-linked immunosorbent assays (ELISAs). Mean levels of antibodies to the whole HCMV and to its protein UL94 were not significantly different between the cGVHD and the non-cGVHD subjects. However, the levels of antibodies to HCMV UL70 were significantly higher in non-cGVHD subjects than in those with cGVHD (20.91±15.63 versus 15.00±10.35 ng/mL; p=0.03). This suggests that anti-UL70 antibodies might play a protective role in the development of cGVHD.

Cytomegalovirus infection according to cell source after hematopoietic cell transplantation in pediatric patients

PURPOSE

This study was performed in order to evaluate the incidence and characteristics of cytomegalovirus (CMV) infection in children with acute leukemia according to donor source and graft type.

MATERIALS AND METHODS

We retrospectively identified children with acute leukemia who had received allogeneic hematopoietic cell transplantation at Samsung Medical Center in Korea from October 1998 to December 2009.

RESULTS

In total, 134 recipients were identified. The patients were classified into the following three groups: unrelated cord blood (CB, n=36), related bone marrow or peripheral blood stem cells (RD, n=41), and unrelated bone marrow or peripheral blood stem cells (UD, n=57). The 365-day cumulative incidence of CMV antigenemia was not significantly different among the three groups (CB 67% vs. RD 49% vs. UD 65%, p=0.17). However, CB recipients had the highest median value of peak antigenemia (CB 160/2×10⁵ leukocytes vs. RD 7/2×10⁵ leukocytes vs. UD 19/2×10⁵ leukocytes, p<0.01) and the longest duration of CMV antigenemia than the other stem cell source recipients (CB 87 days vs. RD 17 days vs. UD 28 days, p<0.01). In addition, the 730-day cumulative incidence of CMV disease was the highest in the CB recipients (CB 36% vs. RD 2% vs. UD 5%, p<0.01). Thirteen CB recipients developed CMV disease, in which five of them had more than one organ involvement. Two patients, who were CB recipients, died of CMV pneumonia.

CONCLUSION

This study suggests that CB recipients had both longer and higher cumulative incidences of CMV infection. Therefore, a more aggressive and effective strategy of CMV management should be considered in CB recipients.