The impact of ganciclovir-resistant cytomegalovirus infection after lung transplantation

New Treatment Options for Refractory/Resistant CMV Infection

Despite advances in monitoring and treatment, cytomegalovirus (CMV) infections remain one of the most common complications after solid organ transplantation (SOT). CMV infection may fail to respond to standard first- and second-line antiviral therapies with or without the presence of antiviral resistance to these therapies. This failure to respond after 14 days of appropriate treatment is referred to as "resistant/refractory CMV." Limited data on refractory CMV without antiviral resistance are available. Reported rates of resistant CMV are up to 18% in SOT recipients treated for CMV. Therapeutic options for treating these infections are limited due to the toxicity of the agent used or transplant-related complications. This is often the challenge with conventional agents such as ganciclovir, foscarnet and cidofovir. Recent introduction of new CMV agents including maribavir and letermovir as well as the use of adoptive T cell therapy may improve the outcome of these difficult-to-treat infections in SOT recipients. In this expert review, we focus on new treatment options for resistant/refractory CMV infection and disease in SOT recipients, with an emphasis on maribavir, letermovir, and adoptive T cell therapy.

Molecular Epidemiology of Cytomegalovirus UL97 and UL54 variants in Taiwan

BACKGROUND

The antiviral resistance of cytomegalovirus (CMV) infections is associated with mutations in the CMV UL54 and UL97 gene regions and is a serious problem in immunocompromised patients. However, the molecular epidemiology of UL54 and UL97 in Taiwan is unclear.

METHODS

We conducted a retrospective study of patients with CMV infections between January and December 2016 in two tertiary hospitals, one regional hospital in Taiwan. CMV DNAemia was confirmed by elevated CMV DNA titers. Then the regions of the UL54 and UL97 mutations were amplified by PCR and sequenced.

RESULTS

Of 729 patients with CMV syndrome, 112 CMV DNAemia patients were enrolled. Twelve novel variants in UL54 (P342S, S384F, K434R, S673F, T754M, R778H, C814S, M827I, G878E, S880L, E888K, and S976N) and one novel variant in UL97 (M615T) were discovered. UL97 antiviral resistance mutations (L595S, M460I, and M460V) were found in four patients (3.6%). In the drug resistance strains, the mutation events occurred after 83-150 days of therapy, and drug resistance was also observed in these patients. The following high frequency variants were observed: D605E in UL97 and A885T, N898D, V355A, N685S, and A688V in UL54.

CONCLUSION

The results demonstrate that the positive rate of CMV DNAemia was 15.3% (112/729) among the patients with clinical CMV infection symptoms. The proportion of antiviral resistance CMV strains within CMV DNAemia patients was 3.6%. With the information of polymorphism incidence in the UL54 and UL97 patients from our study, determination of the genetic profile of UL54 and UL97 among immunocompromised populations with refractory CMV infection is recommended.

Characterization of the dynamics of human cytomegalovirus resistance to antiviral drugs by ultra-deep sequencing

Prophylactic or preemptive treatment strategies are required to prevent human cytomegalovirus (CMV) infections in transplant recipients. However, treatment failure occurs when CMV resistant-associated variants (RAVs) are selected. Although the diversity of CMV is lower than that of RNA viruses, CMV appears to show some genetic instability, with possible minor emerging resistance that may be undetectable by Sanger sequencing. We aimed to examine CMV-resistance mutations over time by ultra-deep sequencing (UDS) and Sanger sequencing in a kidney transplant recipient experiencing CMV infection. This patient showed a transient response to three different antiviral drugs (valganciclovir, foscarnet, and maribavir) and four episodes of CMV resistance over two years. The full-length UL97 (2.3kpb) and partial UL54 (2.4kpb) CMV genes were studied by UDS and Sanger sequencing and linkage mutations calculated to determine RAVs. We detected four major and five minor resistance mutations. Minor resistant variants (2-20%) were detected by UDS, whereas major resistance substitutions (>20%) were identified by both UDS and Sanger method. We detected cross-resistance to three drugs, despite high CMV loads, suggesting that the fitness of the viral mutants was not impaired. In conclusion, CMV showed complex dynamic of resistance under antiviral drug pressure, as described for highly variable viruses. The emergence of successive RAVs constitutes a clinically challenging complication and contributes to the difficulty of therapeutic management of patients.

Cytomegalovirus viremia in lung transplantation during and after prophylaxis

BACKGROUND

Lung transplantation has a high risk of cytomegalovirus (CMV) viremia and disease.

METHODS

Valganciclovir was planned for 6 months in CMV recipient seropositive (R+) lung transplants (LTs) and given long-term in D+R- LTs. CMV viremia was monitored regularly during and after prophylaxis in all patients.

RESULTS

Of 137 LTs, 22 were D+R-, 49 D+R+, 43 D-R+, and 23 D-R-, with median follow up 4.1 years (IQR 2.1-6.2 years). CMV viremia at any time occurred in 44.5% of LTs. CMV viral load >10³  c/mL was uncommon (9/77 episodes). CMV viremia occurred at median 665 days (IQR 271-1411 days), in 5.1% LTs <6 months, 20.3% LTs 6-12 months, and 35.8% LTs >12 months. CMV disease occurred in 6 (4.4%) LTs at an overall rate of 1.0 episode per 100 person-years: two of these cases were organ-specific disease, four were CMV syndrome. One case of ganciclovir-resistant CMV was diagnosed. D+R+ and D+R- LTs had higher viremia rates than the D-R+ group. No viremia occurred in D-R- LTs. CMV viremia was not associated with age, gender, type of LT, indication for LT, acute rejection, bronchiolitis obliterans syndrome, or mortality.

CONCLUSIONS

Prophylaxis for 6 months in D+R+ and D-R+, and past 12 months in D+R- LTs, with long-term monitoring in all patients using a sensitive assay, and reinstitution of valganciclovir for low-level viremia was effective at markedly reducing the incidence of CMV disease. CMV D-R- LTs do not need routine CMV monitoring.

Risk Factors and Outcomes of Ganciclovir-Resistant Cytomegalovirus Infection in Solid Organ Transplant Recipients

Background

Ganciclovir-resistant (ganR) cytomegalovirus (CMV) is an emerging and important problem in solid organ transplant (SOT) recipients. Only through direct comparison of ganR- and ganciclovir-sensitive (ganS) CMV infection can risk factors and outcomes attributable specifically to ganciclovir resistance appropriately be determined.

Methods

We performed a retrospective, case-control (1:3) study of SOT recipients with genotypically confirmed ganR-CMV (n = 37) and ganS-CMV infection (n = 109), matched by donor/recipient CMV serostatus, year and organ transplanted, and clinical manifestation. We used χ2 (categorical) and Mann-Whitney (continuous) tests to determine predisposing factors and morbidity attributable to resistance, and Kaplan-Meier plots to analyze survival differences.

Results

The rate of ganR-CMV was 1% (37/3467) overall and 4.1% (32/777) among CMV donor-positive, recipient-negative patients, and was stable over the study period. GanR-CMV was associated with increased prior exposure to ganciclovir (median, 153 vs 91 days, P < .001). Eighteen percent (3/17) of lung transplant recipients with ganR-CMV had received <6 weeks of prior ganciclovir (current guideline-recommended resistance testing threshold), and all non-lung recipients had received ≥90 days (median, 160 [range, 90-284 days]) prior to diagnosis of ganR-CMV. GanR-CMV was associated with higher mortality (11% vs 1%, P = .004), fewer days alive and nonhospitalized (73 vs 81, P = .039), and decreased renal function (42% vs 19%, P = .008) by 3 months after diagnosis.

Conclusions

GanR-CMV is associated with longer prior antiviral duration and higher attributable morbidity and mortality than ganS-CMV. Upcoming revised CMV guidelines should incorporate organ transplant-specific thresholds of prior drug exposure to guide rational ganR-CMV testing in SOT recipients. Improved strategies for prevention and treatment of ganR-CMV are warranted.

Treatment of alpha and beta herpesvirus infections in solid organ transplant recipients

INTRODUCTION

Human herpesviruses frequently cause infections in solid organ transplant (SOT) recipients. Areas covered: We provide an overview of the clinical impact of alpha and beta herpesviruses and highlight the mechanisms of action, pharmacokinetics, clinical indications, and adverse effects of antiviral drugs for the management of herpes simplex virus, varicella zoster virus and cytomegalovirus. We comprehensively evaluated key clinical trials that led to drug approval, and served as the foundation for management guidelines. We further provide an update on investigational antiviral agents for alpha and beta herpesvirus infections after SOT. Expert commentary: The therapeutic armamentarium for herpes infections is limited by the emergence of drug resistance. There have been major efforts for discovery of new drugs against these viruses, but the results of early-phase clinical trials have been less than encouraging. We believe, however, that more antiviral drug options are needed given the adverse side effects associated with current antiviral agents, and the emergence of drug-resistant virus populations in SOT recipients. Likewise, optimized use and strategies are needed for existing and novel antiviral drugs against alpha and beta-herpesviruses in SOT recipients.

CMV Immunoglobulins for the Treatment of CMV Infections in Thoracic Transplant Recipients

Intravenous ganciclovir and, increasingly, oral valganciclovir are now considered the mainstay of treatment for cytomegalovirus (CMV) infection or CMV disease. Under certain circumstances, CMV immunoglobulin (CMVIG) may be an appropriate addition or, indeed, alternative. Data on monotherapy with CMVIG are limited, but encouraging, for example in cases of ganciclovir intolerance. In cases of recurrent CMV in thoracic transplant patients after a disease- and drug-free period, adjunctive CMVIG can be considered in patients with hypogammaglobulinemia. Antiviral-resistant CMV, which is more common among thoracic organ recipients than in other types of transplant, can be an indication for introduction of CMVIG, particularly in view of the toxicity associated with other options, such as foscarnet. Due to a lack of controlled trials, decision-making is based on clinical experience. In the absence of a robust evidence base, it seems reasonable to consider the use of CMVIG to treat CMV in adult or pediatric thoracic transplant patients with ganciclovir-resistant infection, or in serious or complicated cases. The latter can potentially include (i) treatment of severe clinical manifestations, such as pneumonitis or eye complications; (ii) patients with a positive biopsy in end organs, such as the lung or stomach; (iii) symptomatic cases with rising polymerase chain reaction values (for example, higher than 5.0 log₁₀) despite antiviral treatment; (iv) CMV disease or CMV infection or risk factors, such as CMV-IgG–negative serostatus; (vi) ganciclovir intolerance; (vii) patients with hypogammaglobulinemia.

Ganciclovir-resistant cytomegalovirus infections among lung transplant recipients are associated with poor outcomes despite treatment with foscarnet-containing regimens

Ganciclovir-resistant cytomegalovirus (CMV) infections are reported infrequently among lung transplant recipients receiving extended valganciclovir prophylaxis. We performed a single-center, retrospective review of ganciclovir-resistant CMV infections in a program that employed valganciclovir prophylaxis for ≥6 months after lung transplant. CMV infections were diagnosed in 28% (170/607) of patients. UL97 mutations were detected in 9.4% (16/170) of CMV-infected patients at a median of 8.5 months posttransplant (range, 5 to 21) and despite prophylaxis for a median of 7 months (range, 4 to 21). UL97 mutations were canonical; 25% (4/16) of strains carried concurrent UL54 mutations. Ganciclovir-resistant CMV was more likely with breakthrough infections (75% [12/16] versus 19% [30/154]; P = 0.00001) and donor positive/recipient negative (D+/R-) serostatus (75% versus 45% [69/154]; P = 0.03). The median whole-blood CMV load was 4.13 log10 copies/cm(3) (range, 2.54 to 5.53), and 93% (14/15) of patients had low-moderate immune responses (Cylex Immunoknow). Antiviral therapy was successful, failed, or eradicated viremia followed by relapse in 12% (2/16), 31% (5/16), and 56% (9/16) of patients, respectively. Eighty-seven percent (14/16) of patients were treated with foscarnet-containing regimens; toxicity developed in 78% (11/14) of these. Median viral load half-life and time to viremia eradication among foscarnet-treated patients were 2.6 and 23 days, respectively, and did not correlate with protection from relapse. Sixty-nine percent (11/16) of patients developed CMV pneumonitis, and 25% (4/16) died of it. Serum viral load was independently associated with death among foscarnet-treated patients (P = 0.04). In conclusion, ganciclovir-resistant CMV infections remained a major cause of morbidity and mortality following lung transplantation. Foscarnet-based regimens often eradicated viremia rapidly but were ineffective in the long term and limited by toxicity.

The time course of development and impact from viral resistance against ganciclovir in cytomegalovirus infection

(Val)ganciclovir is used to treat cytomegalovirus (CMV) infection following solid organ (SOT) or hematopoietic stem cell (HSCT) transplantation. Treatment failures occur, but the contribution from 39 known ganciclovir-related mutations (GRMs) in the CMV-UL97 gene remains controversial. We propose a categorization of these GRMs potentially useful when interpreting sequence analyses in clinical settings. The UL97 gene was sequenced from first/recurrent CMV infections among consecutive SOT or HSCT recipients during 2004-2009. GRMs were categorized as: Signature GRM (sGRM) if in vitro ganciclovir IC(50) ratio for mutated versus wild-type virus >2 (n = 24); polymorphic GRM (pGRM) if ratio <2 (n = 15). (Val)ganciclovir treatment failure was defined as persistent viremia for 30 days or switch to foscarnet within this period. Of 99 (49 HSCT and 50 SOT) recipients with one CMV infection episode, 15 (13 HSCT and 2 SOT) experienced a total of 19 recurrent infection episodes. The prevalence of sGRM was 0% at start of first episode, whereas at start of recurrent episodes, prevalence was 37%. Only one sGRM was present at a time in individual patients. Patients with CMV containing an sGRM (vs. wild type)-but not with a pGRM-were at excess risk of treatment failure (odds ratio = 70.6 [95% CI:8.2-609.6]; p < 0.001). sGRMs emerged only following longer termed use of antiherpetic drugs and usually in recurrent CMV infection episodes. Risk of ganciclovir treatment failure was raised if an sGRM was detected.

The genetic basis of human cytomegalovirus resistance and current trends in antiviral resistance analysis

Infections due to resistant human cytomegalovirus (CMV) are an emerging problem, particularly in immunocompromised hosts. When managing such patients, clinicians should be aware of the possibility of developing CMV antiviral resistance, especially while on prolonged therapy or if severe immunosuppression is present. CMV resistance to current antiviral agents is mediated by alterations in either the UL97 kinase or DNA polymerase, encoded by the UL97 and UL54 genes, respectively. UL97 mutations are capable of conferring resistance to ganciclovir, while UL54 mutations can impart resistance to ganciclovir, cidofovir, and foscarnet. If treatment failure is suspected to be due to antiviral resistance, CMV resistance analysis should be obtained. Phenotypic resistance assays performed on clinical isolates measure antiviral susceptibilities directly, but are laborious and time-consuming. Therefore, genotypic resistance analysis has become the more common means of diagnosing CMV resistance. Mutations in UL97 or UL54 may be clinically associated with resistance, but their effect on antiviral susceptibility must be confirmed by marker transfer techniques such as recombinant phenotyping.

[Prevention of cytomegalovirus disease in lung transplantation]

Lung transplant recipients, more than other organ transplant recipients, are at particular risk for cytomegalovirus (CMV) infection and disease. CMV prevention avoids the indirect effects of this virus, such as opportunistic fungal infections and obliterative bronchiolitis, the latter being the major limiting factor in the long-term success of lung-transplantation. CMV prevention strategies have significantly reduced CMV disease and CMV-related mortality. Two major strategies are commonly used for CMV prevention: universal prophylaxis and preemptive therapy. In lung transplant recipients, the efficacy and safety of preemptive treatment have not been studied and therefore, cannot be recommended. Universal prophylaxis is the best strategy for preventing CMV disease in lung transplant recipients. There is no consensus on the optimal duration of prophylaxis, but the recently published GESITRA-SEIMC/REIPI 2011 Guidelines for the management of CMV infection in solid-organ transplant patients recommend 6 months posttransplantation. In D+/R- recipients, this period can be prolonged to 12 months if there are difficulties in monitoring at 6 months posttransplantation. The future of prevention will probably depend on immunoguided strategies.

Update and review: state-of-the-art management of cytomegalovirus infection and disease following thoracic organ transplantation

PURPOSE

Cytomegalovirus (CMV) is among the most important viral pathogens affecting solid organ recipients. The direct effects of CMV (eg, infection and its sequela; tissue invasive disease) are responsible for significant morbidity and mortality. In addition, CMV is associated with numerous indirect effects, including immunomodulatory effects, acute and chronic rejection, and opportunistic infections. Due to the potentially devastating effects of CMV, transplant surgeons and physicians have been challenged to fully understand this infectious complication and find the best ways to prevent and treat it to ensure optimal patient outcomes.

SUMMARY

Lung, heart, and heart-lung recipients are at considerably high risk of CMV infection. Both direct and indirect effects of CMV in these populations have potentially lethal consequences. The use of available treatment options depend on the level of risk of each patient population for CMV infection and disease. Those at the highest risk are CMV negative recipients of CMV positive organs (D+/R-), followed by D+/R+, and D-/R+. More than 1 guideline exists delineating prevention and treatment options for CMV, and new guidelines are being developed. It is hoped that new treatment algorithms will provide further guidance to the transplantation community. The first part describes the overall effects of CMV, both direct and indirect; risk factors for CMV infection and disease; methods of diagnosis; and currently available therapies for prevention and treatment. Part 2 similarly addresses antiviral-resistant CMV, summarizing incidence, risk factors, methods of diagnosis, and treatment options. Parts 3 and 4 present cases to illustrate issues surrounding CMV in heart and lung transplantation, respectively. Part 3 discusses the possible mechanisms by which CMV can cause damage to the coronary allograft and potential techniques of avoiding such damage, with emphasis on fostering strong CMV-specific immunity. Part 4 highlights the increased incidence of CMV infection and disease among lung transplant recipients and its detrimental effect on survival. The possible benefits of extended-duration anti-CMV prophylaxis are explored, as are those of combination prophylaxis with valganciclovir and CMVIG.

CONCLUSION

Through improved utilization of information regarding optimized antiviral therapy for heart and lung transplant recipients to prevent and treat CMV infection and disease and through increased understanding of clinical strategies to assess, treat, and monitor patients at high risk for CMV recurrence and resistance, the health care team will be able to provide the coordinated effort needed to improve patient outcomes.

First report of successful treatment of multidrug-resistant cytomegalovirus disease with the novel anti-CMV compound AIC246

We report the first case of cytomegalovirus (CMV) disease treated with AIC246, a novel anti-CMV compound which targets the viral terminase complex and remains active against virus resistant to DNA polymerase inhibitors. A lung transplant recipient developed refractory multidrug-resistant CMV disease involving the lungs, gastrointestinal tract and retina. His disease progressed despite treatment with all DNA polymerase inhibitors; multiple agents reported to have activity against CMV in case series, and reduction in his immunosuppressive medications. AIC246 which is in clinical development was obtained for emergency use, and combined with additional reduction in immunosuppression resulted in rapid clinical, virological and radiological resolution of disease. The patient has remained free of CMV disease or viremia off treatment for greater than 3 months. In summary AIC246, while still in development, may be a promising alternative to current therapies.

Antiviral drug resistance: mechanisms and clinical implications

Antiviral drug resistance is an increasing concern in immunocompromised patient populations, where ongoing viral replication and prolonged drug exposure lead to the selection of resistant strains. Rapid diagnosis of resistance can be made by associating characteristic viral mutations with resistance to various drugs as determined by phenotypic assays. Management of drug resistance includes optimization of host factors and drug delivery, selection of alternative therapies based on knowledge of mechanisms of resistance, and the development of new antivirals. This article discusses drug resistance in herpesviruses and hepatitis B.

Antiviral drug resistance: mechanisms and clinical implications

Antiviral drug resistance is an increasing concern in immunocompromised patient populations, where ongoing viral replication and prolonged drug exposure lead to the selection of resistant strains. Rapid diagnosis of resistance can be made by associating characteristic viral mutations with resistance to various drugs as determined by phenotypic assays. Management of drug resistance includes optimization of host factors and drug delivery, selection of alternative therapies based on knowledge of mechanisms of resistance, and the development of new antivirals. This article discusses drug resistance in herpesviruses and hepatitis B.

Antiviral treatment of cytomegalovirus infection and resistant strains

This review discusses the management of resistant cytomegalovirus and prevention strategies for fatal therapy failures. Five drugs, ganciclovir/valganciclovir, cidofovir, foscarnet and fomivirsen, have been approved so far for the treatment of human cytomegalovirus (HCMV) diseases. Except for fomivirsen, all of the approved drugs share the same target molecule, the viral DNA polymerase. The emergence of drug-resistant HCMV has also been reported for all of them. For optimal care of patients, the clinical virologist has to provide the most meaningful assays for monitoring of therapy and early detection of emerging drug-resistant HCMV. Additionally, a quantitative drug monitoring would be helpful. New antiviral agents are urgently needed with less adverse effects, good oral bioavailability and possibly novel targets or mechanisms of action to avoid cross-resistance and to improve the ability to suppress the selection of resistant virus strains by combination therapy. Compounds like maribavir, leflunomide and artesunate, which exhibit anti-HCMV activity in vitro and in patients need to be evaluated in clinical studies. Besides these, new therapy approaches like immunotherapy or new diagnostic techniques like pyrosequencing have to be considered in the future.

Long-term outcomes of CMV disease treatment with valganciclovir versus IV ganciclovir in solid organ transplant recipients

Though an important cause of morbidity and mortality in solid organ transplantation (SOT), the long-term outcomes of cytomegalovirus (CMV) disease treatment have not been well studied. In a randomized trial, 321 SOT recipients with CMV disease were followed 1 year after treatment with either twice daily intravenous ganciclovir or oral valganciclovir (for 21 days) followed by once daily valganciclovir until day 49 in all patients. Clinical and viral eradication of CMV disease was similar between groups. Clinical recurrence beyond day 49 was found in 15.1% and virological recurrence in 30.0%, no difference between groups (p > 0.77). In a multivariable logistic regression analysis, the only independent predictor for recurrence was failure to eradicate DNAemia by day 21 (clinical: OR 3.9 [1.3-11.3], p = 0.012; virological: OR 5.6 [2.5-12.6], p < 0.0001). Eight patients developed ganciclovir resistance, with no difference between groups (p = 0.62). Twenty patients (valganciclovir: 11, ganciclovir: 9, p = 0.82) died, 12 due to infections, two involving CMV disease. There were no differences in long-term outcomes between treatment arms, further supporting the use of oral valganciclovir for treatment of CMV disease. Persistent DNAemia at day 21, CMV IgG serostatus and development of resistance may be relevant factors for further individualization of treatment.

A single-center experience with ganciclovir-resistant cytomegalovirus in lung transplant recipients: treatment and outcome

BACKGROUND

Cytomegalovirus (CMV) disease is a major cause of morbidity and mortality after lung transplantation despite ganciclovir prophylaxis. The emergence of ganciclovir-resistant CMV in lung transplant patients has been reported, although the optimal strategy for the management of these infections remains uncertain. A review of the results of glanciclovir susceptibility testing in lung transplant recipients was performed.

METHODS

We found 54% (113 of 210) of lung transplant patients developed CMV infection over a 4-year study period with ganciclovir-resistant CMV infection occurring in >5% of patients (6 of 113). The demographic and clinical characteristics of patients who developed ganciclovir-resistant vs -sensitive CMV infection were similar, although 50% (3 of 6) patients who developed resistance were CMV mismatched (D(+)/R(-) serology). All patients' CMV isolates had mutations in the UL97 gene. In addition, the 3 mismatch patients also had CMV with mutations in the UL54 gene.

RESULTS

Treatment with a combination of foscarnet and ganciclovir or foscarnet alone for ganciclovir-resistant infection led to a significant reduction in virologic load in all patients (p = 0.03), although transient increases in viremia were observed in some patients early after treatment. Renal function worsened after treatment, but overall it was not significantly different from pre-treatment values (p = 0.07).

CONCLUSIONS

Single or combination therapy with foscarnet is effective for treatment of ganciclovir-resistant isolates and excessive concern regarding toxicity should not preclude consideration of these treatments when clinically indicated.

Incidence and Clinical Features of Ganciclovir- Resistant Cytomegalovirus Disease in Heart Transplant Recipients

BACKGROUND

The incidence and clinical and virologic aspects of ganciclovir-resistant cytomegalovirus (CMV) disease have not been well-characterized in heart transplant recipients.

METHODS

We retrospectively analyzed all patients who underwent their first heart transplantation during the period from 1 January 1995 through 30 June 2005 at a single health care center. Cox proportional hazard regression was used to assess the relationship between clinical variables and CMV disease. Portions of the UL97 gene were sequenced in patients with slow clinical and/or virologic response to ganciclovir therapy.

RESULTS

Cytomegalovirus disease developed in 32 (11.7%) of 274 patients at a median of 4.2 months after transplantation (range, 1.8-11.6 months after transplantation) and was independently associated with donor-seropositive/recipient-seronegative (D+/R-) serostatus (adjusted hazard ratio, 6.93; P<.001). The incidence of ganciclovir-resistant CMV disease was 1.5% overall (4 of 274 patients), 5% among D+/R- serostatus recipients (4 of 80 patients), and 12.5% among patients who developed CMV disease (4 of 32 patients). Ganciclovir-resistant CMV disease was significantly associated with D+/R- serostatus (4 [5%] of 80 vs. 0 [0%] of 153 patients; P=.02), greater prior exposure to ganciclovir (median duration of exposure, 150 vs. 69 days; P=.003), and substantial morbidity, including prolonged CMV-associated hospitalization (median duration of hospitalization, 66 vs. 0 days; P<.01).

CONCLUSIONS

CMV disease, including ganciclovir-resistant disease, is an important clinical problem in D+/R- heart transplant recipients who receive antiviral prophylaxis. Strategies specifically designed to reduce the incidence and impact of CMV disease in this population are warranted.

New Functional Domains of Human Cytomegalovirus pUL89 predicted by Sequence Analysis and Three-Dimensional Modelling of the Catalytic Site DEXDc

Introduction

Benzimidazole d-ribonucleosides inhibit DNA packaging during human cytomegalovirus (HCMV) replication. Although they have been shown to target pUL56 and pUL89, the large and small subunits of the HCMV terminase respectively, their mechanism of action is not yet fully understood.

Methods and results

To better understand HCMV DNA maturation and the mechanism of action of benzimidazole derivatives, we studied the HCMV pUL89 protein by a genetic approach combined with primary structure analysis. The pUL89 sequence analysis of 25 HCMV strains and counterparts among herpesviruses allowed identification of 12 conserved regions. We also built a three-dimensional model of the pUL89 ATPasic catalytic site, including ATPase motor motifs I, II and III, that may facilitate the development of future antiviral drugs active against HCMV. Finally, we identified several putative functional domains in pUL89, such as pUL89 zinc finger (pUL89-ZF), DNA cutting sites and portal binding sites, that are probably involved in CMV DNA cleavage and packaging.

Critical care perspective on immunotherapy in lung transplantation

Lung transplantation is now a viable therapeutic option in the care of patients with advanced pulmonary parenchymal or pulmonary vascular disease. Lung transplantation, however, with chronic posttransplant immunosuppression, creates a uniquely vulnerable population of patients likely to experience significant life-threatening complications requiring intensive care. The introduction of several novel immunosuppressive agents, such as sirolimus and mycophenolate mofetil, in conjunction with more established agents such as cyclosporine and tacrolimus, has greatly increased treatment options for lung transplant recipients and likely contributed to improved short-term transplant outcomes. Modern transplant immunosuppression, however, is associated with a host of complications such as opportunistic infections, renal failure, and thrombotic thrombocytopenic purpura. The main focus of this review is to provide a comprehensive summary of modern immunotherapy in lung transplantation and to increase awareness of the serious and potentially life-threatening complications of these medications.

Treatment of multidrug-resistant cytomegalovirus retinitis with systemically administered leflunomide

Multiresistant cytomegalovirus (CMV) infection is increasingly recognized in solid organ transplant recipients. Leflunomide is a novel drug with both immunosuppressive and anti-CMV properties. Herein we report a case of a renal transplant recipient treated with leflunomide for multiresistant CMV retinitis, and provide correlation between serum and vitreous levels of leflunomide. She had stabilization of her retinitis and measurable levels of drug in her vitreous fluid and serum. These initial findings suggest that leflunomide may be useful in the treatment of CMV disease, including retinitis in patients after solid organ transplantation.

Preemptive Therapy With Intravenous Ganciclovir for the Prevention of Cytomegalovirus Disease in Lung Transplant Recipients

The most effective strategy for the prevention of cytomegalovirus (CMV) disease in lung transplantation has not been conclusively established. The aim of this study was to determine the efficacy of preemptive ganciclovir therapy for this purpose. Twenty-five consecutive adult patients positive for CMV before transplantation and surviving more than 30 days after the procedure were studied. Mean follow-up was 732.2 days (range, 210-1125). All patients received intravenous (IV) ganciclovir prophylaxis for the first 21 days and subsequently underwent frequent CMV antigenemia monitoring: weekly for the first 3 months, every 15 days between 3 and 6 months, and monthly thereafter. IV ganciclovir was given when antigenemia results were greater than 10 infected cells per 100,000 polymorphonuclears. The study group was compared with a historical group of 30 consecutive patients who had received IV ganciclovir prophylaxis and continued on oral ganciclovir up to day 120 posttransplantation. Eighteen of the 25 patients (72.0%) presented episodes of CMV infection. Six of the 25 patients (24.0%) had CMV disease, including 3 viral syndromes and 3 cases of pneumonitis. Four patients debuted with CMV disease, 1 of them with pneumonitis. CMV resistance to ganciclovir was observed in 2 patients. The incidence of infection was higher than in the historical group (72.0% vs 46.7%; P < .05), but there were no significant differences in the incidence of CMV disease (24.0% vs 40.0%; P = not significant [NS]). Mean time before onset of the first episode of disease was lower in the preemptive therapy group than in the comparison patients (82.8 days; range, 42-240 vs 175 days; range, 90-243; P < .05). In conclusion, preemptive therapy for CMV disease is as effective a prevention strategy as oral ganciclovir prophylaxis. However, the early appearance of CMV disease with preemptive therapy can make this approach inadvisable.

Early onset of ganciclovir-resistant cytomegalovirus infection in a lung-transplant recipient

Ganciclovir resistance in cytomegalovirus (CMV) is an increasing problem in lung-transplant recipients with adverse clinical outcomes. We experienced the successful treatment of ganciclovir-resistant CMV infection in a lung-transplant recipient still receiving CMV prophylaxis. A 24-year-old woman with lymphangioleiomyomatosis underwent a living-donor lobar lung transplantation. She was a primary CMV mismatch (D+/R-) patient. She recovered from her postoperative complications, and was about to be discharged. However, she suffered ganciclovir-resistant CMV infection during prophylactic therapy. She was successfully treated with foscarnet, and is now alive without recurrence 18 months after surgery.

Management of cytomegalovirus infection in lung transplant recipients: evidence-based recommendations

Cytomegalovirus (CMV) continues to cause significant morbidity and mortality in lung transplant recipients. This article presents recommendations based on available evidence for the optimal management of CMV in lung transplant recipients, which have been developed by an expert committee of transplant physicians-surgeons and infectious disease specialists.

Recomendaciones GESITRA-SEIMC y RESITRA sobre prevención y tratamiento de la infección por citomegalovirus en pacientes trasplantados

Cytomegalovirus (CMV) infection remains an important complication of transplantation. The last decade has been characterized by improvements to management that has reduced its morbidity and mortality. The advance has been particularly important in the diagnosis and prevention. Several techniques have been developed that allow the increasingly rapid and sensitive diagnosis. The different preventive strategies include use of appropriate blood products, immune globulin, and antiviral agents either as prophylaxis or pre-emptive therapy. The development of effective oral drugs as valganciclovir also represents a new advance. It is necessary to summarize these advances to facilitate the development of local policies reflecting recent changes. The Group of Study of Infections in Transplantation (GESITRA) of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) has therefore produced actual recommendations in the management of CMV infection after transplantation.

Use of leflunomide in an allogeneic bone marrow transplant recipient with refractory cytomegalovirus infection

Ganciclovir-resistant cytomegalovirus (CMV) infection is an emerging problem in transplant recipients. Foscarnet resistance and cidofovir resistance have also been described, but no previous reports have suggested treatment regimens for patients with CMV refractory to all three of these drugs. Leflunomide, an immunosuppressive drug used in rheumatoid arthritis and in rejection in solid-organ transplantation, has been reported to have novel anti-CMV activity. However, its clinical utility in CMV treatment has not been described previously. We report an allogeneic bone marrow transplant recipient who developed CMV infection refractory to sequential therapy with ganciclovir, foscarnet, and cidofovir. The patient was ultimately treated with a combination of leflunomide and foscarnet. Both phenotypic and genotypic virologic analysis was performed on sequential CMV isolates. The patient's high CMV-DNA viral load became undetectable on leflunomide and foscarnet, but the patient, who had severe graft-versus-host disease (GVHD) of the liver, expired with progressive liver failure and other complications. We concluded that leflunomide is a new immunosuppressive agent with anti-CMV activity, which may be useful in the treatment of multiresistant CMV. However, the toxicity profile of leflunomide in patients with underlying GVHD remains to be defined.

Clinical and immunologic aspects of cytomegalovirus infection in solid organ transplant recipients

Primary cytomegalovirus (CMV) infection is a major cause of morbidity and mortality in recipients after solid organ transplantation (SOT). Widespread and prolonged use of antiviral drugs has changed the natural course of CMV disease by delaying its onset and causing drug resistance. CMV induces a strong cellular immune response, even in immunosuppressed patients, and has developed strategies to evade this immune surveillance. This review summarizes challenges in managing CMV infection in transplant recipients and highlights current insights in the cellular immune response against CMV.

Cytomegalovirus antiviral resistance associated with treatment induced UL97 (protein kinase) and UL54 (DNA polymerase) mutations

HCMV-related illness due to infections with antiviral resistant virus was verified by phenotypic and genotypic assays in 17% (8/47) of high-risk immunocompromised Australian patients. Selective PCR-sequencing of UL97 (protein kinase; PK) and UL54 (DNA polymerase; DNApol) regions important for antiviral sensitivity, identified the majority (6/8) of resistant strains through detection of mutations known to confer antiviral resistance. Additionally, eight UL54 (DNApol) mutations (N408K, T691S, A692V, S695T, L737M, A834P, V955I, and A972V) of unknown phenotype were identified in six specimens from patients with clinical evidence of antiviral resistant infections. One isolate was resistant to ganciclovir (GCV) and another resistant to PFA on phenotypic testing where mutations in UL97 (PK) or UL54 (DNApol) were not detected, suggesting a loss of correlation between phenotype and genotype. Selective PCR-sequencing of UL97 (PK) and UL54 (DNApol) provided rapid and comprehensive results, but missed some resistance detected by phenotypic assays. A combination of phenotypic and genotypic assays is recommended for complete analysis of CMV antiviral resistance, as well as further definition of the clinical relationship between novel UL54 (DNApol) mutations and antiviral resistance.

Bronchiolitis Obliterans Syndrome

Post-transplantation bronchiolitis obliterans syndrome (BOS) is a clinicopathological syndrome characterised histologically by obliterative bronchiolitis (OB) and physiologically by airflow limitation. It affects long-term survival with no consistently effective treatment strategy.An updated review of risk factors for OB/BOS, and approaches to prevention and treatment was performed through a systematic review of relevant studies between January 1990 and February 2005. The initial search identified 853 publications, with 56 articles reviewed after exclusions. Early acute rejection is the most significant risk factor, with late rejection (> or =3 months) also significant. Lymphocytic bronchitis/bronchiolitis is relevant, with later onset associated with greater risk. Viral infections are identified as significant risk factors. Human leukocyte antigen matching and OB/BOS development is a weaker association, but is stronger with acute rejection. Recipient and donor characteristics have a minor role. There is limited evidence that altering immunosuppression is effective in reducing the rate of decline in lung function. BOS reflects an allo-immunological injury, possibly triggered by cytomegalovirus and respiratory viral infections, or noninfectious injury. Immunological susceptibility may be reflected by more frequent acute rejection episodes. Preventative and therapeutic modifications in immunosuppression remain important. Identifying markers of immunological susceptibility and, hence, risk stratification requires further research.

Cytomegalovirus and lung transplantation

Cytomegalovirus (CMV) infection remains a serious problem in lung transplant recipients. Development of potent oral antiviral agents, molecular techniques for the detection of infection and its response to therapy and the emergence of isolates with antiviral resistance have had significant impacts on the approach to CMV in these patients. This article discusses the following issues as part of a comprehensive CMV management strategy in lung transplant recipients: (1) Prevention strategies in the era of potent oral antiviral agents, (2) the role of new diagnostic techniques in the management of CMV, (3) treatment regimens for established CMV infection or disease, (4) the potential impact of treatment of CMV on the indirect effects on long-term allograft function, and (5) the incidence, risk factors for and impact of ganciclovir resistance following lung transplantation.

The UL97 protein kinase of human cytomegalovirus and homologues in other herpesviruses: impact on virus and host

The human herpesviruses, herpes simplex virus 1 (HSV-1), HSV-2, varicella zoster virus (VZV), Epstein-Barr virus (EBV), human cytomegalovirus (HCMV), human herpesvirus 6A (HHV-6A), HHV-6B, HHV-7 and HHV-8, establish persistent infections with possible recurrence during immunosuppression. HCMV replication is inhibited by the nucleoside analogue ganciclovir (GCV), the compound of choice for the treatment of HCMV diseases and preemptive treatment of infections. The viral UL97 protein (pUL97) which shares homologies with protein kinases and bacterial phosphotransferases is able to monophosphorylate GCV. Homologues of pUL97 are found in HSV (UL13), VZV (ORF47), EBV (BGLF4), HHV-6 (U69), HHV-8 (ORF36) as well as in murine CMV (M97) or rat CMV (R97). Several indolocarbazoles have been reported to be specific inhibitors of pUL97. The protein is important for efficient replication of the virus. Autophosphorylation of pUL97 was observed using different experimental systems. Most recently, it has been shown that pUL97 interacts with the DNA polymerase processivity factor pUL44. Indolocarbazole protein kinase inhibitors are promising lead compounds for the development of more specific inhibitors of HCMV.

Pulmonary complications of solid organ and hematopoietic stem cell transplantation

The ability to successfully transplant solid organs and hematopoietic stem cells represents one of the landmark medical achievements of the twentieth century. Solid organ transplantation has emerged as the standard of care for select patients with severe vital organ dysfunction and hematopoietic stem cell transplantation has become an important treatment option for patients with a wide spectrum of nonmalignant and malignant hematologic disorders, genetic disorders, and solid tumors. Although advances in surgical techniques, immunosuppressive management, and prophylaxis and treatment of infectious diseases have made long-term survival an achievable goal, transplant recipients remain at high risk for developing a myriad of serious and often life-threatening complications. Paramount among these are pulmonary complications, which arise as a consequence of the immunosuppressed status of the recipient as well as from such factors as the initial surgical insult of organ transplantation, the chemotherapy and radiation conditioning regimens that precede hematopoietic stem cell transplantation, and alloimmune mechanisms mediating host-versus-graft and graft-versus-host responses. As the population of transplant recipients continues to grow and as their care progressively shifts from the university hospital to the community setting, knowledge of the pulmonary complications of transplantation is increasingly germane to the contemporary practice of pulmonary medicine.

Variability in standard care for cytomegalovirus prevention and detection in pediatric lung transplantation: survey of eight pediatric lung transplant programs

Cytomegalovirus (CMV) infection after pediatric lung transplantation is a significant risk factor for morbidity and mortality in the first year after transplantation. Multiple strategies have been reported for CMV prevention among adult lung transplant programs. In contrast, little information has been reported regarding protocols for prevention and detection of CMV from pediatric programs. We conducted a survey to better understand the range of practice patterns for CMV prevention and detection at pediatric lung transplant centers. A self-administered questionnaire was distributed to 11 pediatric lung transplant centers identified through the International Pediatric Lung Transplant Collaborative in September 2002. A member of the lung transplant team from each institution was asked to provide the methods of CMV prevention and surveillance. Eight of 11 centers surveyed responded to the questionnaire accounting for 45.6% (26 of 57) and 100% (three of three) of the pediatric lung transplants performed in the US and UK in 2001, respectively. All centers used prophylactic therapy against CMV with either ganciclovir or valganciclovir with duration ranging from 3.5 wk to indefinitely. Most centers (six of eight) prescribed a prophylactic regimen based on donor and recipient CMV serostatus. Half (four of eight) of the centers report using CMV hyperimmune globulin in addition to an antiviral agent. Method for CMV detection varied widely, including use of conventional viral culture (n = 1), antigenemia (n = 7), and polymerase chain reaction (n = 2). A wide range of strategies is used to prevent and detect CMV in pediatric lung transplant recipients with little empiric evidence demonstrating the optimal approach. A retrospective analysis among these centers is being conducted to evaluate the efficacy of these approaches.

Impact of prophylaxis with cytogam alone on the incidence of CMV viremia in CMV-seropositive lung transplant recipients

BACKGROUND

Cytomegalovirus (CMV) infection remains a serious problem after lung transplantation. The purpose of this study was to evaluate the efficacy of CytoGam, a CMV hyperimmune globulin (CMV-IGIV), as CMV prophylaxis after lung transplantation.

METHODS

This prospective, randomized, open-label study compared prophylaxis with CMV-IGIV and no prophylaxis in 44 CMV-seropositive lung transplant recipients. The primary end-point was development of CMV viremia during the first year after transplantation.

RESULTS

Cytomegalovirus viremia was detected in 13 of 22 recipients without prophylaxis and in 16 of 22 recipients with CMV-IGIV prophylaxis (p = 0.19). Cytomegalovirus pneumonitis developed in 8 controls vs in 11 CMV-IGIV recipients (p = 0.54). We found no significant difference between the groups in the incidence of positive shell vial assays (6.8% +/- 6.5% without vs 11.2% +/- 10.1% with prophylaxis, p = 0.09) or in the attack rate of CMV pneumonitis (0.41 +/- 0.59 episodes/patient without vs 0.86 +/- 0.99 episodes/patient with prophylaxis, p = 0.07). Similarly, no difference was apparent in the time to onset of CMV viremia, to detection of CMV DNA in peripheral blood leukocytes by polymerase chain reaction, or to development of CMV pneumonitis. The incidence of acute rejection and bronchiolitis obliterans syndrome and the survival rate during the first post-transplant year did not differ between the groups.

CONCLUSIONS

Prophylaxis with CMV-IGIV alone did not decrease CMV viremia or pneumonitis, did not decrease the incidence of acute rejection or bronchiolitis obliterans syndrome, and did not affect 1-year survival of CMV-seropositive lung transplant recipients at our center.

Emergence of ganciclovir-resistant cytomegalovirus in lung transplant recipients

BACKGROUND

Since ganciclovir-resistant cytomegalovirus (CMV) disease was initially described in a patient with acquired immunodeficiency syndrome (AIDS) in 1986, the incidence of ganciclovir-resistant CMV disease appears to be increasing in immunocompromised patients. More recently, there have been sporadic reports of ganciclovir-resistant CMV disease in solid organ transplantation.

METHODS

We retrospectively assessed the incidence of ganciclovir-resistant CMV disease in all lung transplant recipients transplanted between 6/93 and 6/01 at Loyola University Medical Center. All patients underwent routine CMV blood culture, shell vial assay as well as phenotypic and genotypic anti-viral susceptibility testing according to a pre-determined schedule. The number of CMV episodes, intravenous ganciclovir use, acute and chronic rejection and survival data were documented for all patients.

RESULTS

Twelve of 212 (6%) transplant recipients developed ganciclovir-resistant CMV disease. Ganciclovir resistance was associated with a higher number of CMV episodes (3.4 +/- 2.3 episodes/patient vs 1.7 +/- 0.7 episodes/patient [p < 0.05]) and an increased exposure to cumulative intravenous ganciclovir in the primary CMV-mismatched (D(+)R(-)) population (22 +/- 10 vs 13 +/- 7 days [p < 0.05]) compared with patients who did not develop ganciclovir resistance. In addition, the use of daclizumab therapy was associated with a 7-fold greater likelihood of developing ganciclovir resistance (p < 0.0001). The presence of ganciclovir-resistant CMV disease in our population was associated with a decreased survival that could be attributed to CMV disease itself (p < 0.05).

CONCLUSIONS

By screening all lung transplant recipients with CMV disease for ganciclovir resistance, we were able to detect a higher incidence of ganciclovir-resistant CMV disease (6%) than previously seen in solid organ transplantation. High-risk patients (D(+)R(-) CMV serostatus) who receive anti-lymphocytic therapy should be monitored aggressively and treated to prevent the development of ganciclovir resistance and avert a negative outcome.

Clinical characteristics of 13 solid organ transplant recipients with ganciclovir-resistant cytomegalovirus infection

BACKGROUND

Ganciclovir-resistant (GCV-R) cytomegalovirus (CMV) is now being reported with increasing frequency in solid organ transplant recipients.

OBJECTIVE

To describe the clinical characteristics and outcomes of all solid organ transplant patients with GCV-R CMV seen between 1990 and 2000 at a single center.

METHODS

Patients with clinically suspected GCV resistance had viral isolates subjected to phenotypic analysis by plaque reduction assay, and also genotypic analysis. Medical records of the 13 patients with GCV-R CMV were reviewed for demographic, microbiologic, clinical, and pathologic data.

RESULTS

Thirteen patients were identified, including 5 kidney, 1 heart, and 7 lung transplant recipients. All but one patient (92%) were CMV donor seropositive, recipient negative (D+/R-), and 11/13 (85%) had tissue-invasive CMV. CMV viremia was recurrent in 9/13 (69%); in 2 others, the first CMV episode was fatal. Overall, 9/13 (69%) of patients have died, all of CMV or its complications. Of the 10 who received foscarnet, only one survived. All patients had received GCV-based prophylactic regimens; 8/13 patients (62%) had received CMV hyperimmune globulin (CMVIG) as part of prophylaxis, 6/13 (46%) had received oral ganciclovir, and 5/13 (38%) had received intermittent (3 x/week) IV ganciclovir for prophylaxis.

CONCLUSIONS

GCV-R CMV is associated with CMV D+/R- status, tissue-invasive disease, and high mortality even with foscarnet therapy. Exposure to less than fully therapeutic levels of GCV, in the form of oral or intermittent IV GCV, is common. The use of CMVIG in prophylaxis does not appear to prevent resistance. Further work remains to be done to elucidate the risk factors and optimal mode of prophylaxis and treatment for GCV-R CMV.

Use of cytomegalovirus immune globulin and ganciclovir for the prevention of cytomegalovirus disease in lung transplantation

Cytomegalovirus (CMV) infection and disease continue to be significant causes of morbidity and mortality in lung transplant recipients. The potential benefits of CMV prophylaxis extend beyond prevention of the immediate CMV infection to potentially preventing CMV-associated complications, including superinfection due to Aspergillus bacteria, and other opportunistic infections, and bronchiolitis obliterans syndrome (BOS). Longer courses of prophylactic intravenous (IV) ganciclovir, sequential IV/oral therapy, addition of intravenous CMV immune globulin (CMV-IGIV), surveillance tests, and investigation of the role of hypogammaglobulinemia are a few of the strategies and issues being evaluated to improve CMV prophylaxis and, consequently, graft and patient survival.

Cytomegalovirus drug resistance and clinical implications

Antiviral agents are commonly used for cytomegalovirus (CMV) prophylaxis or therapy after solid organ transplantation. Until recently, the detection of drug-resistant CMV in this setting was rare, but ganciclovir resistance has now been reported to occur in 5-10% of high-risk patient subsets, such as those undergoing primary CMV infection. Persistent viral shedding or progressive CMV disease after several weeks of antiviral therapy may indicate a problem with drug resistance, though laboratory testing is required to confirm this. Rapid genotypic assays for specific mutations in the viral UL97 phosphotransferase or UL54 DNA polymerase genes can be used to detect resistance and predict cross-resistance to other drugs. The emergence of drug resistance may be reduced by optimization of host immunity, use of potent antiviral drug regimens, and adherence to dosing regimens that adequately suppress viral replication.

Ganciclovir-resistant cytomegalovirus in organ transplant recipients

Ganciclovir-resistant (GanR) cytomegalovirus (CMV) is an emerging clinical problem in organ transplant recipients, particularly recipients of kidney and pancreas and lung transplants. GanR CMV, a late posttransplantation complication, is observed predominantly among CMV-seronegative recipients of organs from seropositive donors, especially among recipients receiving intensive immunosuppression and having prolonged exposure to ganciclovir. Given the limitations of current diagnostic methods, if GanR CMV is clinically suspected, empirical treatment with intravenously administered foscarnet should be used in conjunction with reductions in immunosuppressive therapy and possibly CMV hyperimmune globulin. Better diagnostic tools and newer, less-toxic antiviral agents with different mechanisms of action are urgently needed to decrease the morbidity associated with this complication in organ transplant recipients.