Ganciclovir-resistant cytomegalovirus in organ transplant recipients

Efficacy of antimicrobials in preventing resistance in solid organ transplant recipients: A systematic review of clinical trials

BACKGROUND

In the absence of effective antimicrobials, transplant surgery is not viable, and antirejection immunosuppressants cannot be administered, as resistant infections compromise the life-saving goal of organ transplantation.

AIM

To evaluate the efficacy of antimicrobials in preventing resistance in solid organ transplant recipients.

METHODS

A systematic review was conducted using a search methodology consistent with the preferred reporting items for systematic reviews and meta-analyses. This review included randomized clinical trials that evaluated the efficacy of antimicrobial agents (prophylactic or therapeutic) aimed at preventing antimicrobial resistance. The search strategy involved analyzing multiple databases, including PubMed/MEDLINE, Web of Science, Embase, Scopus, and SciELO, as well as examining gray literature sources on Google Scholar. A comprehensive electronic database search was conducted from the databases’ inception until May 2024, with no language restrictions.

RESULTS

After the final phase of the eligibility assessment, this systematic review ultimately included 7 articles. A total of 2318 patients were studied. The most studied microorganisms were cytomegalovirus, although vancomycin-resistant enterococci, Clostridioides difficile, and multidrug-resistant Enterobacterales were also analyzed. The antimicrobials used in the interventions were mainly maribavir, valganciclovir, ganciclovir, and colistin-neomycin. Of concern, all clinical trials showed significant proportions of resistant microorganisms after the interventions, with no statistically significant differences between the groups (mean resistance 13.47% vs 14.39%), except for two studies that demonstrated greater efficacy of maribavir and valganciclovir (mean resistance 22.2% vs 41.1% in the control group; P < 0.05). The total reported deaths in three clinical trials were 75, and there were 24 graft rejections in two studies.

CONCLUSION

All clinical trials reported significant proportions of antimicrobial-resistant microorganisms following interventions. More high-quality randomized clinical trials are needed to corroborate these results.

N-arylpyrimidinamine (NAPA) compounds are broadly acting inhibitors of human cytomegalovirus infection and spread

Human cytomegalovirus (HCMV) is a β-herpesvirus that contributes to the disease burden of immunocompromised and immunomodulated individuals, including transplant recipients and newborns. The FDA-approved HCMV drugs can exhibit drug resistance and severe side effects including bone marrow toxicity, gastrointestinal disruption, and nephrotoxicity. In a previous study, we identified the N-arylpyrimidinamine (NAPA) compound series as a new class of HCMV inhibitors that target early stages of infection. Here we describe the inhibitory activity of two potent NAPA analogs, MBXC-4336 and MBX-4992, that broadly block infection and spread. MBXC-4336 and MBX-4992 effectively inhibited infection by diverse HCMV strains and significantly prevented virus spread in fibroblast and epithelial cells as evaluated by quantifying infected cells and viral genome levels. Further, the NAPA compounds limited replication of clinical HCMV isolates, including a ganciclovir-resistant strain. Importantly, combination studies of NAPA compounds with ganciclovir demonstrated additive or synergistic inhibition of HCMV spread. Collectively, NAPA compounds have therapeutic potential for development as a novel class of anti-HCMV drugs.

Characterization of Ganciclovir Dosing for the Management of Cytomegalovirus in Solid Organ Transplant Recipients Receiving Sustained Low-Efficiency Dialysis

BACKGROUND

The optimal dosing of intravenous ganciclovir in patients receiving sustained low-efficiency dialysis (SLED) remains unclear.

OBJECTIVE

The primary objective is to characterize the dosing of ganciclovir for treating and preventing cytomegalovirus (CMV) in Solid Organ Transplant Recipients receiving SLED. The secondary objective is to evaluate the safety and efficacy of the dosing practices described in this study.

METHODS

Retrospective review of electronic medical records from solid organ transplant recipients (SOTRs) admitted to the Medical Surgical Intensive Care Unit at the Toronto General Hospital (TGH) between November 28, 2016, and September 1, 2021, was conducted. Patients concurrently receiving ganciclovir and SLED were included.

RESULTS

Among the 27 encounters for CMV prevention, 18 patients underwent 8-hour SLED, 6 underwent 24-hour SLED, and 3 received other SLED durations. Most patients (80%) on 8-hour SLED began ganciclovir at 2.5 mg/kg/d, whereas 80% of those on 24-hour SLED started at 5 mg/kg/d. No breakthrough viremia occurred at 5 mg/kg/d, with 1 instance at 2.5 mg/kg/d. Cytopenia rates were higher at 5 mg/kg/d (33% vs 20%). For treatment (n = 20), 16 patients underwent 8-hour SLED, 2 underwent 24-hour SLED, and 2 underwent 12-hour SLED. Most (75%) on 8-hour SLED started at 2.5 mg/kg/d, whereas all on 24-hour SLED began at 5 mg/kg/d. Viral eradication rates were 75% and 60% at 2.5 and 5 mg/kg/d, respectively, with higher cytopenia rates at 5 mg/kg/d (37.5% vs 0%). Dose adjustments were primarily in response to refractory disease or cytopenia.

CONCLUSION AND RELEVANCE

At our institution, ganciclovir dosing patterns suggest that for patients requiring 8-hour SLED, there is clinician comfort in using 2.5 mg/kg/d for prevention and 5 mg/kg/d for treatment. In 24-hour SLED, 5 mg/kg/d may be considered for prevention. Higher doses may be considered for CMV treatment; however, we found greater variability in the dosing practices for these patients. Further research with larger sample sizes and ganciclovir drug-level assessments is needed to optimize dosing strategies for CMV treatment.

HerpesDRG: a comprehensive resource for human herpesvirus antiviral drug resistance genotyping

The prevention and treatment of many herpesvirus associated diseases is based on the utilization of antiviral therapies, however therapeutic success is limited by the development of drug resistance. Currently no single database cataloguing resistance mutations exists, which hampers the use of sequence data for patient management. We therefore developed HerpesDRG, a drug resistance mutation database that incorporates all the known resistance genes and current treatment options, built from a systematic review of available genotype to phenotype literature. The database is released along with an R package that provides a simple approach to resistance variant annotation and clinical implication analysis from common sanger and next generation sequencing data. This represents the first openly available and community maintainable database of drug resistance mutations for the human herpesviruses (HHV), developed for the community of researchers and clinicians tackling HHV drug resistance.

Comparison of prophylaxis and preemptive strategy as cytomegalovirus prevention in liver transplant recipients

OBJECTIVES

Prophylaxis (P) or pre-emptive strategy (PS) in high-risk liver transplant recipients (LTRs) are either recommended. We compared the results of each strategy.

METHODS

Two groups of LTR transplanted during two consecutive periods were compared. Only cytomegalovirus (CMV)-mismatched LTR (Donor +/ Recipient -) were included. The primary endpoints were: the onset of polymerase chain reaction-based DNAemia and the proportion of patients with CMV disease. A number of episodes of CMV infection, antiviral therapy, ganciclovir resistance, infectious or immunological complications, cost of both strategies, and survival (1, 5, and 10 years) were also compared.

RESULTS

Forty-eight and 60 patients were respectively included in the P and PS groups. Eighteen (38%) in the P group and 56 (93%) in the PS group had CMV DNAemia (p <.0001) with a similar CMV disease rate (16.7% and 15%). Duration of curative therapy was longer in the PS group: 91 days versus 16 (p <.0001). Acute rejection was less frequent (p = .04) and more patients experienced a ganciclovir-resistant CMV infection in the PS group (10% vs. 0, p = .03). The drug-associated cost of PS was higher (10 004 vs. 4804€) and the median number of rehospitalization days tended to be higher (6 vs. 4, p = .06). Survival at any time was similar.

CONCLUSION

We reported more CMV DNAemias and ganciclovir-resistant CMV events with PS. The cost of the PS strategy was higher.

Management of Cytomegalovirus Infections in the Era of the Novel Antiviral Players, Letermovir and Maribavir

Cytomegalovirus (CMV) infections may increase morbidity and mortality in immunocompromised patients. Until recently, standard antiviral drugs against CMV were limited to viral DNA polymerase inhibitors (val)ganciclovir, foscarnet and cidofovir with a risk for cross-resistance. These drugs may also cause serious side effects. This narrative review provides an update on new antiviral agents that were approved for the prevention and treatment of CMV infections in transplant recipients. Letermovir was approved in 2017 for CMV prophylaxis in CMV-seropositive adults who received an allogeneic hematopoietic stem cell transplant. Maribavir followed four years later, with an indication in the treatment of adult and pediatric transplant patients with refractory/resistant CMV disease. The target of letermovir is the CMV terminase complex (constituted of pUL56, pUL89 and pUL51 subunits). Letermovir prevents the cleavage of viral DNA and its packaging into capsids. Maribavir is a pUL97 kinase inhibitor, which interferes with the assembly of capsids and the egress of virions from the nucleus. Both drugs have activity against most CMV strains resistant to standard drugs and exhibit favorable safety profiles. However, high-level resistance mutations may arise more rapidly in the UL56 gene under letermovir than low-grade resistance mutations. Some mutations emerging in the UL97 gene under maribavir can be cross-resistant with ganciclovir. Thus, letermovir and maribavir now extend the drug arsenal available for the management of CMV infections and their respective niches are currently defined.

Low-Dose vs Standard-Dose Valganciclovir for Cytomegalovirus Prophylaxis After Kidney Transplantation: A Single-Center Retrospective Analysis

BACKGROUND

Prophylactic administration of valganciclovir (VG) is an accepted method for the prevention of cytomegalovirus (CMV) infection after kidney transplantation (KTx). The standard dosage of oral VG is 900 mg/day, adjusted to renal function. There is growing evidence that low-dose 450 mg/day VG might be safe and effective. We compared low-dose vs standard-dose prophylaxis after KTx in a single-center follow-up study.

METHODS

Data from 603 renal transplantations at a single center were retrospectively analyzed (2011-2014, 12-month follow-up). Recipients with donor IgG positive-recipient IgG positive (D+/R+), (D+/R-), and (D-/R+) CMV serostatus were routinely treated with 450 mg/day VG for 3 months. Based on the same prophylactic dose, patients could be categorized into two groups according to their postoperative renal function: those receiving standard-dose VG due to a lower estimated glomerular filtration rate (eGFR) (average eGFR<60 mL/min/1.73 m2) and those receiving low-dose VG due to higher eGFR (average eGFR>60 mL/min/1.73 m2).

RESULTS

Estimated glomerular filtration rate-based VG serum alterations significantly affected the risk of CMV infection with a higher incidence in higher VG levels (standard-dose: 357 patients, CMV: 33 cases (9.2 %); low-dose: 246 patients, CMV: 10 cases (4.1%). The occurrence of known risk factors: serologic risk distribution and rate of induction therapy were not statistically different between the 2 groups. Treatment of an acute rejection episode influenced the infection rate significantly in the standard-dose group. As a side effect of prophylaxis, leucopenia (<3G/L) was 2.46 times higher in standard-dose vs low-dose group.

CONCLUSION

Low-dose VG administration is safe and non-inferior to the standard dose in the prophylaxis of CMV infection after KTx.

Factors Associated With Genotypic Resistance and Outcome Among Solid Organ Transplant Recipients With Refractory Cytomegalovirus Infection

Genotypically resistant cytomegalovirus (CMV) infection is associated with increased morbi-mortality. We herein aimed at understanding the factors that predict CMV genotypic resistance in refractory infections and disease in the SOTR (Solid Organ Transplant Recipients) population, and the factors associated with outcomes. We included all SOTRs who were tested for CMV genotypic resistance for CMV refractory infection/disease over ten years in two centers. Eighty-one refractory patients were included, 26 with genotypically resistant infections (32%). Twenty-four of these genotypic profiles conferred resistance to ganciclovir (GCV) and 2 to GCV and cidofovir. Twenty-three patients presented a high level of GCV resistance. We found no resistance mutation to letermovir. Age (OR = 0.94 per year, IC95 [0.089-0.99]), a history of valganciclovir (VGCV) underdosing or of low plasma concentration (OR= 5.6, IC95 [1.69-20.7]), being on VGCV at infection onset (OR = 3.11, IC95 [1.18-5.32]) and the recipients' CMV negative serostatus (OR = 3.40, IC95 [0.97-12.8]) were independently associated with CMV genotypic resistance. One year mortality was higher in the resistant CMV group (19.2 % versus 3.6 %, p = 0.02). Antiviral drugs severe adverse effects were also independently associated with CMV genotypic resistance. CMV genotypic resistance to antivirals was independently associated with a younger age, exposure to low levels of GCV, the recipients' negative serostatus, and presenting the infection on VGCV prophylaxis. This data is of importance, given that we also found a poorer outcome in the patients of the resistant group.

Pharmacokinetics, Safety, and Tolerability of NPC-21, an Anti-Cytomegalovirus Monoclonal Antibody, in Healthy Japanese and White Adult Men: A Randomized, Placebo-Controlled, First-in-Human Phase 1 Study

NPC-21 (EV2038) is a fully human monoclonal antibody that targets the antigenic domain 1 of glycoprotein B on the human cytomegalovirus (hCMV) envelope. NPC-21 has been shown to have broadly neutralizing activity and to inhibit cell-to-cell transmission of hCMV in preclinical studies. It is currently in development for the prophylactic or preemptive treatment of hCMV in patients receiving a solid-organ transplant or hematopoietic stem cell transplant. A first-in-human phase 1 study was conducted to assess the pharmacokinetics, safety, and tolerability of NPC-21 in healthy adult men. Forty participants (Japanese, n = 32; White, n = 8) were randomly assigned to receive a single intravenous dose of NPC-21 1, 3, 10, or 20 mg/kg or placebo. Six Japanese participants were included in each dose group and six White participants received a 10-mg/kg dose. The placebo group included 8 Japanese participants and 2 White participants. All 40 participants completed the study. Serum concentration, maximum serum concentration, area under the plasma concentration-time curve from time 0 to the last measurable concentration, and area under the plasma concentration-time curve from time 0 to infinity increased dose dependently; dose proportionality was linear. NPC-21 demonstrated a biphasic elimination pattern, with an estimated half-life between 612 and 790 hours. NPC-21 was safe and well tolerated up to 20 mg/kg. All adverse events were mild, and none led to treatment discontinuation or were considered related to the study drug. There were no differences in pharmacokinetics or safety between Japanese and White participants. These results support further investigation of NPC-21.

HCMV Antivirals and Strategies to Target the Latent Reservoir

Human cytomegalovirus (HCMV) is a ubiquitous human herpesvirus. In healthy people, primary infection is generally asymptomatic, and the virus can go on to establish lifelong latency in cells of the myeloid lineage. However, HCMV often causes severe disease in the immunosuppressed: transplant recipients and people living with AIDS, and also in the immunonaive foetus. At present, there are several antiviral drugs licensed to control HCMV disease. However, these are all faced with problems of poor bioavailability, toxicity and rapidly emerging viral resistance. Furthermore, none of them are capable of fully clearing the virus from the host, as they do not target latent infection. Consequently, reactivation from latency is a significant source of disease, and there remains an unmet need for treatments that also target latent infection. This review briefly summarises the most common HCMV antivirals used in clinic at present and discusses current research into targeting the latent HCMV reservoir.

Is It Feasible to Use CMV-Specific T-Cell Adoptive Transfer as Treatment Against Infection in SOT Recipients?

During the last decade, many studies have demonstrated the role of CMV specific T-cell immune response on controlling CMV replication and dissemination. In fact, it is well established that transplanted patients lacking CMV-specific T-cell immunity have an increased occurrence of CMV replication episodes and CMV-related complications. In this context, the use of adoptive transfer of CMV-specific T-cells has been widely investigated and applied to Hematopoietic Stem Cell Transplant patients and may be useful as a therapeutic alternative, to reconstitute the CMV specific T-cell response and to control CMV viremia in patients receiving a transplantation. However, only few authors have explored the use of T-cell adoptive transfer in SOT recipients. We propose a novel review in which we provide an overview of the impact of using CMV-specific T-cell adoptive transfer on the control of CMV infection in SOT recipients, the different approaches to stimulate, isolate and expand CMV-specific T-cells developed over the years and a discussion of the possible use of CMV adoptive cellular therapy in this SOT population. Given the timeliness and importance of this topic, we believe that such an analysis will provide important insights into CMV infection and its treatment/prevention.

Successful Treatment of UL97 Mutation Ganciclovir-Resistant Cytomegalovirus Viremia in a Renal Transplant Recipient With Letermovir and Adjunct Hyperimmune Cytomegalovirus Immunoglobulin: A Case Report

Letermovir is an antiviral agent indicated for primary prophylaxis of cytomegalovirus (CMV) infection and disease in adult allogeneic hematopoietic stem cell transplant recipients. In this case, UL97 mutation that conferred resistance to ganciclovir was seen in a patient 8 months after renal transplant. We report the off-label use of letermovir with adjunct hyperimmune CMV immunoglobulin in the successful treatment of CMV disease. This report is the first to use this combination for treatment of CMV infection with a high viral load. It contributes to the limited available literature supporting the use of letermovir in the treatment of resistant CMV, where current therapeutic options can be suboptimal due to adverse effects and the risk of cross-resistance.

Cell therapy for cytomegalovirus infection

INTRODUCTION

Cytomegalovirus (CMV) infection is widely prevalent but mostly harmless in immunocompetent individuals. In the post hematopoietic stem cell transplant (HSCT) setting unrestricted viral replication can cause end-organ damage (CMV disease) and, in a small proportion, mortality. Current management strategies are based on sensitive surveillance programmes, with the more recent introduction of an effective prophylactic antiviral drug, letermovir, but all aim to bridge patients until reconstitution of endogenous immunity is sufficient to constrain viral replication.

AREAS COVERED

Over the past 25 years, the adoptive transfer of CMV-specific T-cells has developed from the first proof of concept transfer of CD 8 + T-cell clones, to the development of 'off the shelf' third party derived Viral-Specific T-cells (VSTs). In this review, we cover the current management of CMV, and discuss the developments in CMV adoptive cellular therapy.

EXPERT OPINION

Due to the adoption of letermovir as a prophylaxis in standard therapy, the incidence of CMV reactivation is likely to decrease, and any widely adopted cellular therapy needs to be economically competitive. Current clinical trials will help to identify the patients most likely to gain the maximum benefit from any form of cell therapy.

Outcomes of transplant recipients treated with cidofovir for resistant or refractory cytomegalovirus infection

BACKGROUND

Treatment of ganciclovir-resistant (GCV-R)/refractory cytomegalovirus (CMV) infections in blood/marrow transplant (BMT) and solid organ transplant (SOT) recipients remains suboptimal. Cidofovir (CDV), a nucleotide analogue with anti-CMV activity, is nephrotoxic and oculotoxic.

METHODS

We retrospectively evaluated the outcomes of SOT and BMT patients with GCV-R/refractory CMV treated with CDV between 1/1/2008 and 12/31/2017.

DATA COLLECTED

baseline demographics, CMV serostatus, clinical and virologic presentations and outcomes, UL97 and UL54 genotype mutations, drug toxicities, and cause of death. Descriptive statistics were used.

RESULTS

16 patients received CDV for treatment of CMV: six BMT and 10 SOT. Seven (47%) of the patients had high-risk donor/recipient serostatus: six (60%) SOT were D+/R-; one (16.7%) BMT was D-/R+. Median time to CMV DNAemia was 131 days post-transplant (IQR, 37.5-230.3). Proven tissue invasive disease was present in three patients (18.8%). Twelve (75%) had genotype testing; 10 (83.3%) of those had antiviral resistance mutations. While on CDV, six (37.5%) developed nephrotoxicity, and four (25%) developed uveitis (two had both uveitis and nephrotoxicity). Eight (50%) had failure to clear CMV DNAemia despite CDV treatment. Eight (50%) of the patients died; median time to death, after initiation of CDV, was 33.5 days [IQR22-988].

CONCLUSIONS

In the absence of good therapeutic alternatives, CDV is used in GCV-R/refractory CMV infection. However, it is associated with a substantial risk of toxicity and failure to clear CMV DNAemia, highlighting the need for development of newer and less toxic therapies. The high mortality in this group of patients underscores the severity of illness in this population.

Antiviral-resistant cytomegalovirus infections in solid organ transplantation in the Netherlands

Objectives

Antiviral resistance in cytomegalovirus (CMV) may result from mutations in the molecular targets of antiviral agents. The aim of this study was to investigate both the prevalence of resistance-associated mutations and the factors associated with antiviral resistance in solid organ transplant (SOT) patients with repeated high CMV loads during antiviral treatment.

Methods

SOT patients were selected retrospectively, based on CMV loads of >30000 IU/mL at least twice in a period during which treatment was given. Patient samples were tested for antiviral resistance by Sanger sequencing the UL97 and UL54 genes of CMV, which code for the viral kinase and polymerase. Factors predisposing to and resulting from the development of antiviral resistance mutations were analysed.

Results

Multiple samples from 113 SOT patients were tested, showing resistance-associated mutations in 25 patients (22%). A further 20 (18%) patients showed mutations that were not known to be associated with antiviral resistance. Several factors were associated with development of resistance-associated mutations in UL97 as well as UL54, including human leucocyte antigen (HLA) mismatch, which occurred more frequently in the group of patients with resistance mutations. High-level resistance mutations were most frequently seen in UL97.

Conclusions

This study shows that by selecting patients solely on the basis of virological response to treatment, more patients with antiviral resistance mutations are identified. In this study we confirm findings by other groups that primary infections are associated with resistance development. Moreover, we show that HLA mismatch is associated with the development of antiviral resistance, which suggests a role for host immunity in the development of resistance.

Resistant or refractory cytomegalovirus infections after hematopoietic cell transplantation: diagnosis and management

PURPOSE OF REVIEW

Refractory or resistant cytomegalovirus (CMV) infections are challenging complications after hematopoietic cell transplantation (HCT). Most refractory or resistant CMV infections are associated with poor outcomes and increased mortality. Prompt recognition of resistant or refractory CMV infections, understanding the resistance pathways, and the treatment options in HCT recipients are imperative.

RECENT FINDINGS

New definitions for refractory and resistant CMV infections in HCT recipients have been introduced for future clinical trials. Interestingly, refractory CMV infections are more commonly encountered in HCT recipients when compared with resistant CMV infections. CMV terminase complex mutations in UL56, UL89, and UL51 could be associated with letermovir resistance; specific mutations in UL56 are the most commonly encountered in clinical practice. Finally, brincidofovir, maribavir, letermovir, and CMV-specific cytotoxic T-cell therapy expanded our treatment options for refractory or resistant CMV infections.

SUMMARY

Many advances have been made to optimize future clinical trials for management of refractory or resistant CMV infections, and to better understand new resistance mechanisms to novel drugs. New drugs or strategies with limited toxicities are needed to improve outcomes of difficult to treat CMV infections in HCT recipients.

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.

Cytomegalovirus viremia and resistance patterns in immunocompromised children: An 11-year experience

We noted a recent increase in number of immunocompromised children with CMV viremia at our institution. The purpose of this study was to determine the frequency of CMV viremia in this population and evaluate factors associated with drug-resistant mutations. A retrospective review of immunocompromised hosts, 0-21 years of age, who had CMV viremia during 2007-2017. CMV viremia was detected using PCR assays. Genetic mutation assays were performed using PCR sequencing of the phosophotransferase UL 97 gene and the polymerase UL54 gene of CMV using Quest Diagnostics (San Juan Capistrano, CA, USA) or ARUP Labs (Salt Lake City, UT, USA). Thirty-one patients were identified, including 10 (32%) during the last 2 years. Of the 31 patients, 18 had hematopoietic stem cell transplantation (HSCT), 5 had primary immunodeficiency, 4 had malignancies, 3 had heart transplantation and 1 had new Human Immunodeficiency virus (HIV) infection. Antiviral resistance testing was performed on isolates from seven patients: five with persistent viremia (>1 mo), and two prior to starting antiviral therapy. Resistance was identified in three patients' isolates: two with common variable immunodeficiency (CVID) and one with recurrent Hodgkin's lymphoma who had undergone autologous HSCT. The two patients with CVID had chronic diarrhea and malabsorption and had received prolonged oral valganciclovir courses prior to emergence of resistance. The patient with Hodgkin's lymphoma had received a prolonged IV ganciclovir course. All three tested positive for UL97 mutation and two had both UL97 and UL54 gene mutations. Majority of our patients (21/31) with CMV viremia were transplant recipients and ganciclovir resistance developed in 10%. Two had intestinal malabsorption. Treatment with oral valganciclovir should be avoided in patients with poor gut absorption as that may increase the risk of resistance.

Global estimate of phenotypic and genotypic ganciclovir resistance in cytomegalovirus infections among HIV and organ transplant patients; A systematic review and meta-analysis

Human cytomegalovirus (CMV), an opportunistic pathogen belonging to Herpesviridae family, is considered as one of the major causes of morbidity and mortality among wide variety of patients, particularly in transplant recipients and HIV positive patients. As this virus can be resistant to treatment, frequency of CMV in patients who receive organ transplantation and people suffering from AIDS was studied between 1980 and 2019. Medline (via PubMed), Embase, Web of Science, and the Iranian Database were reviewed, and Comprehensive Meta-Analysis (V2.0, Biostat) software analyzed all data. Finally, we used Cochran's Q-statistic to encounter heterogeneity between different studies. Meta-analyses indicated, GCV resistance was 14.1% (95% CI 11.2-17.7); however, in patients suffering from AIDS and organ transplantation were 19.5% (95% CI 14.7-25.4) and 11.4% (95% CI 8.1-15.8), respectively. There were increasing rates in the prevalence of GCV resistance in CMV among transplant recipients, and HIV positive patients. Therefore, evaluation of these refractory infections is beneficial.

CMV Prevention and Treatment in Transplantation: What's New in 2019

PURPOSE OF REVIEW

Transplant recipients are at risk for cytomegalovirus (CMV) infection and associated morbidity and mortality. We summarize recently introduced or currently investigated modalities for prevention and treatment of CMV infection in hematopoietic cell (HCT) and solid organ transplant (SOT) recipients.

RECENT FINDINGS

Letermovir was recently approved for CMV prevention in HCT recipients. Data from real world studies support its role to improve outcomes in this population. Letermovir is currently under investigation for broader patient populations and indications. Maribavir is in late stages of development for CMV treatment and may provide a safer alternative to currently available anti-CMV drugs. Promising CMV vaccine candidates and adoptive cell therapy approaches are under evaluation. CMV immune monitoring assays are predicted to play a more central role in our clinical decision making. In recent years, major advances have been made in CMV prevention and treatment in transplant recipients. Rigorous research is ongoing and is anticipated to further impact our ability to improve outcomes in this population.

Analysis of Ganciclovir-Resistant Cytomegalovirus Infection Caused by the UL97 Gene Mutation in Codons 460 and 520 in Pediatric Patients: A Case Series

Background

Drug-resistant cytomegalovirus (CMV) infection has been increasingly recognized. However, there are limited data in pediatric patients. In this study, the prevalence and factors associated with CMV infection with UL97 mutations in pediatric patients treated with ganciclovir but not responding to treatment were evaluated.

Methods

This retrospective study was conducted from January 2013 to December 2017. All patients who were suspected of having ganciclovir-resistant CMV infection and had never had ganciclovir prophylaxis were included. Genotypic assay for UL97 mutations in codons 460 and 520 conferring ganciclovir resistance was performed. Factors associated with the presence of UL97 mutations were analyzed.

Results

Of 34 patients included, 10 patients (29.4%) had a genotypically confirmed UL97 mutation. The median age (interquartile range [IQR]) was 3 (0.85–8.68) years. Ganciclovir resistance was tested at a median time (IQR) of 22.5 (14.3–31) days after initiation of ganciclovir. All resistant isolates harbored a UL97 mutation in codon 460. Compared with patients infected with CMV without UL97 mutation, those infected with UL97 mutation strains were younger (median age [IQR], 3.02 [0.85–8.68] vs 10.45 [2.7–16.4] years) and had a higher maximum viral load (median [IQR], 5.06 [4.74–6.05] vs 4.42 [4.03–4.87] copies/mL). Six of 10 (60%) patients were successfully treated with high-dose ganciclovir (7.5 mg/kg twice daily).

Conclusions

UL97 mutation ganciclovir-resistant CMV infection was not uncommon in the pediatric population. Screening for this mutation should be considered in patients experiencing virological worsening while ganciclovir is given, even if patients have not previously received ganciclovir prophylaxis.

Management of Ganciclovir Resistant Cytomegalovirus Retinitis in a Solid Organ Transplant Recipient: A Review of Current Evidence and Treatment Approaches

Purpose: Cytomegalovirus retinitis (CMVR) is a serious and potentially sight-threatening infection in immunocompromised individuals. Strategies for the management of drug-resistant CMVR are described. Methods: A case of severe bilateral CMVR in a single lung transplant patient, with UL97 mutation conferring ganciclovir-resistance, is presented. Treatment with standard antiviral agent and adjuvant leflunomide, immunosuppression modifications (calcineurin inhibitors and corticosteroid), intravitreal antiviral therapy and novel use of CMV-immunoglobulin is described. A literature review to support drug-resistant CMVR management is presented. Results: Severe and progressive CMV retinitis was refractory to intravitreal foscarnet and systemic leflunomide. Drug-toxicity restricted systemic antiviral therapy options. The use of combined leflunomide and CMV-immunoglobulins, in the absence of viremia, has not been previously reported. Loss of ganciclovir-resistance was eventually observed permitting successful treatment with systemic and intravitreal ganciclovir. Conclusions: Drug-resistant CMVR is a complex clinical challenge. Multiple systemic and local treatment strategies may be necessary but toxicity, resistance, and co-morbidities may severely restrict available options.

Infectious Complications Following Kidney Transplantation-A Focus on Hepatitis C Infection, Cytomegalovirus Infection and Novel Developments in the Gut Microbiota

The incidence of infectious complications, compared with the general population and the pre-transplant status of the recipient, increases substantially following kidney transplantation, causing significant morbidity and mortality. The potent immunosuppressive therapy given to prevent graft rejection in kidney transplant recipients results in an increased susceptibility to a wide range of opportunistic infections including bacterial, viral and fungal infections. Over the last five years, several advances have occurred that may have changed the burden of infectious complications in kidney transplant recipients. Due to the availability of direct-acting antivirals to manage donor-derived hepatitis C infection, this has opened the way for donors with hepatitis C infection to be considered in the donation process. In addition, there have been the development of medications targeting the growing burden of resistant cytomegalovirus, as well as the discovery of the potentially important role of the gastrointestinal microbiota in the pathogenesis of post-transplant infection. In this narrative review, we will discuss these three advances and their potential implications for clinical practice.

Ganciclovir-resistant post-transplant cytomegalovirus infection due to combined deletion mutation at codons 595-596 of the UL97 gene

The development of antiviral-resistant cytomegalovirus (CMV) infection complicates the management of transplant recipients. We describe the case of a 65-year-old male who developed CMV disease on valganciclovir prophylaxis (donor CMV IgG positive, recipient CMV IgG indeterminate) 30 days after combined liver-kidney transplantation for alcoholic cirrhosis and hepato-renal syndrome. After an initial complete response to treatment dose oral valganciclovir, he developed recurrent CMV viraemia. Resistance testing revealed a UL97 mutation with in-frame deletions of codons 595-596. He was treated successfully with foscarnet and reduction in immunosuppression. This mutation has not been described previously and was suspected to confer ganciclovir resistance. Ganciclovir resistance occurs most commonly due to mutations in the UL97 or UL54 genes, which encode a protein kinase and a DNA polymerase, respectively. The UL97-encoded protein kinase phosphorylates ganciclovir to ganciclovir triphosphate, which competitively inhibits viral replication. Mutations in the UL97 gene are typically point mutations or deletions. We describe a new mutation, del595-596 in the CMV UL97 gene, occurring in the context of clinical treatment failure with standard and double-dose ganciclovir, and successful virological control achieved with foscarnet. This mutation is likely to result in ganciclovir resistance, although recombinant phenotyping is required for confirmation.

Improvement in detecting cytomegalovirus drug resistance mutations in solid organ transplant recipients with suspected resistance using next generation sequencing

OBJETIVES

The aim of this study was to identify CMV drug resistance mutations (DRM) in solid organ transplant (SOT) recipients with suspected resistance comparing next-generation sequencing (NGS) with Sanger sequencing and assessing risk factors and the clinical impact of resistance.

METHODS

Using Sanger sequencing as the reference method, we prospectively assessed the ability of NGS to detect CMV DRM in the UL97 and UL54 genes in a nationwide observational study from September 2013 to August 2016.

RESULTS

Among 44 patients recruited, 14 DRM were detected by Sanger in 12 patients (27%) and 20 DRM were detected by NGS, in 16 (36%). NGS confirmed all the DRM detected by Sanger. The additional six mutations detected by NGS were present in <20% of the sequenced population, being located in the UL97 gene and conferring high-level resistance to ganciclovir. The presence of DRM by NGS was associated with lung transplantation (p = 0.050), the administration of prophylaxis (p = 0.039), a higher mean time between transplantation and suspicion of resistance (p = 0.038) and longer antiviral treatment duration before suspicion (p = 0.024). However, the latter was the only factor independently associated with the presence of DRM by NGS in the multivariate analysis (OR 2.24, 95% CI 1.03 to 4.87).

CONCLUSIONS

NGS showed a higher yield than Sanger sequencing for detecting CMV resistance mutations in SOT recipients. The presence of DRM detected by NGS was independently associated with longer antiviral treatment.

Ganciclovir-Resistant CMV Colitis in a Donor-Seronegative/Recipient-Seronegative Liver Transplant Patient

Cytomegalovirus (CMV) disease in liver transplant patients with donor-seronegative and recipient-seronegative (D–/R–) status is a rarity. Ganciclovir-resistant CMV disease in this population has not been reported in the literature. We present a 62-year-old man who underwent orthotopic liver transplant from a cadaveric donor. The patient’s status was CMV D–/R–, and he had completed 90 days of valganciclovir therapy for CMV prophylaxis, yet he developed CMV disease. We highlight the danger of the liberal use of CMV prophylaxis in this subset of the liver transplant population. To our knowledge, this is the first report of ganciclovir-resistant (GanR) CMV disease in a liver transplant patient with CMV D–/R– status.

Viral Diagnostics

This chapter discusses recent developments in diagnostics for cytomegalovirus (CMV), Epstein-Barr virus (EBV), BK virus (BKV), community respiratory viruses (CRVs), parvovirus, hepatitis viruses, HIV, and other viral agents of importance in solid organ and hematopoietic stem cell transplantation.

Treatment and Prevention of CMV Disease in Transplant Recipients: Current Knowledge and Future Perspectives

This review summarizes the significant impact of cytomegalovirus (CMV) infection on solid organ and hematopoietic stem cell transplant recipients. A discussion of the various CMV prevention and treatment strategies is provided, including a detailed description of each of the available CMV antiviral drugs.

Resistant Cytomegalovirus Infection After Renal Transplantation: Literature Review

BACKGROUND

Resistant cytomegalovirus (R-CMV) is an emerging problem in the renal transplantation population. The most frequent CMVs are high-resistance mutations (UL97 gene).

METHODS

We describe our experience in management of R-CMV after renal transplant at our center (2012-2016).

RESULTS

We encountered 3 cases of R-CMV infection after renal transplant (all primary infections). All 3 patients received induction therapy with corticosteroids, tacrolimus, and mycophenolate mofetil. The first patient (basiliximab induction, preemptive CMV) developed CMV replication on day +53, which responded poorly both to standard-dose valganciclovir (vGCV) and high-dose ganciclovir (GCV) (creatinine clearance [CrCl] >70 mL/min; vGCV 900 mg twice daily for 50 days and GCV 7.5 mg/kg twice daily for 8 days). Hematologic toxicity occurred. The R-CMV test was positive and foscarnet (FOS) was initiated (90 mg/kg twice daily for 21 days). The second patient presented CMV infection (day +30, thymoglobulin induction, CMV prophylaxis), which was not controlled with the high dose (CrCl 23 mL/min; GCV 3.5 mg/kg twice daily and vGCV 900 mg twice daily), resulting in severe neutropenia. R-CMV was detected and FOS initiated (FOS 50 mg/kg twice daily for 7 days and 50 mg/kg every 2 days for 13 days). The third patient's infection occurred on day +22 (basiliximab induction, preemptive CMV). Standard-dose vGCV was uneffective (CrCl >70 mL/min, vGCV 900 mg twice daily) and it did not respond to the high dose (GCV 7.5 mg/kg twice daily and vGCV 2700 mg/d). Moderate hematologic toxicity occurred. R-CMV was diagnosed and FOS treatment begun (FOS 70 mg/kg per day for 2 weeks).

CONCLUSIONS

Resistant CMV infection may be severe due to viral infection and side effects of high-dose antiviral treatment. We presented 3 cases requiring the use of FOS in the absence of response or toxic effects from the usual treatment, with an optimal sustained response (temporary in case 2) and without serious side effects.

Risk Factors for the Development of Cytomegalovirus Resistance in Solid Organ Transplantation: A Retrospective Case-Control Study

BACKGROUND

Cytomegalovirus (CMV) resistance is an emerging problem in solid organ transplant recipients. Risk factors are not well defined.

METHODS

Recipients with CMV viremia of solid organ transplants who underwent CMV resistance testing between January 2010 and March 2016 were divided in 2 groups: proven CMV resistance and refractory CMV infection. A third group was added to compare patients with viremia during the study period with patients with no resistance proven or suspected. We aimed to identify risk factors associated with the occurrence of CMV genotypic resistance.

RESULTS

Forty-nine patients underwent resistance testing. Eleven (22.45%) developed genotypic mutations. Group 1 vs groups 2 and 3 had higher prednisone (P = .01) and tacrolimus levels (P = .03); did not respond to antivirals (P < .0001); and had a higher rate of fungal infections (P = .03). CMV resistance was less common in liver and kidney vs heart, small bowel, and mutivisceral recipients (P = .0007). There was no difference in duration of antiviral prophylaxis, viremia while on antiviral prophylaxis, rate of end-organ disease, graft loss, and overall survival. Persistent clinical disease and viremia despite antiviral therapy was the most important risk factor for development of CMV resistance.

CONCLUSION

Persistent clinical disease despite antiviral therapy is an important risk factor and may in part be due to a high degree of immunosuppression. Graft loss and survival were not impacted by CMV resistance.

Efficient Delivery of Human Cytomegalovirus T Cell Antigens by Attenuated Sendai Virus Vectors

Human cytomegalovirus (HCMV) represents a major cause of clinical complications during pregnancy as well as immunosuppression, and the licensing of a protective HCMV vaccine remains an unmet global need. Here, we designed and validated novel Sendai virus (SeV) vectors delivering the T cell immunogens IE-1 and pp65. To enhance vector safety, we used a replication-deficient strain (rdSeV) that infects target cells in a nonproductive manner while retaining viral gene expression. In this study, we explored the impact that transduction with rdSeV has on human dendritic cells (DCs) by comparing it to the parental, replication-competent Sendai virus strain (rcSeV) as well as the poxvirus strain modified vaccinia Ankara (MVA). We found that wild-type SeV is capable of replicating to high titers in DCs while rdSeV infects cells abortively. Due to the higher degree of attenuation, IE-1 and pp65 protein levels mediated by rdSeV after infection of DCs were markedly reduced compared to those of the parental Sendai virus recombinants, but antigen-specific restimulation of T cell clones was not negatively affected by this. Importantly, rdSeV showed reduced cytotoxic effects compared to rcSeV and MVA and was capable of mediating DC maturation as well as secretion of alpha interferon and interleukin-6. Finally, in a challenge model with a murine cytomegalovirus (MCMV) strain carrying an HCMV pp65 peptide, we found that viral replication was restricted if mice were previously vaccinated with rdSeV-pp65. Taken together, these data demonstrate that rdSeV has great potential as a vector system for the delivery of HCMV immunogens.IMPORTANCE HCMV is a highly prevalent betaherpesvirus that establishes lifelong latency after primary infection. Congenital HCMV infection is the most common viral complication in newborns, causing a number of late sequelae ranging from impaired hearing to mental retardation. At the same time, managing HCMV reactivation during immunosuppression remains a major hurdle in posttransplant care. Since options for the treatment of HCMV infection are still limited, the development of a vaccine to confine HCMV-related morbidities is urgently needed. We generated new vaccine candidates in which the main targets of T cell immunity during natural HCMV infection, IE-1 and pp65, are delivered by a replication-deficient, Sendai virus-based vector system. In addition to classical prophylactic vaccine concepts, these vectors could also be used for therapeutic applications, thereby expanding preexisting immunity in high-risk groups such as transplant recipients or for immunotherapy of glioblastomas expressing HCMV antigens.

Letermovir successfully used for secondary prophylaxis in a heart transplant recipient with ganciclovir-resistant cytomegalovirus syndrome (UL97 mutation)

Letermovir was approved by the Food and Drug Administration (FDA) in November 2017 for use in adult cytomegalovirus (CMV)-seropositive allogeneic stem cell transplant (SCT) recipients for primary prophylaxis of CMV infection and disease. We report off-label use of letermovir for secondary prophylaxis of genotype-confirmed ganciclovir-resistant cytomegalovirus (CMV) syndrome (UL 97 mutation [C603W]) in a heart transplant recipient initially treated with intravenous cidofovir followed by foscarnet, both discontinued due to unacceptable toxicities.

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.

HCMV UL97 phosphotransferase gene mutations may be associated with antiviral resistance in immunocompromised patients in Belém, PA, Northern Brazil

INTRODUCTION

Human cytomegalovirus is one of the causes of opportunist infections in immunocompromised patients, and is triggered by factors such as state of viral latency, weakened immune responses, and development of antiviral resistance to ganciclovir, the only drug offered by the public health system in Brazil to treat the infection. The goal of this study was to identify mutations that may be associated with antiviral resistance in immunocompromised patients.

METHODS

Molecular analysis was performed in 82 blood samples and subjected to genomic DNA extraction by a silica-based method. Three sequences of the HCMV UL97 gene, which encodes a phosphotransferase protein required for activation of ganciclovir, were amplified by polymerase chain reaction. Pyrosequencing methods were applied to one external 2096-bp segment DNA and two internal sequences between nucleotides 1087 to 1828 to detect mutations in this gene.

RESULTS

Approximately 10% of sequences contained mutations between nucleotides 377 and 594, in conserved regions of the UL97 gene, leading to amino acid changes. Eleven coding mutations were identified, including changes leading to amino acid substitutions, E596K and S604F, which were observed in 100% of samples and are described for the first time in Brazil. In addition, one mutation (A594V) that is associated with ganciclovir resistance was detected in a kidney transplant patient.

CONCLUSIONS

Further studies to detect mutations associated with HCMV resistance to antiviral drugs are required to demonstrate the need to increase the variety and availability of drugs used to treat viral infections in the public health care system in Brazil.

Ganciclovir Dosing Strategies and Development of Cytomegalovirus Resistance in a Kidney Transplant Recipient: A Case Report

In renal transplant recipients, delayed graft function and accompanying renal impairment may lead to therapeutic underexposure of valganciclovir. We describe a case of a cytomegalovirus (CMV)-seronegative kidney transplant recipient from a CMV-seropositive donor, whose course was complicated during valganciclovir prophylaxis by CMV disease, ultimately progressing to ganciclovir, foscarnet, and cidofovir resistance. Assessments and adjustments for renal dysfunction, according to both Cockgroft-Gault and Modification of Diet in Renal Disease study equations, are described. Therapy was complicated by outpatient parenteral therapy with pump-administered antiviral therapy, which may have led to drug underexposure and the fostering of antiviral resistance. Suppression was ultimately achieved in conjunction with reduction in immunosuppressive therapy, CMV immunoglobulin, and initiation of leflunomide. At-risk recipients may benefit from 24 hour creatinine clearance assessments, direct creatinine clearance measurement, or therapeutic drug monitoring. Optimal dosing strategies in recipients with impaired kidney function remain undefined, with limited pharmacokinetic data to date.

Ganciclovir

Ganciclovir is synthetic nucleoside analog of guanine closely related to acyclovir but has greater activity against cytomegalovirus. This comprehensive profile on ganciclovir starts with a description of the drug: nomenclature, formulae, chemical structure, elemental composition, and appearance. The uses and application of the drug are explained. The methods that were used for the preparation of ganciclovir are described and their respective schemes are outlined. The methods which were used for the physical characterization of the dug are: ionization constant, solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The chapter contains the spectra of the drug: ultraviolet spectrum, vibrational spectrum, nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis of ganciclovir include the United States Pharmacopeia methods. Other methods of analysis that were reported in the literature include: high-performance liquid chromatography alone or with mass spectrometry, electrophoresis, spectrophotometry, voltammetry, chemiluminescence, and radioimmunoassay. Biological investigation on the drug includes: pharmacokinetics, metabolism, bioavailability, and biological analysis. Reviews on the methods used for preparation or for analysis of the drug are provided. The stability of the drug in various media and storage conditions is reported. More than 240 references are listed at the end of the chapter.

Safety and efficacy of foscarnet for the management of ganciclovir-resistant or refractory cytomegalovirus infections: A single-center study

BACKGROUND

Infection with cytomegalovirus (CMV) is an important cause of morbidity and mortality following solid organ transplantation. Resistance to ganciclovir can rarely develop via mutations in UL97 or UL54. There are limited published studies assessing the safety and efficacy of foscarnet for the management of ganciclovir-resistant or refractory cytomegalovirus infection and many centers are reluctant to utilize this important therapy because of concerns about toxicity.

METHODS

Solid organ recipients transplanted between January 1, 2006 and December 31, 2014 who received at least 1 dose of foscarnet were retrospectively reviewed to assess treatment outcomes, tolerability, and safety of foscarnet.

RESULTS

Ten of 31 (32.3%) patients who received foscarnet during the study period died during treatment with foscarnet, whereas all 21 surviving recipients successfully cleared infection. Of these surviving patients, 3 (14.3%) developed significant renal dysfunction, defined as >25% decline in estimated glomerular filtration rate during treatment; one-third had definitive renal biopsy results consistent with foscarnet-induced toxicity.

CONCLUSION

Although mortality was high in this population, foscarnet use, with proper precautions, was generally safe and significant renal dysfunction was lower than previously reported in other sources, even with extended use.

Human cytomegalovirus UL54 and UL97 mutations for detection of ganciclovir resistance in congenital infection

Aim: Ganciclovir (GCV) is used as an antiviral drug for the treatment of human cytomegalovirus infection. The aim of this study was to demonstrate GCV-resistant human cytomegalovirus in congenitally infected neonates. Patients & methods: DNA of CMV positive newborn samples was extracted and UL97 and UL54 genes were amplified by PCR and real-time PCR. Sequencing of UL97 and UL54 genes were performed and analyzed. Results: UL97 GCV resistance mutation C603W was detected in one newborn. D605E was the most common polymorphism in UL97 observed in 7/13 (53.8%) of samples. N685S, A688V, A885T and N898D were four known common UL54 polymorphisms. Conclusion: The rate of GCV resistance in congenital CMV is low. Common polymorphisms in UL97 and UL54 genes are also reported as new mutations.

Epigenetically repressing human cytomegalovirus lytic infection and reactivation from latency in THP-1 model by targeting H3K9 and H3K27 histone demethylases

Human Cytomegalovirus (hCMV) infects a broad range of the population and establishes life-long latency in the infected individuals. Periodically the latently infected virus can reactivate and becomes a significant cause of morbidity and mortality in immunocompromised individuals. In latent infection, the viral genome is suppressed in a heterochromatic state and viral gene transcription is silenced. Upon reactivation, the repressive chromatin is remodeled to an active form, allowing viral lytic gene transcription, initiated by the expression of viral Immediate Early (IE) genes. During this process, a number of histone modification enzymes, including histone demethylases (HDMs), play important roles in driving IE expression, but the mechanisms involved are not fully understood. To get a better understanding of these mechanisms, we focused on two HDMs, KDM4 and KDM6, which reverse the repressive histone H3-lysine 9 and lysine 27 methylation, respectively. Our studies show that in lytic infection, both demethylases are important in the activation of viral IE gene expression. Simultaneous disruption of both via genetic or chemical methods leads to severely impaired viral IE gene expression and viral replication. Additionally, in an experimental latency-reactivation model in THP-1 cells, the KDM6 family member JMJD3 is induced upon viral reactivation and its knockdown resulted in reduced IE gene transcription. These findings suggest pharmacological inhibition of these HDMs may potentially block hCMV lytic infection and reactivation, and control the viral infection associated diseases, which are of significant unmet medical needs.

Detection of cytomegalovirus drug resistance mutations in solid organ transplant recipients with suspected resistance

BACKGROUND

Current guidelines recommend that treatment of resistant cytomegalovirus (CMV) in solid organ transplant (SOT) recipients must be based on genotypic analysis. However, this recommendation is not systematically followed.

OBJECTIVES

To assess the presence of mutations associated with CMV resistance in SOT recipients with suspected resistance, their associated risk factors and the clinical impact of resistance.

STUDY DESIGN

Using Sanger sequencing we prospectively assessed the presence of resistance mutations in a nation-wide prospective study between September 2013-August 2015.

RESULTS

Of 39 patients studied, 9 (23%) showed resistance mutations. All had one mutation in the UL 97 gene and two also had one mutation in the UL54 gene. Resistance mutations were more frequent in lung transplant recipients (44% p=0.0068) and in patients receiving prophylaxis ≥6 months (57% vs. 17%, p=0.0180). The mean time between transplantation and suspicion of resistance was longer in patients with mutations (239 vs. 100days, respectively, p=0.0046) as was the median treatment duration before suspicion (45 vs. 16days, p=0.0081). There were no significant differences according to the treatment strategies or the mean CMV load at the time of suspicion. Of note, resistance-associated mutations appeared in one patient during CMV prophylaxis and also in a seropositive organ recipient. Incomplete suppression of CMV was more frequent in patients with confirmed resistance.

CONCLUSIONS

Our study confirms the need to assess CMV resistance mutations in any patient with criteria of suspected clinical resistance. Early confirmation of the presence of resistance mutations is essential to optimize the management of these patients.

Human cytomegalovirus pUL97 drug-resistance mutations in congenitally neonates and HIV-infected, no-drug-treated patients

Aim: Human cytomegalovirus (HCMV) treatment is hard to achieve because of viral protein target sequence variations. Objectives: We aimed to find HCMV pUL97 kinase variations in HIV- and congenitally infected patients. Methods: Twenty HCMV-positive DNA samples from nonganciclovir treated congenitally infected neonates and HIV positive patients were used for PCR restriction fragment length polymorphism. Variations were assessed computationally for pUL97 functionality. Results: P521L, D605E and N597Y substitutions were prevalent significantly in congenital infection. Furthermore, we found those mutations have neutral or low impact on pUL97 functionality. In addition, we found a new K599Q substitution in an HIV-infected individual. Conclusion: More prevalent substitutions related to low-grade ganciclovir resistance were found in congenitally infected neonates in comparison with HIV-infected patients.

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.

How I treat resistant cytomegalovirus infection in hematopoietic cell transplantation recipients

Cytomegalovirus (CMV) infection is a significant complication in hematopoietic cell transplantation (HCT) recipients. Four antiviral drugs are used for preventing or treating CMV: ganciclovir, valganciclovir, foscarnet, and cidofovir. With prolonged and repeated use of these drugs, CMV can become resistant to standard therapy, resulting in increased morbidity and mortality, especially in HCT recipients. Antiviral drug resistance should be suspected when CMV viremia (DNAemia or antigenemia) fails to improve or continue to increase after 2 weeks of appropriately dosed and delivered antiviral therapy. CMV resistance is diagnosed by detecting specific genetic mutations. UL97 mutations confer resistance to ganciclovir and valganciclovir, and a UL54 mutation confers multidrug resistance. Risk factors for resistance include prolonged or previous anti-CMV drug exposure or inadequate dosing, absorption, or bioavailability. Host risk factors include type of HCT and degree of immunosuppression. Depending on the genotyping results, multiple strategies can be adopted to treat resistant CMV infections, albeit no randomized clinical trials exist so far, after reducing immunosuppression (if possible): ganciclovir dose escalation, ganciclovir and foscarnet combination, and adjunct therapy such as CMV-specific cytotoxic T-lymphocyte infusions. Novel therapies such as maribavir, brincidofovir, and letermovir should be further studied for treatment of resistant CMV.

Outcomes in Transplant Recipients Treated With Foscarnet for Ganciclovir-Resistant or Refractory Cytomegalovirus Infection

BACKGROUND

Antiviral-resistant or refractory cytomegalovirus (CMV) infection is challenging, and salvage therapies, foscarnet, and cidofovir, have significant toxicities. Several investigational anti-CMV agents are under development, but more information is needed on outcomes of current treatments to facilitate clinical trial design for new drugs.

METHODS

Records of solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients at a single center over a 10-year period were reviewed retrospectively to characterize those who had received foscarnet treatment for ganciclovir-resistant or refractory CMV infection. Data were collected on virologic responses, mortality, and nephrotoxicity.

RESULTS

Of 39 patients (22 SOT, 17 HCT), 15 had documented ganciclovir resistance mutations and 11 (28%) of 39 had tissue-invasive CMV. Median duration of foscarnet was 32 days. Virologic failure occurred in 13 (33%) of 39 and relapses of viremia occurred in 31%. Mortality was 12 (31%) of 39 and was higher in HCT than SOT (P = 0.001), although ganciclovir resistance was more common in SOT (P = 0.003). Doses of ganciclovir or valganciclovir were low in 10 (26%) of 39 at some time before switching to foscarnet. Renal dysfunction occurred in 20 (51%) of 39 by end of treatment and in 7 (28%) of 25 after 6 months.

CONCLUSIONS

Outcomes of existing treatment for ganciclovir-resistant or refractory CMV are suboptimal, in terms of virologic clearance, renal dysfunction, and mortality. These data should provide background information for future clinical trials of newer antiviral agents.

The D-form of a novel heparan binding peptide decreases cytomegalovirus infection in vivo and in vitro

Human cytomegalovirus (HCMV) infection in utero can lead to congenital sensory neural hearing loss and mental retardation. Reactivation or primary infection can increase the morbidity and mortality in immune suppressed transplant recipients and AIDS patients. The current standard of care for HCMV disease is nucleoside analogs, which can be nephrotoxic. In addition resistance to current treatments is becoming increasingly common. In an effort to develop novel CMV treatments, we tested the effectiveness of the D-form of a novel heparan sulfate binding peptide, p5R_D, at reducing infection of ganciclovir (GCV) resistant HCMVs in vitro and MCMV in vivo. HCMV infection was reduced by greater than 90% when cells were pretreated with p5R_D. Because p5R_D acts by a mechanism unrelated to those used by current antivirals, it was effective at reducing GCV resistant HCMVs by 85%. We show that p5R_D is resistant to common proteases and serum inactivation, which likely contributed to its ability to significantly reduced infection of peritoneal exudate cells and viral loads in the spleen and the lungs in vivo. The ability of p5R_D to reduce HCMV infectivity in vitro including GCV resistant HCMVs and MCMV infection in vivo suggests that this peptide could be a novel anti-CMV therapeutic.

Characterising variation in five genetic loci of cytomegalovirus during treatment for congenital infection

Cytomegalovirus (CMV) is the most common congenital infection in humans and a leading cause of sensorineural hearing loss. Ganciclovir (6 mg/kg twice daily for 42 days) has been shown to reduce hearing deterioration and is used in clinical practice. Vaccines and passive administration of antibody are being evaluated in randomized controlled trials in allograft candidates, women of childbearing age, and pregnant women with primary CMV infection. To help define genetic variation in each of the targets of these therapeutic interventions, we amplified and sequenced genes UL97 (site utilised for ganciclovir phosphorylation), UL55 (glycoprotein B (gB) vaccine target) and UL128, UL130, and UL131a (specific monoclonal antibody targets). Serial blood, saliva, and urine samples (total 120) obtained from nine infants with symptomatic congenital CMV treated with 42 days' ganciclovir were analyzed. All samples tested were UL97 wild type at baseline and none developed mutations during treatment, showing no selection of resistance. The prevalences of UL55 genotypes were 28% gB1, 22% gB2, 1% gB3, and mixed in 20% samples. No mutations were noted in UL128-131a. Phylogenetic tree analysis showed that sequences with variations were found in multiple body sites of individual patients, so there was no evidence of body site compartmentalization of particular strains of CMV. The significance of these results for changes in diagnostic practices and therapeutic interventions against CMV are discussed. J. Med. Virol. 89:502-507, 2017. © 2016 Wiley Periodicals, Inc.