Pharmacologic and immunologic management of cytomegalovirus infection after solid organ and hematopoietic stem cell transplantation

Prevention and management of cytomegalovirus infection and disease in kidney transplant: A consensus statement of the Transplantation Society of Taiwan

Kidney transplant recipients have an increased risk of cytomegalovirus (CMV) infection and disease. A strategy for mitigating the risk of CMV infection in kidney transplant recipients has not yet been established in Taiwan. The Transplantation Society of Taiwan aimed to develop a consensus by expert opinion on the prevention and management of CMV infection. Based on the results of Consensus Conference, we suggested low-dose valganciclovir prophylaxis (450 mg once daily) for kidney transplant recipients. The prophylaxis duration was ≥6 months for high-risk (D+/R-) patients and 3 months for moderate-risk (R+) patients. Even for low-risk (D-/R-) patients, prophylaxis for at least 3 months is recommended because of the high seroprevalence of CMV in Taiwan. CMV prophylaxis was suggested after anti-thymocyte globulin treatment but not after methylprednisolone pulse therapy. Routine surveillance after prophylaxis, secondary prophylaxis after CMV disease treatment, and mTOR inhibitors for primary CMV prophylaxis were not recommended. Letermovir and marabavir are emerging CMV agents used for prophylaxis and refractory CMV disease. CMV immunoglobulins have been used to treat refractory CMV disease in Taiwan. We hope this consensus will help professionals manage patients with CMV in Taiwan to improve the quality of care.

Tailoring cytomegalovirus prophylaxis based on T cell immunity panel assessment in kidney transplant patients at high risk of cytomegalovirus

BACKGROUND

Valganciclovir prophylaxis against cytomegalovirus (CMV) is recommended for solid organ transplant recipients, but is associated with drawbacks, including expense and leukopenia. Our center adopted a strategy of serial assessment with a CMV-specific T cell immunity panel (CMV-TCIP) and cessation of valganciclovir prophylaxis upon demonstration of adequate CD4+ responses in kidney transplant patients at high risk of CMV disease.

METHODS

We retrospectively reviewed adult recipients of a kidney or pancreas transplant between August 2019 and July 2021 undergoing serial CMV-TCIP monitoring. Included patients were considered high risk for CMV, defined by donor positive (D+)/recipient negative (R-) CMV IgG serostatus, or recipient positive (R+) patients who received induction with a lymphocyte-depleting agent. Prophylaxis was discontinued after a patient's first CMV-specific CD4+ T cell value of ≥0.20%. Risk of clinically significant CMV infection (csCMVi) in those who underwent early discontinuation of CMV prophylaxis and predictors of CMV T cell immunity were analyzed.

RESULTS

Of 54 included patients, 22 stopped prophylaxis early due to CMV-specific CD4+ T cell immunity at a median of 4.7 (IQR: 3.8-5.4) months after transplant. No instances of csCMVi were observed in the 22 patients who had prophylaxis discontinued early, of whom 19/22 were CMV R+ and 3/22 were CMV D+/R-. Donor/recipient CMV serostatus was predictive of immunity (p <.001).

CONCLUSION

Early discontinuation of valganciclovir prophylaxis in patients with CMV CD4+ T cellular immunity appears safe and potentially beneficial in this preliminary series, especially in R+ patients. Further study is warranted, given that truncated prophylaxis may yield patient-level benefits.

Long-term CMV monitoring and chronic rejection in renal transplant recipients

Introduction

Cytomegalovirus (CMV) is well established to be an independent risk factor for graft loss after kidney transplantation (KTx). Monitoring for CMV in the chronic phase is not defined in the current guideline. The effects of CMV infection, including asymptomatic CMV viremia, in the chronic phase are unclear.

Methods

We performed a single-center retrospective study to investigate incidence of CMV infection in the chronic phase, defined as more than 1 year after KTx. We included 205 patients who received KTx between April 2004 and December 2017. The CMV pp65 antigenemia assays to detect CMV viremia were continuously performed every 1-3 months.

Results

The median duration of the follow-up was 80.6 (13.1-172.1) months. Asymptomatic CMV infection and CMV disease were observed in 30.7% and 2.9% in the chronic phase, respectively. We found that 10-20% of patients had CMV infections in each year after KTx which did not change over 10 years. The history of CMV infection in the early phase (within 1 year after KTx) and chronic rejection were significantly associated with CMV viremia in the chronic phase. CMV viremia in the chronic phase was significantly associated with graft loss.

Discussion

This is the first study to examine the incidence of CMV viremia for 10 years post KTx. Preventing latent CMV infection may decrease chronic rejection and graft loss after KTx.

Viral Nucleases from Herpesviruses and Coronavirus in Recombination and Proofreading: Potential Targets for Antiviral Drug Discovery

In this review, we explore recombination in two very different virus families that have become major threats to human health. The Herpesviridae are a large family of pathogenic double-stranded DNA viruses involved in a range of diseases affecting both people and animals. Coronaviridae are positive-strand RNA viruses (CoVs) that have also become major threats to global health and economic stability, especially in the last two decades. Despite many differences, such as the make-up of their genetic material (DNA vs. RNA) and overall mechanisms of genome replication, both human herpes viruses (HHVs) and CoVs have evolved to rely heavily on recombination for viral genome replication, adaptation to new hosts and evasion of host immune regulation. In this review, we will focus on the roles of three viral exonucleases: two HHV exonucleases (alkaline nuclease and PolExo) and one CoV exonuclease (ExoN). We will review the roles of these three nucleases in their respective life cycles and discuss the state of drug discovery efforts against these targets.

Cyclin-Dependent Kinases (CDKs) and the Human Cytomegalovirus-Encoded CDK Ortholog pUL97 Represent Highly Attractive Targets for Synergistic Drug Combinations

Human cytomegalovirus (HCMV) is a pathogenic human herpesvirus associated with serious, potentially life-threatening symptoms in the immunocompromised or immunonaïve host. The limitations encountered by antiviral therapy options currently available include a narrow panel of accessible targets, the induction of viral drug resistance as well as severe drug dosage-mediated side-effects. Improved drug-targeting strategies to resolve these issues are the focus of our investigations. In particular, pharmaceutical kinase inhibitors (PKIs), either directed to host kinases or directed to the viral protein kinase pUL97, have been considered to overcome these restrictions. Recently, we reported the identification of a synergistic combination of two PKIs directed to host cyclin-dependent kinase 7 (CDK7) and viral CDK ortholog pUL97. Here, we substantiate these findings with the following results: (i) true drug synergy was exhibited by various chemical classes of PKI pairs directed to pUL97 and CDK7; (ii) no putative amplification of cytotoxicity by these drug combinations was observed; (iii) a reduction in drug dosage levels for synergistic combinations was defined on a quantitative basis and compared to monotreatments; (iv) the quantities of target proteins CDK7 and pUL97 expressed in HCMV-infected cells were assessed by confocal imaging, indicating a strong down-modulation of CDK7 levels as a result of synergistic drug treatment; (v) the functional importance of these target kinases, both binding to cyclin H, was illustrated by assessing HCMV replication under the viral genomic deletion of ORF-UL97 or cellular cyclin knock-out; (vi) new combinations of HCMV-specific drug synergy were demonstrated for solely host-directed treatments using PKIs against CDK2, CDK7, CDK8 and/or CDK9 and (vii) a triple PKI combination provided further support for the synergy approach. With these combined findings, this study highlights the potential of therapeutic drug combinations of approved, developmental and preclinical PKIs for expanding future options for anti-HCMV therapy.

Circulatory follicular helper T lymphocytes associate with lower incidence of CMV infection in kidney transplant recipients

Primary infection and/or reactivation of cytomegalovirus (CMV) in kidney transplant recipients (KTR) favor rejection and mortality. T follicular helper cells (TFH) could contribute to protection against CMV. Circulatory TFH (cTFH) were studied pretransplant and early posttransplant in 90 CMV seropositive KTR not receiving antithymocyte globulin or antiviral prophylaxis, followed-up for 1 year. Patients who presented CMV infection had significantly lower cTFH and activated cTFH pretransplant and early posttransplant. Pretransplant activated cTFH were also lower within patients who developed CMV disease. Pre- and 14 days posttransplant activated cTFH were an independent protective factor for CMV infection (HR 0.41, p = .01; and 0.52, p = .02, respectively). KTR with low cTFH 7 days posttransplant (<11.9%) had lower CMV infection-free survival than patients with high cTFH (28.2% vs. 67.6%, p = .002). cTFH were associated with CMV-specific neutralizing antibodies (Nabs). In addition, IL-21 increased interferon-γ secretion by CMV-specific CD8⁺ T cells in healthy controls. Thus, we show an association between cTFH and lower incidence of CMV infection, probably through their cooperation in CMV-specific Nab production and IL-21-mediated enhancement of CD8⁺ T cell activity. Moreover, monitoring cTFH pre- and early posttransplant could improve CMV risk stratification and help select KTR catalogued at low/intermediate risk who could benefit from prophylaxis.

Development of a PROTAC-Based Targeting Strategy Provides a Mechanistically Unique Mode of Anti-Cytomegalovirus Activity

Human cytomegalovirus (HCMV) is a major pathogenic herpesvirus that is prevalent worldwide and it is associated with a variety of clinical symptoms. Current antiviral therapy options do not fully satisfy the medical needs; thus, improved drug classes and drug-targeting strategies are required. In particular, host-directed antivirals, including pharmaceutical kinase inhibitors, might help improve the drug qualities. Here, we focused on utilizing PROteolysis TArgeting Chimeras (PROTACs), i.e., hetero-bifunctional molecules containing two elements, namely a target-binding molecule and a proteolysis-inducing element. Specifically, a PROTAC that was based on a cyclin-dependent kinase (CDK) inhibitor, i.e., CDK9-directed PROTAC THAL-SNS032, was analyzed and proved to possess strong anti-HCMV AD169-GFP activity, with values of EC50 of 0.030 µM and CC50 of 0.175 µM (SI of 5.8). Comparing the effect of THAL-SNS032 with its non-PROTAC counterpart SNS032, data indicated a 3.7-fold stronger anti-HCMV efficacy. This antiviral activity, as illustrated for further clinically relevant strains of human and murine CMVs, coincided with the mid-nanomolar concentration range necessary for a drug-induced degradation of the primary (CDK9) and secondary targets (CDK1, CDK2, CDK7). In addition, further antiviral activities were demonstrated, such as the inhibition of SARS-CoV-2 replication, whereas other investigated human viruses (i.e., varicella zoster virus, adenovirus type 2, and Zika virus) were found insensitive. Combined, the antiviral quality of this approach is seen in its (i) mechanistic uniqueness; (ii) future options of combinatorial drug treatment; (iii) potential broad-spectrum activity; and (iv) applicability in clinically relevant antiviral models. These novel data are discussed in light of the current achievements of anti-HCMV drug development.

A Systematic Review of the Clinical Pharmacokinetics, Pharmacodynamics and Toxicodynamics of Ganciclovir/Valganciclovir in Allogeneic Haematopoietic Stem Cell Transplant Patients

BACKGROUND

Ganciclovir (GCV) and valganciclovir (VGCV) are the first-line agents used to prevent and treat cytomegalovirus (CMV) infection in allogeneic haematopoietic stem cell transplant (alloHCT) patients.

OBJECTIVE

The aim of this work was to describe available data for the clinical pharmacokinetics, pharmacodynamics and toxicodynamics of GCV and VGCV and the potential of a therapeutic drug monitoring strategy to improve outcomes in the alloHCT population.

METHODS

We systematically reviewed the pharmacokinetics (dose-exposure), pharmacodynamics (exposure-efficacy) and toxicodynamics (exposure-toxicity) of GCV and VGCV in alloHCT patients with CMV infection. Studies including alloHCT patients treated for CMV infection reporting the pharmacokinetics, pharmacodynamics and toxicodynamics of GCV or VGCV were searched for using the PUBMED and EMBASE databases from 1946 to 2019. Only studies involving participants > 12 years of age and available in the English language were included.

RESULTS

A total of 179 patients were included in the 14 studies that met the inclusion criteria, of which 6 examined GCV pharmacokinetics only, while 8 also examined GCV pharmacodynamics and toxicodynamics. Reported pharmacokinetic parameters showed considerable interpatient variability and were different from other populations, such as solid organ transplant and human immunodeficiency virus-infected patients. Only one study found a correlation between neutropenia and elevated peak and trough GCV concentrations, with no other significant pharmacodynamic and toxicodynamic relationships identified. While therapeutic drug monitoring of GCV is performed in some institutions, no association between GCV therapeutic drug monitoring and clinical outcomes was identified.

CONCLUSION

Further studies of the pharmacokinetics, pharmacodynamics and toxicodynamics of GCV/VGCV in alloHCT patients are required to identify a more robust therapeutic range and to subsequently quantify the potential value of therapeutic drug monitoring of GCV/VGCV in the alloHCT population.

Combinatorial Drug Treatments Reveal Promising Anticytomegaloviral Profiles for Clinically Relevant Pharmaceutical Kinase Inhibitors (PKIs)

Human cytomegalovirus (HCMV) is a human pathogenic herpesvirus associated with a variety of clinical symptoms. Current antiviral therapy is not always effective, so that improved drug classes and drug-targeting strategies are needed. Particularly host-directed antivirals, including pharmaceutical kinase inhibitors (PKIs), may help to overcome problems of drug resistance. Here, we focused on utilizing a selection of clinically relevant PKIs and determined their anticytomegaloviral efficacies. Particularly, PKIs directed to host or viral cyclin-dependent kinases, i.e., abemaciclib, LDC4297 and maribavir, exerted promising profiles against human and murine cytomegaloviruses. The anti-HCMV in vitro activity of the approved anti-cancer drug abemaciclib was confirmed in vivo using our luciferase-based murine cytomegalovirus (MCMV) animal model in immunocompetent mice. To assess drug combinations, we applied the Bliss independence checkerboard and Loewe additivity fixed-dose assays in parallel. Results revealed that (i) both affirmative approaches provided valuable information on anti-CMV drug efficacies and interactions, (ii) the analyzed combinations comprised additive, synergistic or antagonistic drug interactions consistent with the drugs’ antiviral mode-of-action, (iii) the selected PKIs, especially LDC4297, showed promising inhibitory profiles, not only against HCMV but also other α-, β- and γ-herpesviruses, and specifically, (iv) the combination treatment with LDC4297 and maribavir revealed a strong synergism against HCMV, which might open doors towards novel clinical options in the near future. Taken together, this study highlights the potential of therapeutic drug combinations of current developmental/preclinical PKIs.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cytomegalovirus Infection in an Adult Patient With Neuromyelitis Optica and Acute Hemorrhagic Rectal Ulcer: Case Report and Literature Review

Background: Previous infectious or inflammatory events may be involved in the pathogenesis of neuromyelitis optica (NMO), potentially by triggering an autoimmune response. Cytomegalovirus (CMV)-related NMO (CMV-NMO) is rarely reported. Acute hemorrhagic rectal ulcer (AHRU) is a rare disease with a largely unknown pathogenesis. Herein, we reported a co-NMO and AHRU case associated with CMV infection. In addition, we review previously reported cases of CMV-NMO and CMV-AHRU. Case presentation: A 40-year-old female diagnosed with aquaporin4 (AQP4)-IgG⁺ NMO and a poor response to high-dose intravenous methylprednisolone and immunoglobulin, followed by three rounds of plasma exchange was transferred to Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. She developed repeated acute lower gastrointestinal hemorrhage from the third day of admission. Abdominal computed tomography angiography (CTA) and interventional angiography did not detect any bleeding vessel. Bedside colonoscopy revealed a large ulcer-like lesion at 10 cm above the anus. Rectal biopsy pathology confirmed a CMV infection on day 23 post-admission, and cerebrospinal fluid (CSF) pathogen gene sequencing detected CMV gene copies on day 25 post-admission. After 2 weeks of treatment with ganciclovir and sodium phosphinate, the patient's lower gastrointestinal bleeding stopped, and her limb muscle strength and visual acuity gradually improved. After 4 weeks of antiviral therapy, colonoscopy showed that the intestinal wall of the original lesion was smooth. Hematoxylin and eosin (HE) staining and immunohistochemistry (IHC) of a biopsy specimen was negative for CMV, her right eye vision was normal, and limb muscle strength had recovered. Serum AQP4-IgG was negative, and lesions on brain magnetic resonance imaging (MRI) manifested shrinkage. Conclusions: The benefits of antiviral therapy remain unclear; however, clinicians should be aware of the possibility of CMV-related NMO, if NMO was refractory to high-dose intravenous methylprednisolone, immunoglobulin, and plasma exchange. Moreover, clinicians should consider the possibility of CMV-related AHRU when recurrent acute lower gastrointestinal bleeding occurs in a patient.

Cytomegalovirus in solid organ transplant recipients-Guidelines of the American Society of Transplantation Infectious Diseases Community of Practice

Cytomegalovirus (CMV) is one of the most common opportunistic infections that affect the outcome of solid organ transplantation. This updated guideline from the American Society of Transplantation Infectious Diseases Community of Practice provides evidence-based and expert recommendations for screening, diagnosis, prevention, and treatment of CMV in solid organ transplant recipients. CMV serology to detect immunoglobulin G remains as the standard method for pretransplant screening of donors and transplant candidates. Antiviral prophylaxis and preemptive therapy are the mainstays of CMV prevention. The lack of a widely applicable viral load threshold for diagnosis and preemptive therapy is highlighted, as a result of variability of CMV nucleic acid testing, even in the contemporary era when calibrators are standardized. Valganciclovir and intravenous ganciclovir remain as drugs of choice for CMV management. Strategies for managing drug-resistant CMV infection are presented. There is an increasing use of CMV-specific cell-mediated immune assays to stratify the risk of CMV infection after solid organ transplantation, but their role in optimizing CMV prevention and treatment efforts has yet to be demonstrated. Specific issues related to pediatric transplant recipients are discussed.