Letermovir Primary Prophylaxis in High-Risk Hematopoietic Cell Transplant Recipients: A Matched Cohort Study

Reexploring cytomegalovirus serology in allogeneic hematopoietic cell transplantation

PURPOSE OF REVIEW

Discuss the recent evidence on cytomegalovirus (CMV) serology in allogeneic hematopoeic cell transplant (HCT) recipients.

RECENT FINDINGS

Whereas the role CMV-specific cellular mediated immunity has recently emerged as an important factor of CMV DNAemia posttransplant, the value of CMV serology has remained unchanged through decades, associated with donor selection and posttransplant prophylactic and monitoring strategies. In this review, we describe and discuss the emerging reports on the association between the magnitude of pretransplant CMV immunoglobulin G (IgG) titer and the posttransplant incidence of CMV DNAemia, as CMV IgG titer could become an additional tool in CMV risk assessment in the future.

SUMMARY

Pretransplant recipient CMV serology may have significant implications in posttransplant CMV reactivation in allogeneic HCT recipients.

Impact of Primary Letermovir Prophylaxis Versus Preemptive Antiviral Therapy for Cytomegalovirus on Economic and Clinical Outcomes after Hematopoietic Cell Transplantation

Preemptive therapy (PET) historically has been the primary strategy to reduce early-onset cytomegalovirus (CMV) reactivation after allogeneic hematopoietic cell transplantation (HCT) but is associated with antiviral-associated toxicities and increases in healthcare resource utilization and cost. Despite its high cost, letermovir (LTV) prophylaxis has largely supplanted PET due to its effectiveness and tolerability. Direct comparisons between LTV and PET approaches on economic and clinical outcomes after allogeneic HCT remain limited. Objective: To compare total cost of care (inpatient and outpatient) between LTV prophylaxis and PET through day+180 after allogeneic HCT. Adult allogeneic CMV seropositive (R+) HCT recipients who initiated LTV <30 days after HCT between 01/01/18 and 12/31/18 were matched 1:1 to allogeneic CMV R+ HCT recipients between 01/01/15 and 12/31/17 (PET cohort). Patients were grouped into high-risk (HR) or standard-risk (SR) for CMV to compare the LTV and PET cohorts. Direct costs for each patient's index HCT admission and all subsequent inpatient and outpatient care through day+180 after HCT were determined and converted into 2021 US dollars and then to Medicare proportional dollars (MPD). A secondary analysis using 2019 average wholesale price was conducted to specifically evaluate anti-CMV medication costs. There were a total of 176 patients with 54 HR CMV pairs and 34 SR CMV pairs. No differences in survival between LTV and PET for both HR and SR CMV groups were observed. The rate of clinically significant CMV infection decreased for both HR CMV (11/54, 20.4% versus 38/54, 70.4%, P < .001) and SR CMV (1/34, 2.9% versus 12/34, 35.3%, P < .001) patients who were given LTV prophylaxis with corresponding reductions in val(ganciclovir) and foscarnet (HR CMV only) use. Among HR CMV patients, LTV prophylaxis was associated with reductions in CMV-related readmissions (3/54, 5.6% versus 18/54, 33.3%, P < .001) and outpatient visits within the first 100 days after HCT (20 versus 25, P = .002), and a decreased median total cost of care ($36,018 versus $75,525, P < .001) in MPD was observed. For SR CMV patients on LTV, a significant reduction in the median inpatient cost ($15,668 versus $27,818, P < .001) was found, but this finding was offset by a higher median outpatient cost ($26,145 versus $20,307, P = .030) that was not CMV-driven. LTV prophylaxis is highly effective in reducing clinically significant CMV reactivations for both HR and SR HCT recipients. In this study, LTV prophylaxis was associated with a decreased total cost of care for HR CMV patients through day+180. Specifically, reductions in CMV-related readmissions, exposure to CMV-directed antiviral agents, and outpatient visits in the first 100 days after HCT were observed. SR CMV patients receiving LTV prophylaxis benefited by having a reduced inpatient cost of care due to lowered room and pharmacy costs.

Refractory/Resistant Cytomegalovirus Infection in Transplant Recipients: An Update

Despite the significant progress made, CMV infection is one of the most frequent infectious complications in transplant recipients. CMV infections that become refractory or resistant (R/R) to the available antiviral drugs constitute a clinical challenge and are associated with increased morbidity and mortality. Novel anti-CMV therapies have been recently developed and introduced in clinical practice, which may improve the treatment of these infections. In this review, we summarize the treatment options for R/R CMV infections in adult hematopoietic cell transplant and solid organ transplant recipients, with a special focus on newly available antiviral agents with anti-CMV activity, including maribavir and letermovir.

Revisiting Cytomegalovirus Serology in Allogeneic Hematopoietic Cell Transplant Recipients

BACKGROUND

Allogeneic hematopoietic cell transplant recipients (allo-HCTRs) with positive cytomegalovirus (CMV) serology may have false-positive results due to blood product transfusion-associated passive immunity.

METHODS

This single-center cohort study included allo-HCTRs with negative baseline (at malignancy diagnosis) CMV serology and indeterminate/low-positive (CMV IgG titer, ≥0.6-<50 U/mL) pretransplant CMV serology with negative pretransplant plasma CMV DNAemia. The CMV status of those patients was reclassified from R+ to R- (CMVR- reclassification group). We compared those patients to allo-HCTRs with negative (CMV IgG titer <0.6 U/mL) pretransplant CMV IgG (CMVR- group). We describe the number and type of patients whose pretransplant CMV status was reclassified from indeterminate/positive to negative. We reviewed all plasma CMV DNAemia tests performed during the first 6 months posttransplant in both groups to assess the safety of this approach.

RESULTS

Among 246 (84.5%) of 291 transplanted patients identified as CMVR+ pretransplant, 60 (24.4%) were reclassified from CMV serology indeterminate (N:10)/low-positive (N:50) to R-. Only 1 of 60 patients (1.67%) in the CMVR- reclassification group versus 3 of 44 (6.8%; P = .30) in the CMVR- group developed CMV DNAemia during the follow-up period. There were no significant differences in the number of CMV DNAemia tests performed, CMV DNAemia range, and time posttransplant between the 2 groups.

CONCLUSIONS

One of 4 allo-HCT CMVR+ may be falsely flagged as R+, with significant impact on donor selection and prophylaxis administration. A 2-step approach including CMV serology testing at hematologic malignancy diagnosis in allo-HCT candidates and careful review of pretransplant CMV IgG titers may help correctly classify CMV serology status.

Letermovir prophylaxis for cytomegalovirus reactivation in allogeneic hematopoietic cell transplant recipients: Single center Canadian data

BACKGROUND

Cytomegalovirus (CMV) is associated with morbidity and mortality following allogeneic hematopoietic cell transplantation (alloHCT). Letermovir is a novel antiviral agent that prevents CMV reactivation in alloHCT patients, with limited data regarding influence on post-alloHCT outcomes.

METHODS

We retrospectively examined 273 alloHCT recipients, 158 in the non-letermovir cohort (NLC), and 115 in the cohort using letermovir prophylaxis (LC). Patients that received letermovir were CMV-seropositive and met criteria for high risk of CMV reactivation.

RESULTS

Median start of letermovir was 21 days post-alloHCT, median duration of prophylaxis was 86 days. Letermovir prophylaxis demonstrated a statistically significant reduction in first CMV reactivation (at 200 days post 63.9% in the NLC vs. 35.7% in the LC; p < .001). On univariate analysis at 1 year, overall survival (OS) for NLC was 79.6% and 79.5% for LC (p = .54). Non relapse mortality (NRM) at 1 year for NLC was 12% and 12.3% for LC (p = .69). Cumulative incidence of relapse (CIR) at 1 year was 13.9% for NLC versus 17.1 for the LC (p = .27). On multivariable analysis, there was no significant difference between the two cohorts for OS, NRM, and CIR.

CONCLUSIONS

Letermovir prophylaxis started at day +21 post-alloHCT reduced CMV reactivation, with no impact on posttransplant outcomes.

Impact of letermovir prophylaxis in CMV reactivation and disease after allogenic hematopoietic cell transplantation: a real-world, observational study

Letermovir for CMV prevention in CMV-seropositive adults undergoing allo-HCT was implemented at our program in 2021. This study investigates the results from the use of letermovir. The study includes all the 140 CMV-seropositive patients who underwent an allo-HCT during the years 2020, 2021, and 2022 at our institution. Thirty-eight (27.4%) of these patients received letermovir, administered from day + 7 to day + 100 and restarted if patients were on treatment with steroids. The day + 180 and 1-year cumulative incidences of CMV reactivation were 5.3% and 12.1% for patients who received letermovir and 52.9% and 53.9% for those who did not (P < 0.001) (HR 0.19, P < 0.001). Four (10.5%) of these thirty-eight patients had a CMV reactivation, but only 2 (5.3%) cases occurred during the administration of letermovir. During the first year after allo-HCT, 13 (9.2%) patients had CMV disease; the day + 180 and 1-year cumulative incidences were 2.6% and 6.0% for patients who received letermovir and 9.9% and 12.3% for those who did not (P = 0.254) (HR 1.01, P = 0.458). Two (4.2%) of the patients included in the letermovir group had CMV disease, but both of them after letermovir discontinuation. Letermovir induced a protective effect on CMV reactivation risk, but its use was not associated with a significant reduction of CMV disease. The fact that the CMV disease in patients who received letermovir occurred after the discontinuation of the drug, questions whether CMV prophylaxis should be used in patients with high risk for CMV reactivation or disease.

Efficacy and safety of letermovir prophylaxis for cytomegalovirus infection after hematopoietic stem cell transplantation

Letermovir is a specific inhibitor of cytomegalovirus (CMV) terminase complex. Several studies have reported that letermovir can effectively prevent CMV activation after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aimed to identify the efficacy and safety of letermovir prophylaxis for CMV infection after allo-HSCT with a systemic review and meta-analysis. A literature search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. PubMed and Embase databases were searched. A total of 28 studies were included. The incidence of CMV activation at 14 weeks after HSCT was 0.10 (95% confidence interval [CI], 0.06-0.18), which was 0.10 (95% CI, 0.04-0.21) and 0% in adult and children (2 studies were included and both of them were 0%). In addition, the incidence of CMV activation at 14 weeks after allo-HSCT was 0.11 (95% CI, 0.06-0.21) and 0.07 (only 1 study included), respectively, in retrospective and prospective studies. The incidence of CMV activation at 100 and 200 days after HSCT was 0.23 (95% CI, 0.16-0.33) and 0.49 (95% CI, 0.32-0.67), respectively. The incidence of CMV disease at 14 weeks and at 6 months after HSCT was 0.01 (95% CI, 0.01-0.02) and 0.03 (95% CI, 0.01-0.09), respectively. Thus, our systemic review and meta-analysis suggested that letermovir prophylaxis was safe and effective for CMV activation after allo-HSCT.

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

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

A new direction for cytomegalovirus prophylaxis among transplant recipients: Benefits and nonviral outcomes of letermovir use as primary CMV prophylaxis

PURPOSE OF REVIEW

Letermovir has changed the game of primary prophylaxis against cytomegalovirus (CMV) for hematopoietic stem cell transplant (HSCT) and more recently, solid organ transplant recipients. This is largely due to letermovir's similar efficacy in protecting against CMV reactivation and disease, along with its superior safety profile, notably reduced myelotoxicity, and lack of renal dose adjustment compared to standard agents like valganciclovir. This review will describe the potential benefits and clinical considerations of letermovir as prophylaxis among transplant recipients, with a focus on recent evidence describing nonviral outcomes of CMV.

RECENT FINDINGS

Recent evidence has demonstrated improved safety (e.g., less myelosuppression) and tolerability with no difference in rates of CMV infection or disease in kidney transplant recipients given letermovir compared to valganciclovir. Real-world studies and meta-analyses in HSCT populations have explored various nonviral outcomes with letermovir use. Letermovir prophylaxis was associated with reduced mortality, lower rates of graft versus host disease, delayed CMV immune reconstitution, improved tolerability with extended durations, and decreased healthcare utilization.

SUMMARY

Letermovir is an effective antiviral agent for CMV prevention and has demonstrated enhanced safety, which may allow for extended durations of primary prophylaxis among transplant recipients along with other improved clinical outcomes by mitigating the indirect effects of CMV.

Human herpesvirus-6 reactivation and disease after allogeneic haematopoietic cell transplantation in the era of letermovir for cytomegalovirus prophylaxis

OBJECTIVES

Letermovir for cytomegalovirus (CMV) prophylaxis in allogeneic haematopoietic cell transplant (HCT) recipients has decreased anti-CMV therapy use. Contrary to letermovir, anti-CMV antivirals are also active against human herpesvirus-6 (HHV-6). We assessed changes in HHV-6 epidemiology in the post-letermovir era.

METHODS

We conducted a retrospective cohort study of CMV-seropositive allogeneic HCT recipients comparing time periods before and after routine use of prophylactic letermovir. HHV-6 testing was at the discretion of clinicians. We computed the cumulative incidence of broad-spectrum antiviral initiation (foscarnet, (val)ganciclovir, and/or cidofovir), HHV-6 testing, and HHV-6 detection in blood and cerebrospinal fluid within 100 days after HCT. We used Cox proportional-hazards models with stabilized inverse probability of treatment weights to compare outcomes between cohorts balanced for baseline factors.

RESULTS

We analysed 738 patients, 376 in the pre-letermovir and 362 in the post-letermovir cohort. Broad-spectrum antiviral initiation incidence decreased from 65% (95% CI, 60-70%) pre-letermovir to 21% (95% CI, 17-25%) post-letermovir. The cumulative incidence of HHV-6 testing (17% [95% CI, 13-21%] pre-letermovir versus 13% [95% CI, 10-16%] post-letermovir), detection (3% [95% CI, 1-5%] in both cohorts), and HHV-6 encephalitis (0.5% [95% CI, 0.1-1.8%] pre-letermovir and 0.6% [95% CI, 0.1-1.9%] post-letermovir) were similar between cohorts. First HHV-6 detection occurred at a median of 37 days (interquartile range, 18-58) in the pre-letermovir cohort and 27 (interquartile range, 25-34) in the post-letermovir cohort. In a weighted model, there was no association between the pre-versus post-letermovir cohort and HHV-6 detection (adjusted hazard ratio, 1.08; 95% CI, 0.44-2.62).

DISCUSSION

Despite a large decrease in broad-spectrum antivirals after the introduction of letermovir prophylaxis in CMV-seropositive allogeneic HCT recipients, there was no evidence for increased clinically detected HHV-6 reactivation and disease.

Effectiveness of letermovir for cytomegalovirus prophylaxis in allogeneic hematopoietic stem cell transplant recipients: A global systematic review

OBJECTIVE(S)

Letermovir (LET), a novel antiviral, has largely supplanted more traditional preemptive therapy (PET) for cytomegalovirus (CMV) prophylaxis in allogeneic hematopoietic stem cell transplant (allo-HCT) patients. Use of LET demonstrated efficacy against placebo in phase III randomized controlled trials, but is considerably more expensive than PET. This review aimed to evaluate the real-world effectiveness of LET in preventing clinically significant CMV infection (csCMVi) for allo-HCT recipients and related outcomes.

DESIGN

A systematic literature review was performed using an a priori protocol using PubMed, Scopus, and ClinicalTrials.gov from January 2010 to October 2021.

SETTING AND PARTICIPANTS

Studies were included if they met the following criteria: LET compared with PET, CMV-related outcomes, patients aged 18 years or older, and English language-only articles. Descriptive statistics were used to summarize study characteristics and outcomes.

OUTCOME MEASURES

CMV viremia, csCMVi, CMV end-organ disease, graft-versus-host-disease, all-cause mortality.

RESULTS

A total of 233 abstracts were screened, with 30 included in this review. Randomized trials demonstrated efficacy of LET prophylaxis in preventing csCMVi. Observational studies demonstrated varying degrees of effectiveness of LET prophylaxis compared with use of PET alone. All studies with a comparator group resulted in lower rates of csCMVi for patients using LET. Included studies varied widely by CMV viral load threshold cutoff and CMV test units, limiting synthesis of results owing to high heterogeneity.

CONCLUSION

LET reduces risk of csCMVi, but lack of standardized clinical definitions on how to evaluate csCMVi and related outcomes largely prevent synthesis of results. Clinicians must consider this limitation in the context of evaluating the effectiveness of LET to other antiviral therapies, especially for patients at risk of late-onset CMV. Future studies should focus on prospective data collection through registries and concordance of diagnostic definitions to mitigate study heterogeneity.

Longitudinal Detection of Twenty DNA and RNA Viruses in Allogeneic Hematopoietic Stem Cell Transplant Recipients Plasma

Metagenomics revealed novel and routinely overlooked viruses, representing sources of unrecognized infections after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aim to describe DNA and RNA virus prevalence and kinetics in allo-HSCT recipients' plasma for one year post HSCT. We included 109 adult patients with first allo-HSCT from 1 March 2017 to 31 January 2019 in this observational cohort study. Seventeen DNA and three RNA viral species were screened with qualitative and/or quantitative r(RT)-PCR assays using plasma samples collected at 0, 1, 3, 6, and 12 months post HSCT. TTV infected 97% of patients, followed by HPgV-1 (prevalence: 26-36%). TTV (median 3.29 × 10⁵ copies/mL) and HPgV-1 (median 1.18 × 10⁶ copies/mL) viral loads peaked at month 3. At least one Polyomaviridae virus (BKPyV, JCPyV, MCPyV, HPyV6/7) was detected in >10% of patients. HPyV6 and HPyV7 prevalence reached 27% and 12% at month 3; CMV prevalence reached 27%. HSV, VZV, EBV, HHV-7, HAdV and B19V prevalence remained <5%. HPyV9, TSPyV, HBoV, EV and HPg-V2 were never detected. At month 3, 72% of patients had co-infections. TTV and HPgV-1 infections were highly prevalent. BKPyV, MCPyV and HPyV6/7 were frequently detected relative to classical culprits. Further investigation is needed into associations between these viral infections and immune reconstitution or clinical outcomes.

Cytomegalovirus Therapy: Role of Letermovir in Prophylaxis and Treatment in Transplant Recipients

Cytomegalovirus (CMV) is a common viral pathogen in the transplant population and is associated with significant morbidity and mortality. CMV prevention is paramount; however, selecting the best preventive strategy depends on many factors including donor-recipient CMV serostatus, transplant-specific risks, antiviral toxicities and cost. Novel CMV therapeutics such as letermovir (LTV) are desperately needed to optimize CMV management. Uniquely among CMV antiviral therapies, LTV inhibits the viral terminase complex in the CMV DNA synthesis pathway and disrupts viral genome packaging. Further, it lacks side effects frequently associated with other CMV antiviral therapies and evades common mechanisms of resistance. LTV is approved by the US Food and Drug Administration for CMV prevention in adult CMV-seropositive hematopoietic cell transplant recipients but is increasingly applied off-label for prophylaxis and treatment. This review summarizes important concepts of CMV management in transplantation, with a specific focus on LTV pharmacology and clinical experience to date alongside future prospects for its application.

Influence of letermovir treatment on gut inflammation in people living with HIV on antiretroviral therapy: protocol of the open-label controlled randomised CIAO study

INTRODUCTION

Chronic cytomegalovirus (CMV) infection is very frequent in people living with HIV (PLWH). High anti-CMV IgG titres, which may be linked to transient CMV replication, have been associated with earlier mortality, CD8 T-cell expansion, lower CD4/CD8 ratio and increased T-cell senescence. We previously showed that anti-CMV IgG titres correlated with gut permeability in PLWH on antiretroviral therapy (ART), which was associated with microbial translocation, systemic inflammation and non-infectious/non-AIDS comorbidities. Letermovir, a novel anti-CMV drug with a good safety profile, was recently approved for anti-CMV prophylaxis in allogeneic haematopoietic stem cell transplant recipients. A drastic and selective reduction of both low-grade replication and clinically significant CMV infections, combined with an improved immune reconstitution have been reported. In vitro, letermovir prevented CMV-induced epithelial disruption in intestinal tissues. Based on these findings, we aim to assess whether letermovir could inhibit CMV subclinical replication in CMV-seropositive PLWH receiving ART and, in turn, decrease CMV-associated gut damage and inflammation.

METHOD AND ANALYSIS

We will conduct a multi-centre, open-label, randomised, controlled clinical trial, including a total of 60 CMV-seropositive ART-treated PLWH for at least 3 years, with a viral load <50 copies/mL and CD4+ count >400 cells/µL. Forty participants will be randomised to receive letermovir for 14 weeks and 20 participants will receive standard of care (ART) alone. Plasma, pheripheral blood mononuclear cells (PBMCs), and stool samples will be collected. Colon biopsies will be collected in an optional substudy. We will assess the effect of letermovir on gut damage, microbial translocation, inflammation and HIV reservoir size.

ETHICS AND DISSEMINATION

The study was approved by Health Canada and the Research Ethics Boards of the McGill University Health Centre (MUHC-REB, protocol number: MP37-2022-8295). Results will be made available through publications in open access peer-reviewed journals and through the CIHR/CTN website.

TRIAL REGISTRATION NUMBER

NCT05362916.

New trends in the management of cytomegalovirus infection after allogeneic hematopoietic cell transplantation: a survey of the Infectious Diseases Working Pary of EBMT

The management of cytomegalovirus (CMV) infection was assessed with a survey performed in 2020 by the Infectious Diseases Working Party of European Society for Blood and Marrow Transplantation (EBMT). One-hundred-eighty of the 579 EBMT centres (31%) responded. CMV monitoring with quantitative PCR for CMV-DNAemia was used by 97% of centres while the duration of monitoring was variable according to the patient immune recovery and the ongoing immunosuppressive therapy. CMV prophylaxis for high-risk patients was used in 101 (56%) of centres: letermovir in 62 centres (61%), aciclovir/valaciclovir in 19 centres (19%), ganciclovir/valganciclovir in 17 centres (17%), foscarnet in 3 (3%). The most used trigger for pre-emptive therapy was a threshold of >10³ copies/ml or >10³ IU/ml. Ganciclovir/valganciclovir confirmed the preferred first line treatment both for pre-emptive and CMV disease therapy. CMV-cytotoxic T-cells were used mainly in the setting of relapsing/refractory CMV disease. Forty-eight centres reported CMV refractory/resistant infection due to mutated CMV strain.This survey showed that letermovir prophylaxis is adopted by more than half of centres using a prophylaxis approach for CMV infection. How letermovir prophylaxis will modify other important pillars of daily CMV management, such as frequency of CMV-DNAemia monitoring and preemptive therapy, remain a matter of investigation.

Cytomegalovirus infection in transplant recipients: newly approved additions to our armamentarium

BACKGROUND

The burden that cytomegalovirus (CMV) portends for haematopoietic and solid-organ transplant recipients cannot be understated. Valganciclovir and ganciclovir have successfully been used for prevention and treatment of CMV infections, although with serious side effects such as leucopenia and some development of resistance. Until recently, available therapies for ganciclovir-resistant CMV have significant toxicities. Although advances have been made in the field, the unmet medical needs for effective and well-tolerated therapies are significant.

OBJECTIVES

This review aims to summarise the current and emerging CMV antiviral drugs and discusses future perspectives in the field.

SOURCES

We searched for relevant articles with pertinent keywords: "Cytomegalovirus OR CMV", "Transplant" and "Antiviral". Articles published after 2019 were given preference. Articles were reviewed by the authors for relevance and impact to the subject of interest.

CONTENT

We outline in this review current advances in prophylaxis of CMV infection with letermovir, breakthrough CMV infections while on or after prophylaxis, the development of resistant and refractory CMV infections, and the newly approved anti-CMV agent, maribavir, in haematopoietic and solid-organ transplant recipients.

IMPLICATIONS

Prevention of CMV infections after transplant has improved greatly over the past few years. Despite major advancements, breakthrough CMV infections and development of refractory and resistant CMV infections remain major complications post transplantation. We highlight emerging therapeutics that tolerably and effectively prevent and treat CMV infections, especially refractory and resistant cases.

Real-World Outcomes Associated With Letermovir Use for Cytomegalovirus Primary Prophylaxis in Allogeneic Hematopoietic Cell Transplant Recipients: A Systematic Review and Meta-analysis of Observational Studies

Background

A systematic review and meta-analysis of real-world observational studies was conducted to summarize the impact of letermovir cytomegalovirus (CMV) primary prophylaxis (PP) among adult allogeneic hematopoietic cell transplant (allo-HCT) recipients.

Methods

Systematic searches in Medline/PubMed, Embase, and conferences (from database inception to October 2021) were conducted to identify studies for inclusion. Random-effects models were used to derive pooled estimates on the relative effectiveness of letermovir PP compared to controls.

Results

Forty-eight unique studies (N = 7104 patients) were included, most of which were comparative, single-center, and conducted in the United States. Letermovir PP was associated with statistically significant reduction in odds of CMV reactivation (pooled odds ratio [pOR], 0.13 and 0.24; P < .05), clinically significant CMV infection (pOR, 0.09 and 0.19; P < .05), and CMV disease (pOR, 0.31 and 0.35; P < .05) by day +100 and day +200 after allo-HCT, respectively. Letermovir PP was associated with significantly lower odds of all-cause (pOR, 0.73; P < .01) and nonrelapse mortality (pOR, 0.65; P = .01) beyond day 200 after allo-HCT.

Conclusions

Letermovir for CMV PP was effective in reducing the risk of CMV-related complications overall and mortality beyond day 200 among adult allo-HCT recipients.

Risk factor analysis for cytomegalovirus reactivation under prophylaxis with letermovir after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Letermovir has been approved as a novel cytomegalovirus (CMV) prophylactic agent after allogeneic hematopoietic stem cell transplantation (HSCT). However, there are still insufficient data to properly evaluate the real-world role of letermovir, and the risk factors for CMV reactivation under letermovir prophylaxis have not been clarified.

METHODS

We performed a single-institution retrospective analysis of patients under prophylaxis with or without letermovir who underwent allogeneic HSCT between March 2012 and December 2019. In August 2018, letermovir was added to the clinical practice at our institution for the prophylaxis of CMV reactivation in allogeneic HSCT recipients. Patients who underwent HSCT without prophylactic letermovir from March 2012 until September 2018 served as a historical control.

RESULTS

The cumulative incidence of clinically significant CMV infection (CS-CMVi) was significantly lower in the letermovir group than in the historical control group not receiving letermovir (30.2% vs. 71.6%, p < .05, at 100 days). In addition, the cumulative incidence of non-relapse mortality (NRM) at day 500 was significantly lower in the letermovir group (4.7% vs. 19.8%, p < .05). We then performed a risk factor analysis for developing CS-CMVi in the letermovir group. The only significant factor identified by this multivariable analysis was transplantation from a CMV seronegative donor to a seropositive recipient (Hazard ratio = 2.76, 95% confidence interval 1.14-6.68, p < .05).

CONCLUSION

Our study showed that letermovir prophylaxis significantly reduced the incidence of CS-CMVi and NRM in a real-world setting and that the CMV serostatus of the donor remained as a risk factor for CS-CMVi even under letermovir prophylaxis.

Therapeutic Drug Monitoring of Orally Administered Letermovir Prophylaxis in Allogeneic Hematopoietic Stem Cell Transplant Recipients

With balanced safety-efficacy profile, letermovir anti-cytomegalovirus (CMV) prophylaxis is used in hematopoietic stem cell transplant recipients (HSCTR). We assessed feasibility and usefulness of letermovir therapeutic drug monitoring (TDM) in HSCTR. We performed a prospective observational study on letermovir-TDM including 40 consecutive adult CMV-seropositive allogeneic-HSCTR who received orally (PO) administered letermovir. Minimal blood concentrations of letermovir (C_trough) were measured on days 3 and 7 postletermovir initiation and weekly thereafter. Letermovir-C_trough remained stable during the first 70 days post-HSCT at a median of 286 μg/L (interquartile range, 131 to 591 μg/L), with large interpatient/intrapatient variability. No associations between breakthrough clinically significant CMV infection or detectable CMV DNAemia and letermovir-C_trough were observed. Patients with letermovir-associated adverse events had higher letermovir-C_trough than patients without (400 versus 266 μg/L, P = 0.02). Letermovir-C_trough was similar in patients with or without gastrointestinal symptoms (280 versus 300 μg/L, P = 0.49). Acute grade ≥2 GvHD was associated with higher letermovir-C_trough (479 versus 248 μg/L, P = 0.001), including gastrointestinal GvHD (499 versus 263 μg/L, P = 0.004). Concomitantly administered posaconazole and cyclosporine were associated with higher letermovir-C_trough (707 versus 259 μg/L, P < 0.001 and 437 versus 248 μg/L, P = 0.01, respectively). In multivariable analysis, both posaconazole (odds ratio [OR], 4.9; 95% confidence interval [CI], 2.4 to 9.7; P < 0.0001) and cyclosporine-adjusted letermovir dose at 240 mg daily (OR, 3.5; 95% CI, 1.4 to 9.0; P = 0.01) were independently associated with higher letermovir-C_trough. In conclusion, administration of PO letermovir led to measurable and relatively stable letermovir-C_trough, without noticeable associations with clinical efficacy. Letermovir exposure was not affected by gastrointestinal symptoms, but with posaconazole and cyclosporine administration. Associations between letermovir and concomitantly administered agents and adverse events warrant additional clinical studies.

Cytomegalovirus as an Uninvited Guest in the Response to Vaccines in People Living with HIV

In stark contrast to the rapid development of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), an effective human immunodeficiency virus (HIV) vaccine is still lacking. Furthermore, despite virologic suppression and CD4 T-cell count normalization with antiretroviral therapy (ART), people living with HIV (PLWH) still exhibit increased morbidity and mortality compared to the general population. Such differences in health outcomes are related to higher risk behaviors, but also to HIV-related immune activation and viral coinfections. Among these coinfections, cytomegalovirus (CMV) latent infection is a well-known inducer of long-term immune dysregulation. Cytomegalovirus contributes to the persistent immune activation in PLWH receiving ART by directly skewing immune response toward itself, and by increasing immune activation through modification of the gut microbiota and microbial translocation. In addition, through induction of immunosenescence, CMV has been associated with a decreased response to infections and vaccines. This review provides a comprehensive overview of the influence of CMV on the immune system, the mechanisms underlying a reduced response to vaccines, and discuss new therapeutic advances targeting CMV that could be used to improve vaccine response in PLWH.

Predictors of breakthrough clinically significant cytomegalovirus infection during letermovir prophylaxis in high-risk hematopoietic cell transplant recipients

Letermovir prophylaxis in allogeneic hematopoietic cell transplant recipients significantly reduces the incidence of clinically significant cytomegalovirus infection. However, breakthrough infections still occur despite adequate prophylaxis. In the present retrospective cohort study, we identified clinically relevant predictive factors for clinically significant CMV breakthrough infection during letermovir prophylaxis. Low‐grade CMV replication (21–149 IU/ml), both at the time of letermovir initiation or during prophylaxis, was a significant risk factor for breakthrough clinically significant CMV infection. In addition, development of acute gastrointestinal graft‐versus‐host disease was significantly associated with breakthrough infection. Altogether these findings could call clinicians' attention to closer CMV monitoring and allow for prompt preemptive treatment initiation.