Cytomegalovirus prevention in thoracic organ transplantation: A single-center evaluation of letermovir prophylaxis

Letermovir should be first-line cytomegalovirus prophylaxis in lung transplant recipients

Universal cytomegalovirus (CMV) prophylaxis is recommended for at-risk lung transplant recipients. Valganciclovir is currently the preferred first-line agent. Valganciclovir-related myelosuppression, however, can lead to drug discontinuation or reduction in anti-metabolite immunosuppression. Variable valganciclovir pharmacokinetics in the setting of renal injury are also associated with development of resistant CMV. Letermovir, a newer anti-CMV agent, is an attractive alternative for first-line prophylaxis in many lung transplant recipients. Initially investigated in bone marrow transplant, there are now multiple retrospective studies of lung transplant recipients who were switched from valganciclovir to letermovir because of tolerability, dosing, or resistance. These studies have reaffirmed the safety and efficacy of letermovir in the lung transplant population. Despite this, letermovir continues to be recommended as second-line prophylaxis with use limited to those who fail valganciclovir. We argue that there are now sufficient data to support letermovir use in lung transplant recipients at high risk for valganciclovir toxicity. This includes patients with renal insufficiency, advanced age, cytolytic immunosuppression, high risk of rejection, and telomere biology disorders, among other conditions. First-line letermovir would reduce the risk of VGCV-related myelosuppression and attendant reduction in immunosuppression, as well as development of CMV resistance due to variable renal function and VGCV pharmacokinetics.

Impact of Letermovir for Cytomegalovirus Primary Prophylaxis on Myelosuppression and Immunosuppression in Lung Transplant Recipients

BACKGROUND

Cytomegalovirus (CMV) is associated with detrimental outcomes after lung transplantation (LTX); primary prophylaxis (PPX) with valganciclovir (VGC) is guideline-recommended. VGC is associated with myelosuppression, spurring interest in letermovir (LTV).

METHODS

Adults undergoing LTX between January 1, 2021, and July 30, 2022 at our institution who were converted from VGC to LTV for PPX were evaluated. Outcomes included antimetabolite dosing during PPX, the incidence and frequency of myelosuppressive events, and the time to the first myelosuppressive event.

RESULTS

Twenty-nine LTX recipients met the inclusion criteria. Most patients received non-lymphocyte-depleting induction (96.6%) and had moderate risk CMV serostatus (D+/R+, 48.3%). Patients transitioned from VGC to LTV 177 days (IQR 102 days) post-transplant. After conversion to LTV, patients tolerated higher daily doses of mycophenolate (721 mg vs. 1000 mg, p = 0.008) or azathioprine (33.3 mg vs. 62.5 mg, p = 0.478). The incidence of myelosuppressive events was reduced (100.0% vs. 62.1%, p < 0.001) including leukopenia (96.6% vs. 58.6%, p = 0.001), severe leukopenia (82.8% vs 31.0%, p < 0.001) and neutropenia requiring GCSF (96.6% vs. 48.3%, p < 0.001) while on VGC compared to LTV. While on LTV, patients had a reduced rate of myelosuppressive events compared to VGC (1 event per 6.2 patient days vs. 1 event per 14.7 patient days, p < 0.001). While on LTV, one patient had breakthrough viremia (3.4%) that was treated with (val)ganciclovir.

CONCLUSIONS

In this single-center study, patients tolerated higher doses of antimetabolite immunosuppression, and the incidence and frequency of myelosuppressive events were reduced while on LTV compared to VGC. This evidence expands upon the current literature demonstrating improved tolerability of LTV in LTX recipients.

Use of letermovir for cytomegalovirus primary prophylaxis in lung transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is a driver of negative outcomes after lung transplant (LTX) and primary prophylaxis (PPX) with valganciclovir (VGC) is standard-of-care. VGC is associated with myelosuppression, prompting interest in letermovir (LTV).

METHODS

Adults receiving LTX between April 1, 2015, and July 30, 2022, at our institution were evaluated. Patients were excluded if low CMV risk (D-/R-), survived <90 days post-LTX, or transferred care before PPX withdrawal. Primary outcomes were leukopenia (white blood cell count [WBC] ≤ 3.0 × 109/L), severe leukopenia (WBC ≤ 2.0 × 109/L), and neutropenia (absolute neutrophil count ≤ 1500 cells/µL) requiring granulocyte-colony stimulating factor (GCSF) on PPX. Secondary outcomes included breakthrough CMV infection and post-PPX CMV infection.

RESULTS

204 patients met inclusion criteria: 175 patients on VGC and 29 patients on LTV (after VGC conversion). Most patients received bilateral LTX (62.7%) with non-lymphocyte-depleting induction (96.6%) and moderate-risk serostatus (D+/R+, 48.5%). Patients transitioned from VGC to LTV after a mean of 178 days (SD 80.8 days) post-transplant. Patients on VGC experienced significantly more leukopenia (82.3% vs. 58.6%, p = 0.008), severe leukopenia (57.1% vs. 31.0%, p = 0.016), and neutropenia requiring GCSF (70.9% vs. 51.7%, p = 0.048). Breakthrough (5.7% vs. 3.4%, p = 0.955) and post-PPX (24.6% vs. 37.9%, p = 0.199) infections were similar. A subgroup analysis of patients with high-risk serostatus showed similar trends, though did not reach statistical significance.

CONCLUSIONS

In this single-center study, the incidence of leukopenia and neutropenia requiring GCSF were reduced with LTV compared to VGC. Breakthrough and post-PPX infections were not significantly different. This evidence suggests that LTV has comparable efficacy with reduced myelosuppression compared to VGC in LTX recipients, and may be an appropriate alternative for PPX.

Current Perspectives on Letermovir and Maribavir for the Management of Cytomegalovirus Infection in Solid Organ Transplant Recipients

Cytomegalovirus (CMV) infection is arguably the most important infectious complication that negatively affects the outcome of solid organ transplantation. For decades, CMV management after transplantation has relied on antiviral drugs that inhibit viral DNA polymerase (ganciclovir, foscarnet, and cidofovir). However, their use has been complicated by myelosuppression, nephrotoxicity, and selection of drug-resistant viruses. During the past few years, the therapeutic armamentarium for the management of CMV in solid organ transplant recipients has expanded with the approval of letermovir for CMV prophylaxis in high-risk CMV D+/R- kidney recipients, and maribavir for the treatment of refractory and resistant CMV infection. Both drugs offer significant improvement when compared to standard anti-CMV therapies; letermovir was as efficacious for CMV prevention, whereas maribavir was more effective in treating refractory and resistant CMV infections. Both letermovir and maribavir have favorable safety profiles compared to CMV DNA polymerase inhibitors, without the risk of neutropenia and leukopenia associated with ganciclovir and renal toxicities associated with foscarnet and cidofovir. Moreover, letermovir and maribavir are orally bioavailable, which allows convenient outpatient treatment. However, letermovir and maribavir have a significant drug interaction potential in solid organ transplant recipients, resulting in higher levels of calcineurin inhibitors (cyclosporine and tacrolimus) and mTOR inhibitors (sirolimus and everolimus). Both letermovir and maribavir are CMV-specific and do not have clinical efficacy against other herpes viruses. Thus, there is a need for additional antiviral drugs to prevent herpes simplex and other herpes viruses when clinically indicated. This article provides a comprehensive review of the clinical data supporting the use of letermovir and maribavir in clinical practice. The author provides perspectives on the role of these newly approved drugs in the current management landscape of CMV infection in solid organ transplantation.

The changing landscape of infections in the lung transplant recipient

PURPOSE OF REVIEW

Infections in lung transplant recipients remain a major challenge and can affect lung allograft function and cause significant morbidity and mortality. New strategies for the prevention and treatment of infection in lung transplantation have emerged and are reviewed.

RECENT FINDINGS

For important vaccine preventable infections (VPIs), guidance has been updated for at risk solid organ transplant (SOT) recipients. However, data on the efficacy of newer vaccines in lung transplant, including the respiratory syncytial virus (RSV) vaccine, are limited. Studies demonstrate improved vaccination rate with Infectious Diseases consultation during pretransplant evaluation. Two new antiviral agents for the treatment and prevention of cytomegalovirus (CMV) in SOT, letermovir and maribavir, are being incorporated into clinical care. CMV-specific cell-mediated immune function assays are more widely available. Antibiotics for the management of multidrug resistant pathogens and Burkholderia cepacia complex have been described in case series and case reports in lung transplant.

SUMMARY

Although new vaccines and novel therapies for preventing and treating infections are available, larger studies evaluating efficacy in lung transplant recipients are needed.

Advances in lung transplantation: 60 years on

Lung transplantation is a well-established treatment for advanced lung disease, improving survival and quality of life. Over the last 60 years all aspects of lung transplantation have evolved significantly and exponential growth in transplant volume. This has been particularly evident over the last decade with a substantial increase in lung transplant numbers as a result of innovations in donor utilization procurement, including the use donation after circulatory death and ex-vivo lung perfusion organs. Donor lungs have proved to be surprisingly robust, and therefore the donor pool is actually larger than previously thought. Parallel to this, lung transplant outcomes have continued to improve with improved acute management as well as microbiological and immunological insights and innovations. The management of lung transplant recipients continues to be complex and heavily dependent on a tertiary care multidisciplinary paradigm. Whilst long term outcomes continue to be limited by chronic lung allograft dysfunction improvements in diagnostics, mechanistic understanding and evolutions in treatment paradigms have all contributed to a median survival that in some centres approaches 10 years. As ongoing studies build on developing novel approaches to diagnosis and treatment of transplant complications and improvements in donor utilization more individuals will have the opportunity to benefit from lung transplantation. As has always been the case, early referral for transplant consideration is important to achieve best results.

Evaluating the efficacy and safety of letermovir compared to valganciclovir for the prevention of human cytomegalovirus disease in adult lung transplant recipients

BACKGROUND

Lung transplant recipients are at high risk for severe cytomegalovirus (CMV) disease. Off-label use of letermovir (LET) may avert myelotoxicity associated with valganciclovir (VGCV), but data in lung transplantation are limited. This study aims to evaluate the outcomes of LET prophylaxis among lung transplant recipients.

METHODS

This retrospective, matched cohort study included lung transplant recipients who received LET for primary CMV prophylaxis following VGCV intolerance. Patients were matched 1:1 to historical VGCV controls based on age, serostatus group, and time from transplant. The primary outcome was CMV breakthrough within 1 year post-LET initiation; secondary outcomes included hematologic changes.

RESULTS

A total of 124 lung transplant recipients were included per group (32% CMV mismatch, D+R-), with LET initiated a median of 9.6 months post-transplantation. One CMV breakthrough event (0.8%) was observed in the LET group versus four (3.2%) in the VGCV group (p = .370). The median (interquartile range) white blood cell (WBC) count was 3.1 (2.1-5.6) at LET initiation which increased to 5.1 (3.9-7.2) at the end of follow-up (p <.001). For VGCV controls, WBC was 4.8 (3.4-7.2) at baseline and 5.4 (3.6-7.2) at the end of follow-up; this difference was not statistically significant (p = .395). Additionally, 98.4% of LET patients experienced ≥1 leukopenia episode in the year prior to LET compared to 71.8% the year after initiation (p <.001). Similar results were observed for neutropenia (48.4% and 17.7%, p <.001).

CONCLUSION

LET prophylaxis was associated with a low rate of CMV reactivation and leukopenia recovery. LET may represent a reasonable prophylaxis option for lung transplant recipients unable to tolerate VGCV.

Real-life use of letermovir prophylaxis for cytomegalovirus in heart transplant recipients

INTRODUCTION

Cytomegalovirus (CMV) remains the predominant opportunistic infection following solid organ transplantation (SOT). While valganciclovir is the drug of choice for CMV prophylaxis, its utility can be compromised due to the risk of cytopenia. Letermovir, a novel agent approved for CMV prophylaxis in allogeneic hematopoietic stem cell transplant recipients and high-risk kidney transplant recipients, exhibits reduced toxicity. This study aims to present the practical application of letermovir as both primary and secondary prophylaxis against CMV in heart transplant recipients (HTR).

METHODS

In this observational, retrospective, single-center study, we included all consecutive adult HTRs from June 2020 to January 2022 who were administered letermovir for CMV prophylaxis. We documented instances of CMV breakthrough infections, side effects related to letermovir, changes in neutropenia following the switch from valganciclovir to letermovir, and any drug interactions with the immunosuppressive regimen.

RESULTS

The study comprised 10 patients: two received primary prophylaxis with letermovir due to a high risk of CMV infection (donor-positive, recipient-negative serostatus), and eight received it as secondary prophylaxis following a CMV infection. The median duration of letermovir administration was 8 months (range 3-12 months). No CMV breakthrough infections were reported while on prophylaxis. However, three patients experienced CMV breakthrough infections after discontinuing letermovir prophylaxis (30%). No significant side effects were observed, although one patient reported digestive intolerance. Among the nine patients on tacrolimus, six needed reduced doses after switching to letermovir.

CONCLUSION

This real-life study appears to support the effectiveness of letermovir prophylaxis in HTR. Nonetheless, the risk of CMV infection post-treatment cessation is notable. Further drug monitoring and research on the efficacy of letermovir for CMV prophylaxis in SOT patients is warranted.

Letermovir prophylaxis for cytomegalovirus in lung-transplant recipients: a comprehensive study with literature review of off-label use and real-world experiences

Letermovir, initially approved for cytomegalovirus (CMV) prophylaxis in hematopoietic stem-cell transplantation, has gained attention for off-label use in lung-transplant (LTx) recipients. Given the high susceptibility of LTx recipients to CMV infection, this study explores the effectiveness and safety of letermovir prophylaxis. A retrospective analysis of using letermovir for LTx recipients at Tohoku University Hospital (January 2000 to November 2023) was conducted. Case summaries from other Japanese transplant centers and a literature review were included. Six cases at Tohoku University Hospital and one at Kyoto University Hospital were identified. Prophylactic letermovir use showed positive outcomes in managing myelosuppression and preventing CMV replication. The literature review supported the safety of letermovir in high-risk LTx recipients. Despite limited reports, our findings suggest letermovir's potential as prophylaxis for LTx recipients intolerant to valganciclovir. Safety, especially in managing myelosuppression, positions letermovir as a promising option. However, careful consideration is important in judiciously integrating letermovir into the treatment protocol.

Incidence of valganciclovir-related leukopenia and neutropenia in solid organ transplant recipients at high risk of cytomegalovirus disease

BACKGROUND

Valganciclovir (VGCV) prophylaxis is associated with an increased risk of hematologic side effects. We analyzed the impact of VGCV prophylaxis on leukopenia and neutropenia rates and explored risk factors for its occurrence.

METHODS

Retrospective cohort study of adult cytomegalovirus (CMV)-seronegative solid organ transplantation (SOT) recipients of either CMV-seropositive (CMV D+/R-) or CMV-seronegative (CMV D-/R-) donors between July 2005 and March 2019. CMV D+/R- SOT recipients received 3-12 months of VGCV prophylaxis whereas CMV D-/R- SOT recipients received no VGCV prophylaxis. Competing risk regression was used to calculate risk factors for significant neutropenia (neutrophil count < 1000/μL).

RESULTS

A total of 430 CMV-seronegative SOT recipients (median age of 52.1 years, 76.5% males) were included, of which 203 (47.2%) were CMV D+/R- and 227 (52.8%) CMV D-/R-. The unadjusted incidence rate ratio of significant neutropenia attributable to VGCV exposure in the first year post-transplant was 13.50 (95% confidence interval 7.36-27.11). Acute rejection occurred more frequently in neutropenic patients at 32.5% compared to 19.1% in those without neutropenia (p = .033). On multivariate analysis, VGCV prophylaxis for 1-90 days and 91-180 days versus no VGCV were the strongest risk factors for significant neutropenia with a sub-distribution hazard ratio of 39.6 (95% CI, 8.57-182.6) and 13.2 (95% CI, 5.46-32.0), respectively.

CONCLUSIONS

VGCV prophylaxis is limited by high rates of neutropenia. Future prospective studies are needed to assess alternative CMV prophylactic strategies in SOT recipients.

Immune aging: biological mechanisms, clinical symptoms, and management in lung transplant recipients

While chronologic age can be precisely defined, clinical manifestations of advanced age occur in different ways and at different rates across individuals. The observed phenotype of advanced age likely reflects a superposition of several biological aging mechanisms which have gained increasing attention as the world contends with an aging population. Even within the immune system, there are multiple age-associated biological mechanisms at play, including telomere dysfunction, epigenetic dysregulation, immune senescence programs, and mitochondrial dysfunction. These biological mechanisms have associated clinical syndromes, such as telomere dysfunction leading to short telomere syndrome (STS), and optimal patient management may require recognition of biologically based aging syndromes. Within the clinical context of lung transplantation, select immune aging mechanisms are particularly pronounced. Indeed, STS is increasingly recognized as an indication for lung transplantation. At the same time, common aging phenotypes may be evoked by the stress of transplantation because lung allografts face a potent immune response, necessitating higher levels of immune suppression and associated toxicities, relative to other solid organs. Age-associated conditions exacerbated by lung transplant include bone marrow suppression, herpes viral infections, liver cirrhosis, hypogammaglobulinemia, frailty, and cancer risk. This review aims to dissect the molecular mechanisms of immune aging and describe their clinical manifestations in the context of lung transplantation. While these mechanisms are more likely to manifest in the context of lung transplantation, this mechanism-based approach to clinical syndromes of immune aging has broad relevance to geriatric medicine.

Bring it on again: antimicrobial stewardship in transplant infectious diseases: updates and new challenges

Advancement in solid organ transplantation and hematopoietic stem cell transplant continues to improve the health outcomes of patients and widens the number of eligible patients who can benefit from the medical progress. Preserving the effectiveness of antimicrobials remains crucial, as otherwise transplant surgeries would be unsafe due to surgical site infections, and the risk of sepsis with neutropenia would preclude stem cell transplant. In this review, we provide updates on three previously discussed stewardship challenges: febrile neutropenia, Clostridioides difficile infection, and asymptomatic bacteriuria. We also offer insight into four new stewardship challenges: the applicability of the "shorter is better" paradigm shift to antimicrobial duration; antibiotic allergy delabeling and desensitization; colonization with multidrug-resistant gram-negative organisms; and management of cytomegalovirus infections. Specifically, data are accumulating for "shorter is better" and antibiotic allergy delabeling in transplant patients, following successes in the general population. Unique to transplant patients are the impact of multidrug-resistant organism colonization on clinical decision-making of antibiotic prophylaxis in transplant procedure and the need for antiviral stewardship in cytomegalovirus. We highlighted the expansion of antimicrobial stewardship interventions as potential solutions for these challenges, as well as gaps in knowledge and opportunities for further research.

Real-life experience in two cases of secondary prophylaxis with letermovir for CMV infection in solid organ transplantation

IMPORTANCE

This observation provides comprehensive data on the clinical correlates of both cytomegalovirus (CMV) genotypic follow-up and clinical monitoring and outcomes for two different solid organ transplantation recipients that received letermovir as secondary prophylaxis. Our study emphasizes that monitoring of CMV disease in the patient and early genotypic detection of resistance mutations are essential when using new antiviral drugs for off-label indication in patients experiencing CMV relapses or not responding to standard antiviral therapy. These cases and the bibliography reviewed can be helpful for other researchers and clinicians working in the field to optimize the use of new treatments for transplant recipients since drug-resistant CMV infection is an important emerging problem even with new developments in antiviral treatment.

Updates in Cytomegalovirus Prevention and Treatment in Solid Organ Transplantation

The authors summarize recent updates in the prevention and management of cytomegalovirus (CMV) in solid organ transplant (SOT) recipients with a focus on CMV seronegative recipients of organs from seropositive donors (CMV D+/R-) who are at highest risk of CMV infection and disease. They discuss advantages of preemptive therapy for CMV disease prevention in CMV D+/R- liver transplant recipients, letermovir for CMV prophylaxis, and updates in the development of monoclonal antibodies and vaccines as immune-based preventative strategies. They review the roles of maribavir and virus-specific T cells for management of resistant or refractory CMV infection in SOT recipients.

Letermovir for pre-emptive cytomegalovirus therapy after allogeneic hematopoietic cell transplantation

BACKGROUND

Cytomegalovirus (CMV) is a common cause of morbidity after allogeneic haematopoietic cell transplantation (alloHCT). Pre-emptive therapy (PET) with valganciclovir (VGC) is associated with haematological toxicity.

METHODS

We included alloHCT patients from 2018 to 2021 where letermovir (LTV) was used for CMV PET because of cytopenias.

RESULTS

Ten patients were included. Six received VGC prior to LTV. VGC was commenced at median d42, given for median 40 days. LTV was commenced at median d90, given for median 54 days. At commencement of antiviral, CMV viral load was higher for VGC at 3.7 log10 IU/mL, compared to LTV at 2.9 log10 IU/mL. Viral load reduction occurred at 0.18 log10 IU/mL per week for VGC, compared to 0.17 log10 IU/mL per week for LTV. There was no clinically significant CMV viremia after stopping LTV. Cytopenias improved on LTV.

CONCLUSION

LTV was effective in controlling CMV viremia when it was given at a lower starting CMV viral load and later post alloHCT than VGC. Further study is required of LTV as upfront PET following alloHCT.

Early post-transplant leukopenia in heart transplant recipients and its impact on outcomes

BACKGROUND

Leukopenia in the early period following heart transplantation (HT) is not well-studied. The aim of this study was to evaluate risk factors for the development of post-transplant leukopenia and its consequences for HT recipients.

METHODS

Adult patients at a large-volume transplant center who received HT between January 1, 2010 and December 31, 2020 were included. The incidence of leukopenia (WBC ≤3 × 10³ /μL) in the first 90-days following HT, individual risk factors, and its effect on 1-year outcomes were evaluated.

RESULTS

Of 506 HT recipients, 184 (36%) developed leukopenia within 90-days. Median duration of the first leukopenia episode was 15.5 days (IQR 8-42.5 days). Individuals who developed leukopenia had lower pre-transplant WBC counts compared to those who did not (6.1 × 10³ /μL vs. 6.9 × 10³ /μL, p = .02). Initial immunosuppressive and infectious chemoprophylactic regimens were not significantly different between groups. Early leukopenia was associated with a higher mortality at 1-year (6.6% vs. 2.1%, p = .008; adjusted HR 3.0) and an increased risk of recurrent episodes. Rates of infection and rejection were not significantly different between the two groups.

CONCLUSIONS

Leukopenia in the early period following HT is common and associated with an increased risk of mortality. Further study is needed to identify individuals at highest risk for leukopenia prior to transplant and optimize immunosuppressive and infectious chemoprophylactic regimens for this subgroup.

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.

Evaluation of Two Different CMV-Immunoglobulin Regimens for Combined CMV Prophylaxis in High-Risk Patients following Lung Transplant

BACKGROUND

The clinical benefits of the common off-label use of cytomegalovirus (CMV)-specific immunoglobulin (CMV-Ig) combined with antivirals in organ transplantation have not been previously assessed. The objective was to compare the risk of CMV infection and other post-transplantation outcomes between two CMV-Ig prophylaxis regimens in lung transplant recipients; Methods: Retrospective study of 124 donor CMV positive/recipient negative (D+/R-) patients receiving preventive ganciclovir/valganciclovir for 12 months, of whom 62 received adjunctive CMV-Ig as per label indication (short regimen [SR-Ig]; i.e., 7 doses over 2.5 months) and were compared to 62 who received an extended off-label regimen (ER-Ig) consisting of 17 doses over one year after transplantation.

RESULTS

The incidence of CMV infection or disease, acute rejection, chronic lung allograft dysfunction, and survival did not differ between the two CMV-Ig schedules. Although the time to the first CMV infection after transplantation was shorter in the ER-Ig than in the SR-Ig adjunctive group (log-rank: p = 0.002), the risk was independently predicted by antiviral cessation (odds ratio = 3.74; 95% confidence interval = 1.04-13.51; p = 0.030), whereas the CMV-Ig schedule had no effect.

CONCLUSIONS

Extending the adjunctive CMV-Ig prophylaxis beyond the manufacturer's recommendations up to one year does not confer additional clinical benefits regarding lung post-transplantation outcomes.

Letermovir for cytomegalovirus prophylaxis in high-risk heart transplant recipients

Letermovir is a novel agent for the prevention of cytomegalovirus (CMV) infection and disease that, unlike traditional CMV DNA polymerase inhibitors, does not carry the risk of myelosuppression. The purpose of this study was to evaluate the safety, efficacy, and clinical application of letermovir for CMV prophylaxis in heart transplant (HT) recipients. Between November 1, 2019, and October 1, 2021, at a single, tertiary care hospital, 17 HT recipients were initiated on letermovir due to leukopenia while on valganciclovir. Fifteen (88%) had high-risk mismatch (CMV D+/R-). Median time on letermovir was 5 months (interquartile range, 2-8 months.) At the end of the study period, nine of 17 patients (52.9%) were still on letermovir and four of the 17 (23.5%) had successfully completed the prophylaxis window on letermovir and been switched to the pre-emptive strategy. One patient developed clinically significant CMV viremia in the setting of being unable to obtain medication due to insurance barriers but was later successfully restarted on letermovir. One patient was unable to tolerate letermovir due to symptoms of headache and myalgias. Two patients developed low-level non-clinically significant CMV viremia and were switched back to valacyclovir. All patients had tacrolimus dosages reduced at time of letermovir initiation to minimize the risk of supratherapeutic tacrolimus concentration. One patient required hospitalization due to symptomatic tacrolimus toxicity. For HT recipients who cannot tolerate valganciclovir, letermovir presents an alternative for CMV prophylaxis. Close monitoring for breakthrough CMV and calcineurin inhibitor levels is necessary. Larger studies are required to further delineate its use and help provide further evidence of its safety and efficacy.