Resistant Cytomegalovirus Infection Research Articles

Novelties for the management of cytomegalovirus after kidney transplantation

Cytomegalovirus (CMV) infection is the main opportunistic infection observed after kidney transplantation. Despite the use of prevention strategies, CMV disease still occurs, especially in high-risk patients (donor seropositive/recipient seronegative). Patients may develop complicated CMV, i.e. recurrent, refractory or resistant CMV infection. CMV prevention relies on either universal prophylaxis or preemptive therapy. In high-risk patients, universal prophylaxis is usually preferred. Currently, valganciclovir is used in this setting. However, valganciclovir can be responsible for severe leucopenia and neutropenia. A novel anti-viral drug, letermovir, has been recently compared to valganciclovir. It was as efficient as valganciclovir to prevent CMV disease and induced less hematological side-effects. It is still not available in France in this indication. Recent studies suggest that immune monitoring by ELISPOT or Quantiferon can be useful to determine the duration of prophylaxis. Other studies suggest that prophylaxis may be skipped in CMV-seropositive kidney-transplant patients given mTOR inhibitors. Refractory CMV is defined by the lack of decrease of CMV DNAemia of at least 1 log10 at 2 weeks after effective treatment. In case of refractory CMV infection, drug resistant mutations should be looked for. Currently, maribavir is the gold standard therapy for refractory/resistant CMV. At 8 weeks therapy and 8 weeks later, it has been shown to be significantly more effective than other anti-viral drugs, i.e. high dose of ganciclovir, foscarnet or cidofovir. However, a high rate of relapse was observed after ceasing therapy. Hence, other therapeutic strategies should be evaluated in order to improve the sustained virological rate.

Consensus Definitions of Cytomegalovirus (CMV) Infection and Disease in Transplant Patients Including Resistant and Refractory CMV for Use in Clinical Trials: 2024 Update From the Transplant Associated Virus Infections Forum.

Cytomegalovirus (CMV) infection and disease are important causes of morbidity and mortality in transplant recipients. For the purpose of developing consistent reporting of CMV outcomes in clinical trials, definitions of CMV infection and disease were developed and most recently published in 2017. Since then, there have been major developments, including registration of new antiviral agents. Therefore, the Transplant Associated Virus Infections Forum, which consists of scientists, clinicians, regulators, and industry representatives, has produced an updated version of these definitions that incorporates recent knowledge with the aim of supporting clinical research and drug development. This also includes an update regarding the definition of resistant and refractory CMV infections previously published in 2019. As the field evolves, the need for updates of these definitions is clear, and collaborative efforts among clinicians, scientists, regulators, and industry representatives can provide a platform for this work.

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.

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 Tcells for management of resistant or refractory CMV infection in SOT recipients.

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.

Prevalence of cytomegalovirus antiviral drug resistance in transplant recipients

Cytomegalovirus (CMV) is a significant human pathogen, especially for immunocompromised patients, often treated with one or more antiviral drugs. Although the prevalence of resistance is low, the impact of drug resistant CMV infections on patient outcomes is high and genotypic testing is recommended when resistance is suspected. To assess the prevalence of CMV drug resistance mutations among samples submitted for genotypic testing, 2750 patient sample results were analyzed. Testing was performed by sequencing for ganciclovir (GCV), cidofovir (CDV), foscarnet (FOS), maribavir (MBV) and/or letermovir (LMV) resistance conferring mutations. Of the 2750 patient samples, 826 (30.04%) had resistance to one or more anti-CMV drug. Resistance mutations were most common in UL97, with 27.64% and 9.96% of samples having GCV and MBV mutations, respectively. Resistance mutations in UL54 were less common, with 6.11%, 5.98% and 1.76% of samples having GCV, CDV and FOS mutations, respectively. For LMV, resistance mutations in UL56 were present in 7.17% of samples, with mutations at codon 325 representing 80.95% of the observed LMV resistance mutations. Resistance to two drugs was identified in 215 samples and to 3 or more drugs in 35 samples. While a high prevalence of CMV resistance mutations was identified, this must be taken in the context of healthcare providers submitting samples from patients with suspected resistant CMV strains. For these patients, rapid monitoring for resistance allows treatment modifications based on objective results rather than empiric drug selection, which is particularly relevant given the presence of mutations conferring resistance to more than one drug.

733. Letermovir treatment for refractory or resistant cytomegalovirus infection or disease with concurrent organ dysfunction: an interim analysis of a Phase 2 open label study.

Abstract Background Cytomegalovirus (CMV) disease is associated with increased morbidity and mortality following solid organ and hematopoietic cell transplantation. Currently, standard of care CMV treatments often have significant myelosuppressive or renal toxicities. Given letermovir’s favorable safety profile when used prophylactically, it may be a safe and efficacious alternative agent for CMV treatment. Methods A proof-of-concept, open-label trial was conducted in patients who lacked effective therapeutic options or presented with baseline organ dysfunction. Participants were eligible for enrollment if they were ≥12 years old and had documented CMV infection refractory to treatment defined as failure to achieve >1 log reduction in CMV viral load (VL) (when VL > 500 IU/mL) or lack of clinical improvement for CMV end-organ disease after ≥14 days of standard CMV treatment. Alternatively, patients with severe myelosuppression and renal dysfunction at baseline or genotypic antiviral resistance were also eligible. Participants were excluded if their current CMV infection developed while receiving letermovir for CMV prophylaxis. Letermovir was administered daily (480 mg PO/IV) for up to 12 weeks, with optional additional 12 weeks of treatment for secondary prophylaxis if clinically indicated. Results Ten patients met eligibility criteria and were enrolled. Reasons for enrollment included ganciclovir resistance (1/10), refractory CMV infection (6/10), renal dysfunction (7/10), and myelosuppression (7/10). The median baseline CMV VL was 1272 IU/ml [interquartile range (IQR); 925, 2546]. Six patients completed the study, three died due to complications of primary disease, and one discontinued due to diarrhea. Five patients (50%) had documented CMV viremia clearance, with a median time to first unquantifiable/undetectable CMV VL of 13 days [IQR; 9,18] and a median treatment duration of 53 days [IQR; 15,84]. Infections and GI disorders were the most common adverse events (AE), none considered related to study drug. No unexpected AE were observed during letermovir treatment. Conclusion Letermovir may be a safe and tolerable alternative for patients with treatment refractory CMV infection or for patients with severe baseline myelosuppression and renal dysfunction. Disclosures Matthew Cheng, MD, AstraZeneca: Honoraria|Cidara Therapeutics: Grant/Research Support|Scynexis Inc.: Grant/Research Support Sandra Burchett, MD, MSc, merck: Grant/Research Support Sarah P. Hammond, MD, F2G: Advisor/Consultant|F2G: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|pfizer: Advisor/Consultant|Scynexis: Grant/Research Support Nicolas C. Issa, MD, AiCuris: Grant/Research Support|Merck: Grant/Research Support Francisco M. Marty, MD, SM, AlloVir: Advisor/Consultant|Amplyx: Advisor/Consultant|Amplyx: Grant/Research Support|Ansun: Grant/Research Support|Avir: Advisor/Consultant|Chimerix: Grant/Research Support|Cidara: Grant/Research Support|F2G: Advisor/Consultant|F2G: Grant/Research Support|Gilead: Grant/Research Support|Janssen: Advisor/Consultant|Kyorin: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Regeneron: Advisor/Consultant|Regeneron: Grant/Research Support|ReViral: Advisor/Consultant|Scynexis: Grant/Research Support|Symbio: Advisor/Consultant|Takeda: Grant/Research Support|United Medical: Advisor/Consultant|WHISCO: Grant/Research Support.

Adoptive Immunotherapy for Prophylaxis and Treatment of Cytomegalovirus Infection.

Cytomegalovirus (CMV), a member of the Herpesviridae family, is frequent among hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients in absence of antiviral prophylaxis, and is a major cause of morbidity and mortality in these vulnerable populations. Antivirals such ganciclovir, valganciclovir, and foscarnet are the backbone therapies, however drug toxicity and antiviral resistance may render these agents suboptimal in treatment. Newer therapies such as letermovir and maribavir have offered additional approaches for antiviral prophylaxis as well as treatment of drug resistant CMV infection, though may be limited by cost, drug intolerance, or toxicity. Adoptive immunotherapy, the transfer of viral specific T-cells (VSTs), offers a new approach in treatment of drug-resistant or refractory viral infections, with early clinical trials showing promise with respect to efficacy and safety. In this review, we will discuss some of the encouraging results and challenges of widespread adoption of VSTs in care of immunocompromised patients, with an emphasis on the clinical outcomes for treatment and prophylaxis of CMV infection among high-risk patient populations.

Antiviral resistance in human cytomegalovirus due to UL54 mutations without UL97 mutations

Background: The concurrent detection of human cytomegalovirus (CMV) with UL97 and UL54 mutations is crucial for prescribing adequate antiviral treatment when drug-resistant CMV infection is suspected. We investigated the frequency of resistance-conferring mutations among patients with persistent or recurrent CMV infection and further reviewed the subgroup with UL54 mutations without UL97 mutations. Methods: Patients with persistent or recurrent CMV infection after 4 weeks of treatment with ganciclovir or foscarnet were consecutively enrolled between November 2012 and May 2019. The direct sequencing of UL97 and UL54 was performed to detect resistance mutations in CMV. Results: A total of 101 sequencing datasets were obtained from 65 enrolled patients. CMV UL97 and UL54 mutations were detected in 15.4% (10/65) and 9% (6/65) of patients, respectively. The CMV retrieved from two patients (3%) had mutations in both genes. Four patients with CMV UL54 mutations alone had a history of haploidentical peripheral blood stem cell transplantation, and foscarnet was administered for over 4 weeks to these patients; 21.5% of patients had suspected resistant CMV infection with either UL97 or UL54 mutations. Conclusion: In this study, CMV UL54 mutations but not UL97 mutations were found in patients subjected to prolonged foscarnet administration for CMV disease.

467 - Assessment of Discontinuations and Anti-Cytomegalovirus Treatment Switching in Post-Transplant Refractory/ Resistant Cytomegalovirus Infections: Safety and Sensitivity Analyses from a Phase 3 Randomized Trial

467 - Assessment of Discontinuations and Anti-Cytomegalovirus Treatment Switching in Post-Transplant Refractory/ Resistant Cytomegalovirus Infections: Safety and Sensitivity Analyses from a Phase 3 Randomized Trial

Multifocal EBV-associated smooth muscle tumors in a patient with cytomegalovirus infection after liver transplantation: a case report from Shiraz, Iran

IntroductionImmunodeficient patients, including the recipients of solid organs, exhibit an increase in the incidence of neoplasms. Post-transplant smooth muscle tumor (PTSMT) is a distinct and infrequent entity of these groups of neoplasms. Epstein–Barr virus (EBV) is considered to be involved in the etiology of this neoplasm.Case reportA 28-year-old man who underwent liver transplantation presented with abdominal pain and diarrhea for several months. He had a history of resistant systemic cytomegalovirus (CMV) infection after transplantation. Radiologic evaluation and colonoscopy revealed multiple liver, spleen, lung, and colon lesions. Microscopic assessment of colon and liver lesions using IHC study were in favor of spindle cell proliferation with mild atypia and a mild increase in mitotic rate without any necrosis, with features of smooth muscle tumor. Considering the transplantation history, EBER chromogenic in situ hybridization (CISH) study on paraffin blocks was requested, which demonstrated EBV RNA in tumor cell nuclei, suggesting EBV-associated smooth muscle tumor. In addition, PCR for CMV on paraffin blocks was positive. PCR for EBV and CMV viremia were negative. The dosage of immunosuppressive agents was reduced, and currently, he is being followed, with slow expansion in the size of the lesions.ConclusionAlthough the incidence of post-transplant smooth muscle tumors (PTSMTs) is low, it should be remained in the differential diagnosis in post-transplantation patients, especially dealing with multifocal tumors. As strong stimulant for smooth muscle tumors, close follow-up and screening for EBV and CMV infection and early treatment at the time of diagnosis are recommended to avoid these virus-induced tumors.

Letermovir treatment for CMV infection in kidney and pancreas transplantation: A valuable option for complicated cases.

Cytomegalovirus (CMV) infection remains a major challenge in solid organ transplantation. Ganciclovir has changed the prognosis, but with the expense of possible viral resistance. New antiviral drugs, such as letermovir, have not been studied sufficiently in kidney and pancreas transplant recipients. We reviewed abdominal organ transplants recipients with CMV infection from the national transplant registry and identified patients treated with letermovir from electronic medical records. We report on letermovir treatment in one kidney and three simultaneous pancreas and kidney (SPK) transplant patients with refractory or ganciclovir-resistant CMV infection (UL54/ UL97 mutation). In SPK patients, persistent leukopenia undermined immunosuppressive and antiviral treatment, favoring life-threatening bacterial infections or ganciclovir resistance. All patients achieved viral clearance after letermovir monotherapy of 1.5-6 months. Letermovir was well tolerated and leukopenia resolved. Adjustments of calcineurin inhibitor doses were challenging. One acute rejection occurred because of under immunosuppression. After the end of treatment, recurrent low-grade CMV-DNAemia was common requiring reinitiating antiviral therapy to achieve viral clearance. To conclude, letermovir was a well-tolerated valuable option for the treatment of refractory or resistant CMV infection in kidney and pancreas transplantation.

21. Efficacy and Safety of Maribavir as a Rescue Treatment for Investigator Assigned Therapy in Transplant Recipients With Refractory or Resistant Cytomegalovirus Infections in the SOLSTICE Study: Phase 3 Trial Results

BackgroundRefractory or resistant (R/R) cytomegalovirus (CMV) infection after hematopoietic cell transplant (HCT) and solid organ transplant (SOT) cause serious, potentially fatal complications; therapeutic options are limited. In a Phase 3 study (NCT02931539), maribavir (MBV) was superior to investigator-assigned therapy (IAT; val/ganciclovir, foscarnet, cidofovir) for CMV clearance (Wk 8) and clearance plus symptom control (Wk 8 through Wk 16) in HCT/SOT recipients with R/R CMV infections. Here we present further study results on efficacy and safety of MBV in the rescue arm.MethodsPatients (pts) were stratified and randomized 2:1 to MBV (400 mg/bid) or IAT for 8-wk treatment then 12-wk follow-up. After minimum 3 wks’ treatment, pts in the IAT group meeting criteria (worsening/lack of improvement of CMV infection or failure to achieve viremia clearance plus IAT intolerance) could enter a MBV rescue arm (8-wk treatment, 12-wk follow-up). In the rescue arm, efficacy was evaluated by confirmed CMV viremia clearance (plasma CMV DNA < 137 IU/mL in 2 consecutive tests ≥ 5 days apart) at end of Wk 8 and confirmed clearance with symptom control at Wk 8 through Wk 16. Safety was assessed.ResultsA total of 352 pts were randomized (MBV: 235, IAT: 117, randomized set). Confirmed CMV viremia clearance at Wk 8 was achieved in 131 (55.7%) and 28 (23.9%) pts, respectively, in the randomized set. Having met criteria, 22 (18.8%) pts entered the MBV rescue arm; at entry, 6 (27.3%) pts had developed neutropenia and 9 (40.9%) had increased serum creatinine (Table 1). At Wk 8 of rescue therapy, 11 (50.0%) pts achieved confirmed CMV viremia clearance; 6 (27.3%) pts had CMV clearance with symptom control at Wk 8 maintained through Wk 16 (Table 2). All 22 pts reported treatment-emergent adverse events (TEAEs; Table 3); most common TEAEs of special interest were nausea, vomiting, and diarrhea (54.5%), and taste disturbance (50.0%). Neutropenia and acute kidney injury TEAEs were reported by 0 and 3 pts in the rescue arm, respectively.Table 1. Summary of patients from IAT-randomized group meeting criteria for entry into MBV rescue arm* Table 2. Patients achieving confirmed CMV viremia clearance at end of Wk 8 (end of treatment) or achieving confirmed CMV viremia clearance and symptom control at end of Wk 8 maintained through Wk 16 Table 3. Treatment-emergent adverse events during the on-rescue observation period ConclusionRescue arm data show MBV was efficacious for R/R CMV infection in HCT/SOT recipients inadequately responding to IAT with/without intolerance and had a similar safety profile to that reported for pts in the randomized MBV group.Disclosures Marcus Pereira, MD, Hologic (Scientific Research Study Investigator)Merck (Scientific Research Study Investigator)Takeda (Scientific Research Study Investigator, Advisor or Review Panel member) Carlos Cervera, MD, PhD, Avir Pharma (Consultant, Advisor or Review Panel member)Lilly (Consultant, Advisor or Review Panel member)Merck (Consultant, Advisor or Review Panel member, Research Grant or Support)Sunovion (Consultant, Advisor or Review Panel member)Takeda (Consultant, Advisor or Review Panel member)Veritas Pharma (Consultant, Advisor or Review Panel member) Camille Kotton, MD, Shire/Takeda (Advisor or Review Panel member) Camille Kotton, MD, UpToDate (Individual(s) Involved: Self): I write chapters on zoonoses for UpToDate., Independent Contractor Joseph Sasadeusz, MBBS, PhD, Abbvie (Grant/Research Support, Other Financial or Material Support, Consulting fee: speaker)Gilead (Other Financial or Material Support, Speaker)Merck (Grant/Research Support, Consulting fee: speaker)Takeda (Grant/Research Support) Jingyang Wu, MS, Shire Human Genetic Therapies, Inc., a Takeda company (Employee, Other Financial or Material Support, Holds stock/stock options) Martha Fournier, MD, Shire Human Genetic Therapies, Inc., a Takeda company (Employee, Other Financial or Material Support, Holds stock/stock options)Shire ViroPharma, a Takeda company (Other Financial or Material Support, This study was funded by Shire ViroPharma, a Takeda company)

Use of letermovir-valganciclovir combination as a step-down treatment after foscarnet for ganciclovir-resistant CMV infection in kidney transplant recipients.

BackgroundLetermovir (LTV) might be an alternative treatment to nephrotoxic foscarnet (FOS) in Ganciclovir (GCV) resistant cytomegalovirus (CMV) infection. However, its efficacy in controlling active CMV viremia is unclear, as it is only approved for CMV prophylaxis in hematopoietic stem‐cell transplantation.MethodsThis case series describes 14 kidney transplant recipients (KTR) with moderate‐level GCV resistant CMV infection, treated by different step‐down strategies after initial FOS therapy: (1) Observation without antiviral follow‐up or switch to valganciclovir (VGCV) (pre‐LTV era), and (2) Switch to LTV±VGCV (LTV era).ResultsOne patient died under FOS. Thirteen patients were followed under step‐down regimens. All but two patients had ongoing CMV viremia when stopping FOS. In pre‐LTV era, 5/9 (56%) experienced a CMV breakthrough > 10 000 IU/ml calling for another course of FOS, as compared to 1/4 (25%) in the LTV era. Addition of VGCV to LTV at low‐level viral breakthrough, addressing a possible developing resistance against LTV, prevented viral surge in two patients. In the pre‐LTV era, CMV‐related death or graft loss occurred in three of nine (33%), compared to no death or graft loss in the LTV era.ConclusionA step‐down strategy combining LTV+VGCV, might allow to safely stop FOS at ongoing low‐level viremia.

Incidence of refractory cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation.

Post-transplant cytomegalovirus (CMV) disease can be almost completely avoided by current infection control procedures. However, CMV reactivation occurs in more than half of patients, and some patients can develop clinically resistant CMV infections. Whether resistance is due to the host's immune status or a viral resistance mutation is challenging to confirm. Therefore, a prospective observational analysis of refractory CMV infection was conducted in 199 consecutive patients who received allogeneic hematopoietic stem cell transplantation at a single institution. Among them, 143 (72%) patients received anti-CMV drugs due to CMV reactivation, and only 17 (8.5%) exhibited refractory CMV infection. These patients had clinically refractory infection. However, viral genome analysis revealed that only one patient exhibited a mutation associated with the anti-CMV drug resistance. Clinical resistance was mainly correlated with host immune factors, and the incidence of resistance caused by gene mutations was low at the early stage after a transplantation.

CMV Infection in Hematopoietic Stem Cell Transplantation: Prevention and Treatment Strategies.

Purpose of ReviewCytomegalovirus (CMV) remains a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). New strategies and methods for prevention and management of CMV infection are urgently needed. We aim to review the new developments in diagnostics, prevention, and management strategies of CMV infection in Allo-HSCT recipients.Recent FindingsThe approval of the novel anti-CMV drug letermovir in 2017 has led to an increase in the use of antiviral prophylaxis as a preferred approach for prevention in many centers. Real-world studies have shown efficacy similar to the clinical trial. CMV-specific T cell-mediated immunity assays identify patients with immune reconstitution and predict disease progression. Phase 2 trials of maribavir have shown its efficacy as preemptive therapy and treatment of resistant and refractory CMV infections. Adoptive T cell therapy is an emerging option for treatment of refractory and resistant CMV. Of the different CMV vaccine trials, PepVax has shown promising results in a phase 1 trial.SummaryCMV cell-mediated immunity assays have potential to be used as an adjunctive test to develop individualized management plan by identifying the patients who develop immune reconstitution; however, further prospective interventional studies are needed. Maribavir and adoptive T cell therapy are promising new therapies for treatment of CMV infections. CMV vaccine trials for prevention are also under way.

1104. Risk Factors and Outcomes of Refractory and/or Resistant Cytomegalovirus (CMV) Infection after Allogeneic Hematopoietic Stem Cell Transplantation

BackgroundThe epidemiology of CMV end-organ disease (EOD) after Hematopoietic Cell Transplant (HCT) in the era of preemptive therapy (PET) is defined. In contrast, less data exists on refractory and/or resistant (R/R) CMV. We report on 1) the incidence; 2) risk factors and outcomes of R/R CMV by 1-year post HCT.MethodsRetrospective review of 167 CMV seropositive (R+) recipients of first marrow or peripheral blood HCT from 1/2014 - 12/2017 managed by PET. Refractory CMV was defined as failure to achieve >1 log10 decrease in CMV viral load (VL) and having VL >1,000 IU/mL after ≥14 day of PET. Resistant CMV required genotypic confirmation of resistance mutation(s) in UL54 and/or UL97 genes. End organ disease (EOD) was defined by standard criteria. Patients (pts) were followed through 1-year post HCT and were categorized in two mutually exclusive groups as R/R and no R/R. Demographics, clinical characteristics and outcomes were extracted from medical records and hospital databases. Univariable and multivariable logistic models were used to identify risk factors for R/R CMV.ResultsOf 167 PET recipients, 91 (54.5%) received ex vivo T cell depleted (TCD) HCT; 40 (24.0%) had mismatched donor; and 26 (15.6%) had multiple myeloma. 66/167 (39.5%) pts developed refractory CMV (6 pts also had resistant CMV). Time from HCT to CMV viremia was shorter in R/R group: median (IQR) 21.5 (17.2-27.8) days compared to no R/R group: 26 (19-32) days (p=0.031). Maximum VL was higher for R/R compared to no R/R: median (IQR) 9,118 (2,849-18,456) and 868 (474-1,908), respectively (p< 0.001). In multivariable model, risk factors for R/R included TCD HCT (p< 0.0001) and higher VL at PET initiation (p=0.0002). In contrast, CMV seropositive donor (p=0.035) was protective (Figure 1). CMV EOD developed in 28.2% of R/R and 16.2% of no R/R groups (p=0.085) (Figure 2). Overall survival at 1 year was 59.1% for R/R compared to 83.1% for no R/R group (p=0.00027) (Figure 3).Figure 1. Adjusted odds ratio (OR) and 95% confidence interval (CI) from multivariable model evaluating risk factors of refractory/resistant (R/R) CMV. Figure 2. Cumulative incidence curves of CMV end-organ disease (EOD) at 1-year post HCT Figure 3. Kaplan-Meier survival curves of overall survival (OS) at 1-year post HCT Conclusion1) Refractory and/or resistant CMV occurred in 39,5% of PET recipients. 2) T-cell depletion and higher CMV VL at PET initiation were risk factors for R/R CMV in multivariable models. 3) R/R CMV was associated with more EOD and worse overall survival.Disclosures Sergio Giralt, MD, Amgen (Advisor or Review Panel member, Research Grant or Support, Served an advisory board for Amgen, Actinuum, Celgene, Johnson & Johnson, JAZZ pharmaceutical, Takeda, Novartis, KITE, and Spectrum pharma and has received research support from Amgen, Actinuum, Celgene, Johnson & Johnson, and Miltenyi, Takeda.) Miguel-Angel Perales, MD, Abbvie (Other Financial or Material Support, Honoraria from Abbvie, Bellicum, Celgene, Bristol-Myers Squibb, Incyte, Merck, Novartis, Nektar Therapeutics, Omeros, and Takeda.)ASTCT (Other Financial or Material Support, Volunteer member of the Board of Directors of American Society for Transplantation and Cellular Therapy (ASTCT), Be The Match (National Marrow Donor Program, NMDP), and the CIBMTR Cellular Immunotherapy Data Resource (CIDR) Committee)Cidara Therapeutics (Advisor or Review Panel member, Other Financial or Material Support, Serve on DSMBs for Cidara Therapeutics, Servier and Medigene, and the scientific advisory boards of MolMed and NexImmune.)Kite/Gilead (Research Grant or Support, Other Financial or Material Support, Received research support for clinical trials from Incyte, Kite/Gilead and Miltenyi Biotec.) Genovefa Papanicolaou, MD, Chimerix (Research Grant or Support)Merck&Co (Research Grant or Support, Investigator and received funding and consulting fees from Merck, Chimerix, Shire and Astellas)

Emergence of letermovir resistance in solid organ transplant recipients with ganciclovir resistant cytomegalovirus infection: A case series and review of the literature.

Ganciclovir (GCV)-resistant cytomegalovirus (CMV) infection is a common problem among solid organ transplant (SOT) recipients without prior CMV immunity (CMV D+/R-). GCV-resistant CMV represents a particular challenge for CMV management. Letermovir is a recently licensed antiviral agent for primary CMV prophylaxis in allogenic hematopoietic stem cell transplant (HSCT) recipients. Given the favorable safety profile and its oral bioavailability letermovir may be considered a valuable off-label option for secondary prophylaxis of GCV-resistant CMV in SOT recipients. Here, we describe our experience with letermovir as secondary prophylaxis for GCV-resistant CMV in two renal transplant recipients and review the literature in regard of previously published cases. Letermovir resistance emerged after a few months of secondary prophylaxis in the two renal transplant recipients. In both cases, the previously described UL56 C325Y letermovir resistance mutation was detected. In vitro studies of letermovir suggest a relatively low genetic barrier to resistance. Therefore, caution is warranted when using letermovir as secondary prophylaxis for GCV-resistant CMV infection.

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

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. 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. 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.

Drug-resistant cytomegalovirus infection after lung transplantation: Incidence, characteristics, and clinical outcomes.

Cytomegalovirus (CMV) infection and development of CMV drug resistance can cause significant morbidity and mortality in patients with lung transplantation (LTX). We investigated the incidence of CMV drug resistance in adult patients with LTX and characterized this patient group and its outcomes. We analyzed a single-center retrospective cohort of 735 patients who received LTX between January 2012 and October 2017. We assessed the incidences of CMV UL97 and UL54 genotyping for clinically suspected drug resistance and confirmed drug resistance. Case-matched controls (3 control patients for each resistant patient) were identified by matching for CMV serological status, development of CMV disease or significant viremia (≥3,000 IU/ml), and transplantation date. The incidence of drug-resistant CMV was 1.98% (11/556) in donor and/or recipient CMV-positive patients and 4.7% (7/150) in donor-positive/recipient-negative patients. Altogether, 27 patients were tested for drug resistance, and 11 strains were resistant, 8 sensitive, and 8 inconclusive. No differences in immunosuppression, acute rejection, or pre-transplant sensitization were seen between case-matched groups. The peak CMV viral load and mean duration of viremia were significantly higher in the resistant group (324,000 vs. 117,000 mean IU/ml, p = 0.048 and 140 vs. 55 days, p < 0.001, respectively). The resistant group had increased overall mortality after onset of viremia compared with controls (3-year mortality 70% vs. 30%; p = 0.01). Drug-resistant CMV infection is rare, but patients who develop it have decreased overall survival. Peak CMV viral load and duration of CMV viremia were associated with development of resistant CMV infection.