Outcomes for patients with EBV-positive PTLD post-allogeneic HCT after failure of rituximab-containing therapy.

Epstein-Barr virus-positive (EBV+) post-transplant lymphoproliferative disease (PTLD) is an ultra-rare and aggressive condition that may occur following allogeneic hematopoietic cell transplant (HCT) due to immunosuppression. Approximately half of EBV+ PTLD cases are relapsed or refractory (R/R) to initial rituximab-containing therapy. There are limited treatment options and no standard of care for patients with R/R EBV+ PTLD, and little is known about their treatment history and outcomes. We performed a multinational, multicenter, retrospective chart review of patients with R/R EBV+ PTLD following HCT to describe patients' demographic and disease characteristics, treatment history, and overall survival (OS) from rituximab failure. Among 81 patients who received initial treatment with rituximab as monotherapy (84.0%) or in combination with chemotherapy (16.0%), median time from HCT to PTLD diagnosis was 3.0 months and median OS was 0.7 months. Thirty-six patients received a subsequent line of treatment. The most frequent causes of death were PTLD (56.8%), graft-versus-host disease (13.5%) and treatment-related mortality (10.8%). In multivariate analysis, early PTLD onset and lack of response to initial treatment were associated with mortality. This real-world study demonstrates that the prognosis of patients with R/R EBV+ PTLD following HCT remains poor, highlighting the urgent unmet medical need in this population.

Impact of Baseline and Week 2 and Week 4 Posttransplant CMV Cell-Mediated Immunity on Risk of CMV Infections and Mortality in Recipients of Allogeneic Hematopoietic Cell Transplant.

Background: Cytomegalovirus (CMV) infection is a common opportunistic infection after allogeneic hematopoietic cell transplant (alloHCT). We explored whether a change in CMV cell-mediated immunity during the first month after transplant predicts the risk of development of CMV infection and all-cause mortality. Methods: This follow-up analysis is based on data from the REACT study, a multicenter prospective observational study of recipients of alloHCT who were CMV-seropositive. Production of interferon γ following ex vivo stimulation with CMV antigens IE1 (immediate early 1) and pp65 (phosphoprotein 65) was assessed by CMV ELISPOT assay at baseline and 2 and 4 weeks after transplant. Clinically significant CMV infection (CS-CMVi) was defined as CMV viremia and/or disease necessitating antiviral therapy. We evaluated the impact of CMV CMI changes on the risk of CS-CMVi and post transplant mortality. Results: The analysis included 226 recipients of alloHCT with CMV cell-mediated immunity data at baseline and 2 and/or 4 weeks after transplant. CS-CMVi occurred in 64 patients (28%). On Cox regression analyses, independent predictors of CS-CMVi included a negative Δ change from baseline to week 2 of pp65 spot counts (hazard ratio, 3.65 [95% CI, 1.65-8.04]; P = .001) to week 4 of IE1 spot counts (hazard ratio, 2.79 [95% CI, 1.46-5.35]; P = .002), anti-thymocyte globulin conditioning regimen, type of transplant, female sex, and corticosteroid use. Kaplan-Meir analysis showed a significant association of a negative IE1 change from baseline to week 4 and increased all-cause mortality after transplant (log rank test = 0.041). Conclusions: A decrease in CMV-specific T-cell responses during the first month after transplant may predict CS-CMVi and is associated with all-cause mortality in recipients of alloHCT.

Immunogenicity and Safety of Booster SARS-CoV-2 mRNA Vaccine Dose in Allogeneic Hematopoietic Stem Cell Transplantation Recipients.

Allogeneic hematopoietic stem cell transplantation (HSCT) recipients are susceptible to severe outcomes of Coronavirus disease 2019 (COVID-19). Most guidelines recommend a fourth dose (ie, booster) of COVID-19 vaccine to reduce the infection risk, and observational studies are needed to determine the immunogenicity and safety of the booster dose in this population. The primary outcome was to determine the quantitative anti-receptor-binding domain (RBD) antibody titers after the fourth dose of the COVID-19 vaccine. The secondary outcomes included adverse effects and all-cause mortality. This single-group prospective cohort included allogeneic HSCT recipients age ≥18 years who received their fourth dose of COVID-19 mRNA vaccine between December 15, 2021, and August 2, 2022. We excluded patients with a history of COVID-19 diagnosis and those who received i.v. Ig within 21 days of antibody testing or rituximab within 6 months before study entry. We used regression models to determine the contributing factors significantly associated with post-fourth dose anti-RBD titer. Sixty-seven patients (median age, 59.5 years; IQR, 53.5 to 65.5 years; 33 males [61%]) received the fourth dose of vaccine, and 54 were included in the anti-RBD titer analysis. The median anti-RBD titers at 4 to 6 weeks after the third and fourth doses differed significantly (13,350 U/mL [IQR, 2618 to 34,740 U/mL] and 44,500 U/mL [IQR, 11,163 to 84,330 U/mL], respectively; P < .0001). In univariate analysis, the post-third dose anti-RBD titer (ß = .70; 95% CI, .54 to .87; P < .001) and treatment with mycophenolate compounds (ß = -1.05; 95% CI, -1.97 to -1.12; P = .03) significantly predicted the antibody response to the fourth dose. In multivariate analysis, the inverse association between treatment with mycophenolate compounds and the post-fourth dose anti-RBD antibody titer was not significant (ß = -.57; 95% CI, -1.32 to .19; P = .14), whereas the significant association between the anti-RBD titers following the third and fourth doses did not change considerably (ß = .66; 95% CI, .47 to .86; P < .001). The most frequent adverse event was vaccination site soreness (44%), followed by fatigue (16%), myalgia (4%), and headache (2%). No recipient experienced new or worsened preexisting graft-versus-host disease within 40 days of vaccination, and no patient died. Six patients (11%) developed breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection not associated with hospitalization or severe outcomes. The fourth dose of the COVID-19 vaccine appears to be highly immunogenic and safe in allogeneic HSCT recipients. Further studies are needed to determine the neutralizing antibody titers against SARS-CoV-2 subvariants and the effectiveness and immunogenicity of bivalent vaccines in allogeneic HSCT recipients.

Safety and Immunogenicity After a Three-Dose SARS-CoV-2 Vaccine Schedule in Allogeneic Stem Cell Transplant Recipients.

In allogeneic stem cell transplant (Allo-SCT) recipients, the cell-mediated and humoral immunogenicity of the 3-dose SARS-CoV-2 vaccination schedule has not been investigated in prospective studies. In a prospective cohort, we recruited 122 Allo-SCT recipients since August 2021, when Ontario began offering a 3-dose vaccine schedule for Allo-SCT recipients. We determined humoral and cell-mediated immunity and adverse effects of the 3-dose SARS-COV-2 vaccination schedule in Allo-SCT recipients. In immunogenicity analysis (n = 95), the median (interquartile range [IQR]) antibody titer against the receptor-binding domain (RBD) of the spike (S) protein after the third dose (10,358.0 U/mL [IQR = 673.9-31,753.0]) was significantly higher than that after the first (10.2 U/mL [IQR = 0.6-37.0]) and the second doses (125.6 U/mL [IQR = 2.8-1251.0]) (P < .0001). The haploidentical donor status was an independent risk factor (adjusted odds ratio = 7.67, 95% confidence interval [CI], 1.86-31.60) for suboptimal antibody response (anti-RBD < 100 U/mL). S-specific CD4+ and CD8+ T-cell responses were measured in a subset of Allo-SCT recipients (n = 20) by flow cytometry. Most developed antigen-specific CD4+ (55%-80%) and CD8+ T-cells (80%) after 2 doses of vaccine. Frequencies of CD4+ polyfunctional (P = .020) and IL-2 monofunctional (P = .013) T-cells significantly increased after the third dose. Twenty-three episodes (23/301 doses [7.6%]) of new-onset or worsening pre-existing graft-versus-host disease (GVHD) occurred, including 4 episodes after the third dose. We observed 4 relapses (3.27%). Seven patients developed SARS-CoV-2 infection despite vaccination, although none required hospitalization. In conclusion, the 3-dose SARS-CoV-2 vaccine schedule provided immunity associated with a low risk of GVHD and other adverse effects. This prospective cohort showed that the third dose of SARS-CoV-2 vaccine in allogeneic stem cell transplant recipients promoted better humoral and cellar immune responses than after the initial series without increasing the risk of GVHD or severe adverse effects.

Maribavir for Refractory Cytomegalovirus Infections With or Without Resistance Post-Transplant: Results From a Phase 3 Randomized Clinical Trial.

BACKGROUND: Therapies for refractory cytomegalovirus infections (with or without resistance [R/R]) in transplant recipients are limited by toxicities. Maribavir has multimodal anti-cytomegalovirus activity through the inhibition of UL97 protein kinase. METHODS: In this phase 3, open-label study, hematopoietic-cell and solid-organ transplant recipients with R/R cytomegalovirus were randomized 2:1 to maribavir 400 mg twice daily or investigator-assigned therapy (IAT; valganciclovir/ganciclovir, foscarnet, or cidofovir) for 8 weeks, with 12 weeks of follow-up. The primary endpoint was confirmed cytomegalovirus clearance at end of week 8. The key secondary endpoint was achievement of cytomegalovirus clearance and symptom control at end of week 8, maintained through week 16. RESULTS: 352 patients were randomized (235 maribavir; 117 IAT). Significantly more patients in the maribavir versus IAT group achieved the primary endpoint (55.7% vs 23.9%; adjusted difference [95% confidence interval (CI)]: 32.8% [22.80-42.74]; P < .001) and key secondary endpoint (18.7% vs 10.3%; adjusted difference [95% CI]: 9.5% [2.02-16.88]; P = .01). Rates of treatment-emergent adverse events (TEAEs) were similar between groups (maribavir, 97.4%; IAT, 91.4%). Maribavir was associated with less acute kidney injury versus foscarnet (8.5% vs 21.3%) and neutropenia versus valganciclovir/ganciclovir (9.4% vs 33.9%). Fewer patients discontinued treatment due to TEAEs with maribavir (13.2%) than IAT (31.9%). One patient per group had fatal treatment-related TEAEs. CONCLUSIONS: Maribavir was superior to IAT for cytomegalovirus viremia clearance and viremia clearance plus symptom control maintained post-therapy in transplant recipients with R/R cytomegalovirus. Maribavir had fewer treatment discontinuations due to TEAEs than IAT. Clinical Trials Registration. NCT02931539 (SOLSTICE).

Evaluating the Role of STAT3 in CD4+ T Cells in Susceptibility to Invasive Aspergillosis.

We aimed to determine whether T cell-specific STAT3 deletion influences the immune response to Aspergillus in the immunosuppressed context in CD4 Stat3-/- mice. Immunosuppressed and nonimmunosuppressed CD4 Stat3-/- mice and littermate Stat3flox/flox (Stat3fl/fl) mice were infected with Aspergillus fumigatus in an aerosol chamber, and the weight, activity, appearance, and respiratory rate of the mice were monitored daily for 21 days to evaluate their survival. Aspergillus infection was confirmed by lung fungal culture counts, histology, and a galactomannan test. Cytokines were measured at 3 days postinfection in bronchoalveolar lavage (BAL) fluid and serum. Immunosuppressed CD4 Stat3-/- mice began succumbing to infection by day 4, and by day 7, only 30% of mice survived. Immunosuppressed Stat3fl/fl mice started to succumb to the disease on day 5, and 40% of mice remained by day 7. The nonimmunosuppressed control Stat3fl/fl and CD4 Stat3-/- mice maintained their weight over the study period, without any evidence of infection by A. fumigatus by histology. In the BAL fluid, tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interferon gamma (IFN-γ), IL-17A, and IL-22 levels were elevated in Stat3fl/fl immunosuppressed mice compared to immunosuppressed CD4 Stat3-/- mice at 3 days postinfection. STAT3 in CD4+ T cells modulates the production of cytokines in the IL-17 pathway in immunosuppressed mice. However, it has no meaningful effect on the clearance of Aspergillus or the concomitant increase in susceptibility to Aspergillus infection.

Evaluation of Recombinant Herpes Zoster Vaccine for Primary Immunization of Varicella-seronegative Transplant Recipients.

BACKGROUND: Immunization of varicella-zoster virus (VZV)-seronegative solid organ transplant (SOT) patients using the live-attenuated varicella vaccine is generally contraindicated, leaving no widely applicable immunization option. The recombinant subunit herpes zoster vaccine (RZV) is indicated for VZV-seropositive persons to prevent shingles but could potentially also protect VZV-seronegative persons against varicella. We performed a safety and immunogenicity evaluation of RZV in VZV-seronegative SOT recipients as an option for protection. METHODS: VZV-seronegative adult SOT patients with no history of varicella/shingles vaccine or disease were given 2 doses of RZV vaccine 2-6 mo apart. Blood was drawn prevaccination (V1), before the second dose (V2), and 4 wk after the second dose (V3). Humoral immunity (anti-glycoprotein E) and cell-mediated immunity were evaluated, with polyfunctional cells defined as cells producing ≥2 cytokines. RESULTS: Among 31 eligible VZV-seronegative SOT patients screened, 23 were enrolled. Median age was 38 y and median time since transplant procedure was 3.8 y. The most frequent transplant types were liver (35%) and lung (30%). Median anti-glycoprotein E levels significantly increased from V1 to V3 (P = 0.001) and V2 to V3 (P < 0.001), even though only 55% had a positive seroresponse. Median polyfunctional CD4 T-cell counts increased from V1 to V2 (54/106 versus 104/106 cells; P = 0.041) and from V2 to V3 (380/106; P = 0.002). Most adverse events were mild with no rejection episodes. CONCLUSIONS: RZV was safe and elicited significant humoral and cellular responses in VZV-seronegative SOT patients and has the potential to be considered as a preventive strategy against primary varicella.

Long-lasting cluster of nosocomial pneumonia with a single Pneumocystis jirovecii genotype involving different organ allograft recipients.

Pneumocystis pneumonia (PCP) outbreaks may occur in solid organ transplant (SOT) patients. Transmissibility of Pneumocystis jirovecii among SOT and non-SOT patients has not been investigated. Ten SOT (ie, 4 heart, 4 kidney, 2 liver allograft recipients) and 11 non-SOT (ie, 7 HIV-infected, 3 hematologic malignancies, and 1 stem cell transplant) patients with PCP were admitted to London Health Sciences Center (LHSC) from October 2014 to August 2016. We investigated the course of illness and outcome of PCP in SOT and non-SOT patients. Post-transplant PCP was frequently an acute-onset disease (90% vs. 18.2%, p = .01) requiring ICU admission (70% vs. 20%, p = .03) and hemodialysis (60% vs. 0, p = .003). Mortality was more frequent in SOT patients (40% vs. 18.1%, p = .36). Multilocus sequence typing (MLST) demonstrated circulation of a single genotype of P. jirovecii among SOT patients. However, 8 different genotypes were detected from non-SOT patients. Reinstitution of prophylaxis successfully controlled post-transplant cluster until end of observation period in October 2019. No transmission was detected from non-SOT patients to SOT recipients. Detection of a single P. jirovecii genotype from all SOT recipients highlights the likelihood of nosocomial transmission. No source control method is recommended by current guidelines. Improvement of preventive strategies is required.

Ex-vivo delivery of monoclonal antibody (Rituximab) to treat human donor lungs prior to transplantation.

BACKGROUND: Ex-vivo lung perfusion (EVLP) is an innovative platform for assessing donor lungs in the pre-transplant window. In this study, we demonstrate an extension of its utility by administering the anti-CD20 monoclonal antibody, Rituximab, during EVLP. We hypothesized that this would lead to targeted depletion of allograft B-cells which may provide significant clinical benefit, including the potential to reduce latent Epstein-Barr virus (EBV) and decrease the incidence of post-transplant lymphoproliferative malignancies. METHODS: Twenty human donor lungs rejected for transplantation were placed on EVLP with (n = 10) or without (n = 10) 500 mg of Rituximab. Safety parameters such as lung physiology and inflammatory cytokines were evaluated. We measured the delivery efficacy through flow cytometry, immunohistochemistry and ELISA. An in-vitro culture assay, in the presence of complement, was further conducted to monitor whether B-cell depletion would occur in Rituximab-perfused samples. FINDINGS: Rituximab was successfully delivered to human lungs during EVLP as evidenced by flow cytometric binding assays where lung tissue and lymph node biopsies demonstrated occupied CD20 epitopes after perfusion with the antibody. Lymph nodes from Rituximab perfusions demonstrated a 10.9 fold-reduction in CD20+ staining compared to controls (p = 0.0003). In lung tissue, Rituximab resulted in an 8.75 fold-reduction in CD20+ staining relative to controls (p = 0.0002). This decrease in CD20+ binding illustrates the successful delivery and occupation of epitopes after perfusion with the Rituximab. No apparent safety concerns were seen as exhibited by markers associated with acute cell injury (e.g., proinflammatory cytokines), cell death (e.g., TUNEL staining), or pulmonary physiology. In a post-perfusion tissue culture model, the addition of complement (human serum) resulted in evidence of B-cell depletion consistent with what would be expected with posttransplant activation of bound Rituximab. INTERPRETATION: Our experiments illustrate the potential of EVLP as a platform to deliver monoclonal antibody therapies to treat donor lungs pretransplant with the goal of eliminating a latent virus responsible for considerable morbidity after lung transplantation. FUNDING: Supported by the University Health Network Transplant Center.

High incidence but low mortality of EBV-reactivation and PTLD after alloHCT using ATG and PTCy for GVHD prophylaxis.

We explore risk factors and impacts of post-transplant EBV-Reactivation (EBV-R) and PTLD in 270 patients that underwent RIC alloHCT using ATG-PTCy and cyclosporine for GVHD prophylaxis. Twenty-five (12%) patients had probable (n = 7) or proven (n = 18) PTLD. Patients were managed with reduction of immunosuppression and 22 with weekly rituximab (375 mg/m2 IV). ORR was 84%; 8 (32%) recipients died, and one-year OS and NRM of patients with PTLD was 59.7% and 37%, respectively. One hundred seventy-two (63.7%) recipients had EBV-R. One-year OS and RFS of patients with EBV-R were 68.2% and 60.6%, and of EBV-Negative patients were 62.1% and 50.1%, respectively. High incidence but low mortality of EBV-R and PTLD was documented. EBV-R induced a protective effect on RFS in multivariable analysis (HR 0.91, p = .011). Therefore, EBV-R may have a protective effect on RFS in this setting. Further research is necessary to evaluate the interplay of EBV-R, immune reconstitution, and post-transplant outcomes.

Short-course, direct-acting antivirals and ezetimibe to prevent HCV infection in recipients of organs from HCV-infected donors: a phase 3, single-centre, open-label study.

BACKGROUND: An increasing percentage of potential organ donors are infected with hepatitis C virus (HCV). After transplantation from an infected donor, establishment of HCV infection in uninfected recipients is near-universal, with the requirement for post-transplant antiviral treatment. The aim of this study was to determine if antiviral drugs combined with an HCV entry blocker given before and for 7 days after transplant would be safe and reduce the likelihood of HCV infection in recipients of organs from HCV-infected donors. METHODS: HCV-uninfected organ recipients without pre-existing liver disease were treated with ezetimibe (10 mg; an HCV entry inhibitor) and glecaprevir-pibrentasvir (300 mg/120 mg) before and after transplantation from HCV-infected donors aged younger than 70 years without co-infection with HIV, hepatitis B virus, or human T-cell leukaemia virus 1 or 2. Recipients received a single dose 6-12 h before transplant and once a day for 7 days after surgery (eight doses in total). HCV RNA was assessed once a day for 14 days and then once a week until 12 weeks post-transplant. The primary endpoint was prevention of chronic HCV infection, as evidenced by undetectable serum HCV RNA at 12 weeks after transplant, and assessed in the intention-to-treat population. Safety monitoring was according to routine post-transplant practice. 12-week data are reported for the first 30 patients. The trial is registered on ClinicalTrials.gov, NCT04017338. The trial is closed to recruitment but follow-up is ongoing. FINDINGS: 30 patients (23 men and seven women; median age 61 years (IQR 48-66) received transplants (13 lung, ten kidney, six heart, and one kidney-pancreas) from 18 HCV-infected donors. The median donor viral load was 5·11 log10IU/mL (IQR 4·55-5·63) and at least three HCV genotypes were represented (nine [50%] donors with genotype 1, two [11%] with genotype 2, five [28%] with genotype 3, and two [11%] with unknown genotype). All 30 (100%) transplant recipients met the primary endpoint of undetectable HCV RNA at 12 weeks post-transplant, and were HCV RNA-negative at last follow-up (median 36 weeks post-transplant [IQR 25-47]). Low-level viraemia was transiently detectable in 21 (67%) of 30 recipients in the early post-transplant period but not after day 14. Treatment was well tolerated with no dose reductions or treatment discontinuations; 32 serious adverse events occurred in 20 (67%) recipients, with one grade 3 elevation in alanine aminotransferase (ALT) possibly related to treatment. Non-serious transient elevations in ALT and creatine kinase during the study dosing period resolved with treatment completion. Among the serious adverse events were two recipient deaths due to causes unrelated to study drug treatment (sepsis at 49 days and subarachnoid haemorrhage at 109 days post-transplant), with neither patient ever being viraemic for HCV. INTERPRETATION: Ezetimibe combined with glecaprevir-pibrentasvir given one dose before and for 7 days after transplant prevented the establishment of chronic HCV infection in recipients of different organs from HCV-infected donors. This study shows that an ultra-short course of direct-acting antivirals and ezetimibe can prevent the establishment of chronic HCV infection in the recipient, alleviating many of the concerns with transplanting organs from HCV-infected donors. FUNDING: Canadian Institutes of Health Research; the Organ Transplant Program, University Health Network.

KDIGO Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation.

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation is intended to assist health care professionals worldwide who evaluate and manage potential candidates for deceased or living donor kidney transplantation. This guideline addresses general candidacy issues such as access to transplantation, patient demographic and health status factors, and immunological and psychosocial assessment. The roles of various risk factors and comorbid conditions governing an individual's suitability for transplantation such as adherence, tobacco use, diabetes, obesity, perioperative issues, causes of kidney failure, infections, malignancy, pulmonary disease, cardiac and peripheral arterial disease, neurologic disease, gastrointestinal and liver disease, hematologic disease, and bone and mineral disorder are also addressed. This guideline provides recommendations for evaluation of individual aspects of a candidate's profile such that each risk factor and comorbidity are considered separately. The goal is to assist the clinical team to assimilate all data relevant to an individual, consider this within their local health context, and make an overall judgment on candidacy for transplantation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Guideline recommendations are primarily based on systematic reviews of relevant studies and our assessment of the quality of that evidence, and the strengths of recommendations are provided. Limitations of the evidence are discussed with differences from previous guidelines noted and suggestions for future research are also provided.

Summary of the Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation.

The 2020 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline on the Evaluation and Management of Candidates for Kidney Transplantation is intended to assist health care professionals worldwide who evaluate and manage potential candidates for deceased or living donor kidney transplantation. This guideline addresses general candidacy issues such as access to transplantation, patient demographic and health status factors, immunological and psychosocial assessment. The roles of various risk factors and comorbid conditions governing an individual's suitability for transplantation such as adherence, tobacco use, diabetes, obesity, perioperative issues, causes of kidney failure, infections, malignancy, pulmonary disease, cardiac and peripheral arterial disease, neurologic disease, gastrointestinal and liver disease, hematologic disease, and bone and mineral disorder are also addressed. This guideline provides recommendations for evaluation of individual aspects of a candidate's profile such that each risk factor and comorbidity are considered separately. The goal is to assist the clinical team to assimilate all data relevant to an individual, consider this within their local health context, and make an overall judgment on candidacy for transplantation. The guideline development process followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. Guideline recommendations are primarily based on systematic reviews of relevant studies and our assessment of the quality of that evidence. The strengths of recommendations are provided in the full report. Limitations of the evidence are discussed with differences from previous guidelines noted and suggestions for future research are also provided.

Cytomegalovirus (CMV) Cell-Mediated Immunity and CMV Infection After Allogeneic Hematopoietic Cell Transplantation: The REACT Study.

BACKGROUND: Cytomegalovirus (CMV) infection remains an important cause of morbidity and mortality in allogeneic hematopoietic cell transplant (allo-HCT) recipients. CMV cell-mediated immunity (CMV-CMI) as determined by a peptide-based enzyme-linked immunospot (ELISPOT) CMV assay may identify patients at risk for clinically significant CMV infection (CS-CMVi). METHODS: The CS-CMVi was defined as CMV viremia and/or disease necessitating antiviral therapy. CMV-CMI was characterized as high when the intermediate-early 1 (IE-1) antigen spot counts (SPCs) were >100 (cutoff 1) or when the IE-1 and phosphoprotein 65 antigen SPCs were both >100 SPCs per 250 000 cells (cutoff 2), and a low CMV-CMI when SPCs were below these thresholds. In this prospective multicenter study, we evaluated CMV-CMI every 2 weeks from the pretransplant period until 6 months posttransplantation in 241 allo-HCT recipients with positive CMV serostatus. The primary endpoint was CS-CMVi occurring within 2 weeks of the last measurement of CMV-CMI. RESULTS: CS-CMVi occurred in 70 allo-HCT recipients (29%). CMV-CMI was low in patients who experienced CS-CMVi (94%), whereas those who had a high CMV-CMI were less likely to have CS-CMVi (P < .0001). Patients with CS-CMVi had higher all-cause mortality (P = .007), especially those with low CMV-CMI (P = .035). On multivariable analysis, CMV-CMI, sex, race, antithymocyte globulin, and steroid use were independent predictors of CS-CMVi, and the time from transplant to engraftment was the only predictor of mortality. CONCLUSIONS: Measurement of CMV-CMI using a novel ELISPOT assay would be useful clinically to monitor allo-HCT recipients and distinguish between those at risk of developing CS-CMVi and requiring antiviral prophylaxis or therapy and those who are protected.

Letermovir as Salvage Therapy for Cytomegalovirus Infection in Transplant Recipients.

BACKGROUND: Letermovir, a new viral terminase complex inhibitor, has been approved for the prevention of cytomegalovirus (CMV) infection in hematopoietic stem cell transplant patients. However, data on the efficacy and safety of letermovir for the treatment of CMV infection in transplant recipients remain scarce. METHODS: We performed a single-center retrospective study of stem cell and organ transplant recipients who received letermovir for the treatment of CMV infection from November 2017 to October 2018. RESULTS: Six patients were included, and 5 were evaluable. All received letermovir in the context of a refractory or resistant CMV infection including asymptomatic CMV viremia (n = 3), CMV syndrome (n = 1), and CMV pneumonitis and colitis (n = 1). The 3 asymptomatic patients experienced a decrease of the viral load (VL) to <200 IU/mL after letermovir therapy. One patient displayed a partial VL response (2-log of VL reduction) but a good clinical response, and one who received a suboptimal dose of letermovir experienced an increase of viremia. There were no treatment-related adverse effects. CONCLUSIONS: We demonstrate mixed efficacy in patients with refractory CMV infection suggesting that letermovir may be a useful therapeutic adjunct, potentially in combination with other antivirals.

Innate and Adaptive Immune Correlates of Chronic and Self-limiting EBV DNAemia in Solid-organ Transplant Recipients.

BACKGROUND: Epstein-Barr virus (EBV) DNAemia is a major risk factor for posttransplant lymphoproliferative disorder; however, immune correlates of EBV DNAemia in the transplant setting are limited. METHODS: Peripheral blood mononuclear cells were collected from 30 transplant recipients with self-limiting EBV DNAemia (SLD; n = 11) or chronic EBV DNAemia (CD; n = 19) at enrollment and 4-8 weeks later. Mass cytometry was used to characterize innate and T-cell immune correlates of EBV DNAemia. Furthermore, flow cytometry was used to measure the frequency of EBV-specific T-cell responses between groups following stimulation with an EBV-infected cell lysate. RESULTS: Unsupervised analysis of the innate compartment (CD3CD19 cells) identified 5 CD11c clusters at higher abundance in the SLD group (false discovery rate ≤ 1%). These clusters expressed CD11b, CD45RO, CD14, CD123, CD127, and CD38, among others. Unsupervised profiling of the T-cell compartment (CD3CD19) revealed 2 CD4 T-cell clusters at higher frequency among those with SLD (false discovery rate ≤ 1%), which expressed CD45RA, CCR7, CD27, CD28, and CD40L-suggestive of a naive T cell (TN). Manual biaxial gating confirmed increased frequencies of conventional dendritic cells (3.1% versus 2.1%; P = 0.023) and CD4 TN (4.4% versus 1.9%; P = 0.018) among those with SLD. Last, frequencies of interferon-γ-producing EBV-specific CD4 T cells were significantly lower in the CD group relative to those with SLD (4243 versus 250 cells/10 cells; P = 0.015). CONCLUSIONS: CD is associated with a reduction of CD11c cells, CD4 TN, and interferon-γ-producing EBV-specific CD4 T cells, suggesting an interplay between innate and adaptive immune compartments may be important for regulating EBV DNAemia.

Immunogenicity and Safety of the Adjuvanted Recombinant Zoster Vaccine in Chronically Immunosuppressed Adults Following Renal Transplant: A Phase 3, Randomized Clinical Trial.

BACKGROUND: The incidence of herpes zoster is up to 9 times higher in immunosuppressed solid organ transplant recipients than in the general population. We investigated the immunogenicity and safety of an adjuvanted recombinant zoster vaccine (RZV) in renal transplant (RT) recipients ≥18 years of age receiving daily immunosuppressive therapy. METHODS: In this phase 3, randomized (1:1), observer-blind, multicenter trial, RT recipients were enrolled and received 2 doses of RZV or placebo 1-2 months (M) apart 4-18M posttransplant. Anti-glycoprotein E (gE) antibody concentrations, gE-specific CD4 T-cell frequencies, and vaccine response rates were assessed at 1M post-dose 1, and 1M and 12M post-dose 2. Solicited and unsolicited adverse events (AEs) were recorded for 7 and 30 days after each dose, respectively. Solicited general symptoms and unsolicited AEs were also collected 7 days before first vaccination. Serious AEs (including biopsy-proven allograft rejections) and potential immune-mediated diseases (pIMDs) were recorded up to 12M post-dose 2. RESULTS: Two hundred sixty-four participants (RZV: 132; placebo: 132) were enrolled between March 2014 and April 2017. gE-specific humoral and cell-mediated immune responses were higher in RZV than placebo recipients across postvaccination time points and persisted above prevaccination baseline 12M post-dose 2. Local AEs were reported more frequently by RZV than placebo recipients. Overall occurrences of renal function changes, rejections, unsolicited AEs, serious AEs, and pIMDs were similar between groups. CONCLUSIONS: RZV was immunogenic in chronically immunosuppressed RT recipients. Immunogenicity persisted through 12M postvaccination. No safety concerns arose. CLINICAL TRIALS REGISTRATION: NCT02058589.

Vaccination for the post-kidney transplant population.

PURPOSE OF REVIEW: Kidney transplant recipients are at high risk of contracting infections, some of which are considered vaccine-preventable, because of their highly immunosuppressed state. In this vulnerable group of patients, infection can lead to poor outcomes including graft failure and death, thus vaccination in the posttransplant population is an important strategy in order to mitigate this risk. The present review is aimed at providing an update on recent advances with respect to vaccination strategies in kidney transplant recipients. RECENT FINDINGS: General principles behind vaccination in kidney transplantation have remained consistent over many years. More recently, efforts have been focused on developing newer strategies for vaccination against influenza and herpes zoster in organ transplant recipients. Newer data on the immunogenicity of vaccines directed against pneumococcal disease, human papillomavirus, and hepatitis B virus in kidney transplant recipients have become available and will also be discussed in the present review. SUMMARY: Kidney transplant recipients are highly-vulnerable to contracting serious infections by way of their immunosuppressed state and their dampened ability to mount an immunogenic response to vaccines. Thus, ongoing advances in vaccination strategies in this group of patients should be an important area of focus of future research in order to help promote healthier living and greater survival postkidney transplant.

Vaccination of solid organ transplant candidates and recipients: Guidelines from the American society of transplantation infectious diseases community of practice.

These updated guidelines of the AST IDCOP review vaccination of solid organ transplant candidates and recipients. General principles of vaccination as well as the use of specific vaccines in this population are discussed. Vaccination should be reviewed in the pre-transplant setting and appropriate vaccines updated. Both inactivated and live vaccines can be given pre-transplant. The timing of vaccination post-transplant should be taken into account. In the post-transplant setting, inactivated vaccines can be administered starting at 3 months post-transplant with the exception of influenza which can be given as early as one month. Inactivated vaccines can be safely administered post-transplant. There is accumulating data that live-attenuated vaccines can also be given to select post-transplant patients. Close contacts of transplant patients can receive most routine live vaccines. Specific vaccines including pneumococcal, influenza, hepatitis B, HPV, and meningococcal vaccines are discussed. Newer vaccines for seasonal influenza vaccine and herpes zoster are highlighted. Live-attenuated vaccines such as measles, mumps, rubella, and varicella are also discussed. Emerging data on live-attenuated vaccines post-transplant are highlighted.

A prospective multicenter observational study of cell-mediated immunity as a predictor for cytomegalovirus infection in kidney transplant recipients.

T cell immunity is essential for the control of cytomegalovirus (CMV) infection after transplantation. We evaluated a CMV-specific peptide-based enzyme-linked immunosorbent spot (ELISPOT) assay to determine whether assay results could predict subsequent CMV events. Adult kidney transplant recipients at 43 centers underwent ELISPOT testing to enumerate interferon gamma (IFN-γ) binding spot-forming units (sfu) after stimulation of cells with an overlapping peptide pool of CMV phosphoprotein 65 (pp65) and immediate early-1 (IE-1) protein at the end of antiviral prophylaxis (EOP) and various time points thereafter. The primary outcome was a CMV event in the first posttransplant year. In 583 kidney transplant recipients (260 seropositive donor [D+]/seronegative recipient [R-] and 277 R+), CMV events occurred in 44 of 368 eligible patients (11.8%) at a median of 227 days (range 92-360) posttransplant. A cutoff value of >40 sfu/2.5 × 105  cells for either IE-1 or pp65 was derived as a threshold for positivity, with a negative predictive value of >97% for CMV events. CMV events were significantly lower in assay positive vs assay negative patients (3.0% vs 19.5%, P < .0001 for pp65). Time to CMV event post-EOP was significantly greater in those with sfu >40 at EOP (P < .0001). In this large, multicenter trial of kidney transplant recipients, we show that an assessment of CMV-specific immunity using a novel ELISPOT assay is able to predict protection from CMV infection.