Donor Serostatus Research Articles

Pre-Transplant Frequencies of FoxP3+CD25+ in CD3+CD8+ T Cells as Potential Predictors for CMV in CMV-Intermediate Risk Kidney Transplant Recipients.

Cytomegalovirus (CMV) infection detrimentally influences graft survival in kidney transplant recipients, with the risk primarily determined by recipient and donor serostatus. However, recipient CD8+ T cells play a crucial role in CMV control. The optimal preventive strategy (prophylaxis vs. pre-emptive treatment), particularly for seropositive (intermediate risk) recipients, remains uncertain. We investigated CD8+ T cell subpopulation dynamics and CMV occurrence (DNAemia ≥ 100IU/mL) in 65 kidney transplant recipients, collecting peripheral blood mononuclear cells before (T1) and 1year after transplantation (T2). Comparing the two timepoints, we found an increase in granulocyte, monocyte and CD3+CD8+ T cells numbers, while FoxP3+CD25+, LAG-3+ and PD-1+ frequencies were reduced at T2. CMV DNAemia occurred in 33 recipients (55.8%) during the first year. Intermediate risk patients were disproportionally affected by posttransplant CMV (N = 29/45, 64.4%). Intermediate risk recipients developing CMV after transplantation exhibited lower leukocyte, monocyte, and granulocyte counts and higher FoxP3+CD25+ frequencies in CD3+CD8+ T cells pre-transplantation compared to patients staying CMV negative. Pre-transplant FoxP3+CD25+ in CD3+CD8+ T cells had the best discriminatory potential for CMV infection prediction within the first year after transplantation (AUC: 0.746). The FoxP3+CD25+ CD3+CD8+ T cell subset may aid in selecting intermediate risk kidney transplant recipients for CMV prophylaxis.

#1569 Cytomegalovirus (CMV) infection in renal transplant patients managed with early pre-emptive treatment

Abstract Background and Aims Human Cytomegalovirus (CMV) can cause significant morbidity in transplant recipients. Primary CMV infection in CMV seronegative recipients (R−) and reactivation of CMV in seropositive recipients (R+) post-transplant can lead to CMV end organ disease (EOD). At Royal Free Hospital (RFH), London, United Kingdom, CMV EOD is prevented through pre-emptive therapy (PET), which utilises quantitative real-time PCR (qPCR) in whole blood to monitor all transplant patients and guide therapeutic interventions (1). PET is started in D+R− transplant patients following the first detectable CMV DNA (≥200 copies/ml) in blood (2). For CMV seropositive patients, PET is started when CMV DNA is ≥3000 copies/ml. This differs from many transplant centres which provide CMV anti-viral prophylaxis for the first 3-6 months post-transplant to patients at high risk of developing CMV EOD. In this observational study, the effectiveness of our PET approach and differences in CMV viral replication kinetics was retrospectively analysed in renal transplant recipients of differing CMV serostatus. Method A retrospective review of results from electronic patient records and laboratory information management system for patients who underwent renal transplantation from April 2021 to January 2023 was conducted. Patients were divided into four groups based on organ donor and recipient CMV IgG serostatus (D+R−, D+R+, D−R+, D−R−). Those who were followed up for less than 90 days or had unknown donor serostatuses were excluded. Results A total of 227 patients who received renal transplantation between April 2021 to January 2023 were identified. Of which, 11% (25/227) were D+R−, 42.3% (96/227) were D+R+, 33% (75/227) were D−R+ and 13.7% (31/227) were D−R−. Within each group, 60% (15/25) of D+R−, 61.5% (59/96) of D+R+ and 48% (36/75) of D−R+ patients developed CMV viraemia during the monitoring period. Of CMV viraemic patients, all D+R− (15/15), 54.2% (32/59) of D+R+ and 27.8% (10/36) of D−R+ patients were treated with valganciclovir as per our PET protocol. None of the D−R− patients developed any CMV viraemia. The mean peak viral load for patients with viraemia requiring treatment with valganciclovir was 4772 copies/ml (range 210-30000 copies/ml) in D+R−, 5050 copies/ml (range 3000-30000 copies/ml) and 5050 copies/ml (range 3300-18000 copies/ml) in D+R+ and D−R+ groups respectively. The mean time to first viraemia was 59 days (range 15-332) for the D+R−, 40 days (range 7-177) for D+R+ and 43 days (range 15-91) for D−R+ patients. Furthermore, the mean duration of viraemia was 34 days for D+R−, 37.5 days for D+R+ and 30.5 days for D−R+ groups. 19 patients had CMV viraemia recurrence requiring re-treatment, 63%were D+R− (12/19), 32% were D+R+ (6/19) and 5% (1/19) were D−R+. Across all four groups, two patients developed CMV EOD. One D+R+ patient was found to have CMV in respiratory sample and one D−R+ patient had CMV on colon biopsy. One D+R− patient developed UL97 mutations (M460I and A594V) conferring ganciclovir resistance due to poor compliance and was treated with maribavir. Conclusion PET is a safe and effective approach which reduces the risk of CMV EOD and antiviral medication resistance in SOT patients. Our PET approach provides monitoring of all patients regardless of CMV serostatus thereby reducing the risk of CMV EOD in all patients by ensuring early treatment of viraemia.

Allogeneic Hematopoietic Cell Transplantation in the 7 th Decade of Life and Beyond

Background The upper age limit for patients undergoing allogeneic hematopoietic cell transplantation (HCT) has increased over the past several years due to continued improvements in supportive care and increased expertise in management of older recipients of allogeneic HCT. This change is particularly important for hematologic malignancies such as acute myeloid leukemia (AML) where the median age at diagnosis is in the late 60s and HCT provides, in many instances, the only potential chance of cure. While some previous analyses have suggested favorable post-HCT outcomes for older AML patients in general, information is limited about allogeneic HCT for patients aged 70 years or older. Here, we set out to retrospectively analyze post-HCT outcomes for those aged 70+ and compare these outcomes to those aged 60-69 in a large single-center observational study. Methods Eligible patients were identified using our Fred Hutchinson Cancer Center database of transplant outcomes. All patients signed consents at time of HCT. Severity of disease was categorized as previously described (McDonald GB et al Ann Intern Med 2020). Kaplan-Meier estimates were used to evaluate overall survival (OS) and relapse-free survival (RFS); cumulative incidence estimates were used to summarize relapse and non-relapse mortality (NRM). Multivariable Cox regression models were fit to compare outcomes across age groups after adjusting for potential imbalances in various factors between groups. In addition, we used a multivariable model for overall mortality (OM) to identify risk factors for death in this population. Results We identified 1237 patients given allogeneic HCT between 2000-2022 aged at least 60 years old, 229 (18.5%) of whom were of age 70+. Baseline characteristics included severity of disease, donor type, patient CMV serostatus, conditioning intensity (Table 1). The median OS among patients 60-69 was 2.8 years (95% confidence interval, 2.4-3.6 years) and among those 70+, 1.8 years (1.3-2.9 years). Point estimates of OS at 3, 5, and 7 years were 49% (46-52%), 46% (43-49%), and 37% (34-40%), respectively for patients aged 60-69, and 43% (36-49%), 38% (31-45%), and 28% (21-36%), respectively, for patients age 70+. In the subgroup of patients age 75+ (n=29), the 3- and 5-year point estimates of OS were each 41% (22-59%). The unadjusted hazard ratio (HR, 70+ vs. 60-69) for death was 1.24 (1.04-1.49, p=0.02). However, after adjusting for various factors (Table 2), the adjusted HR for death was 1.02 (0.76-1.36, p=0.90), suggesting the apparent reduction in OS for the 70+ group relative to the 60-69 group was largely due to a higher proportion of adverse risk factors in the 70+ group. Median RFS for the two groups were 1.9 years (1.4-2.3 years) and 1.3 years (0.9-1.8 years), respectively. Similar to the HR for death, the unadjusted HR for RFS failure was significant at 1.23 (1.03-1.46, p=0.02), but the adjusted HR for was no longer significant at 0.96 (0.72-1.26, p=0.74). The unadjusted and adjusted HRs for relapse were 1.10 (0.84-1.44, p=0.51) and 0.77 (0.50-1.17, p=0.22), respectively, and for NRM 1.33 (1.06-1.67, p=.02) and 1.12 (0.77-1.61, p=0.56), respectively. Factors that were demonstrably associated with increased mortality included severity of disease, patient/donor CMV serostatus, conditioning intensity, and type of donor (Table 2). Conclusions We report here on one of the largest groups of patients aged 70+ receiving allogeneic HCT in a single center. Our results suggest that allogeneic HCT is feasible and potentially safe in this age group as compared to the group aged 60-69. These results should be encouraging for consideration of patients 70+ for allogeneic HCT. We are in process of complementing our analyses with information on comorbidities. On the other hand, 7-year OS for all older pts (60-80.9 years old) ranged from 28-37%, highlighting the need for dedicated HCT trials targeting this group of older patients to further improve outcomes.

2702. A Case Series of Kidney Transplant Recipients on Belatacept with CMV Infection in a Single Academic Center

Abstract Background Cytomegalovirus (CMV) infection has been increasingly observed among kidney transplant recipients (KTR) on belatacept for immunosuppression. Clinical outcomes of CMV infection among KTR on belatacept are not well described. We aimed to evaluate further in this case series from a single center. Methods We performed a retrospective study of KTR on belatacept who developed CMV infection and were hospitalized between the period of 1/1/2017-12/31/2022. Data collected were: demographics, transplant and CMV parameters, allograft outcomes, and co-infection. Descriptive statistics was performed. Results Of the 1,468 KTR, 387 received belatacept and have been hospitalized. Ten of the 387 (2.6%) had CMV infection. Among the 10, 60% were female and 20% were black. Median age was 59 years (range 32-78) and median time from transplant to first CMV infection was 6 months (range 1-228). Five had CMV DNAemia and 5 had CMV disease. Among the 5 with CMV DNAemia, 1 was CMV D+/R- and 4 was CMV R+. Of the 5 with CMV disease, 2 were CMV D+/R- and 3 were CMV R+. Corresponding clinical outcomes are reported in Figure 1. Belatacept administration was uninterrupted in 7/10 KTR. Of these 7, the highest median peak and the longest duration of CMV DNAemia were seen in the CMV D+/R- only. CMV infection relapse (3/7), allograft rejection (1/7), and allograft loss (1/7) occurred in those with uninterrupted belatacept infusion. Bacterial co-infections occurred in 6/10 KTR. All survived > 90 days after CMV diagnosis. KTR with interrupted belatacept (n=3) were eventually changed to alternative regimen of azathioprine, tacrolimus, and everolimus.Table 1.Patient demographicsFigure 1.CMV clinical outcomes Conclusion High risk KTR who received uninterrupted belatacept at time of CMV infection were observed to have the high level and prolonged duration of CMV DNAemia. Renal allograft rejection/loss and CMV relapse were also observed with uninterrupted belatacept administration regardless of CMV donor serostatus. This limited data suggests that KTR with either CMV D+/R- or CMV R+ may have poor clinical outcomes with continued belatacept administration in the setting of CMV infection. Prospective, multi-center studies are needed to better assess the impact of belatacept management during CMV infection. Disclosures All Authors: No reported disclosures

Pretransplant BKV-IgG serostatus and BKV-specific ELISPOT assays to predict BKV infection after kidney transplantation.

Polyomavirus (BKV) infection can lead to major complications and damage to the graft in kidney transplant recipients (KTRs). We investigated whether pretransplant BK serostatus and BK-specific cell-mediated immunity (CMI) predicts post-transplant BK infection. A total of 93 donor-recipient pairs who underwent kidney transplantation (KT) and 44 healthy controls were examined. Assessment of donor and recipient BKV serostatus and BKV-CMI in recipients was performed prior to transplantation using BKV-IgG ELISA and BKV-specific IFN-g ELISPOT assays against five BK viral antigens (LT, St, VP1, VP2, and VP3). BK viremia was diagnosed when blood BKV-DNA of 104 copies/mL or more was detected during follow-up periods. Anti-BKV IgG antibody was detected in 74 (79.6%) of 93 KTRs and in 68 (73.1%) of 93 KT donors. A greater percentage of KTRs who received allograft from donors with high levels of anti-BKV IgG had posttransplant BK viremia (+) than KTRs from donors with low anti-BKV IgG (25.5% [12/47] vs. 4.3% [2/46], respectively; P = 0.007). Pretransplant total BKV-ELISPOT results were lower in BK viremia (+) patients than in patients without viremia (-) 20.5 [range 9.9-63.6] vs. 72.0 [43.2 - 110.8]; P = 0. 027). The sensitivity and specificity of the total BKV-ELISPOT assay (cut-off ≤ 53 spots/3×105 cells) for prediction of posttransplant BK viremia were 71.4 (95% CI: 41.9-91.6) and 54.4 (42.8-65.7), respectively. The combination of high donor BKV-IgG, low recipient BKV-IgG, and low total BKV-ELISPOT results improved specificity to 91.1%. Our study highlights the importance of pretransplant BKV-IgG serostatus and BKV-specific CMI in predicting posttransplant BKV infection in KTRs. The combination of high donor BKV-IgG, low recipient BKV-IgG, and low total BKV-ELISPOT results predicted BK viremia after KT. Pretransplant identification of patients at highrisk for BK viremia could enable timely interventions and improve clinical outcomes of KTRs.

What is the optimal antimicrobial prophylaxis to prevent postoperative infectious complications after liver transplantation? A systematic review of the literature and expert panel recommendations.

Antimicrobial prophylaxis is well-accepted in the liver transplant (LT) setting. Nevertheless, optimal regimens to prevent bacterial, viral, and fungal infections are not defined. To identify the optimal antimicrobial prophylaxis to prevent post-LT bacterial, fungal, and cytomegalovirus (CMV) infections, to improve short-term outcomes, and to provide international expert panel recommendations. Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central. Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel. CRD42021244976. Of 1853 studies screened, 34 were included for this review. Bacterial, CMV, and fungal antimicrobial prophylaxis were evaluated separately. Pneumocystis jiroveccii pneumonia (PJP) antimicrobial prophylaxis was analyzed separately from other fungal infections. Overall, eight randomized controlled trials, 21 comparative studies, and five observational noncomparative studies were included. Antimicrobial prophylaxis is recommended to prevent bacterial, CMV, and fungal infection to improve outcomes after LT. Universal antibiotic prophylaxis is recommended to prevent postoperative bacterial infections. The choice of antibiotics should be individualized and length of therapy should not exceed 24hours (Quality of Evidence; Low | Grade of Recommendation; Strong). Both universal prophylaxis and preemptive therapy are strongly recommended for CMV prevention following LT. The choice of one or the other strategy will depend on individual program resources and experiences, as well as donor and recipient serostatus. (Quality of Evidence; Low | Grade of Recommendation; Strong). Antifungal prophylaxis is strongly recommended for LT recipients at high risk of developing invasive fungal infections. The drug of choice remains controversial. (Quality of Evidence; High | Grade of Recommendation; Strong). PJP prophylaxis is strongly recommended. Length of prophylaxis remains controversial. (Quality of Evidence; Very Low | Grade of Recommendation; Strong).

Time to initiation of pre-emptive therapy for cytomegalovirus impacts overall survival in pediatric hematopoietic stem cell transplant recipients

Background aimsCytomegalovirus (CMV) reactivation is a significant complication following allogeneic hematopoietic stem cell transplant (HSCT) and affects upwards of 40% of pediatric HSCT patients. Pre-emptive therapy remains the only effective treatment strategy available for pediatric patients following CMV reactivation. Little is known about how the timing of induction treatment following CMV reactivation impacts outcomes in pediatric patients, especially following ex vivo T-cell-depleted (TCD) HSCT. MethodsThe authors evaluated how the timing of induction treatment after CMV reactivation impacts overall survival (OS) and CMV disease in pediatric patients undergoing TCD HSCT at a single institution. The authors retrospectively analyzed patients treated on the pediatric service who received an initial ex vivo TCD HSCT at Memorial Sloan Kettering Cancer Center (MSKCC) from January 2010 to June 2018. CMV reactivation was defined as ≥1 CMV polymerase chain reaction >500 copies/mL in whole blood or >137 IU/mL in plasma within the first 180 days after allogeneic HSCT. To analyze the impact of the timing of induction treatment, the authors’ primary study outcome was OS and secondary outcome was CMV disease. ResultsA total of 169 patients who underwent an initial allogeneic TCD HSCT on the pediatric service at MSKCC from January 2010 to June 2018 were included in the analysis. Thirty-seven (22%) patients reactivated CMV during the first 180 days following HSCT. Of those patients who reactivated CMV, CMV donor/recipient (D/R) serostatus was as follows: D+/R+ n = 28 (76%) and D–/R+ n = 9 (24%). There was no CMV reactivation observed among recipients who were CMV-seronegative irrespective of donor serostatus. In those patients who reactivated CMV, the median time from HSCT to CMV reactivation was 24 days (interquartile range, 20–31). Eleven patients ultimately developed CMV disease in addition to CMV viremia, whereas the remaining patients had only CMV viremia. The cumulative incidence of CMV reactivation at 60 days was 45.2% (95% confidence interval [CI], 32.8–57.5) in the D+/R+ subgroup and 31% (95% CI, 14.2–47.9) in the D–/R+ subgroup. For those patients who reactivated CMV, 30 (81%) received induction treatment with ganciclovir or foscarnet. To analyze the impact of the timing of induction treatment on clinical outcomes, the authors restricted the analysis to those patients who reactivated CMV and received induction treatment (n = 30). The timing of induction treatment was significantly associated with OS, with optimal timing of initiation within a week of CMV reactivation (P = 0.02). There was no significant impact on the timing of induction treatment and risk of CMV disease (P = 0.30). ConclusionsIn ex vivo TCD HSCT in pediatric patients, early initiation of induction treatment after CMV reactivation is associated with improved OS.

Immunosuppressive regimens on conversion of cytomegalovirus infection to disease in liver transplant recipients.

Cytomegalovirus (CMV) disease is one of the most common infectious complications after liver transplantation. It is the cause of numerous morbidity and mortalities. Intensity of immunosuppression defined as overall immunosuppressive drug dosage seems to affect infectious complications. The main purpose of this study is to investigate the intensity of immunosuppression on conversion of CMV infection to disease in this population. In this cross-sectional study, we retrospectively evaluated and analyzed the data of all recipients who underwent orthotopic liver transplantation (OLT) between March 2014 and March 2016 and had positive serum PCR for CMV after transplantation in follow- up course. Of 134 recipients, only 66 adult liver transplant recipients were eligible to be studied. Multiple variables such as MELD score, cold ischemic time, warm ischemic time, operative data, immunosuppressive drugs and regimen, plasma CMV viral load, donor and recipient CMV IgG serostatus were recorded and analyzed. of the 66 patients, 50 (76%) had CMV infection and 16 (24%) had disease. There was significant association between donor CMV IgG serostatus, extra corticosteroid pulse therapy, acute cellular rejection, serum tacrolimus level and conversion of CMV infection to CMV disease (P=0.005, 0.001, 0.031, 0.031). It seems that the intensity of immunosuppression has influence on conversion rate of CMV infection to disease in liver recipients.

JC and Human polyomavirus 9 after kidney transplantation: An exploratory serological cohort study.

Human polyomaviruses (HPyVs) cause disease in immunocompromised patients. BK polyomavirus (BKPyV) for instance persistently infects the kidneys. In kidney transplant recipients, (KTRs) BKPyV can cause allograft nephropathy. JCPyV, MCPyV, TSPyV and HPyV9 reside in the kidneys too, or have been detected in urine. In this study, we investigate exposure to JCPyV, MCPyV, TSPyV and HPyV9 after kidney transplantation by serological means. Serum samples from 310 KTR collected before and 6 months after transplantation (n=620), from 279 corresponding kidney donors collected before transplantation, and from blood donor controls collected one year apart (n=174) were assessed for HPyV species-specific IgG responses using a multiplex immunoassay. KTR HPyV IgG kinetics were compared to those of healthy blood donors by linear mixed modeling, and related to those of their donors by linear regression. In the KTR, increased IgG levels during follow-up were observed for JCPyV (14.8%), MCPyV (7.1%), TSPyV (10.6%), and for HPyV9 (8.1%), while blood donor antibody levels remained stable. Seroconversion was observed for JCPyV (6.5%), MCPyV (2.3%), TSPyV (1.3%), and for HPyV9 (6.5%). The linear mixed model analysis showed that antibody increase was significant for JCPyV (p < 0.001) and HPyV9 (p < 0.001). Post-transplant JCPyV and HPyV9 antibody responses were associated with donor antibody levels against these HPyVs, respectively. KTR are exposed to JCPyV and HPyV9 after transplantation. Whether the allograft serves as the source, as indicated by the donor serostatus association, deserves further study.

Association of Donor and Recipient Cytomegalovirus Serostatus on Graft and Patient Survival in Liver Transplant Recipients.

Among solid organ transplant recipients, donor cytomegalovirus (CMV) seropositive (D+) and recipient seronegative (R-) status are associated with an increased risk of graft loss and mortality after kidney or lung transplantation. Whether a similar relationship exists among liver transplant recipients (LTR) is unknown. We assessed graft loss and mortality among adult LTRs from January 1, 2010, to March 14, 2020, in the Organ Procurement and Transplantation Network database. We used multivariable mixed Cox proportional hazards regression to analyze the association of donor and recipient CMV serostatus group with graft loss and mortality, with donor seronegative (D-) and recipient seronegative (R-) as the reference group. Among 54,078 LTRs, the proportion of D-R-, D- and recipient seropositive (R+), D+R-, and D+R+ was 13.4%, 22.5%, 22%, and 42%, respectively. By unadjusted Kaplan-Meier survival curve estimates, survival by the end of follow-up was 73.3%, 73.5%, 70.1%, and 69.7%, among the D-R-, D-R+, D+R-, and D+R+ groups, respectively. By multivariable Cox regression, the CMV D+R- serogroup, but not other serogroups, was independently associated with increased risks of graft loss (adjusted hazard ratio [aHR], 1.13; 95% confidence interval [CI], 1.05-1.22) and mortality (aHR, 1.13; 95% CI, 1.05-1.22). The magnitude of the association of the CMV D+R- serostatus group with mortality was similar when the Cox regression analysis was restricted to the first year after transplant and beyond the first year after transplant: aHR, 1.13 (95% CI, 1.01-1.27) and aHR, 1.13 (95% CI, 1.02-1.25), respectively. Even in an era of CMV preventive strategies, CMV D+R- serogroup status remains independently associated with increased graft loss and mortality in adult LTRs. Factors in addition to direct CMV-associated short-term mortality are likely, and studies to define the underlying mechanism(s) are warranted.

Unknown cytomegalovirus serostatus in primary immunodeficiency disorders: A new category of transplant recipients.

Cytomegalovirus (CMV) serostatus of recipient (R) and donor (D) influences hematopoietic stem cell transplant (HSCT) outcome. However, it is not a reliable indicator of CMV infection in primary immunodeficiency disorder (PIDD) recipients who are unable to make adequate antigen-specific immunoglobulin (Ig) or who receive intravenous Ig (IVIg) prior to testing. Since no data exist on PIDD with unknown CMV serostatus, we aimed to evaluate the relationship between pre-HSCT recipient and donor serostatus and incidence of CMV infection in recipients with unknown serostatus. A retrospective analysis of all pediatric PIDD HSCTs (2007-2018) was performed at University of California San Francisco. Recipients were separated into categories based on pre-transplant serostatus: 1) seropositive (R(+)), 2) seronegative (R(-)), and 3) unknown serostatus (R(x)). Patients with pre-HSCT active CMV viremia were excluded. A total of 90 patients were included, 69% male. The overall incidence of CMV infection was 20%, but varied in R(+), R(-), and R(x) at 80%, 0%, and 14%, (P-value=.0001). Similarly, 5-year survival differed among groups, 60% R(+), 100% R(-), and 90% of R(x) (P-value=.0045). There was no difference in CMV reactivation by donor serostatus (P-value=.29), however, faster time to clearance of CMV was observed for R(x)/D(+) group (median 9.5days (IQR 2.5-18), P-value=.024). We identify a novel group of recipients, R(x), with an intermediate level of survival and CMV incidence post-HSCT, when compared to seropositive and seronegative recipients. No evidence of CMV transmission from D(+) in R(-) and R(x) was observed. We believe R(x) should be considered as a separate category in future studies to better delineate recipient risk status.

Increased Risk of for Cytomegalovirus Reactivation after Allogeneic HSCT in T-Cell Depleted Patients

Background: Reactivation of Cytomegalovirus (CMV) is frequent after allogeneic hematopoietic stem cell transplantation (HSCT), occurring in approximately 70% of CMV seropositive patients. CMV reactivation is associated with higher non-relapse mortality (NRM) and worse overall survival (OS), but data in patients from Latin American countries, in which seroprevalence of CMV is higher, are lacking. Objectives: We analyzed the potential risk factors for CMV reactivation and the possible impact of CMV reactivation or primo-infection on HSCT outcomes. Patients and Methods: We performed an observational, retrospective study in 262 consecutive adult patients who underwent HSCT between April 2007 and April 2020 in two centers. The median follow-up was 30 months. Results: The median age was 50 years (range 18 to 83), most patients (58%) were male, had acute leukemia (acute myeloid leukemia in 40%, and acute lymphoblastic leukemia in 19%), and received transplants from alternative donors (matched unrelated in 32% and haploidentical in 36%). Most transplants were from peripheral blood stem cells (73%), with reduced-intensity conditioning regimens (76%). T-cell depletion was performed in 71% (post-transplant cyclophosphamide in 40%, antithymocyte globulin - ATG in 29%, and alemtuzumab in 2%). Pre-HSCT CMV IgG serostatus of donor (D) and recipient (R) was as follows: D+/R+ in 64%, D-/R+ in 22%, D+/R- in 8%, and D-/R- in 6% only. No patient received primary CMV prophylaxis. CMV reactivations were observed in 164 patients (63%), and all received preemptive therapy at the discretion of the treating physician. The CI for CMV reactivation at 100 days (CICMV) was 74% in D-/R+, 65% in D+/R+, 30% in D+/R-, and 0% in D-/R-, p&amp;lt;0.01, Figure 1). The CICMV was higher in patients receiving transplants with T-cell depletion (67% vs. 47% without T-cell depletion, p&amp;lt;0.01), and in patients with acute graft-versus-host disease (GVHD, 91% vs. 53% without GVHD, p=0.01). By multivariate analyses, all three factors remained associated with the CMV reactivation: pre-HSCT positive CMV serostatus (Hazard Ratio - HR: 6.06; 95% Confidence Interval - 95%CI 2.76.-13.35), T-cell depletion (HR 1.65, 95%CI 1.20-2.27), and acute GVHD (HR 1.67, 95%CI 1.31-2.14). By multivariate analysis, there was no significant association between CMV reactivation and the risk of acute GVHD, chronic GVHD, mortality, relapse, or survival. Conclusion: An increased frequency of CMV reactivation was observed in recipients with positive CMV serostatus, T-cell depletion, and acute GVHD. CMV reactivation had no significant impact on HSCT outcomes. Our findings may help to identify a group of patients who could benefit from closer monitoring and possibly primary prophylaxis with novel agents, such as letermovir. Disclosures No relevant conflicts of interest to declare.

Cytomegalovirus T-Cell Responses Predict CMV Infection and Disease After Renal Transplant

Risk assessment for cytomegalovirus (CMV) infection and disease among transplantation recipients is based on donor and recipient serostatus. However,

Timing of Induction Treatment for Reactivation of Cytomegalovirus Impacts Overall Survival in Pediatric Allogeneic Hematopoietic Cell Transplant

Background Despite significant advances in viral detection and treatment, reactivation of cytomegalovirus (CMV) remains a major complication following allogeneic hematopoietic cell transplant (allo-HCT). Methods to decrease the risk of CMV reactivation and long-term sequelae of CMV disease include controlling for known risk factors and administering appropriate antiviral treatments. Although they are shown to be effective, these treatments carry considerable adverse effects that may limit their use. The optimal timing to initiate induction treatment remains unclear, especially in the pediatric population. Design We performed a retrospective analysis of patients who received initial conventional or ex-vivo T-cell depleted (TCD) allo-HCT on the pediatric service from January 2010 – June 2018 at Memorial Sloan Kettering Cancer Center. CMV reactivation was defined as ≥ 1 CMV PCR >500 in whole blood or >137 in plasma within 180 days post-transplant. Induction treatment was typically initiated for CMV PCR ≥ 1000 in whole blood, ≥ 300 in plasma, or rising viremia from baseline. Hospital databases and medical records were utilized to identify patients and collect clinical data. Time-dependent Cox models and multi-state models to account for competing risks were used. This study was approved by Institutional Review Board. Results Our study consisted of 227 patients (54 days - 27 years old) who underwent allo-HCT for malignant (N=143) and non-malignant (N=84) diseases. TCD represented 76% of all allografts. CMV donor (D) and recipient (R) serostatus were: D+/R+ N=90, D+/R- N=29, D-/R+ N=38, D-/R- N=70. Cumulative incidence of CMV reactivation was 24.8% and 15 patients (27%) developed CMV disease. Median time to CMV reactivation was 24 days (IQR 14-33). Of the 56 patients who reactivated, 41 (73%) patients received induction treatment. The median time from CMV reactivation to induction treatment was 6 days (IQR 1-15). D+/R+ serostatus was a predictor for CMV reactivation when compared to D-/R+ (HR=2.1, [95% CI 1.1 - 4, P Conclusions A short interval between CMV reactivation and initiation of induction treatment was significantly associated with improved OS in TCD HCT. Earlier treatment did not translate into improved outcomes, which may be confounded by high-risk patients receiving induction therapies earlier. Further evaluation into CMV prophylaxis and prompt initiation of induction treatment on additional CMV outcomes will help optimize treatment options and improve clinical outcomes.

CMV Viral Load Kinetics as Surrogate Endpoints for Antiviral Prophylaxis Trials

<h3>Introduction</h3> The paradigm for preventing clinically significant cytomegalovirus (CMV) infection and CMV disease after hematopoietic cell transplantation (HCT) has shifted from preemptive treatment to antiviral prophylaxis with the approval of letermovir. Previously, our group validated the use of quantitative CMV DNA viral load as a surrogate endpoint for tissue-invasive CMV disease (ASBMT 2018) in the <i>pre-emptive treatment setting</i>. <h3>Objectives</h3> To address whether CMV viral load kinetics could serve as valid surrogate endpoints for CMV disease in the <i>prophylactic setting</i>, we performed CMV viral load testing of frozen serum samples collected during a placebo-controlled randomized trial of ganciclovir (GCV) given at engraftment (Goodrich et al. Ann Intern Med 1993). Because this study pre-dated the approval of ganciclovir, CMV disease occurred in an extremely high proportion of patients, allowing us to link viral load kinetics with CMV disease, which would not be possible in the modern treatment environment. <h3>Methods</h3> We calculated each patient's CMV viral load kinetics (mean, peak, maximum change, percentage of positive viral loads) from samples collected during the first five weeks after randomization and analyzed their value as surrogates for CMV disease by 24 weeks after randomization. First, we tested each marker for fulfillment of the Prentice criteria for valid surrogate endpoints using multivariable logistic regression, including quantifying the degree to which each marker captured the effect of ganciclovir on CMV disease. Secondly, to determine the ability of the viral load markers to predict CMV disease, we developed a ‘SuperLearner' machine learning model and quantified prediction accuracy by cross-validated area under the receiver-operator characteristic curves (cv-AUCs). <h3>Results</h3> Mean, peak, change, and percentage of positive viral loads were significantly higher in the placebo group than in the ganciclovir group. See viral loads by group in Fig 1. Percentage of positive viral load satisfied Prentice criteria as a valid surrogate endpoint for CMV disease by week 24 after randomization (Fig 2). All kinetics explained greater than 80% of ganciclovir's reduction in CMV disease (mean: 86%, peak: 83%, maximum change: 95%, percent positive: 94%). We found that a SuperLearner model that included all four viral load kinetics, CMV donor serostatus, acute graft-versus-host disease, and baseline viral load predicted CMV disease with 91% cv-AUC in the placebo group, 78% in the ganciclovir group, and 82% in the combined groups (Fig 3). <h3>Conclusion</h3> We have shown for the first time in a clinical endpoint-rich, placebo-controlled antiviral prophylaxis trial that CMV viral load kinetics fulfill the Prentice criteria as valid surrogate endpoints and have high predictive value for CMV disease after HCT.

CMV-Specific T Cells Restricted By Shared and Donor, but Not By Host HLA Molecules Reconstitute in the First 180 Days after Allogeneic HSCT and Protect from CMV Reactivation: Results of a Prospective Observational Study

Introduction: Cytomegalovirus (CMV) reactivation and disease are important risk factors after allogeneic hematopoietic stem cell transplantation (allo-HSCT), and strongly affect morbidity and mortality after transplant. CMV-specific T cell reconstitution controls CMV reactivation and protects against serious adverse events but a protective level of CMV-specific T cell response or standardized method for its monitoring have not been yet determined. Methods: We designed a prospective, single-center observational study to assess if the kinetic and quality of CMV specific T-cell reconstitution impact the incidence and severity of CMV reactivations. We have enrolled 84 consecutive patients affected by hematological malignancies receiving allo-HSCT followed by Cyclophosphamide and Rapamycin between December 2017 and February 2019. Here we report preliminary data on the first 61 patients. Patients received allo-HSCT from family (siblings=10; HLA haploidentical=24), unrelated HLA-matched (n= 24) donors or cord blood (CB, n=3). The CMV serostatus of host (H) and donor (D) pairs was: H+/D+(n=40, 65%), H+/D-(n=20, 33%) and H-/D+ (n=1, 2%); H-/D-(7% of the overall transplanted population at our center) were excluded. CMV DNAemia was assessed weekly in whole blood (WB). Absolute numbers of polyclonal and CMV-specific T cells were quantified by flow cytometry using Troucount™Tubes (BD) and Dextramer®CMV-Kit (Immudex), respectively, in the graft and fresh WB at days -7, +30, +45, +60, +90, +120, +150, +180 and +360. Dextramer CMV kit includes reagents for the identification of CMV-specific lymphocytes restricted for several HLA class I molecules: A*01:01/*02:01/*03:01/*24:02 and B*07:02/*08:01/*35:01. These alleles allowed the longitudinal evaluation of 54 out of 61 (89%) patients. Results: At a median follow-up of 226 days post-HSCT, 31 (57%) patients experienced a CMV-related clinically relevant event (CRE, median +63 days), including 8 patients (15%) with CMV disease (median +59 days). Univariate analyses showed that the incidence of CMV clinically-relevant reactivation (CRE) was influenced by H/D CMV serostatus (0.90 in H+/D- versus 0.44 in H+/D+pairs, p=0.015) and by previous acute Graft-versus-Host Disease (aGvHD) requiring systemic immunosuppression (0.82 in aGvHD grade II-IV versus 0.52 in aGvHD grade 0-I, p=0.051). The disease status at transplant, the donor type (HLA-matched versus HLA-haploidentical/CB donors), donor's or host's age did not significantly affect the probability to develop CRE. For each time-point, we compared the absolute number of CMV-specific lymphocytes in patients experiencing or not a subsequent CRE. Our data demonstrate that higher levels of CMV-specific CD8+T cells in the donor apheresis and at +45 days after allo-HSCT are associated with reduced risk of subsequent CRE (median CMV-specific CD8+cells/kg in the apheresis=5x103in CRE-positive patients (CRE+) and 5x105in CRE-negative patients (CRE-), p=0.012; median CMV-specific CD8+at +45 days=0.14 cells/μL in CRE+and 1.21 cells/μL in CRE-, p=0.034). Furthermore, patients with any Dextramer positivity at +45 days displayed a lower incidence of CRE compared with subjects who were negative (CRE probability: 0.5 vs 1.0, p=0.003). Conversely, the absolute number of neither polyclonal CD3+CD8+T lymphocytes nor total CD3+T cells correlate with subsequent CRE. Taking advantage of the HLA mismatched-HSCT setting, we then dissected CMV-specific T-cell response according to HLA restriction elements (H/D=shared n=45, D-restricted n=14, H-restricted n=11). In H+/D+pairs, we observed a fast and similar kinetic of reconstitution of CMV-specific lymphocytes restricted by H/D and D HLAs. Conversely, in H+/D-pairs, we detected only CMV-specific CD8+lymphocytes restricted for H/D haplotypes. Host-restricted cells remained undetectable for the first 180 days after HSCT. Conclusion: Early after allo-HSCT and in the donor apheresis, the level of CMV-specific CD8+T cells measured by Dextramer staining differs in patients experiencing or not subsequent CRE. Furthermore, our findings indicate that CMV reactivations can prime H/D-restricted T cells presumably educated in the donor thymus; conversely, D- and H-restricted donor-derived lymphocytes have not yet undergone neither cross-priming nor thymic education respectively. Disclosures Brix: Immudex: Employment. Bonini:Kite/Gilead: Consultancy; Intellia Therapeutics: Consultancy; Intellia Therapeutics: Research Funding; Novartis: Consultancy; GSK: Consultancy; Allogene: Consultancy; Molmed: Consultancy; TxCell: Consultancy; -: Patents &amp; Royalties: Adoptive T cell therapy field.

91. Differential Impact of Cytomegalovirus (CMV) Donor (D) Serostatus on Rates and Kinetics of CMV Viremia among CMV Seropositive Recipients (R+) of Ex vivo T-cell Depleted (TCD) and Unmodified (CONV) Hematopoietic Cell Transplants (HCT)

BackgroundIn unmodified (CONV) HCT, CMV donor seropositivity (D+) conveys partial protection against CMV disease mediated by the transfer of donor CMV T-cell immunity through the allograft. Ex vivo T-cell depletion by CD34 selection affords a stringent depletion of donor T cells, thus transfer of donor T-cell immunity to CMV would be negligible. We evaluate the impact of CMV D serostatus on rates and kinetics of CMV viremia by Day (D)100 post-HCT in a contemporary cohort of CONV and TCD recipients from a single center.MethodsA retrospective cohort study of R+ adult recipients of first peripheral blood or marrow HCT for hematologic malignancies (excluding multiple myeloma) from June 2010 to December 2017 at MSKCC. Routine CMV monitoring by a quantitative PCR assay occurred weekly from D14 through D100. Patients were treated preemptively. CMV viral burden was assessed as the time-averaged area under the viremia curve over 100 days from HCT (AAUC) calculated as the sum of the area of trapezoids of AUC viral loads divided by the number of weeks of follow-up viremia. The median AAUC for all patients with CMV reactivation (AAUC50) was used to classify patients as CMV controllers (AAUC ≤ AAUC50) or noncontrollers (AAUC >AAUC50).ResultsOf 509 R+, 290 (57%) patients received CONV and 219 (43%) TCD HCT; from 300 (59%) D+ and 209 (41%) D− donors. In CONV, CMV viremia occurred with similar frequency in D+ (65%) and D− (62%), P = 0.6. In contrast, in TCD, CMV viremia occurred more frequently in D+ compared with D− (83% vs. 71%, P = 0.03). Among CONV, D+ was associated with lower CMV burden (median AAUC) compared with D− (0.791 vs. 1.13, respectively, P = 0.0004). In contrast, in TCD, AAUC was similar between D− and D+ (1.19 vs. 1.35; P = 0.86). Among CONV with CMV viremia, D− were more likely to be noncontrollers compared with D+ (56% vs. 31%, respectively, P = 0.001). In contrast, among TCD with CMV viremia the proportion of noncontrollers was similar between D− and D+ (61% vs. 60%, respectively; P = 1).ConclusionDonor CMV serostatus has a differential effect on rates and kinetics of CMV viremia in R+ TCD and CONV HCT recipients. D+ is associated with less CMV viremia and less CMV burden in CONV but not in TCD. Our findings, if confirmed, have implications for donor selection algorithms. Disclosures All Authors: No reported Disclosures.

Comprehensive viromewide antibody responses by systematic epitope scanning after hematopoietic cell transplantation

AbstractFurther insight into humoral viral immunity after hematopoietic cell transplantation (HCT) could have potential impact on donor selection or monitoring of patients. Currently, estimation of humoral immune recovery is inferred from lymphocyte counts or immunoglobulin levels and does not address vulnerability to specific viral infections. We interrogated the viral antibody repertoire before and after HCT using a novel serosurvey (VirScan) that detects immunoglobulin G responses to 206 viruses. We performed VirScan on cryopreserved serum from pre-HCT and 30, 100, and 365 days after myeloablative HCT from 37 donor-recipient pairs. We applied ecologic metrics (α- and β-diversity) and evaluated predictors of metrics and changes over time. Donor age and donor/recipient cytomegalovirus (CMV) serostatus and receipt systemic glucocorticoids were most strongly associated with VirScan metrics at day 100. Other clinical characteristics, including pre-HCT treatment and conditioning, did not affect antiviral repertoire metrics. The recipient repertoire was most similar (pairwise β-diversity) to that of donor at day 100, but more similar to pre-HCT self by day 365. Gain or loss of epitopes to common viruses over the year post-HCT differed by donor and recipient pre-HCT serostatus, with highest gains in naive donors to seropositive recipients for several human herpesviruses and adenoviruses. We used VirScan to highlight contributions of donor and recipient to antiviral humoral immunity and evaluate longitudinal changes. This work builds a foundation to test whether such systematic profiling could serve as a biomarker of immune reconstitution, predict clinical events after HCT, or help refine selection of optimal donors.

CMV reactivation in allogeneic hematopoietic stem cell transplant patients receiving post-transplant cyclophosphamide.

e18533 Background: Post transplant cyclophosphamide (PTCY) has been shown to be an effective treatment for prevention of graft versus host disease (GVHD). However, this increased immune suppression rates may increase the risk of CMV reactivation. There is limited published data addressing CMV reactivation in this patient population. Additionally there is no data on the efficacy of prophylactic letermovir in the patients who have received PTCY. In this study we analyzed the incidence of CMV reactivation in patients treated with PTCY and those not treated with PTCY, as well as the efficacy of letermovir in preventing CMV reactivation in the PTCY population. Methods: We conducted a retrospective review of MUD, MRD, and haploidentical stem cell transplant patients at our institution from 1/1/2014 until 12/10/2018. We analyzed the incidence of CMV reactivation (PCR &gt; 137 DNA IU/ml), peak of CMV PCR titer and time to reactivation within the first 100 days post-transplant. Results: There were 150 patients with at least 60 days of follow-up that were included in this study. These patients were split into three groups: No post-transplant cyclophosphamide (NPTCY) (N = 64), received post-transplant cyclophosphamide (PTCY) (N = 70), and received PTCY and letermovir prophylaxis. (L-PTCY) (N = 15). The incidence of CMV reactivation was increased in the PTCY patients when compared to the NPTCY (44% vs 29%). In the NPTCY patients the donor (D) serostatus increased the risk of CMV reactivation (Recipient (R)+ D+ 73% vs R+D-36%) conversely in the PTCY group the donor CMV status did not influence reactivation rates (R+D+ 52% vs R+D- 81%). The CMV reactivation rate in the L-PTCY patients was lower when compared to the PTCY patients (21% vs 44%), additionally the L-PTCY patients had much lower peak CMV titers compared to PTCY group (445 vs 2112 IU/ml). Conclusions: This study demonstrates that there is an increased incidence of CMV reactivation in patients who receive PTCY. Additionally, the donor CMV serostatus does not appear to influence the incidence of CMV reactivation in patients receiving post-transplant CY. Although the number of patients in the L-PTCY group is small, it does appear to be an effective prophylactic treatment in patients receiving PTCY.

Cytomegalovirus Infection and Disease in Lung Transplant Recipients

Purpose Cytomegalovirus (CMV) infection causes significant morbidity and mortality in lung transplant recipients (LTR), the most important risk factor for which is the serostatus of donor (D) and recipient (R). Our program employs a CMV prophylaxis strategy. In 2016, our protocol for management of D+ R- changed from 3-6 months of valganciclovir (VGCV) with CMV hyperimmune globulin to 12 months of VGCV with human normal immunoglobulin. Aims: To determine the effect of changing CMV prophylaxis protocol for D+ R- on the incidence of CMV infection/disease in LTR. Methods We retrospectively reviewed laboratory results and clinical notes from all LTR transplanted between 1/01/2014 - 31/12/2017 in the National Heart and Lung Transplant Centre, Ireland. Data were collected for a minimum of ten months post-transplant, with a longer follow-up of those transplanted earlier. Results Data were available on 134 of 137 LTR, Table 1. There were fewer episodes of infection (14 v 30, p = 0.19) and less tissue invasive disease (TID) (0 v 4, p = 0.14) in the D+ R- 2016-17 group. The average time to infection/disease was longer (9 v 7.7 months) in the 2016-17 group. The incidence of CMV infection and disease was 29% in LTR transplanted in 2016-17 and 36% in 2014-15. Conclusion Recent guidelines (1) advocate a minimum of 6 months VGCV prophylaxis in D+ R- LTR. Our data demonstrates there is a trend for less adverse events such as TID with a longer duration. The average time to infection in the 2016-17 group of 9 months suggests some patients are not tolerating prophylaxis and terminating early. In conclusion, following a change in protocol less CMV infection episodes and no invasive CMV disease were reported in our cohort. Reduction in CMV disease and infection will reduce graft loss, morbidity and mortality. Innovations to improve tolerability of VGCV may further delay time to infection.