Risk Of Cytomegalovirus Reactivation Research Articles

Comparison of Cytomegalovirus Reactivation in Children After Allogeneic Hematopoietic Cell Transplantation in 2 Transplant Eras

Reactivation of cytomegalovirus (CMV) is typically considered harmless as long as the immune system remains unaffected by medications or other factors. CMV reactivation may occur as a result of acute graft-versus-host disease of Grades II to IV. One possible factor contributing to this risk is the rise in the number of donors who lack genetic similarities or relationships. We hypothesized that the anti-CMV IgG level before transplantation could potentially serve as an indicator of the likelihood of CMV reactivation following hematopoietic cell transplantation. We examined a cohort of young individuals who underwent allogeneic HCT between 1998 and 2022 to evaluate the occurrence of CMV reactivation. The patients were divided into 2 time periods: 1998 to 2016 (comparison group) and 2017 to 2022 (intervention group). Between 1998 and 2016, 292 patients underwent hematopoietic HCT. Recipients from 2017 to 2022 experienced a slightly higher risk of CMV reactivation than those from 1998 to 2016. The comparison of prophylactic and preemptive medication showed no significant difference between the periods (P = .32). Patients treated from 1998 to 2016 experienced a 23% decrease in the risk of symptomatic CMV reactivation and related illnesses compared to those treated from 2017 to 2022 (P = .08 and .15, respectively). Our study showed that the intervention group had more symptomatic CMV reactivations. Various factors may contribute to this, including CD19-directed immunotherapy and the CMV status of the recipient before transplantation.

Cytomegalovirus reactivation is frequent in multiple myeloma patients treated with daratumumab-based regimens.

Viral reactivations are frequent in hematologial patients due to their cancer-related and drug-induced immunosuppressive status. Daratumumab, an anti-CD38 monoclonal antibody, is used for multiple myeloma (MM) treatment, and causes immunosuppression by targeting CD38-expressing normal lymphocytes. In this single-center two-arm real-life experience, we evaluated incidence of cytomegalovirus (CMV) reactivation in MM patients treated with daratumumab-based regimens as first- or second-line therapy. A total of 101 consecutive MM patients were included in this study and were divided into two cohorts: daratumumab and nondaratumumab-based (control) regimens. Patients treated with >2 lines of therapies were excluded to reduce the confounding factor of multi-treated cases. Primary endpoint was the CMV reactivation rate. CMV reactivation rate was significantly higher in the daratumumab cohort compared to control group (33% vs. 4%; p < 0.001), also with higher CMV-DNA levels (>1000 UI/mL in 12% of cases; p < 0.05). However, only one subject developed a CMV disease with severe pneumonia, while 12% of patients were successfully treated with preemptive therapy with valganciclovir. No subjects in the control cohort required anti-CMV agents (p = 0.02). Our single-center retrospective experience showed that daratumumab might significantly increase the risk of CMV reactivation in MM, while currently underestimated and related to morbility and mortality in MM patients under treatments. However, further validation on larger and prospective clinical trials are required.

Impact of cytomegalovirus (CMV) seroconversion pre-allogeneic hematopoietic cell transplantation on posttransplant outcomes.

Cytomegalovirus (CMV) reactivation post-allogeneic hematopoietic cell transplantation (post-alloHCT) increases morbidity and mortality. We sought to determine the frequency of CMV seroconversion in patients pre-alloHCT and to investigate the impact on posttransplant outcomes. We retrospectively investigated 752 adult patients who underwent alloHCT at our center from January 2015 to February 2020 before the adoption of letermovir prophylaxis. CMV serology was assessed at consult and pretransplant. The cohort was divided into four groups based on pretransplant CMV seroconversion: negative to positive (Group 1), positive to negative (Group 2), consistently negative (Group 3), and consistently positive (Group 4). Eighty-nine patients (12%) had seroconverted from negative to positive, 17 (2%) from positive to negative, 151 (20%) were consistently seronegative, and 495 (66%) were consistently seropositive pretransplant. For the four CMV serostatus groups, cumulative incidence of CMV reactivation at 6 months posttransplant was 4.5%, 47.1%, 6.6%, and 76.6% for Groups 1, 2, 3, and 4, respectively (p < .0001). No differences between groups were seen regarding Grade III-IV acute graft-versus-host disease (GVHD) (p = .91), moderate/severe chronic GVHD (p = .41), or graft failure (p = .28). On multivariable analysis, there was no impact of CMV serostatus group on overall survival (p = .67), cumulative incidence of relapse (p = .83) or non-relapse mortality. alloHCT patients who demonstrate CMV seroconversion pretransplant from negative to positive have a very low risk of CMV reactivation posttransplant. The observed seroconversion may be due to passive CMV immunity acquired through blood products. Quantitative CMV immunoglobulin G/immunoglobulin M pretransplant may help differentiate between true seroconversion and passively transmitted CMV immunoglobulin.

Expansion of effector memory Vδ2neg γδ T cells associates with cytomegalovirus reactivation in allogeneic stem cell transplant recipients.

Cytomegalovirus (CMV) reactivation is a significant concern following allogeneic stem cell transplantation. While previous research has highlighted the anti-CMV reactivation effect of γδ T cells in immunocompromised transplant patients, their characterization in recipients at high risk of CMV reactivation remains limited. This study focused on D+/R+ recipients (where both donor and recipient are CMV seropositive) at high risk of CMV reactivation. We analyzed 28 patients who experienced CMV recurrence within 100 days post-allogeneic hematopoietic stem cell transplantation, along with 36 matched recipients who did not experience CMV recurrence. Clinical data from both groups were compared, and risk factors for CMV reactivation were identified. Additionally, CMV viral load was measured, and flow cytometric analysis was conducted to assess changes in peripheral blood γδ T cell proportions, subpopulation distribution, and differentiation status. We also analyzed the CDR3 repertoire of the TCR δ chain in different γδ T cell subsets. Functional analysis was performed by measuring the lysis of CMV-infected cells upon stimulation. CMV reactivation post-transplantation was associated with acute graft-versus-host disease (aGvHD) and reactivation of non-CMV herpesviruses. Notably, CMV reactivation led to sustained expansion of γδ T cells, primarily within the Vδ2neg γδ T cell subpopulation, with a trend toward differentiation from Naive to effector memory cells. Analysis of the δ chain CDR3 repertoire revealed a delay in the reconstitution of clonal diversity in Vδ2neg γδ T cells following CMV reactivation, while Vδ2pos T cells remained unaffected. Upon stimulation with CMV-infected MRC5 cells, the Vδ2neg γδ T cell subpopulation emerged as the primary effector cell group producing IFN-γ and capable of lysing CMV-infected cells. Moreover, our findings suggest that NKG2D is not necessary involved in Vδ2neg γδ T cell-mediated anti-CMV cytotoxicity. This study provides novel insights into the role of γδ T cells in the immune response to CMV reactivation in transplantation recipients at high risk of CMV infection. Specifically, the Vδ2neg γδ T cell subpopulation appears to be closely associated with CMV reactivation, underscoring their potential role in controlling infection and reflecting CMV reactivation in HSCT patients.

Immunomonitoring via ELISPOT Assay Reveals Attenuated T-Cell Immunity to CMV in Immunocompromised Liver-Transplant Patients.

Assessing immune responses to cytomegalovirus (CMV) after liver transplant in patients on immunosuppressive therapy remains challenging. In this study, employing ELISPOT assays, 52 liver-transplant recipients were evaluated for antiviral T-cell activity in peripheral blood mononuclear cells (PBMCs), measuring interferon-γ (IFN-γ) secretion upon stimulation with CMV-specific peptides (CMV peptide pool, CMV IE-1, and pp65 antigens). Parameters such as stimulation index, mean spot size, and mean spot count were measured. The study found that heightened immunosuppression, especially with prednisolone in triple therapy, significantly dampened CMV-specific immune responses. This was demonstrated by decreased IFN-γ production by CMV-specific T-cells (CMV peptide pool: p = 0.036; OR = 0.065 [95% CI: 0.005-0.840], pp65 antigen: p = 0.026; OR = 0.048 [95% CI: 0.003-0.699]). Increased immunosuppression correlated with reduced IFN-γ secretion per cell, reflected in smaller mean spot sizes for the CMV peptide pool (p = 0.019). Notably, shorter post-transplant intervals correlated with diminished antiviral T-cell IFN-γ release at two years (CMV peptide pool: p = 0.019; IE antigen: p = 0.010) and five years (CMV peptide pool: p = 0.0001; IE antigen: p = 0.002; pp65 antigen: p = 0.047), as did advancing age (pp65 antigen: p = 0.016, OR = 0.932, 95% CI: 0.881-0.987). Patients with undetectable CMV antigens had a notably higher risk of CMV reactivation within six months from blood collection, closely linked with triple immunosuppression and prednisolone use. These findings highlight the intricate interplay between immunosuppression, immune response dynamics, and CMV reactivation risk, emphasizing the necessity for tailored immunosuppressive strategies to mitigate CMV reactivation in liver-transplant recipients. It can be concluded that, particularly in the early months post-transplantation, the use of prednisolone as a third immunosuppressant should be critically reconsidered. Additionally, the use of prophylactic antiviral therapy effective against CMV in this context holds significant importance.

Donor aKIR genes influence the risk of EBV and CMV reactivation after anti-thymocyte globulin-based haploidentical hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) offers the highest curative potential for patients with hematological malignancies. Complications including infection, graft-versus-host disease (GVHD), and relapse reflect delayed or dysregulated immune reconstitution. After transplantation, NK cells rapidly reconstitute and are crucial for immune surveillance and immune tolerance. NK cell function is tightly regulated by killer immunoglobin-like receptors (KIRs). Previous studies have revealed that donor KIRs, especially some activated KIRs (aKIRs) are closely related to transplant outcomes. Here, we performed a retrospective study, including 323 patients who received haploidentical (haplo) HSCT in our center. In univariate analysis, donor KIR2DS1, KIR2DS3 and KIR3DS1 gene protected patients with lymphoid disease from Epstein-Barr virus (EBV) and cytomegalovirus (CMV) reactivation, while donor KIR2DS1, KIR2DS5 and KIR3DS1 gene conferred a higher risk of CMV reactivation for patients with myeloid disease. Multivariate analysis confirmed that donor telomeric (Tel) B/x and KIR2DS3 gene best protected patients with lymphoid disease from EBV (p = 0.017) and CMV reactivation (p = 0.004). In myeloid disease, grafts lacking Tel B/x and KIR2DS5 gene correlated with the lowest risk of CMV reactivation (p = 0.018). Besides, donor aKIR genes did not influence the rates of GVHD, relapse, non-relapse mortality (NRM) and overall survival (OS) in this study. The reactivation of EBV and CMV was associated with poor prognosis of haplo-HSCT. In conclusion, we found that donor aKIR genes might have a synergistic effect on CMV and EBV reactivation after haplo-HSCT. Whether the influence of donor aKIR genes varies with disease types remained to be studied.

Implementation of CMV-T-Track® in Clinical Routine to Guide Management of CMV Reactivation

Background: Despite Letermovir prophylaxis, reactivation of cytomegalovirus (CMV), requiring close monitoring and preemptive antiviral treatment, remains to be an issue after allogeneic hematopoietic stem cell transplantation (HSCT). Monitoring CMV-specific cellular immunity can help to identify patients at risk and may guide monitoring intervals and therapeutic decisions. CMV T-Track®, a standardized IFN-γ ELISpot assay, conducted after the end of treatment of a first CMV reactivation was shown to identify patients at risk of recurrent reactivation with a positive predictive value (patients with a negative test after the first CMV reactivation had a subsequent recurrent CMV reactivation) of 80%. As these results originate from a clinical trial with a distinct patient population, we analyzed its usefulness and value within the clinical routine. Here we describe the results within the clinical routine in an unselected patient cohort and the influence of different GvHD prophylaxis on T-Track® outcome, as well as factors promoting CMV reactivation despite positive test results. Methods: In total, 169 patients were monitored for CMV reactivation with CMV-PCR for 365 days after HSCT and CMV immunity was measured using CMV T-Track® at d+100. CMV T-Track® was repeated at d+200 and+ 300 in case of a negative first test result d+100. Patient characteristics: 125 patients received ATG, 24 Alemtuzumab i.v. and 12 ptCy. 8 patients were transplanted from an HLA-identical sibling and received no T cell depleting (TCD) agent. CMV-serostatus: Donor(D)+/recipient(R)+ in 123, D+/R- in 9, D-/R+ in 34 and D-/R- in 3 patients. All CMVpos recipients received Letermovir prophylaxis until d+100. Results: At d+100 164/169 tests produced a robust result, only 5 tests were invalid. 110 patients had a positive T-Track® at d+100, with a higher percentage in patients with a CMVpos donor (99/132 (75%) vs. (10/37 (27%)). After Alemtuzumab we observed the lowest rate of positive T-Track® 10/24 (42%) at d+100, followed by ATG 83/125 (66%), whereas pTCy showed a good response 11/12 (92%). Only 5/8 (63%) patients without TCD had a positive test result. 9/10 (90%) of patients with a positive T-Track® d+100 despite a CMVneg donor had a positive CMV-PCR before d+100, whereas only 3/27 (11%) CMVireamias were detected in those without CMV immunity. In patients with a CMVpos donor 59/108 (55%) had a documented reactivation leading to a positive T Track®, in contrast to 9/33 (27%) with a negative T-Track®. 18/20 (90%) patients developed a positive T-Track® at d+200 after CMViraemia between d+100 and d+200. 24 patients were persistently negative at d+300. Despite a positive T-Track® at d+100, 28/110 (25%) patients needed treatment for CMV reactivation. In most of them immunosuppressive treatment for GvHD was initiated after d+100: 20/28 (71%) high dose corticosteroids, 1/28 (4%) Ruxolitinib. Excluding patients, that received additional immunosuppression after d+100 only 7/89 (8%) developed a CMV reactivation despite a positive d+100 T-Track®. This yields a negative predictive value of 0,921 for the result of T-Track® at d+100. 25/59 (42%) patients with a negative T-Track® at d+100 subsequently developed a treatment requiring CMV reactivation. Discussion/Conclusion: CMV T-Track® is feasible in clinical routine and can help identify patients at risk for CMV reactivation. In our cohort 110/169 (65%) patients showed a cellular immune response against CMV at day +100. Excluding patients that received additional immunosuppression in the later course, only 7/89 (8%) developed a CMV reactivation after a positive d+100 T-Track®. With this T-Track® result at d+100 has a negative predictive value of 0,921. CMV negative donor was the strongest predictor for a negative test result. Alemtuzumab was the only TCD associated with a negative impact. CMVireamia increases CMV immune response and is mandatory in patients with a CMV negative donor to establish CMV-immunity. We therefore consider CMV T-Track® a useful tool in clinical routine to identify patients with sufficient CMV-immunity at d+100. This could help to guide monitoring intervals or therapeutic decisions such as prolonged prophylaxis or need for preemptive treatment.

2730. Clinically significant cytomegalovirus infection in patients with lymphoma and no prior cellular therapy

Abstract Background Reactivation of cytomegalovirus (CMV) is commonly reported in lymphoma patients who undergo cellular therapy, with often poor outcomes. The risk for CMV reactivation in patients with lymphoma prior to cellular therapy is not well understood. As new alternative immunosuppressive therapies emerge for lymphoma, understanding baseline risk for CMV reactivation is paramount to improve clinical and oncologic outcomes. Our goal was to identify risk factors, and describe outcomes associated with clinically significant CMV infection (CS-CMVi) in lymphoma patients with no prior cellular therapy. Methods We performed a retrospective cohort study for all lymphoma patients who underwent testing for CMV by PCR from blood between 1/2017 and 12/2020. Patients with prior history of transplantation or chimeric antigen receptor therapy were excluded. Patients with and without CS-CMVi were identified for risk factor analysis by univariate analysis. Results A total of 217 lymphoma patients were included in our analysis; CS-CMVi was identified in 41 (19%) patients. When compared to patients without CS-CMVi (control group), lymphoma patients with CS-CMVi were more likely to have history of HIV (5% vs 0%; p= 0.0350), primary central nervous system lymphoma (7% vs 1%; p= 0.0220) and relapsed disease (54% vs 25%; p= 0.0005) (Table 1). CS-CMVi was also more common if testing was done at time of relapse diagnosis (32% vs 10%; p= 0.0007), during work up for infection (98% vs 68%; p &amp;lt; 0.0001) and more often (3 vs 1; p &amp;lt; 0.0001) (table 1). Mortality and remission rates within 1 year of testing were worse in patients with CS-CMVi (table 2 and figure 1). Conclusion CS-CMVi in lymphoma patients is associated with poor outcomes including oncologic outcomes. Further analysis to better define patients with lymphoma at high-risk for CS-CMVi should be studied for future preventative strategies. Disclosures Fareed Khawaja, MBBS, MEDSCAPE: Honoraria|Viracor: Grant/Research Support Roy F. Chemaly, MD/MPH, Eurofins-VViracor: Grant/Research Support|Karius: Advisor/Consultant

Low-Dose ATG Has the Same Risk of CMV Reactivation after Allogeneic PBSCT As Ptcy, but Letemovir Is Effective in Preventing CMV Reactivation

[Introduction] Allogeneic peripheral blood stem cell transplantation (allo-PBSCT) is a curative treatment for hematological malignancies but has a risk of a chronic graft-versus-host disease (GVHD) compared to other donor sources. Post-transplant cyclophosphamide (PTCY) has been spread rapidly worldwide from HLA haploidentical-SCT (Haplo-SCT) to HLA matched-SCT. Although PTCY was theoretically thought to preserve non-alloreactive T cells which can contribute to fight infection, recent studies showed that PTCY was associated with the increased incidence of cytomegalovirus (CMV) infection. Letermovir (LTV), a novel anti-CMV agent, was useful for the prevention of CMV reactivation after SCT including Haplo-SCT using PTCY. On the other hand, low-dose antithymocyte globulin (ATG) is an alternative and useful option for GVHD prophylaxis in allo-PBSCT and often used in Japan. However, the risk of post-transplant CMV reactivation and the protective effect of LTV when using low-dose ATG remain to be elucidated. [Methods] We retrospectively analyzed 222 recipients who received allo-PBSCT using PTCY or low-dose ATG at Hokkaido University Hospital from January 2013 to July 2021. Of the 121 patients who underwent PBSCT with PTCY, 69 (all patients underwent Haplo-PBSCT) were without LTV prophylaxis and 52 (34 patients, Haplo-PBSCT) were with LTV. On the other hand, of the 101 patients who underwent PBSCT with low-dose ATG, 66 (12 patients, Haplo-PBSCT) were without LTV and 35 (2 patients, Haplo-PBSCT) were with LTV. LTV was administered on the day 0 at a dosage of 480 mg daily. All patients were monitored for CMV reactivation by using the anti-CMV pp65 monoclonal antibody HRP-C7 assay at least weekly from neutrophil engraftment to discharge and after discharge monthly until day 180 after SCT. CMV reactivation was defined as the start of CMV preemptive therapy, generally initiated when there are 2 or more CMV antigen positive cells per 50000 white blood cells. Moreover, CMV disease was defined by organ dysfunction attributable to CMV. [Results] Baseline characteristics of the patients are summarized in Table 1. Although more patients in ATG group compared to PTCY group received myeloablative conditioning regimen significantly, there was no significant difference between the groups in terms of sex, age, underlying disease, disease risk at SCT, and CMV serostatus. GVHD prophylaxis in PTCY consisted of CY (40-50 mg/kg on day 3 and 4), tacrolimus (from day 5), and mycophenolate mofetil (from day 5), whereas that in ATG consisted of ATG at a total dose of 2-3 mg/kg around day -2, tacrolimus (from day -1) and short-term methotrexate. LTV prophylaxis significantly reduced the cumulative incidence of CMV reactivation at 180 days after SCT in PTCY group (69.6% without LTV vs. 22.4% with LTV, p&amp;lt;0.001) and ATG group (62.6% without LTV vs. 18.9% with LTV, p&amp;lt;0.001; Figure 1.). Importantly, although CMV disease were occurred in 2 patients in PTCY (1 gastritis and 1 retinitis) and 8 focuses in 7 patients (3 pneumoniae, 3 enteritis, 1 retinitis, and 1 glossitis) in ATG without LTV prophylaxis, none of the patients receiving LTV developed CMV disease in both group. Moreover, LTV did not affect overall survival, the cumulative incidence of non-relapse mortality, relapse, acute GVHD, and engraftment of neutrophil and platelet. Interestingly, the cases of early CMV reactivation within 100 days after SCT under LTV prophylaxis was significantly more frequent in ATG than in PTCY (p=0.0345). [Conclusion] CMV reactivation occurred with similar frequency after allo-PBSCT with low-dose ATG as after that with PTCY. LTV was effective for prevention of CMV reactivation in both GVHD prophylaxis methods. CMV breakthrough reactivation may be likely to occur in PBSCT with low-dose ATG compared to that with PTCY even under LTV prophylaxis, and careful CMV monitoring may be required.

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

Cytomegalovirus (CMV) is associated with morbidity and mortality following allogeneic hematopoietic cell transplantation (alloHCT). Letermovir is a novel antiviral agent that prevents CMV reactivation in alloHCT patients, with limited data regarding influence on post-alloHCT outcomes. We retrospectively examined 273 alloHCT recipients, 158 in the non-letermovir cohort (NLC), and 115 in the cohort using letermovir prophylaxis (LC). Patients that received letermovir were CMV-seropositive and met criteria for high risk of CMV reactivation. Median start of letermovir was 21 days post-alloHCT, median duration of prophylaxis was 86 days. Letermovir prophylaxis demonstrated a statistically significant reduction in first CMV reactivation (at 200 days post 63.9% in the NLC vs. 35.7% in the LC; p < .001). On univariate analysis at 1 year, overall survival (OS) for NLC was 79.6% and 79.5% for LC (p = .54). Non relapse mortality (NRM) at 1 year for NLC was 12% and 12.3% for LC (p = .69). Cumulative incidence of relapse (CIR) at 1 year was 13.9% for NLC versus 17.1 for the LC (p = .27). On multivariable analysis, there was no significant difference between the two cohorts for OS, NRM, and CIR. Letermovir prophylaxis started at day +21 post-alloHCT reduced CMV reactivation, with no impact on posttransplant outcomes.

Cytomegalovirus reactivation under pre-emptive therapy following allogeneic hematopoietic stem cell transplant: Pattern, survival, and risk factors in the Republic of Korea.

Pre-emptive therapy for cytomegalovirus (CMV) reactivation has been used in allogeneic hematopoietic stem cell transplantation (allo-HSCT). It is unclear if this strategy has poorer clinical outcomes in CMV-endemic areas and if more aggressive prophylaxis is required. We retrospectively analyzed the patterns and survival after CMV reactivation in patients undergoing pre-emptive therapy following allo-HSCT and assessed high-risk patients who could benefit from aggressive CMV prophylaxis in endemic areas. Of the 292 patients who underwent allo-HSCT, 70.5% (donor+ or recipient+) were CMV seropositive. CMV reactivation occurred in 139 patients (47.6%), with a median of 31.5 days from day 0 of allo-HSCT. The overall survival of patients with CMV reactivation who received pre-emptive therapy did not differ from those without reactivation. Of the 139 patients with CMV reactivation, 78 (56.1%) underwent ≥2 rounds of pre-emptive therapy. In multivariate analysis, the risk of CMV reactivation was higher in patients with multiple myeloma, with CMV seropositivity of the recipient and donor, administered with a higher dose of anti-thymocyte globulin (ATG), and with acute graft-versus-host disease (aGVHD) ≥ grade 2. Although half of the patients with allo-HSCT were administered with pre-emptive therapy for CMV, CMV reactivation did not affect their survival, indicating the advantages of pre-emptive therapy, even in CMV-endemic areas. The cost-effectiveness of more aggressive CMV prophylaxis should be re-evaluated in patients at a high risk for CMV reactivation.

Oral Versus Intravenous Anti-CMV Preemptive Strategies in Allogeneic Stem Cell Transplant Patients with CMV Reactivation: Experience from the National Center of Bone Marrow Transplantation, Tunis, Tunisia

Cytomegalovirus (CMV) infection is a common and severe complication following allogeneic stem cell transplantation (ASCT) and requires effective preemptive antiviral therapy. Both oral and intravenous (IV) antiviral agents effectively reduce CMV viral load and achieve viral clearance. Studies comparing oral and IV anti-CMV preemptive treatment in ASCT patients with CMV reactivation showed a potential difference in treatment response and safety profiles between the two administration routes. We retrospectively compared the efficacy and safety of oral with intravenous (IV) anti-CMV preemptive therapy in ASCT recipients with CMV reactivation. A descriptive retrospective study included patients who received their first ASCT between January 2018 and June 2022. The monitoring oral load was assessed weekly using a quantitative polymerase chain reaction in plasma. Fifty-five patients developing 72 CMV reactivations were included. The median age was 29 years (range, 6-50). The main underlying diseases were acute leukemia and aplastic anemia. Before ASCT, 96% of patients were at high risk of CMV reactivation. CMV reactivations were observed at a median of 43 days (range, 16-270) post-ASCT. The median viral load at CMV reactivation was 248 copies/mL (range, 150-4800). The first-line preemptive treatment was oral in 51 (71%) of the episodes (Valganciclovir, n = 40; Leflunomide, n = 11) and IV in 21 (29%) of the episodes (Foscarnet, n = 16; Ganciclovir, n = 5). Response to first-line therapy was not statistically significant between the two groups (74% vs 76%, p = 0.88). Thirteen (25%) and 5 (24%) episodes needed second or subsequent-line therapy in the oral and IV groups, respectively. The hematological toxicity was significantly higher in the oral group (61% vs 29%, p = 0.01). The mean duration of hospital stay per patient in the oral and IV groups was 7 days and 49 days (p &lt; 10&lt;sup&gt;-3&lt;/sup&gt;), respectively. More non-CMV documented infections were observed in the IV group (38% vs 4%, p = 0.001). After a median follow-up of 18 months (range, 2-55), the 2-year-overall survival, event-free survival and cumulative incidence of non-relapse mortality were 85%, 75% and 6%, respectively. Our results showed that the oral preemptive therapy for CMV reactivations after ASCT was as effective as IV formulations and needed less hospital stay time. However, it is associated with more hematological toxicity.

Torque teno virus viremia and QuantiFERON®-CMV assay in prediction of cytomegalovirus reactivation in R+ kidney transplant recipients.

Cytomegalovirus (CMV) is the most frequent infectious complication following solid organ transplantation. Torque teno viruses (TTV) viremia has been proposed as a biomarker of functional immunity in the management of kidney transplant recipients (KTR). The QuantiFERON®-CMV (QF-CMV) is a commercially available assay that allows the assessment of CD8+ T-cell responses in routine diagnostic laboratories. In a prospective national multicenter cohort of 64 CMV-seropositive (R+) KTR, we analyzed the value of TTV load and the two markers of the QF-CMV assay [QF-Ag (CMV-specific T-cell responses) and QF-Mg (overall T-cell responses)], alone and in combination, in prediction of CMV reactivation (≥3 log10 IU/ ml) in the first post-transplant year. We compared previously published cut-offs and specific cut-offs optimized from ROC curves for our population. Using the conventional cut-off (3.45 log10 copies/ml), TTV load at D0 [inclusion visit on the day of transplantation before induction (D0)], or at M1 (1-month post-transplant visit) perform better in predicting CMV viremia control than CMV reactivation. Survival analyses suggest a better performance of our optimized TTV cut-offs (3.78 log10 copies/ml at D0 and 4.23 log10 copies/ml at M1) for risk stratification of CMV reactivation in our R+ KTR cohort. The QF-CMV (QF-Ag = 0.2 IU/ml, and QF-Mg = 0.5 IU/ml) also appears to better predict CMV viremia control than CMV reactivation. Moreover, survival analyses suggest that the QF-Mg would perform better than the QF-Ag in stratifying the risk of CMV reactivation. The use of our optimized QF-Mg cut-off (1.27 IU/ml) at M1 further improved risk stratification of CMV reactivation. Using conventional cut-offs, the combination of TTV load and QF-Ag or TTV load and QF-Mg did not improve prediction of CMV viremia control compared to separate analysis of each marker but resulted in an increase of positive predictive values. The use of our cut-offs slightly improved risk prediction of CMV reactivation. The combination of TTV load and QF-Ag or TTV load and QF-Mg could be useful in stratifying the risk of CMV reactivation in R+ KTR during the first post-transplant year and thereby have an impact on the duration of prophylaxis in these patients. ClinicalTrials.gov registry, identifier NCT02064699.

Absolute lymphocyte counts (ALC) recovery and risk of viral reactivation in the setting of haploidentical hematopoietic stem cell transplant.

e19065 Background: The impact of early absolute lymphocyte repopulation after allogeneic hematopoietic stem cell transplant has historically been shown to predict the risk of post-transplant infection, and subsequently, non-relapse mortality (NRM). Previous studies have shown that ALC recovery after allogeneic stem cell transplant is associated with risk of viral reactivation and survival. In this study we aim to investigate the role of ALC recovery in the contemporary era with myeloablative haploidentical hematopoietic stem cell transplant (HI-HSCT). Methods: We retrospectively analyzed adult patients at University of Southern California (USC) Norris Cancer Hospital who received myeloablative conditioning haplo-HSCT (Fludarabine with 12 Gy of radiation) from 2014 to 2020. The primary endpoint was correlation between ALC recovery day 21 and risk of viral reactivation including cytomegalovirus (CMV), Epstein-Barr Virus (EBV) and BK virus. ALC recovery cut off was chosen to be 175/uL on day +21 and 500/uL on day +60 based on prior reports. Results: 58 patients were identified as recipients of MAC haploidentical-HSCT. 17 had ALC recovery at day +21. Mean age was 49 years, 31 (53.4%) were males and 27 (46.6%) were females. 41 (70%) patients were Hispanic, 12 (20%) were non-Hispanic White, and the majority had AML (51%). 76% received &gt; 5*106/kg CD34+ cell dose and 78% received CD3 + cell dose &lt; 3*108/kg. Serum CMV, EBV and urine BK virus were detected in 38 (65.5%), 8 (15.7%) and 11 (32.4%) respectively. Clinically significant CMV reactivation (required treatment with antiviral therapy) was detected in 26 (44.8%) patients. Lack of ALC recovery on day +21 did not show correlation with CMV, EBV and BK virus reactivation. Also, the risk of CMV reactivation was not related to day +60 ALC recovery (p-value = 0.469). On univariate analysis, ALC recovery day +21, day +60, and CMV reactivation did not show correlation with overall survival. In multivariate analysis when adjusted for age and pre-transplant CMV status, higher CD 3+ cell dose of &gt; 3*108/kg was associated with reduced risk of CMV reactivation HR = 0.35 (0.15-0.85) p-value = 0.02. Conclusions: Previous studies have established ALC recovery as a predictor of better outcome. This has not been established in patients undertaking myeloablative HI-HSCT. Our study shows that lack of ALC recovery on day +21 does not affect CMV, EBV and BK virus reactivation and risk of CMV reactivation does not correlate with day +60 ALC recovery. Also, ALC recovery and CMV reactivation does not impact overall survival. The use of Letermovir, effective CMV therapies and close viral surveillance in contemporary practice is likely responsible for mitigating poor outcomes with CMV reactivation. Graft composition needs to be studied prospectively, as higher CD3+ cell dose may present an opportunity to reduce CMV reactivation in HI-HSCT.

Use of Letermovir for CMV Prophylaxis after Allogeneic Hematopoietic Stem Cell Transplantation: Review of the Literature and Single-Center Real-Life Experience

Cytomegalovirus (CMV) reactivation after allogeneic hematopoietic stem cell transplant (allo-HSCT) is mainly due to an increase of latent viremia in previously exposed patients. Furthermore, CMV reactivation in this setting has a significant impact on patient survival. Traditional approach to CMV reactivation post allo-HSCT was a pre-emptive treatment with antivirals in the case of increased viremia. However, since 2017, a new antiviral compound, letermovir, has been introduced in clinical practice and is deeply changing the common CMV approach. The toxicity profile of letermovir allowed its use in prophylaxes in patients at high risk of CMV reactivation. This review will focus on the present role of letermovir post allo-HSCT and discuss some possible future applications of the drug. Finally, our single center CMV management in view of the recent introduction of letermovir will be discussed.

Impact of GVHD prophylaxis on CMV reactivation and disease after HLA-matched peripheral blood stem cell transplantation.

The kinetics of early and late cytomegalovirus (CMV) reactivation after hematopoietic cell transplantation using various methods of graft-versus-host-disease (GVHD) prophylaxis are poorly defined. We retrospectively compared CMV reactivation and disease among 780 seropositive patients given HLA-matched peripheral blood stem cell (PBSC) grafts and calcineurin inhibitor plus posttransplantation cyclophosphamide (PTCy; n= 44), mycophenolate mofetil (MMF; n= 414), or methotrexate (MTX; n= 322). Transplantation occurred between 2007 and 2018; CMV monitoring/management followed uniform standard practice. Hazards of CMV reactivation at various thresholds were compared. Spline curves were fit over average daily viral load and areas under the curve (AUC) within 1 year were calculated. PTCy and MMF were associated with an increased risk of early (day ≤100) CMV reactivation ≥250 IU/mL after multivariate adjustment. The viral load AUC at 1 year was highest with MMF (mean difference= 0.125 units vs MTX group) and similar between PTCy and MTX (mean difference= 0.016 units vs MTX group). CMV disease risk was similar across groups. There was no interaction between GVHD prophylaxis and CMV reactivation on chronic GVHD risk. Despite PTCy-associated increased risk of early CMV reactivation, the CMV disease risk by 1 year was low in HLA-matched PBSC transplant recipients. In contrast, MMF was associated with higher overall CMV viral burden in the 1 year posttransplant. Although different mechanisms of immunosuppressive agents may affect CMV reactivation risk, effective prevention of GVHD may reduce corticosteroid exposure and mitigate infection risk over time.

Prospective Evaluation of CD45RA+/CCR7- Effector Memory T (TEMRA) Cell Subsets in Patients with Primary and Secondary Brain Tumors during Radiotherapy of the Brain within the Scope of the Prospective Glio-CMV-01 Clinical Trial.

Radiotherapy (RT) of the brain is a common treatment for patients with high-grade gliomas and brain metastases. It has previously been shown that reactivation of cytomegalovirus (CMV) frequently occurs during RT of the brain. This causes neurological decline, demands antiviral treatment, and is associated with a worse prognosis. CMV-specific T cells are characterized by a differentiated effector memory phenotype and CD45RA+ CCR7- effector memory T (TEMRA) cells were shown to be enriched in CMV seropositive individuals. In this study, we investigated the distribution of TEMRA cells and their subsets in the peripheral blood of healthy donors and, for the first time, prospectively within the scope of the prospective Glio-CMV-01 clinical trial of patients with high-grade glioma and brain metastases during radiation therapy as a potential predictive marker. First, we developed a multicolor flow cytometry-based assay to monitor the frequency and distribution of TEMRA cells in a longitudinal manner. The CMV serostatus and age were considered as influencing factors. We revealed that patients who had a reactivation of CMV have significantly higher amounts of CD8+ TEMRA cells. Further, the distribution of the subsets of TEMRA cells based on the expression of CD27, CD28, and CD57 is highly dependent on the CMV serostatus. We conclude that the percentage of CD8+ TEMRA cells out of all CD8+ T cells has the potential to serve as a biomarker for predicting the risk of CMV reactivation during RT of the brain. Furthermore, this study highlights the importance of taking the CMV serostatus into account when analyzing TEMRA cells and their subsets.

Cytomegalovirus breakthrough and resistance during letermovir prophylaxis.

Letermovir is a relatively new antiviral for prophylaxis against cytomegalovirus (CMV) after allogeneic hematopoietic cell transplantation (HCT). CMV-seropositive HCT recipients who received letermovir prophylaxis from 2018 to 2020 at our center were evaluated for letermovir resistance and breakthrough CMV reactivation. Two-hundred twenty-six letermovir recipients were identified and 7/15 (47%) with CMV DNAemia ≥200 IU/mL were successfully genotyped for UL56 resistance. A single C325Y resistance mutation was identified in an umbilical cord blood recipient. Ninety-five (42%), 43 (19%), and 15 (7%) patients had breakthrough CMV at any level, ≥150 IU/mL, and ≥500 IU/mL, respectively. Risk factors for breakthrough CMV reactivation at each viral threshold were examined. Cumulative steroid exposure was the strongest risk factor for CMV at all evaluated viral thresholds. Graft-versus-host disease prophylaxis with post-transplantation cyclophosphamide (aHR 2.34, 95% CI 1.28-4.28, p = 0.001) or calcineurin inhibitors plus mycophenolate (aHR 2.24, 95% CI 1.30-3.86, p = 0.004) were also associated with an increased risk of CMV reactivation at any level. De novo letermovir resistance is rare and can be successfully treated using other antivirals. Letermovir effectively prevents clinically significant CMV, however, subclinical CMV reactivation occurs frequently at our center.

491. Characterizing the Association of Pre-Existing Cytomegalovirus (CMV)-specific Humoral Immunity with CMV Reactivation Risk after Hematopoietic Cell Transplantation (HCT)

Abstract Background There is renewed interest in CMV-specific humoral immune protection due to recent murine data suggesting that strain-specific antibodies may inhibit CMV cell-to-cell spread (Science. 2019; 363:288). To characterize the nature of antibody protection against CMV after HCT, we tested pre-HCT sera in a cohort of CMV D-R+ allogeneic HCT recipients from the pre-letermovir era using VirScan, a technology that measures pathogen-specific humoral immunity (IgG) at the epitope level. Methods Patients (age 0-70 years) who received 1st, myeloablative, HCT for acute leukemia or myelodysplastic syndrome and who underwent PCR surveillance and preemptive therapy were included. VirScan was used on sera collected pre-HCT. Cumulative incidence curves and multivariable Cox regression analyses were used to determine the association of pre-HCT CMV antibody epitopes scores with CMV reactivation (any, &amp;gt;150 IU/mL, &amp;gt;500 IU/mL) in the first 8 weeks post-HCT. Results 170 CMV D-R+ HCT recipients were tested a median of 26 days (range 7-37 days) prior to HCT and had a median of 37 CMV antibody epitopes (IQR 29-50 epitopes, range 14-77 epitopes). The cumulative incidence of CMV reactivation was higher in patients with greater pre-HCT CMV antibody epitopes at each evaluated PCR threshold (Figure 1) and the effect appeared more pronounced in adults (Figure 2). High (≥ 4th quartile vs. 1st quartile), pre-HCT CMV antibody epitopes were associated with an increased risk of any CMV reactivation (adjusted Hazard Ratio [aHR]=4.1, 95% confidence interval [CI] 2.1-7.7, p&amp;lt; 0.001) and at &amp;gt;150 IU/mL (aHR=3.0, 95% CI 1.4-6.5 p=0.006) after adjusting for age, HLA-matching, and pre-HCT T-cell depletion ( &amp;gt;150 IU/mL only). Figure 1Figure 2 Conclusion We observed a paradoxically increased risk of CMV reactivation in patients with high pre-HCT CMV VirScan scores. It is possible that pre-HCT CMV-specific humoral immunity as measured by VirScan is reflective of the burden of latent CMV or that CMV-specific antibodies may mediate antibody-dependent enhancement after HCT and thus facilitate reactivation. Future studies are needed to validate our findings in diverse cohorts and to elucidate the underlying mechanism of increased VirScan scores and associated risks of CMV reactivation. Disclosures Rachel A. Bender Ignacio, MD, MPH, Abbvie: Advisor/Consultant|SeaGen: Advisor/Consultant Joshua A. Hill, MD, Allovir: Advisor/Consultant|Allovir: Grant/Research Support|Covance/CSL: Advisor/Consultant|CRISPR: Advisor/Consultant|Deverra: Grant/Research Support|Gilead: Grant/Research Support|Karius: Advisor/Consultant|Karius: Grant/Research Support|Merck: Grant/Research Support|Octapharma: Advisor/Consultant|OptumHealth: Advisor/Consultant|Oxford Immunotec: Grant/Research Support|Pfizer: Advisor/Consultant|Symbio: Advisor/Consultant|Takeda: Advisor/Consultant Geoffrey Hill, M.D., FRACP, FRCPA, Applied Molecular Transport: Grant/Research Support|Compass Therapeutics: Grant/Research Support|Generon Corporation: Advisor/Consultant|Heat Biologics: Grant/Research Support|iTeos Therapeutics: Advisor/Consultant|iTeos Therapeutics: Grant/Research Support|Laevoroc Oncology: Grant/Research Support|NapaJen Pharma: Advisor/Consultant|Neoleukin Therapeutics: Advisor/Consultant|Serplus Technology: Grant/Research Support|Syndax Pharmaceuticals: Grant/Research Support Michael J. Boeckh, MD PhD, Allovir: Advisor/Consultant|Amazon: Grant/Research Support|Ansun Biopharma: Grant/Research Support|EvrysBio: Advisor/Consultant|Gates Ventures: Grant/Research Support|Gilead Sciences: Advisor/Consultant|Gilead Sciences: Grant/Research Support|GlaxoSmithKline: Advisor/Consultant|GlaxoSmithKline: Grant/Research Support|Helocyte: Advisor/Consultant|Janssen: Advisor/Consultant|Janssen: Grant/Research Support|Kyorin Pharmaceuticals: Advisor/Consultant|Merck: Advisor/Consultant|Merck: Grant/Research Support|Moderna: Advisor/Consultant|Moderna: Grant/Research Support|Regeneron: Grant/Research Support|ReViral: Advisor/Consultant|Symbio: Advisor/Consultant|Takeda: Grant/Research Support|Vir Biotechnology: Advisor/Consultant|Vir Biotechnology: Grant/Research Support.

Letermovir Prophylaxis for High-Risk Allogenic Transplantation Recipients, Real- World Israeli Experience

Introduction: Cytomegalovirus (CMV) infection is a common complication after allogeneic hematopoietic-cell transplantation (alloHCT) causing significant morbidity and mortality. The standard approach for preventing clinically significant CMV infection (CS-CMVi) and CMV disease (CMVd), is preemptive therapy (PET) upon detection of CMV reactivation. In 2017 letermovir was approved for CMV prophylaxis in CMV-seropositive allogeneic HCT recipients from transplantation through day 100 after alloHCT. At 2020, letermovir was approved in Israel for prophylaxis in CMV-seropositive alloHCT recipients who were at higher risk for CMV reactivation (seronegative donor, HLA mismatched unrelated donor, haploidentical family donor, ex-vivo T cell depleted graft or recipient suffering from acute Graft Versus Host Disease (aGVHD) requiring >1mg/kg steroid therapy). There is paucity of real-world data regarding the efficacy and outcomes of letermovir prophylaxis in the post-transplant setting. The aim of our study was to report the real-world Israeli experience with letermovir prophylaxis in terms of incidence of CS-CMVi, CMVd and aGVHD, chronic Graft Versus Host Disease (cGVHD), survival and all-cause mortality. Methods: We retrospectively analyzed a cohort of 45 alloHCT recipients at high risk for CMV reactivation, from 4 Israeli transplant centers, who underwent alloHCT between January 2020 and -December 2021 and received letermovir prophylaxis (study group). A comparison was performed, to a matched historical cohort of 45 alloHCT recipients, who underwent alloHCT between 2014 and 2020 and were treated according to PET policy (control group). Matching was guided by the risk for CMV reactivation. Results: Demographics (recipient's age, gender, ethnicity), disease and pre-transplant characteristics (disease status at transplantation, donor match, conditioning intensity, graft source) of the two groups were comparable accept for a higher percentage of ABO minor mismatch in the control group versus the study group (37% compared to 6%, respectively; p=0.028). There was a higher rate of CS-CMVi during the first 100 days post-transplant in the control group versus the study group (53/3% compared to 35.6%, respectively; p=0.09). There was no difference in CMVd rate between the two groups as well as in relapse rate and overall survival. Acute and chronic GVHD incidence was higher in the control group compared to the study group (71.1% vs 60%; p=0.186 and 57.8% vs 33.3%; p= 0.02, respectively). Conclusions: Our real -world Israeli experience cohort of letermovir prophylaxis in high risk alloHCT recipients demonstrates a significant reduction in GVHD occurrence in patients receiving letermovir prophylaxis. GVHD is a significant cause of morbidity and mortality in alloHCT recipients. Our real-world experience is in line with the well-established contiguity and causal relation between CMV infection and GVHD, showing a reduction in CS-CMVi during the prophylaxis period with a corresponding reduction in acute and chronic GVHD. Our cohort is limited by its retrospective nature and a relatively small sample size. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal