Impact of Anti-CMV IgG Titers and CD34 Count Prior to Hematopoietic Stem Cell Transplantation from Alternative Donors on CMV reactivation

Reexploring cytomegalovirus serology in allogeneic hematopoietic cell transplantation

PURPOSE OF REVIEW

Discuss the recent evidence on cytomegalovirus (CMV) serology in allogeneic hematopoeic cell transplant (HCT) recipients.

RECENT FINDINGS

Whereas the role CMV-specific cellular mediated immunity has recently emerged as an important factor of CMV DNAemia posttransplant, the value of CMV serology has remained unchanged through decades, associated with donor selection and posttransplant prophylactic and monitoring strategies. In this review, we describe and discuss the emerging reports on the association between the magnitude of pretransplant CMV immunoglobulin G (IgG) titer and the posttransplant incidence of CMV DNAemia, as CMV IgG titer could become an additional tool in CMV risk assessment in the future.

SUMMARY

Pretransplant recipient CMV serology may have significant implications in posttransplant CMV reactivation in allogeneic HCT recipients.

Revisiting Cytomegalovirus Serology in Allogeneic Hematopoietic Cell Transplant Recipients

BACKGROUND

Allogeneic hematopoietic cell transplant recipients (allo-HCTRs) with positive cytomegalovirus (CMV) serology may have false-positive results due to blood product transfusion-associated passive immunity.

METHODS

This single-center cohort study included allo-HCTRs with negative baseline (at malignancy diagnosis) CMV serology and indeterminate/low-positive (CMV IgG titer, ≥0.6-<50 U/mL) pretransplant CMV serology with negative pretransplant plasma CMV DNAemia. The CMV status of those patients was reclassified from R+ to R- (CMVR- reclassification group). We compared those patients to allo-HCTRs with negative (CMV IgG titer <0.6 U/mL) pretransplant CMV IgG (CMVR- group). We describe the number and type of patients whose pretransplant CMV status was reclassified from indeterminate/positive to negative. We reviewed all plasma CMV DNAemia tests performed during the first 6 months posttransplant in both groups to assess the safety of this approach.

RESULTS

Among 246 (84.5%) of 291 transplanted patients identified as CMVR+ pretransplant, 60 (24.4%) were reclassified from CMV serology indeterminate (N:10)/low-positive (N:50) to R-. Only 1 of 60 patients (1.67%) in the CMVR- reclassification group versus 3 of 44 (6.8%; P = .30) in the CMVR- group developed CMV DNAemia during the follow-up period. There were no significant differences in the number of CMV DNAemia tests performed, CMV DNAemia range, and time posttransplant between the 2 groups.

CONCLUSIONS

One of 4 allo-HCT CMVR+ may be falsely flagged as R+, with significant impact on donor selection and prophylaxis administration. A 2-step approach including CMV serology testing at hematologic malignancy diagnosis in allo-HCT candidates and careful review of pretransplant CMV IgG titers may help correctly classify CMV serology status.

Human virome profiling identified CMV as the major viral driver of a high accumulation of senescent CD8+ T cells in patients with advanced NSCLC

Circulating senescent CD8+ T (T8sen) cells are characterized by a lack of proliferative capacities but retain cytotoxic activity and have been associated to resistance to immunotherapy in patients with advanced non-small cell lung cancer (aNSCLC). We aimed to better characterize T8sen and to determine which factors were associated with their accumulation in patients with aNSCLC. Circulating T8sen cells were characterized by a higher expression of SA-βgal and the transcription factor T-bet, confirming their senescent status. Using whole virome profiling, cytomegalovirus (CMV) was the only virus associated with T8sen. CMV was necessary but not sufficient to explain high accumulation of T8sen (T8senhigh status). In CMV+ patients, the proportion of T8sen cells increased with cancer progression. Last, CMV-induced T8senhigh phenotype but not CMV seropositivity itself was associated with worse progression-free and overall survival in patients treated with anti-PD-(L)1 therapy but not with chemotherapy. Overall, CMV is the unique viral driver of T8sen-driven resistance to anti-PD-(L)1 antibodies in patients with aNSCLC.

CMV-IgG pre-allogeneic hematopoietic stem cell transplantation and the risk for CMV reactivation and mortality

Cytomegalovirus (CMV) represents one of the most common infectious complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Currently, a common diagnostic test used to stratify the risk for CMV infection in allo-HSCT recipients is the qualitative CMV serology of donor and recipient. A positive serostatus of the recipient is the most important risk factor for CMV reactivation and associated with reduced overall survival post-transplantation (TX). Direct and indirect effects of CMV are involved in the poorer survival outcome. The present study investigated if the quantitative interpretation of anti-CMV IgG before allo-HSCT might serve as a novel parameter for the identification of patients at risk for CMV reactivation and worse outcome post-TX. For this purpose, a cohort of 440 allo-HSCT recipients over a period of 10 years was retrospectively analyzed. Our findings indicated that patients with high CMV IgG pre-allo-HSCT had a higher risk to develop CMV reactivation, including clinically relevant infections, and a worse prognosis 36 months post-allo-HSCT as compared to recipients with low CMV IgG values. In the letermovir (LMV) era, this group of patients might benefit from a closer CMV monitoring, and hence, earlier intervention if needed, especially after discontinuation of prophylaxis.

Unique Reduced-Intensity Conditioning Haploidentical Peripheral Blood Stem Cell Transplantation Protocol for Patients with Hematologic Malignancy

Reduced-intensity conditioning (RIC) haploidentical (haplo-) hematopoietic stem cell transplantation (HSCT) requires more hematopoietic progenitor and stem cells (HPSCs) to promote engraftment and immune reconstitution and needs a stronger graft-versus-leukemia effect. Peripheral blood stem cells (PBSCs) offer advantages over bone marrow; however, the use of higher-dose non-T cell-depleted (non-TCD) in vitro PBSCs may increase the occurrence of severe graft-versus-host disease (GVHD). This prospective, single-arm clinical study was performed to investigate using high-dose non-TCD in vitro PBSCs as the graft source, using fludarabine/Ara-C/busulfan (FAB) as the conditioning regimen, using rabbit antithymocyte globulin to remove T cells in vivo, and enhancing GVHD prophylaxis with an IL-2 receptor antagonist in RIC-haplo-HSCT in patients with hematologic malignancies age 50 to 70 years or <50 years with comorbidities (Hematopoietic Cell Transplantation Comorbidity Index score ≥2) classified as intermediate to high risk. The primary endpoint was day 100 acute GVHD (aGVHD). A total of 47 patients were enrolled; the median age was 52 years (range, 30 to 68 years), the median duration of follow-up was 34 months (range, 2 to 99 months), and the medium-infused doses of mononuclear cells, CD34⁺ cells, and CD3⁺ cells were 15.93 × 10⁸/kg, 8.68 × 10⁶/kg, and 5.57 × 10⁸/kg, respectively. The cumulative incidence of grade II-IV aGVHD at day 100 was 30.3% (95% confidence interval [CI], 15.9% to 44.8%), and that of grade III-IV aGVHD was 10.2% (95% CI, .6% to 19.8%). The 2-year cumulative incidence of chronic GVHD (cGVHD) was 34.9% (95% CI, 19.0% to 50.8%). The 2-year cumulative incidences of localized and extensive cGVHD were 26.1% (95% CI, 11.80% to 40.40%) and 8.7% (95% CI, 3.26% to 20.65%), respectively. The 2-year cumulative incidence of relapse was 17.3% (95% CI, 5.1% to 29.5%), the 2-year overall survival rate was 71.2% (95% CI, 57.9% to 84.5%), and the 2-year disease-free survival rate was 66.2% (95% CI, 52.1% to 80.3%). The incidence of aGVHD was not high, and the overall efficacy was good. This study demonstrates that this unique RIC-haplo-PBSC transplantation protocol was effective in treating hematologic malignancies. Nonetheless, larger prospective multicenter clinical trials and experimental studies should be performed to further confirm our findings.

Efficacy of Cytomegalovirus Specific Immunoglobulins to Reduce CMV Reactivation in Pediatric Hematopoietic Stem Cell Transplant Recipients

Cytomegalovirus (CMV) infection is a serious complication of pediatric hematopoietic stem cell transplant (HSCT). To date, antiviral therapy has been the mainstay of prophylaxis, with conflicting results regarding the benefits of CMV-specific immunoglobulins (CMV-Ig). After introducing prophylactic CMV-Ig to HSCT recipients at risk (seropositive recipient and/or donor), we conducted a single-center retrospective study comparing the incidence and severity of CMV infection with and without CMV-Ig. We identified 49 'at risk' recipients from 76 consecutive HSCTs over 3.5 years, in addition to standard antiviral prophylaxis, 10 patients received CMV-Ig and 39 did not. There was no significant difference in donor type, cell source, conditioning, or CMV status between the groups. We observed a potential trend toward reduction of incidence of CMV reactivation in patients exposed to CMV-Ig (30%) compared with those who weren't (38.4%). Besides, no symptomatic or lethal infection was observed in the CMV-Ig group, and time to recovery seemed shorter (21 [±7] vs 51.4 [±55] days) and peak titers lower (4578 [±4788] vs 24131 [±49257]) with CMV-Ig. No adverse events were noted. The statistical significance of the results was limited by the small sample size. These data raise interest in prophylactic CMV-Ig as a safe way of potentially reducing the severity and duration of CMV reactivation in HSCT.

Diagnosis and treatment for the early stage of cytomegalovirus infection during hematopoietic stem cell transplantation

Cytomegalovirus (CMV) infection remains a frequent complication after hematopoietic stem cell transplantation (HSCT) and causes significant morbidity and mortality in transplantation recipients. In this review, we highlight the role of major risk factors that are associated with the incidence of CMV infection. Advances in immunosurveillance may predict CMV infection, allowing early interventions to prevent severe infection. Furthermore, numerous therapeutic strategies against CMV infection after HSCT are summarized. A comprehensive understanding of the current situation of CMV treatment may provide a hint for clinical practice and even promote the development of novel strategies for precision medicine.

A Predicted Model for Refractory/Recurrent Cytomegalovirus Infection in Acute Leukemia Patients After Haploidentical Hematopoietic Stem Cell Transplantation

Objective

We aimed to establish a model that can predict refractory/recurrent cytomegalovirus (CMV) infection after haploidentical donor (HID) hematopoietic stem cell transplantation (HSCT).

Methods

Consecutive acute leukemia patients receiving HID HSCT were enrolled (n = 289). We randomly selected 60% of the entire population (n = 170) as the training cohort, and the remaining 40% comprised the validation cohort (n = 119). Patients were treated according to the protocol registered at https://clinicaltrials.gov (NCT03756675).

Results

The model was as follows: Y = 0.0322 × (age) – 0.0696 × (gender) + 0.5492 × (underlying disease) + 0.0963 × (the cumulative dose of prednisone during pre-engraftment phase) – 0.0771 × (CD34+ cell counts in graft) – 1.2926. The threshold of probability was 0.5243, which helped to separate patients into high- and low-risk groups. In the low- and high-risk groups, the 100-day cumulative incidence of refractory/recurrent CMV was 42.0% [95% confidence interval (CI), 34.7%–49.4%] vs. 63.7% (95% CI, 54.8%–72.6%) (P &lt; 0.001) for total patients and was 50.5% (95% confidence interval (CI), 40.9%–60.1%) vs. 71.0% (95% CI, 59.5%–82.4%) (P = 0.024) for those with acute graft-versus-host disease. It could also predict posttransplant mortality and survival.

Conclusion

We established a comprehensive model that could predict the refractory/recurrent CMV infection after HID HSCT.

Clinical Trial Registration

https://clinicaltrials.gov, identifier NCT03756675.

ELISPOT assay of interferon-γ secretion for evaluating human cytomegalovirus reactivation risk in allo-HSCT recipients

Human cytomegalovirus (HCMV) is a common cause of significant morbidity and mortality in transplant recipients after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We evaluated interferon-γ (IFN-γ) secretion by HCMV NLV-specific CD8⁺ T cells in HCMV-reactivated allo-HSCT recipients using an enzyme-linked immunospot (ELISPOT) assay at 3 months post-transplantation. Blood samples from 47 recipients were tested for HCMV DNAemia, HCMV pp65 antigenemia, and anti-HCMV immunoglobulins (IgG/IgM) over 3 months post-transplantation. Of the 47 transplant recipients, 26 were HLA-A*02 positive and 21 were HLA-A*02 negative. The results were essentially consistent between the 47 transplant recipients and the HLA-A*02-positive recipients. HCMV DNAemia was not linearly correlated with IFN-γ spot-forming cells (SFCs) counts; IFN-γ SFCs counts did not differ significantly between the HCMV DNAemia-positive and -negative groups, whereas the HCMV-DNA virus loads were inversely correlated with the IFN-γ SFCs counts. HCMV pp65 antigenemia was not linearly correlated with IFN-γ SFCs counts; IFN-γ SFCs counts in the HCMV pp65 antigenemia-positive and -negative groups were similar. More IFN-γ SFCs counts were detected in transplant recipients with high anti-HCMV-IgG antibody titers than in those with low anti-HCMV-IgG titers pre-transplantation in the 47 recipients. Anti-HCMV-IgG antibody titers were positively linearly correlated with IFN-γ SFCs counts in HLA-A*02-positive recipients. The HCMV infection indicators used to monitor HCMV reactivation had different values in transplant recipients. The use of the IFN-γ SFCs counts measured by ELISPOT to evaluate the risk of HCMV reactivation needs further study.

Prediction of Cytomegalovirus Reactivation by Recipient Cytomegalovirus-IgG Titer before Allogeneic Hematopoietic Stem Cell Transplantation

Recipient cytomegalovirus (CMV) seropositivity is known to be a risk factor for CMV reactivation after allogeneic hematopoietic stem cell transplantation (allo-HCT). We explored the association of CMV-IgG titer of recipients with CMV reactivation after allo-HCT and developed a model for predicting CMV reactivation for the purpose of identifying a high-risk group. In addition, we evaluated the impact of CMV-IgG titer on survival outcomes and acute graft-versus-host disease (GVHD). We retrospectively analyzed 309 patients who achieved neutrophil engraftment after allo-HCT and evaluated whether pretransplantation recipient CMV-IgG titer was associated with transplantation outcomes, including CMV reactivation. Using the best cutoff value determined by a receiver operating characteristic curve analysis, we divided the study cohort into 3 groups: high-titer, low-titer, and negative. CMV reactivation occurred most frequently in the high-titer group, followed by the low-titer and negative groups (81%, 37%, and 16%, respectively, at 180 days after allo-HCT; P < .01). In a multivariate analysis, recipient CMV-IgG titer was significantly associated with subsequent CMV reactivation (hazard ratio [HR], 9.31 in the high-titer group [P < .01] and 2.91 in the low-titer group [P = .023]). CMV diseases were observed exclusively in the high-titer group. Overall survival (OS) was lower in the high-titer group compared with the other 2 groups (2-year OS, 56%, 60%, and 80%, respectively; P = .075), whereas the cumulative incidences of grade II-IV acute GVHD, nonrelapse mortality (NRM), and relapse were not significantly different among the 3 groups. In multivariate analyses, CMV-IgG titer was not associated with increased risks of these outcomes, although CMV reactivation itself was identified as a risk factor for NRM (HR, 3.05; P = .002). Our data demonstrate that a higher titer of recipient CMV-IgG is predictive of CMV reactivation after allo-HCT. Further investigation is needed to determine how to apply these results to prophylactic or preemptive strategies against CMV, considering recipient CMV-IgG titer for effective risk stratification.