Impact of Donor and Recipient Cytomegalovirus Serostatus on Outcomes of Antithymocyte Globulin-Conditioned Hematopoietic Cell Transplantation

Dual T-cell depletion with individually tailored anti-thymocyte globulin and attenuated dose of post-transplant cyclophosphamide in haploidentical peripheral stem cell transplantation

This study aimed to assess the efficacy of dual T-cell suppression using individually tailored doses of antithymocyte globulin (ATG) and attenuated dose of post-transplant cyclophosphamide (PTCy) in haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We conducted a retrospective analysis of 78 adults with acute leukemia or myelodysplastic syndrome who underwent haplo-HSCT using intravenous busulfan and fludarabine conditioning. Thirty-two patients received attenuated ATG/PTCy, while 46 patients received ATG (7.5 mg/kg) as GVHD prophylaxis. The 100-day cumulative incidence of grade III-IV (9.7% vs. 32.4%, P = 0.018) acute GVHD, as well as 2-year moderate-severe chronic GVHD (13.9% vs. 43.9%, P = 0.018) in the ATG/PTCy group were significantly lower than those in the ATG group. The 2-year overall survival was comparable between the two groups. However, 2-year GVHD-free, relapse-free survival in the ATG/PTCy group was significantly higher compared to that in the ATG group (38.9% vs. 21.7%, P = 0.021). Moreover, during post-engraftment period, the ATG/PTCy group exhibited lower incidences of life-threatening bacterial (12.5% vs. 37%, P = 0.033) and viral infection (0% vs. 17.4%, P = 0.035) than the ATG group. In conclusion, the combination of individually tailored ATG and low-dose PTCy appears to be a promising strategy in haplo-HSCT.

Optimizing Access to Unrelated Donors in Canada: Re-Examining the Importance of Donor Factors on Outcomes Following Hematopoietic Cell Transplantation

HLA-matched allogeneic hematopoietic cell transplantation (HCT) is a curative therapy for many patients. Unrelated HLA-matched donors are the most frequently used donor for HCT. When more than one donor transplant option is available, transplant centers can select donors based on non-HLA factors. With improved ability to prevent and treat immune complications, such as graft-versus-host disease and infections, it may be possible to proceed more often using HLA-mismatched donors, allowing greater consideration of non-HLA factors, such as donor age, CMV serostatus, and ABO blood group matching, which have demonstrated important impacts on transplant outcomes. Additional factors to consider are donor availability rates and the usage of domestic donors to optimize outcomes. A review of non-HLA factors and considerations on the selection of optimal unrelated donors for HCT are provided within this updated current context.

Investigation of KIR/HLA relationship and other clinical variables after T-cell-replete haploidentical bone marrow transplantation in patients with acute myeloid leukemia (AML)

BACKGROUND

KIR/HLA mismatch in hematopoietic stem cell transplantation (HSCT), particularly in patients with acute myeloid leukemia (AML), was related to decreased recurrence rates, improved engraftment, and a reduction in graft-versus-host disease, according to recent research (GVHD). Uncertainty exists about the impact of KIR/HLA mismatch on haploidentical-HSCTs treated with post-transplant cyclophosphamide (PTCy). We attempted to analyze the effects of KIR/HLA mismatch on clinical outcomes on transplant outcomes using the cohort of 54 AML patients who received a haplo-HSCT with PTCy.

RESULTS

In contrast to KIR/HLA match, our findings showed that donor KIR/HLA mismatch was substantially associated with superior OS (HR, 2.92; (P = 0.04)). Moreover, donor KIR/HLA mismatch (KIR2DS1_D/C2⁺ _R and KIR2DS2_D/C1⁺ _R mismatch versus KIR2DL1_D/C2^- _R mm, KIR2DL2/3_D/C1^- _R mm and KIR3DL1_D/Bw4^- mm) was correlated with the improvements in OS (HR, 0.74; P = 0.085) and activating. KIR/HLA mismatch versus KIR/HLA match was significantly correlated with improvements in OS (HR, .46; P = 0.03) and inhibitory. KIR/HLA mismatch versus KIR/HLA match was enhancement in the OS (HR, .93; P = 0.06). Despite a higher rate of aGvHD (grade I-IV) in the patients with KIR/HLA mismatch compared to KIR/HLA matched (57% vs. 33% (p = 0.04). However, the KIR/HLA mismatch group saw a decreased relapse rate (3.2% vs. 23%, p = 0.04).

CONCLUSION

This analysis shows the significance of KIR/HLA Incompatibility, other clinical variables like CMV, the relationship between donor/recipient and donor age, and the relationship between donor/recipient and donor age in the haplo-donor selection process. It also suggests that KIR and HLA mismatching between donor and recipient could be routinely performed for haplo-donor selection and may improve clinical outcomes after haplo-HSCTs with PTCy.

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.

Donor Selection for Allogeneic Hematopoietic Cell Transplantation

BACKGROUND

In Germany, each year over 3000 patients with malignant and non-malignant hematologic and systemic diseases are treated by allo - geneic hematopoietic cell transplantation (HCT). Genetic donor-recipient disparities, especially those concerning variable human leukocyte antigens (HLA), mediate both an immunotherapeutic effect and the risk of damage to healthy tissues ("graft-versus-host disease"). The adoption of evidencebased strategies for donor selection has been crucial for the continuous improvement of survival rates after allogeneic HCT, with over 50% of patients transplanted for standard indications-such as early-stage acute myeloid leukemia-alive at three years post-transplant.

METHODS

The PubMed database was selectively searched for literature on immunogenetic and clinical factors relevant to allogeneic HCT, as part of the process of establishing a German consensus statement on HCT donor selection.

RESULTS

The most important factor in donor selection is a match for the five major HLA loci (HLA-A, -B, -C, -DR, -DQ), either in genetically HLAidentical siblings or in unrelated but fully HLA-compatible donors from international registries. Additional selection criteria for the latter include com - patibility for the HLA-DP locus, donor age and sex, cytomegalovirus serostatus, and blood group. Related donors identical for only 50% of the HLA genes (haploidentical donors) as well as unrelated donors with a single HLA mismatch are both valid alternatives although they are associated with an up to 10% higher risk of mortality.

CONCLUSION

The refinement of donor selection strategies has been instrumental for the continuous improvement of patient survival rates after allogeneic HCT witnessed over the past decades. An interdisciplinary approach to donor selection based on up-to-date scientific evidence is crucial for optimizing patient outcomes.

Rituximab Toxicity after Preemptive or Therapeutic Administration for Post-Transplant Lymphoproliferative Disorder

Rituximab is commonly used as prevention, preemption, or therapeutically for post-transplant lymphoproliferative disorder (PTLD) after hematopoietic cell transplantation (HCT). Although it is generally assumed that rituximab toxicity (ie, infections resulting from hypogammaglobulinemia and neutropenia) is negligible in relation to mortality due to PTLD, limited evidence supports the validity of this assumption. We sought to determine the impact of rituximab on immunoglobulin levels, neutrophil count, infection density, and mortality outcomes. This study retrospectively analyzed 349 HCT recipients, 289 of whom did not receive rituximab and 60 of whom received rituximab preemptively or therapeutically at a median of 55 days post-transplantation. IgM, IgG, and IgA levels at 6 months and 12 months post-transplantation were lower in patients who received rituximab compared with those who did not (significant at P < .05 for IgM and IgA at 6 months and for IgM and IgG at 12 months). Rituximab recipients also had a higher incidence of severe neutropenia (<.5/nl) between 3 and 24 months (subhazard ratio [SHR], 2.3; P = .020). Regarding non-Epstein-Barr viral infections/PTLD, the rituximab group had a higher infection density between 3 and 24 months compared with the no-rituximab group (3.8 versus 1.6 infections per 365 days at risk; incidence rate ratio, 2.2; P < .001). The rituximab group also had a higher incidence of fatal infections (SHR, 3.1; P = .026), higher nonrelapse mortality (SHR, 2.4; P = .006), and higher overall mortality (hazard ratio, 1.7; P = .033). There were no significant between-group differences in the incidence of clinically significant graft-versus-host disease, graft failure, or relapse. Based on this study, rituximab given for PTLD is associated with substantial morbidity and mortality. Whether the benefit of preemptive rituximab outweighs the risk remains to be determined. © 2022 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Incomplete chimerism following myeloablative and anti-thymocyte globulin-conditioned hematopoietic cell transplantation is a risk factor for relapse and chronic graft-versus-host disease

BACKGROUND AIMS

The value of routine chimerism determination after myeloablative hematopoietic cell transplantation (HCT) is unclear, particularly in the setting of anti-thymocyte globulin (ATG)-based graft-versus-host disease (GVHD) prophylaxis.

METHODS

Blood samples were collected at 3 months post-HCT from 558 patients who received myeloablative conditioning and ATG-based GVHD prophylaxis. Chimerism was assessed using multiplex polymerase chain reaction of short tandem repeats in sorted T cells (CD3+) and leukemia lineage cells (CD13+CD33+ for myeloid malignancies and CD19+ for B-lymphoid malignancies). ATG exposure was determined using a flow cytometry-based assay. The primary outcomes of interest were relapse and chronic GVHD (cGVHD).

RESULTS

Incomplete (<95%) T-cell chimerism and leukemia lineage chimerism were present in 17% and 4% of patients, respectively. Patients with incomplete T-cell chimerism had a significantly greater incidence of relapse (36% versus 22%, subhazard ratio [SHR] = 2.03, P = 0.001) and lower incidence of cGVHD (8% versus 25%, SHR = 0.29, P < 0.001) compared with patients with complete chimerism. In multivariate modeling, patients with high post-transplant ATG area under the curve and any cytomegalovirus (CMV) serostatus other than donor/recipient seropositivity (non-D+R+) had an increased likelihood of incomplete T-cell chimerism. Patients with incomplete leukemia lineage chimerism had a significantly greater incidence of relapse (50% versus 23%, SHR = 2.70, P = 0.011) and, surprisingly, a greater incidence of cGVHD (45% versus 20%, SHR = 2.64, P = 0.003).

CONCLUSIONS

High post-transplant ATG exposure and non-D+R+ CMV serostatus predispose patients to incomplete T-cell chimerism, which is associated with an increased risk of relapse. The increased risk of cGVHD with incomplete B-cell/myeloid chimerism is a novel finding that suggests an important role for recipient antigen-presenting cells in cGVHD pathogenesis.

Lower dose of ATG combined with basiliximab for haploidentical hematopoietic stem cell transplantation is associated with effective control of GVHD and less CMV viremia

Currently, the graft-versus-host disease (GVHD) prophylaxis consists of an immunosuppressive therapy mainly based on antithymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). GVHD remains a major complication and limitation to successful allogeneic haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We modified the ATG-based GVHD prophylaxis with the addition of basiliximab in the setting of haplo-HSCT and attempted to explore the appropriate dosages. We conducted a retrospective analysis of 239 patients with intermediate- or high-risk hematologic malignancies who received haplo-HSCT with unmanipulated peripheral blood stem cells combined or not with bone marrow. All patients received the same GVHD prophylaxis consisting of the combination of methotrexate, cyclosporine or tacrolimus, mycofenolate-mofetil, and basiliximab with different doses of ATG (5-9mg/kg). With a median time of 11 days (range, 7-40 days), the rate of neutrophil engraftment was 96.65%. The 100-day cumulative incidences (CIs) of grade II-IV and III-IV aGVHD were 15.8 ± 2.5% and 5.0 ± 1.5%, while the 2-year CIs of total cGVHD and extensive cGVHD were 9.8 ± 2.2% and 4.1 ± 1.5%, respectively. The 3-year CIs of treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DFS) were 14.6 ± 2.6%, 28.1 ± 3.4%, 60.9 ± 3.4%, 57.3 ± 3.4%, respectively. Furthermore, the impact of the reduction of the ATG dose to 6 mg/kg or less in combination with basiliximab on GVHD prevention and transplant outcomes among patients was analyzed. Compared to higher dose of ATG(>6mg/kg), lower dose of ATG (≤6mg/kg) was associated with a significant reduced risk of CMV viremia (52.38% vs 79.35%, P<0.001), while the incidences of aGVHD and cGVHD were similar between the two dose levels. No significant effect was found with regard to the risk of relapse, TRM, and OS. ATG combined with basiliximab could prevent GVHD efficiently and safely. The optimal scheme of using this combined regimen of ATG and basiliximab is that administration of lower dose ATG (≤6mg/kg), which seems to be more appropriate for balancing infection control and GVHD prophylaxis.

Modified combination of anti-thymocyte globulin (ATG) and post-transplant cyclophosphamide (PTCy) as compared with standard ATG protocol in haploidentical peripheral blood stem cell transplantation for acute leukemia

In haploidentical peripheral blood stem cell transplantation (haplo-PBSCT), the combination of anti-thymocyte globulin and post-transplant cyclophosphamide (ATG/PTCy) has a synergistic impact in preventing graft-versus-host disease (GvHD). However, little is known about the long-term consequences of the new combination approach. Our goal is to evaluate the efficacy of ATG/PTCy versus a standard ATG regimen by focusing at long-term outcomes in a more homogeneous group of patients. We retrospectively included 118 adult patients up to 60 years with acute leukemia who underwent haplo-PBSCT at our single institution, following the same myeloablative conditioning regimen. From 2010 to 2020, 78 patients received a modified combination of ATG (2.5 mg/kg/day, on days −3, −2, and −1) and PTCy (40 mg/kg/day on days +3 and +4) compared to 40 patients who had a standard ATG-based regimen (2.5 mg/kg/day from days −4 to −1) from 2008 to 2015. The median follow-up time for all patients was 5.36 years, respectively. The cumulative incidence (CI) of neutrophil and platelet engraftment, as well as CMV reactivation, did not differ statistically between the two groups. The CI of the acute GvHD of grades II–IV and III–IV and extensive chronic GvHD were considerably lower in the ATG/PTCy (34.6%, 8.97%, and 13.63%) than in the ATG cohort (57.5%, 30%, and 38.23%) as validated by multivariable modeling. Additionally, compared to the ATG arm, the ATG/PTCy was a hazard factor associated with a higher risk of relapse (HR = 2.23, p = 0.039). The probability of 5-year overall survival, disease-free survival, and GvHD-free relapse-free survival in the ATG/PTCy group (53.34%, 49.77%, and 36.04%) was comparable with the ATG group (47.5%, 42.5%, and 22.5%), respectively. Our finding suggested that a modified ATG/PTCy combination resulted in a lower risk of acute and chronic GvHD and a higher risk of relapse than the standard ATG-based protocol but had no effect on long-term outcomes. However, certain adjustments in the immunosuppression protocol are warranted to improve the outcome.

Outcomes of haploidentical peripheral stem cell transplantation with combination of post-transplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) compared to unrelated donor transplantation in acute myeloid leukemia: A retrospective 10-year experience

In the evolution of haploidentical hematopoietic stem cell transplantation (haplo-HSCT), In vivo T-cell modulation with concomitant use of anti-thymocyte globulin (ATG) and high-dose post-transplant cyclophosphamide (PTCy) provides a novel promising method on transplant outcomes; however, the long-term effects of this therapy are mostly unknown. We retrospectively compared the long-term outcomes of adult acute myeloid leukemia (AML) patients undergoing a haplo-HSCT (n = 92) with a new modified combination of ATG and PTCy in the context of peripheral blood stem cell (PBSC) and myeloablative conditioning (MAC) with an otherwise similar group of AML patients who received an unrelated donor (URD) HSCT (n = 57) with ATG protocol from February 2010 to December 2020 at our single-center (HORCSCT). Median follow-up was 3.73 and 4.28 years for haploidentical and URD-HSCT, respectively. In haplo-HSCT, the cumulative incidence of grades II-IV and III-IV acute graft versus host disease (aGvHD) and extensive chronic GvHD (cGvHD) was much lower than in URD (27% versus 56% for grades II-IV, 8.7% versus 24.5% for grades III-IV, and 15.4% versus 34.7% for extensive cGvHD, respectively). Five-year overall survival (OS) was 54.03% for haplo and 54.48% for URD (p = 0.927); GvHD-free relapse-free survival (GRFS) was 44.1% and 29.86% (p = 0.149); relapse incidence was 15.79% and 26.95% (p = 0.72); and non-relapse mortality (NRM) was 29.48% and 26.32% (p = 0.73), respectively. Using multivariable analyses, when compared to Haplo, URD was a significant predictor of relapse (HR=1.80, p = 0.039); however, no difference in OS, GRFS, and NRM was noted between haplo and URD. Therefore, given the favorable results with haplo-HSCT and considering donor availability promptly with low cost, it conservatively suggested that haplo-HSCT with the introduced protocol could be viewed as the first alternative for patients with AML in the absence of matched sibling donors.

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

BACKGROUND AIMS

Cytomegalovirus (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.

METHODS

The 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.

RESULTS

A 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).

CONCLUSIONS

In ex vivo TCD HSCT in pediatric patients, early initiation of induction treatment after CMV reactivation is associated with improved OS.

Operational tolerance after hematopoietic stem cell transplantation is characterized by distinct transcriptional, phenotypic, and metabolic signatures

The mechanisms underlying operational tolerance after hematopoietic stem cell transplantation in humans are poorly understood. We studied two independent cohorts of patients who underwent allogeneic hematopoietic stem cell transplantation from human leukocyte antigen-identical siblings. Primary tolerance was associated with long-lasting reshaping of the recipients' immune system compared to their healthy donors with an increased proportion of regulatory T cell subsets and decreased T cell activation, proliferation, and migration. Transcriptomics profiles also identified a role for nicotinamide adenine dinucleotide biosynthesis in the regulation of immune cell functions. We then compared individuals with operational tolerance and nontolerant recipients at the phenotypic, transcriptomic, and metabolomic level. We observed alterations centered on CD38⁺-activated T and B cells in nontolerant patients. In tolerant patients, cell subsets with regulatory functions were prominent. RNA sequencing analyses highlighted modifications in the tolerant patients' transcriptomic profiles, particularly with overexpression of the ectoenzyme NT5E (encoding CD73), which could counterbalance CD38 enzymatic functions by producing adenosine. Further, metabolomic analyses suggested a central role of androgens in establishing operational tolerance. These data were confirmed using an integrative approach to evaluating the immune landscape associated with operational tolerance. Thus, balance between a CD38-activated immune state and CD73-related production of adenosine may be a key regulator of operational tolerance.

Human Cytomegalovirus Seroprevalence Among Blood Donors in the Madinah Region, Saudi Arabia

Background and objective

Human cytomegalovirus (HCMV), a double-stranded DNA virus of the Herpesviridae family, can remain latent for long periods of time. HCMV may cause severe illness in immunocompromised patients and is associated with congenital anomalies. This study aimed to determine the anti-HCMV immunoglobulin G (IgG) and IgM antibody seroprevalence among blood-donating Saudi men in the Madinah region.

Methods

A total of 375 blood-donating Saudi men were recruited from the Central Blood Bank in Madinah, the Kingdom of Saudi Arabia (KSA), and stratified into three age groups: 18-30, 31-40, and 41-61 years. Anti-HCMV IgG and IgM antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). Pearson’s correlation coefficient was used to correlate antibody levels with variables.

Results

Most of the tested samples (95.73%, n=356) were positive for anti-HCMV IgG antibodies, but only 1.6% (n=6) were positive for both IgM and IgG antibodies, and all of them belonged to the age groups of 31-40 and 41-61 years. A strong inverse correlation was found between anti-HCMV IgG antibody levels and age (r=−0.51, p<0.0001). Additionally, there was an inverse correlation between anti-HCMV IgG antibody levels and body mass index (BMI) (r=−0.11, p=0.036). No correlations were found between anti-HCMV IgG levels and hemoglobin levels or blood groups of the participants.

Conclusions

Blood-donating Saudi men in Madinah had a high seroprevalence of anti-HCMV IgG antibodies, indicating previous viral exposure. Age and BMI might influence the humoral immunologic memory response against HCMV, which appears to be endemic in Madinah.

Development and Dynamics of Cytomegalovirus UL97 Ganciclovir Resistance Mutations in Transplant Recipients Detected by Next-Generation Sequencing

Background

(Val)ganciclovir resistance mutations in CMV UL97 (UL97-GCV-R) complicate anti-CMV therapy in recipients of solid organ and hematopoietic stem cell transplants, but comprehensive data on prevalence, emergence, and outcome are scarce.

Methods

Using next-generation sequencing (NGS; Illumina MiSeq platform), we analyzed UL97-GCV-R in patients with available plasma samples and refractory CMV replication/DNAemia (n = 87) containing viral loads ≥910 IU/mL. Twenty-one patients with CMV DNAemia resolving under antiviral therapy were analyzed as controls. Detected mutations were considered induced and of potential clinical significance if they increased by ≥10% compared with the first detected frequency or if they had a maximum frequency ≥25%.

Results

Nineteen of 87 (21.8%) with refractory CMV replication had ≥1 UL97-GCV-R detected by NGS, in comparison to 0/21 of the controls (P = .02). One-third of the recipients had 2 or more induced UL97-GCV-R mutations. The most frequently induced mutations affected codons 595 (42% [8/19]), 594 (32% [6/19]), and 603 (32% [6/19]). C592G was present in all episodes of both cases and controls at frequencies <15%, but never induced. UL97-GCV-R tended to be more frequent in donor/recipient CMV immunoglobulin G mismatch or following failure to complete primary prophylaxis, and many developed invasive CMV disease.

Conclusions

UL97-GCV-R is common among transplant patients with refractory CMV replication. Early testing by NGS allows for identification of major mutations at codons 595, 594, and 603 and excludes a major role of C592G in ganciclovir resistance. Large prospective studies on UL97-GCV-R are warranted.

In-depth summary over cytomegalovirus infection in allogeneic hematopoietic stem cell transplantation recipients

In this study, we reviewed various aspects of cytomegalovirus infection, including pathophysiology, diagnosis methods, and antiviral treatments. Background: Infections continue to be a major reason of complications like high non-relapse morbidity and mortality rate after allogenic hematopoietic stem cell transplantation. Cytomegalovirus is the most common infection in immunocompromised patients or those with graft-versus-host disease. The Latent-cytomegalovirus disease could increase the risk of reactivation in allogenic hematopoietic stem cell transplantation patients and lead to profound adverse effects on transplantation outcomes. Cytomegalovirus-specific CD4 + and CD8 + T cells reconstitution is crucial for protection against the virus reactivation. Different prophylactic, pre-emptive, and therapeutic anti-viral drugs are available to prevent cytomegalovirus infection/reactivation and treat resistant infections. Conclusion: Although there has been introduced various CMV antiviral treatment strategies like antiviral drugs, Vaccination, passive immunotherapies and adoptive transfer of CMV-specific T cells, further clinical trials are required to approve current therapies.

Risk Factors for the Incidence of and the Mortality due to Post-Transplant Lymphoproliferative Disorder after Hematopoietic Cell Transplantation

Post-transplant lymphoproliferative disorder (PTLD) is a potentially serious complication that occurs following hematopoietic cell transplantation (HCT), in which B cells transformed by Epstein-Barr virus (EBV) proliferate uncontrollably. It is unknown whether risk factors for the incidence of PTLD are identical to those for mortality due to PTLD, a clinically more important outcome. We sought to determine the risk factors influencing the incidence of PTLD and those influencing mortality due to PTLD in a cohort of 1184 allogenic HCT recipients. All patients were predisposed to PTLD, because their graft-versus-host disease (GVHD) prophylaxis included antithymocyte globulin. The overall PTLD incidence was 9.0%, and mortality due to PTLD was 1.1%. In multivariate analysis, risk factors for PTLD incidence include donor+/recipient- (D+/R-) EBV serostatus (subhazard ratio [SHR], 3.3; P = .002), use of a donor other than an HLA-matched sibling donor (non-MSD) (SHR, 1.7; P = .029), receipt of total body irradiation (TBI; SHR, 3.3; P = .008), and the absence of GVHD (SHR, 3.3; P < .001). The sole risk factor for mortality due to PTLD among all patients was D+/R- serostatus (SHR, 5.8; P = .022). Risk factors for mortality due to PTLD among patients who developed PTLD were use of a bone marrow (BM) graft (compared with peripheral blood stem cells [PBSCs]; SHR, 22.8; P < .001) and extralymphatic involvement (SHR, 14.6; P < .001). Interestingly, whereas the absence of GVHD was a risk factor for PTLD incidence, there was a trend toward the presence of GVHD as a risk factor for PTLD mortality (SHR, 4.2; P = .093). Likewise, whereas use of a BM graft was a risk factor for PTLD mortality, there was a trend toward use of a PBSC graft as a risk factor for PTLD incidence (SHR, 0.44; P = .179). Some risk factors for the incidence of PTLD are identical to the risk factors for mortality due to PTLD (ie, D+/R- serostatus), whereas other risk factors are disparate. Specifically, TBI was identified as a risk factor for PTLD incidence but not for PTLD mortality; the absence of GVHD was a risk factor for PTLD incidence, whereas the presence of GVHD was possibly a risk factor for PTLD mortality; and receipt of a PBSC graft was possibly a risk factor for PTLD incidence, whereas receipt of a BM graft was a risk factor for PTLD mortality.

Cytomegalovirus Latency Exacerbated small-for-size Liver Graft Injury through Activation of CCL19/CCR7 in Hepatic Stellate Cells

BACKGROUND

The interplay between cytomegalovirus (CMV) latency and graft malfunction after living donor liver transplantation (LDLT) remains poorly defined due to the complexity of clinical confounding factors. Here, we aimed to investigate the effects of CMV latency on small-for-size graft injury and to get further insight on the pathogenic role of hepatic stellate cells (HSCs) in this process.

METHODS

Rat orthotopic liver transplantation with small-for-size grafts was performed in a CMV latent model developed in immunocompetent Sprague Dawley (SD) rats using Priscott strain. Post-transplant graft injury including hepatocyte damage, stellate cell activation and fibrogenesis were evaluated. Differential gene expression of HSCs in response to CMV latency was screened by cDNA microarray. Clinical validation was further conducted in human biopsies.

RESULTS

CMV latency aggravated hepatocyte apoptosis/necrosis in the early phase, enhanced HSC expansion and graft fibrosis during the middle-late phase in small-for-size liver grafts of the rat model. cDNA microarray mining revealed CCL19/CCR7 as one of the most noteworthy pathways bridging HSC activation and liver graft injury in the presence of CMV latency. Together with CCL19 upregulation, coherent overexpression of CCR7 in accumulated HSCs was confirmed in both rat and human CMV latent recipients. Moreover, addition of CCL19 in vitro promoted HSC migration by increasing the level of matrix metalloproteinase-2 (MMP2).

CONCLUSION

Our data demonstrated that CMV latency aggravated early/late phase liver graft damage and fibrogenesis via CCL19/CCR7/HSCs axis. Blockade of CMV latency-related stellate cell activation may shed light on the strategy of graft protection clinically.

Cytomegalovirus (CMV) management in allogeneic hematopoietic cell transplantation: Pre-transplant predictors of survival, reactivation, and spontaneous clearance

BACKGROUND

Cytomegalovirus (CMV) reactivation is a frequent complication after allogeneic hematopoietic cell transplant (alloHCT).

METHOD

We analyzed 159 alloHCT recipients with 4409 quantitative CMV viral loads to determine pre-transplant predictors of CMV reactivation, clinically significant CMV infection (cs-CMVi, defined as CMV viral load >1000 IU/mL), CMV disease, kinetics of spontaneous clearance of CMV, and survival using a standardized pre-emptive therapy approach to identify at-risk groups to target prevention strategies.

RESULTS

Cs-CMVi was most common in D-/R+ unrelated donor transplants (URD). Spontaneous CMV clearance occurred in 26% of patients who reached a viral load of 56-137 IU/mL, 6% at 138-250 IU/mL and in one patient >250 IU/mL. Median time between the first CMV reactivation (>56 IU/mL) and a viral load >250 IU/mL was 13 days, whereas the time from the first viral load >250 IU/mL to reach a vial load >1000 IU/mL was 4 days. Cs-CMVi was associated with a significant increase in non-relapse mortality (NRM) on multivariate analysis.

CONCLUSIONS

Overall, this study indicates that D-/R+ URD recipients are at high-risk for cs-CMVi- and CMV-related mortality, and are potential candidates for targeted CMV prophylaxis. Spontaneous clearance of CMV beyond a viral load of 250 IU/mL is uncommon, suggesting that this could be used as an appropriate threshold to initiate pre-emptive therapy.

Hematopoietic cell transplant outcomes after myeloablative conditioning with fludarabine, busulfan, low-dose total body irradiation, and rabbit antithymocyte globulin

Optimal conditioning and graft-vs-host disease (GVHD) prophylaxis for hematopoietic cell transplantation (HCT) are unknown. Here, we report on outcomes after low toxicity, myeloablative conditioning consisting of fludarabine, busulfan, and 4 Gy total body irradiation, in combination with thymoglobulin and post-transplant methotrexate and cyclosporine. We retrospectively studied 700 patients with hematologic malignancies who received blood stem cells from 7 to 8/8 HLA-matched unrelated or related donors. Median follow-up of surviving patients was 5 years. At 5 years, overall survival (OS), relapse-free survival (RFS), and chronic GVHD/relapse-free survival (cGRFS) were 58%, 55%, and 40%. Risk factors for poor OS, RFS, and cGRFS were (1). high to very high disease risk index (DRI), (2). high recipient age, and (3). cytomegalovirus (CMV)-seropositive recipient with seronegative donor (D-R+). The latter risk factor applied particularly to patients with lymphoid malignancies. Neither donor other than HLA-matched sibling (7-8/8 unrelated) nor one HLA allele mismatch was risk factors for poor OS, RFS, or cGRFS. In conclusion, the above regimen results in excellent long-term outcomes. The outcomes are negatively impacted by older age, high or very high DRI, and CMV D-R+ serostatus, but not by donor unrelatedness or one HLA allele mismatch.

Risk Factors Analysis for Human Cytomegalovirus Viremia in Donor+/Recipient+ Hematopoietic Stem Cell Transplantation

OBJECTIVE

To assess the rate of, and risk factors for, human cytomegalovirus viremia (HCMV) in donor+/recipient+ (HCMV serostatus matched) hematopoietic stem-cell transplantation (HSCT) recipients.

METHODS

HCMV DNA from 144 donor+/recipient+ HSCT recipients was examined by quantitative polymerase chain reaction (qPCR).

RESULTS

The cumulative incidence of HCMV viremia was 69.4% (100/144) during the 48 weeks after HSCT. In a multivariate analysis, acute graft-versus-host disease (aGVHD) was discovered to be a risk factor for the occurrence of HCMV viremia (P = .006). The cumulative incidence of HCMV viremia and increasing DNA loads were significantly associated with aGVHD occurrence (P = .001 for each). The occurrence of late-term HCMV viremia was associated with aGVHD (P = .001) and a higher DNA load during the first 12 weeks after HSCT (P = .04).

CONCLUSIONS

aGVHD is a risk factor for HCMV viremia. Recipients with aGVHD who have a high HCMV DNA load should be strictly monitored to prevent HCMV activation.

Antirelapse effect of pretransplant exposure to rabbit antithymocyte globulin

It remains unknown why rabbit antithymocyte globulin (ATG; Thymoglobulin) has not affected relapse after hematopoietic cell transplantation (HCT) in randomized studies. We hypothesized that high pre-HCT ATG area under the curve (AUC) would be associated with a low incidence of relapse, whereas high post-HCT AUC would be associated with a high incidence of relapse. We measured serum levels of ATG capable of binding to mononuclear cells (MNCs), lymphocytes, T cells, CD4 T cells, or CD33 cells. We estimated pre- and post-HCT AUCs in 152 adult recipients of myeloablative conditioning and blood stem cells. High pre-HCT AUCs of MNC- and CD33 cell-binding ATG were associated with a low incidence of relapse and high relapse-free survival (RFS). There was a trend toward an association of high post-HCT AUC of lymphocyte-binding ATG with a high incidence of relapse and low RFS. High pre-HCT AUCs were also associated with faster engraftment and had no impact on graft-versus-host disease (GVHD) or fatal infections. High post-HCT AUCs were associated with a low risk of GVHD, seemed associated with an increased risk of fatal infections, and had no impact on engraftment. In conclusion, pre-HCT AUC seems to have a positive, whereas post-HCT AUC seems to have a negative, impact on relapse.

Cytomegalovirus-specific CD8+ T-cells are associated with a reduced incidence of early relapse after allogeneic stem cell transplantation

Leukemia relapse is the main cause for mortality after allogeneic stem cell transplantation (allo-SCT). Donor-derived allo-immune responses eliminate the residual host hematopoiesis and protect against relapse. Cytomegalovirus (CMV) reactivation (CMV-R) after allo-SCT may trigger anti-leukemic effects. The impact of CMV-specific CD8+ T-cells (CMV-CTLs) on the outcome after allo-SCT is currently unknown. Here, we studied the relationship between CMV-CTLs, overall T-cell reconstitution and relapse incidence in 103 patients with acute leukemia (n = 91) or myelodysplastic syndrome (n = 12) following CMV-seropositive recipient/donor (R+/D+) allo-SCT. Patients were subdivided based on the presence or absence of CMV-CTLs at 3 months after allo-SCT. Presence of CMV-CTLs was associated with preceding CMV-R and a fast T-cell reconstitution. Univariate analysis showed a significantly lower 1-, 2- and 5-year cumulative incidence of relapse (CIR) in patients with CMV-CTLs compared to those without CMV-CTLs. Multivariable regression analysis of the outcome performed with other relevant parameters chosen from univariate analysis revealed that presence of CMV-CTLs and chronic graft-versus-host disease (cGvHD) were the only independent factors associated with a low CIR. Onset of relapse was significantly later in patients with CMV-CTLs (median 489 days) than in in those without (median 152 days, p = 0.041) during a five-year follow-up. Presence of CMV-CTLs was associated with a lower incidence of early relapses (1 and 2-years), while cGvHD lead to a lower incidence of late relapses (2 to 5-years). In conclusion, our data show that CMV-CTLs indicate a functional immune-reconstitution protective against early relapse.

PTX3 Polymorphisms Influence Cytomegalovirus Reactivation After Stem-Cell Transplantation

Background: Reactivation of latent human cytomegalovirus (CMV) in patients undergoing allogeneic stem-cell transplantation (HSCT) predisposes to several clinical complications and is therefore a major cause of morbidity and mortality. Although pentraxin-3 (PTX3) has been previously described to bind both human and murine CMV and mediate several host antiviral mechanisms, whether genetic variation in the PTX3 locus influences the risk of CMV infection is currently unknown.

Methods: To dissect the contribution of genetic variation within PTX3 to the development of CMV infection, we analyzed described loss-of-function variants at the PTX3 locus in 394 recipients of HSCT and their corresponding donors and assessed the associated risk of CMV reactivation.

Results: We report that the donor, but not recipient, h2/h2 haplotype in PTX3 increased the risk of CMV reactivation after 24 months following transplantation, with a significant effect on survival. Among recipients with h2/h2 donors, CMV seropositive patients as well as those receiving grafts from unrelated donors, regardless of the CMV serostatus, were more prone to develop viral reactivation after transplantation. Most importantly, the h2/h2 haplotype was demonstrated to display an influence toward risk of CMV reactivation comparable to that conferred by the unrelated status of the donor alone.

Conclusions: Our findings demonstrate the important contribution of genetic variation in donor PTX3 to the risk of CMV reactivation in patients undergoing HSCT, highlighting a promising prognostic value of donor PTX3 to predict risk of CMV reactivation in this clinical setting.

Rabbit Antithymocyte Globulin Serum Levels: Factors Impacting the Levels and Clinical Outcomes Impacted by the Levels

Antithymocyte globulin (ATG) levels and clearance vary significantly among patients receiving the same weight-based dose of ATG. To date, ATG area under the curve (AUC), its determinants, and its impact on clinical outcomes have been examined in pediatric hematopoietic cell transplant (HCT) and adult nonmyeloablative HCT. Here we set out to examine ATG AUC in 219 uniformly treated adults undergoing myeloablative allogeneic HCT at our institution. Sera were collected for the determination of pre- or post-HCT ATG AUC. The lowest quintiles of pre- and post-HCT AUC were associated with inferior chronic graft-versus-host disease (GVHD) and relapse-free survival (cGRFS) and a higher risk of acute GVHD, respectively. The highest pre- or post-HCT ATG AUC quintiles were not associated with risk of death, nonrelapse mortality, or relapse. Factors most strongly associated with AUC were day -2 recipient absolute lymphocyte count, body mass index (BMI), and graft lymphocyte content. To achieve ideal pre-HCT AUC (avoiding low AUC to maximize cGRFS) in this HCT setting, ATG dosing will need to take into consideration recipient weight, BMI, and blood and graft lymphocyte counts. Further studies are required to develop a modern ATG dosing schema and to demonstrate that adjusting ATG dose to target a particular AUC is feasible and leads to improved outcomes.

Reduced-Intensity Conditioning and Dual T Lymphocyte Suppression with Antithymocyte Globulin and Post-Transplant Cyclophosphamide as Graft-versus-Host Disease Prophylaxis in Haploidentical Hematopoietic Stem Cell Transplants for Hematological Malignancies

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HaploHSCT after RIC with ATG, PTCy, and cyclosporine is a feasible transplant regimen.

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Low rates of grade II to IV acute GVHD were observed.

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ATG use leads to higher rates of viral reactivation, particularly CMV and EBV.

Haploidentical hematopoietic stem cell transplantation (haploHSCT) with conditioning regimens using post-transplant cyclophosphamide (PTCy) for peripheral blood stem cell (PBSC) grafts is limited by comparably higher rates of acute and chronic graft-versus-host disease (GVHD). Antithymocyte globulin (ATG) may mitigate this risk. We evaluated haploHSCT after reduced-intensity conditioning (RIC) with ATG, PTCy, and cyclosporine to prevent rejection and GVHD. Fifty adults underwent haploHSCT from August 2016 to February 2018. RIC included fludarabine (30 mg/m²/day on days –5 to –2), busulfan (3.2 mg/m²/day on days –3 and –2), and total body irradiation (200 cGy) on day –1. Unmanipulated PBSCs were infused on day 0. GVHD prophylaxis included ATG (4.5 mg/kg over days –3 to –1), PTCy (50 mg/kg/day on days +3 and +4), and cyclosporine from day +5. Median age was 56 years (range, 22 to 70 years); 25 (73.5%) patients were in first complete remission (CR1), 5 (14.7%) were in second complete remission (CR2), and 8 (23.5%) had active disease. Median time to neutrophil engraftment was 16 days (range, 8 to 43 days). At day +100, the cumulative incidence of acute GVHD of any grade, and grades III to IV was 38.3% and 5.2%, respectively. Mild chronic GVHD was seen in 15.5%. Cytomegalovirus (CMV) reactivation occurred in 37 (74%) cases and CMV disease occurred in 4 (11.5%) cases. Epstein-Barr virus (EBV) reactivation occurred in 21 (61.8%) patients. The incidence of histologically confirmed post-transplantation lymphoproliferative disorder (PTLD) was 5.8%. Four patients received rituximab. There were no CMV, EBV, or PTLD-related deaths. Six-month and 1-year overall survival (OS), cumulative incidence of relapse (CIR), and nonrelapse mortality (NRM) were 73.9%, 10.2%, and 19.4%, respectively, and 48.1%, 16% and 38.2%, respectively. Infection was the most common cause of death (18%). Unmanipulated haploidentical PBSC transplantation following RIC with ATG, PTCy, and cyclosporine as a GVHD prevention strategy results in low rates of acute and chronic GVHD.

Relative Impact of HLA Matching and Non-HLA Donor Characteristics on Outcomes of Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia and Myelodysplastic Syndrome

Increasing donor-recipient HLA disparity is associated with negative outcomes of allogeneic hematopoietic stem cell transplantation (HSCT), but its comparative relevance amid non-HLA donor characteristics is not well established. We addressed this question in 3215 HSCTs performed between 2005 and 2013 in Germany for acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Donors were HLA-matched related (MRD; n = 872) or unrelated (10/10 MUD, n = 1553) or HLA-mismatched unrelated (<10/10 MMUD, n = 790). Overall survival (OS) was similar after MRD compared with 10/10 MUD HSCT, reflecting opposing hazards of relapse (hazard ratio [HR], 1.32; P < .002) and nonrelapse mortality (HR, .63; P < .001). After UD HSCT, increasing HLA disparity was associated with inferior OS (HR, 1.21 [P < .02] and HR, 1.57 [P < .001] for 9/10 and ≤8/10 MMUD, respectively, compared with 10/10 MUD). Among non-HLA donor characteristics, age, sex mismatching (male recipient-female donor), and cytomegalovirus (CMV) mismatching (positive recipient-negative donor) impacted OS. Multivariate subgroup analysis showed that OS was similar after HSCT from the youngest 9/10 MMUD (<30 years) compared with the oldest 10/10 MUD (>40 years) (HR, 1.18; P = .25) and also in male patients transplanted from female 10/10 MUD compared with male 9/10 MMUD (HR, .89; P = .46). In contrast, OS of CMV-positive patients tended to be better with CMV-negative 10/10 MUDs compared with CMV-positive 9/10 MMUDs (HR, 1.31; P = .04). Because of low patient numbers in subgroups, definite conclusions and establishment of a hierarchy among HLA matching and non-HLA donor characteristics could not be made. Our data suggest that the impact of donor age and sex mismatch but not CMV mismatch on outcome of allogeneic HSCT may be comparable with that of single HLA disparity.

Cytomegalovirus (CMV) Disease Despite Weekly Preemptive CMV Strategy for Recipients of Solid Organ and Hematopoietic Stem Cell Transplantation

Background

Transplant recipients presenting with cytomegalovirus (CMV) disease at the time of diagnosis of CMV DNAemia pose a challenge to a preemptive CMV management strategy. However, the rate and risk factors of such failure remain uncertain.

Methods

Solid organ transplantation (SOT) and hematopoietic stem cell transplantation (HSCT) recipients with a first episode of CMV polymerase chain reaction (PCR) DNAemia within the first year posttransplantation were evaluated (n = 335). Patient records were reviewed for presence of CMV disease at the time of CMV DNAemia diagnosis. The distribution and prevalence of CMV disease were estimated, and the odds ratio (OR) of CMV disease was modeled using logistic regression.

Results

The prevalence of CMV disease increased for both SOT and HSCT with increasing diagnostic CMV PCR load and with screening intervals >14 days. The only independent risk factor in multivariate analysis was increasing CMV DNAemia load of the diagnostic CMV PCR (OR = 6.16; 95% confidence interval, 2.09–18.11). Among recipients receiving weekly screening (n = 147), 16 (10.8%) had CMV disease at the time of diagnosis of CMV DNAemia (median DNAemia load 628 IU/mL; interquartile range, 432–1274); 93.8% of these cases were HSCT and lung transplant recipients.

Conclusions

Despite application of weekly screening intervals, HSCT and lung transplant recipients in particular presented with CMV disease at the time of diagnosis of CMV DNAemia. Additional research to improve the management of patients at risk of presenting with CMV disease at low levels of CMV DNAemia and despite weekly screening is warranted.

Selecting the Best Donor for Haploidentical Transplant: Impact of HLA, Killer Cell Immunoglobulin-Like Receptor Genotyping, and Other Clinical Variables

The use of post-transplant cyclophosphamide (PTCy)-based haploidentical (haplo) transplant is increasing worldwide. However, because multiple potential haplo donors are usually available, data-driven guidance is clearly needed to help transplant centers prioritize donors. To that end, we retrospectively analyzed 208 consecutive donor-recipient pairs receiving PTCy-based haplo transplant at a single institution. Median recipient and donor age were 52 years (range, 19 to 75) and 38 years (range, 15 to 73), peripheral blood stem cell was the stem cell source in 66%, and myeloablative conditioning was used in 41%. Median follow-up for surviving patients was 33 months (range, 7 to 130). Donor variables analyzed included age, sex, relationship, cytomegalovirus (CMV) status, ABO compatibility, HLA disparity, and several natural killer (NK) alloreactivity models. Multivariate Cox analysis was used to adjust for known patient, disease, and transplant covariates. Donor characteristics independently associated with improved survival included presence of HLA-DR mismatch, HLA-DP nonpermissive mismatch, killer cell immunoglobulin-like receptor (KIR) receptor-ligand mismatch, and KIR B/x haplotype with KIR2DS2. Donor characteristics associated with inferior survival included parental donor relationship and the use of a CMV-seronegative donor for a CMV-seropositive patient. Increased HLA disparity (≥4/10 HLA allelic mismatches [graft-versus-host direction]) resulted in relapse protection at the expense of increased nonrelapse mortality with no associated survival effect. We further propose a donor risk factor scoring system to permit a more evidence-based selection algorithm for potential haplo donors. This large, single-institution analysis demonstrates the importance of HLA-DR/HLA-DP disparity, NK alloreactivity, and other clinical variables in the haplo donor selection process and suggests that KIR and HLA-DP genotyping should be performed routinely for haplo donor selection.

Comparable survival using a CMV-matched or a mismatched donor for CMV+ patients undergoing T-replete haplo-HSCT with PT-Cy for acute leukemia: a study of behalf of the infectious diseases and acute leukemia working parties of the EBMT

The role of donor CMV serostatus in the setting of non T-cell depleted haplo-HSCT with post-transplant cyclophosphamide (PT-Cy) has not been specifically addressed so far. Here we analyzed the impact of the donor CMV serological status on the outcome of 983 CMV seropositive (CMV+), acute leukemia patients receiving a first, non T-cell depleted haplo-HSCT registered in the EBMT database. The 1-year NRM was 21.3% (95% CI: 18.4-24.8) and 18.8% (95% CI: 13.8-25.5) in the CMV D+/R+ and D-/R+ pairs, respectively (p = 0.40). Similarly, 1-year OS was 55.1% (95% CI: 50.1-58.0) and 55.7% (95% CI: 48.0-62.8) in the same groups (p = 0.50). The other main outcomes were comparable. No difference in NRM nor OS was observed after stratification for the intensity of conditioning and multivariate anaysis confirmed the lack of significant association with NRM or OS. In conclusion, the choice of a CMV-seronegative donor did not impair early survival of CMV-seropositive patients with acute leukemia after a first, non T-cell depleted haploidentical HSCT and PT-Cy among this series of 983 consecutive patients. Future research may focus on the assessment of the hierarchy of all the donor variables.

Emerging concepts in cytomegalovirus infection following hematopoietic stem cell transplantation

Despite the refinements in molecular methods for the detection of cytomegalovirus (CMV) and the advent of highly effective preemptive strategies, CMV remains a leading cause of morbidity and mortality in hematopoietic cell transplant (HCT) recipients. CMV can cause tissue-invasive disease including pneumonia, hepatitis, colitis, retinitis, and encephalitis. Mortality in HCT recipients with CMV disease can be as high as 60%. CMV infection has been associated with increased risk of secondary bacterial and fungal infections, increased risk of graft-versus-host disease, and high rates of non-relapse mortality following HCT. The risk of CMV is highly dependent on the donor (D) and the recipient (R) serostatus (D^-/R⁺>D⁺/R⁺>D⁺/R^->D^-/R^-). Among allogeneic HCT recipients, high-dose corticosteroids, T-cell depletion, graft-versus-host disease, and mismatched or unrelated donors constitute the main predisposing factors. However, not all seropositive individuals with these risk factors develop CMV, which strongly suggests that host factors, such as those regulating CMV-specific T-cell responses, play a major role in predisposition to CMV in HCT recipients. Here, we discuss emerging concepts in CMV infection in HCT with emphasis on immunological factors that govern CMV reactivation and the applicability of immune monitoring to understand correlates of pathogenesis and its potential to guide clinical decision making.

Possible Impact of Cytomegalovirus-Specific CD8+ T Cells on Immune Reconstitution and Conversion to Complete Donor Chimerism after Allogeneic Stem Cell Transplantation

Complete donor chimerism is strongly associated with complete remission after allogeneic stem cell transplantation (allo-SCT) in patients with hematologic malignancies. Donor-derived allo-immune responses eliminate the residual host hematopoiesis and thereby mediate the conversion to complete donor chimerism. Recently, cytomegalovirus (CMV) reactivation was described to enhance overall T cell reconstitution, to increase graft-versus-host disease incidence, and to reduce the leukemia relapse risk. However, the link between CMV and allo-immune responses is still unclear. Here, we studied the relationship between CMV-specific immunity, overall T cell reconstitution, and residual host chimerism in 106 CMV-seropositive patients transplanted after reduced-intensity conditioning including antithymocyte globulin. In accordance with previous reports, the recovery of CMV-specific cytotoxic T cells (CMV-CTLs) was more frequent in CMV-seropositive recipients (R) transplanted from CMV-seropositive than from seronegative donors (D). However, once CMV-CTLs were detectable, the reconstitution of CMV-specific CTLs was comparable in CMV R+/D- and R+/D+ patients. CD3⁺ and CD8⁺ T cell reconstitution was significantly faster in patients with CMV-CTLs than in patients without CMV-CTLs both in the CMV R+/D- and R+/D+ setting. Moreover, CMV-CTL numbers correlated with CD3⁺ and CD8⁺ T cell numbers in both settings. Finally, presence of CMV-CTLs was associated with low host chimerism levels 3 months after allo-SCT. In conclusion, our data provide a first indication that CMV-CTLs in CMV-seropositive patients might trigger the reconstitution of T cells and allo-immune responses reflected by the conversion to complete donor chimerism.