Serious infection risk and immune recovery after double-unit cord blood transplantation without antithymocyte globulin

Immune reconstitution after single-unit umbilical cord blood transplantation using anti-thymoglobulin and myeloablative conditioning in adults with hematological malignancies

This study aimed to investigate the kinetics of immune recovery following umbilical cord blood transplantation (UCBT) in adults who received a myeloablative conditioning (MAC) regimen and antithymocyte globulin (ATG). While the immune recovery kinetics has been extensively studied in pediatric UCBT recipients, limited data exist for adults. We conducted a comprehensive analysis of 221 consecutive adult patients who underwent UCBT with MAC and ATG at a single institution. Our objective was to evaluate the influence of patient, disease, and transplant factors, along with acute graft-versus-host disease (aGVHD), on immune reconstitution and overall survival. Our findings confirm a delayed recovery of T cells, while B and NK cell reconstitution exhibited rapid progress, with NK cell counts reaching normal levels within 3 months post-transplantation and B cells within 6 months. Within CD3+ T cells, CD8+ T cells also experienced a delayed recovery (12 months), but to a lesser extent compared to CD4+ T cells (18 months). Delayed immune recovery of T-cell subsets was associated with the development of aGVHD grade II-IV, older age, CMV negativity, and a female donor. Patients with lymphoproliferative diseases showed slower NK cell recovery. Our study demonstrates that adult patients undergoing MAC with ATG and receiving a single unit UCBT for hematologic malignancies experienced rapid reconstitution of NK and B cells. However, T cell recovery, particularly CD4+ T cells, was significantly delayed. To enhance T cell recovery, it may be crucial to consider UCB units with higher cellularity and optimize ATG doses in conditioning.

Do oral conditions influence the incidence of bloodstream infection after hematopoietic stem cell transplantation? A retrospective study in Japan

PURPOSE

This study aimed to evaluate the incidence of bloodstream infection (BSI) among patients undergoing hematopoietic stem cell transplantation (HSCT) for teeth indicated for extraction.

METHODS

Patients who underwent HSCT at Toranomon Hospital (Tokyo, Japan) between January 2017 and December 2019 were retrospectively evaluated. The incidence of BSI among patients with teeth indicated for extraction who did not undergo extraction (oral high-risk group) and patients who did not have this risk (oral low-risk group) was compared.

RESULTS

Among the 191 consecutive patients included in this study, 119 patients were classified as undergoing high-risk transplantation. BSI after HSCT was observed in 32 out of 60 (53.3%) patients and 56 out of 131 (42.7%) patients in the oral low-risk and oral high-risk groups, respectively (p = 0.173). Multivariable analyses revealed that the presence of > 3 teeth as intraoral sources of infection and age over 50 years were determinants of BSI originating from the oral cavity after engraftment (odds ratio [OR], 9.11; 95% confidential interval [CI] 2.27-36.61]; p = 0.002; OR, 3.22; CI [1.47-7.08], p = 0.004, respectively).

CONCLUSION

In patients undergoing HSCT, the presence of less than three intraoral sources of infection did not affect the incidence of BSI after HSCT.

Haploidentical Cord Blood Transplantation with 8 mg/kg Antithymocyte Globulin as Graft-versus-Host Disease Prophylaxis Compared to Haploidentical Transplantation with 10 mg/kg Antithymocyte Globulin in the Treatment of Acute Leukemia

Clinical outcomes of the transplantation strategy combined with a haploidentical stem cell graft and an unrelated umbilical cord blood unit (haplo-cord HSCT) with low-dose antithymocyte globulin (ATG) as graft-versus-host disease (GVHD) prophylaxis for the treatment of acute leukemia remains unclear. This study aimed to explore the clinical outcomes of haplo-cord HSCT in acute leukemia patients with the GVHD prevention strategy of 8 mg/kg ATG compared with haploidentical transplantation with 10 mg/kg ATG. A total of 130 patients with acute leukemia who underwent allogeneic HSCT between January 2016 and December 2020 were included in this study, including 70 patients who received haploidentical stem cell grafts and unrelated umbilical cord blood units (haplo-cord HSCT) with 8 mg/kg ATG (haplo-cord-ATG8 group) and haploidentical HSCT with 10 mg/kg ATG (haplo-ATG10 group) in 60 patients. Clinical data were collected and analyzed retrospectively. Patients in the haplo-cord-ATG8 group were significantly older compared with the haplo-ATG10 group (P = .000). Haplo-cord HSCT with reduced ATG to 8 mg/kg results in more rapid neutrophil recovery (P = .036). No between-group differences were observed in platelet recovery or the incidences of Epstein-Barr virus viremia, bloodstream infection, or hemorrhagic cystitis. The rate of grade II-IV acute GVHD by day 100 post-transplantation was higher in the haplo-ATG10 group (27.16% versus 11.48%; P = .033), as was the rate of chronic GVHD at 1 year (14.60% versus 3.36%; P = .048). The rate of cytomegalovirus reaction was higher in the haplo-ATG10 group (48.31% versus 26.30%; P = .022). With a median follow-up of 27.4 months for the haplo-cord-ATG8 group and 27.5 months for the haplo-ATG10 group, overall survival (OS) at 2 years was 79.4% versus 62.8% (P = .005), event-free survival (EFS) was 76.3% versus 55.9% (P = .001), the cumulative incidence of relapse was 10.11% versus 25.97% (P = .164), and nonrelapse mortality (NRM) was 14.33% versus 24.43% (P = .0040). Multivariate analysis identified Center for International Blood and Marrow Transplant Research Disease Risk Index was the sole significant predictor of relapse, NRM, OS, and EFS. Haplo-cord HSCT supported by cord blood with 8 mg/kg ATG as GVHD prophylaxis results in better outcomes compared with haplo-HSCT with 10 mg/kg ATG.

Risk factors for bloodstream infection in paediatric haematopoietic stem cell transplantation: a systematic review and meta-analysis

BACKGROUND

Haematopoietic stem cell transplantation (HSCT), a standard treatment for paediatric haematological diseases, is highly associated with bloodstream infection (BSI), which may increase mortality.

AIM

To explore the risk factors for BSI in paediatric HSCT recipients.

METHODS

Three English databases and four Chinese databases were searched from inception to March 17th, 2022. Eligible studies included randomized controlled trials, cohort studies, and case-control studies that enrolled HSCT recipients aged ≤18 years and reported BSI risk factors. Two reviewers independently screened studies, extracted data, and assessed the risk of bias. Using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), certainty of body of evidence was assessed.

FINDINGS

Fourteen studies involving 4602 persons were included. The incidences of BSI and associated mortality in paediatric HSCT recipients were approximately 10-50% and 5-15%, respectively. Meta-analysis of all studies revealed that previous BSI before HSCT (relative effect (RE): 2.28; 95% confidence interval (CI) 1.19-4.34, moderate certainty) and receiving an umbilical cord blood transplant (RE: 1.55; 95% CI: 1.22-1.97, moderate certainty) were probably associated with an increased risk of BSI. Meta-analysis of studies with low risk of bias reassured that previous BSI before HSCT probably increased the risk of BSI (RE: 2.28; 95% CI: 1.19-4.34, moderate certainty), and revealed that steroid use (RE: 2.72; 95% CI: 1.31-5.64, moderate certainty) was likely a risk factor whereas autologous HSCT was probably a protective factor of BSI (RE: 0.65; 95% CI: 0.45-0.94, moderate certainty).

CONCLUSION

These findings could inform the management of paediatric HSCT recipients, helping identify who may benefit from prophylactic antibiotics.

Acute kidney injury and chronic kidney disease in umbilical cord blood transplant recipients

Introduction

Acute kidney injury (AKI) is a frequent early complication post hematopoietic stem cell transplant (HSCT), associated with high morbidity and mortality. Cord blood transplant (CBT) recipients are potentially exposed to more nephrotoxic insults, compared to patients undergoing HSCT from other donor sources. We aimed to identify risk factors for AKI in patients undergoing CBT. We also aimed to identify the impact of AKI on chronic kidney disease (CKD) and survival outcomes by one-year post-CBT.

Methods

Adults and children who underwent a first CBT at our Institution were retrospectively evaluated. AKI was staged according to Kidney Disease Improving Global Outcomes (KDIGO) definitions. Cox regression models were used to estimate the association of demographic factors and post-CBT parameters with the cause-specific hazard of AKI.

Results

We identified 276 patients. Median age was 32 years, 28% (77/276) were children (<18 years) and 129 (47%) were white. A myeloablative conditioning regimen was administered to 243 patients (88%) and 248 (90%) received cyclosporine for GVHD prophylaxis. One-hundred and eighty-six patients (67%) developed AKI by day 60 post-transplant, with 72 (26%) developing severe AKI (stage 2 and 3). In a multivariable analysis, each increase in bilirubin level of 1 mg/dL was associated with a 23% increase in the risk of severe AKI (adjusted HR 1.23, 95% CI 1.13 - 1.34, p<.0001). Conversely, systemic steroid administration appeared to be protective of severe AKI (unadjusted HR 0.36, 95% CI 0.18 - 0.72, p=.004) in a univariate model . Two-hundred-forty-seven patients were evaluable at the one-year time point. Among those, 100 patients (40%) developed CKD one-year post-CBT. Severe AKI was associated with a higher hazard of non-relapse mortality (adjusted HR=3.26, 95% CI 1.65-6.45, p=.001) and overall mortality (adjusted HR=2.28, 95% CI 1.22-4.27, p=.01).

Discussion

AKI is a frequent complication after CBT and is associated with worse outcomes. Questions remain as to the mechanism of the protective role of steroids on kidney function in the setting of CBT.

Antiviral Therapeutics in Pediatric Transplant Recipients

Recipients of solid organ and hematopoietic stem cell transplantation undergo substantial immune suppression, placing them at risk for opportunistic viral infection. Few randomized controlled trials have been dedicated to the treatment of viral infections in children, and current practices are extrapolated from data generated from adult patients. Here we discuss the prevention and treatment of viral infections using available antiviral drugs, as well as novel agents that may provide benefit to pediatric patients in the future.

Efficacy and safety of isavuconazole compared with voriconazole as primary antifungal prophylaxis in allogeneic hematopoietic cell transplant recipients

Voriconazole is frequently discontinued prematurely as primary antifungal prophylaxis (AFP) in allogeneic hematopoietic cell transplant (HCT) recipients due to adverse events. Limited data exists for isavuconazole as AFP. We analyzed adult HCT recipients who received voriconazole or isavuconazole AFP to estimate rate of premature AFP discontinuation, identify risk factors for premature AFP discontinuation, and compare incidence of invasive fungal infection (IFI) and survival at day + 180 post-HCT between patients who received voriconazole/isavuconazole-AFP. This was a propensity score matched cohort analysis of 210 HCT-recipients who received voriconazole-AFP (9/1/2014-12/31/2016; voriconazole-cohort), and 95 HCT-recipients who received isavuconazole-AFP (5/1/2017-10/31/2018; isavuconazole-cohort). AFP discontinuation for any reason prior to completion was defined as "premature". Median (interquartile range, IQR) duration of AFP was longer in the isavuconazole-cohort (94 days, 87-100) vs. the voriconazole-cohort (76 days, 23-94; P-value < 0.0001). Premature AFP discontinuation was more frequent in the voriconazole-cohort (92/210, 43.8%) vs. the isavuconazole-cohort (14/95, 14.7%; P-value < 0.0001). The most common reason for premature discontinuation was biochemical hepatotoxicity (voriconazole-cohort: 48/210, 22.8% vs. isavuconazole-cohort: 5/95, 5.26%; P-value = 0.0002). Transaminase values between baseline and end-of-treatment (EOT) and up to 14 days post-EOT significantly increased in the voriconazole-cohort, but remained unchanged in the isavuconazole-cohort. The incidence of IFI at day + 180 was 2.9% (6/210) and 3.2% (3/95) in the voriconazole-cohort and isavuconazole-cohort, respectively (P-value = 0.881). All-cause mortality at day + 180 was 2.4% (5/210) and 6.3% (6/95) in the voriconazole-cohort and isavuconazole-cohort, respectively (P-value = 0.089). When compared to voriconazole, isavuconazole was a safer and as effective primary AFP during the first 3 months after HCT.

LAY SUMMARY

When compared to voriconazole, isavuconazole is a safer and as effective primary antifungal prophylaxis during the first 3 months after allogeneic hematopoietic cell transplant, with lower rates of hepatotoxicity, and similar rates of fungal infections and all-cause mortality.

Guidelines for Pediatric Unrelated Cord Blood Transplantation-Unique Considerations

Cord blood (CB) is the stem cell source of choice for approximately 30% of pediatric patients undergoing hematopoietic cell transplantation. Cord blood is readily available and is a particularly appealing stem cell source for patients who lack appropriate HLA-matched related or unrelated donors. Pediatric cord blood transplant (CBT) recipients have low rates of disease relapse in the malignant setting and very low rates of chronic graft-versus-host disease (GVHD). In addition, CB has unique properties that make it the stem cell source of choice for some nonmalignant conditions such as metabolic disorders. This review provides evidence-based and experience-based pediatric-specific guidelines for CBT including considerations for infectious disease management, CB unit selection and infusion, conditioning regimen selection, and GVHD management. In addition, it covers unique bedside considerations for pediatric patients and CB banking. In concert with the other topic specific CB guidelines previously published in this series, it provides a comprehensive overview of the clinical management of pediatric CBT.

Guidelines for Infection Prophylaxis, Monitoring and Therapy in Cord Blood Transplantation

As an alternative stem cell source, cord blood (CB) has many advantages. However, delayed engraftment, lack of transferred immunity, and a significant incidence of acute graft-versus-host disease renders CB transplant (CBT) recipients at high risk of infectious complications. This guidance written by CBT and infectious disease experts outlines evidence-based recommendations for the prevention and treatment of opportunistic infections in adult patients undergoing CBT. Topics addressed include bacterial, fungal, viral, pneumocystis jirovcii and toxoplasmosis prophylaxis, suggested PCR monitoring for viruses, therapy for the most commonly encountered infections after CBT. We review key concepts including the recent important role of letermovir in the prevention of CMV reactivation. In instances where there is a paucity of data, practice recommendations are provided, including the duration of antimicrobial prophylaxis.

Robust CD4+ T-cell recovery in adults transplanted with cord blood and no antithymocyte globulin

Quality of immune reconstitution after cord blood transplantation (CBT) without antithymocyte globulin (ATG) in adults is not established. We analyzed immune recovery in 106 engrafted adult CBT recipients (median age 50 years [range 22-70]) transplanted for hematologic malignancies with cyclosporine/mycophenolate mofetil immunoprophylaxis and no ATG. Patients were treated predominantly for acute leukemia (66%), and almost all (96%) underwent myeloablation. Recovery of CD4+ T cells was faster than CD8+ T cells with median CD4+ T-cell counts exceeding 200/mm3 at 4 months. Early post-CBT, effector memory (EM), and central memory cells were the most common CD4+ subsets, whereas effector and EM were the most common CD8+ T-cell subsets. Naive T-cell subsets increased gradually after 6 to 9 months post-CBT. A higher engrafting CB unit infused viable CD3+ cell dose was associated with improved CD4+ and CD4+CD45RA+ T-cell recovery. Cytomegalovirus reactivation by day 60 was associated with an expansion of total, EM, and effector CD8+ T cells, but lower CD4+ T-cell counts. Acute graft-versus-host disease (aGVHD) did not significantly compromise T-cell reconstitution. In serial landmark analyses, higher CD4+ T-cell counts and phytohemagglutinin responses were associated with reduced overall mortality. In contrast, CD8+ T-cell counts were not significant. Recovery of natural killer and B cells was prompt, reaching medians of 252/mm3 and 150/mm3 by 4 months, respectively, although B-cell recovery was delayed by aGVHD. Neither subset was significantly associated with mortality. ATG-free adult CBT is associated with robust thymus-independent CD4+ T-cell recovery, and CD4+ recovery reduced mortality risk.

Immune Reconstitution after Haploidentical Donor and Umbilical Cord Blood Allogeneic Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy for a variety of hematologic diseases. However, this therapeutic platform is limited by an initial period when patients are profoundly immunocompromised. There is gradual immune recovery over time, that varies by transplant platform. Here, we review immune reconstitution after allogeneic HCT with a specific focus on two alternative donor platforms that have dramatically improved access to allogeneic HCT for patients who lack an HLA-matched related or unrelated donor: haploidentical and umbilical cord blood HCT. Despite challenges, interventions are available to mitigate the risks during the immunocompromised period including antimicrobial prophylaxis, modified immune suppression strategies, graft manipulation, and emerging adoptive cell therapies. Such interventions can improve the potential for long-term overall survival after allogeneic HCT.

Phase II Trial of Costimulation Blockade With Abatacept for Prevention of Acute GVHD

PURPOSE

Severe (grade 3-4) acute graft-versus-host disease (AGVHD) is a major cause of death after unrelated-donor (URD) hematopoietic cell transplant (HCT), resulting in particularly high mortality after HLA-mismatched transplantation. There are no approved agents for AGVHD prevention, underscoring the critical unmet need for novel therapeutics. ABA2 was a phase II trial to rigorously assess safety, efficacy, and immunologic effects of adding T-cell costimulation blockade with abatacept to calcineurin inhibitor (CNI)/methotrexate (MTX)-based GVHD prophylaxis, to test whether abatacept could decrease AGVHD.

METHODS

ABA2 enrolled adults and children with hematologic malignancies under two strata: a randomized, double-blind, placebo-controlled stratum (8/8-HLA-matched URD), comparing CNI/MTX plus abatacept with CNI/MTX plus placebo, and a single-arm stratum (7/8-HLA-mismatched URD) comparing CNI/MTX plus abatacept versus CNI/MTX CIBMTR controls. The primary end point was day +100 grade 3-4 AGVHD, with day +180 severe-AGVHD-free-survival (SGFS) a key secondary end point. Sample sizes were calculated using a higher type-1 error (0.2) as recommended for phase II trials, and were based on predicting that abatacept would reduce grade 3-4 AGVHD from 20% to 10% (8/8s) and 30% to 10% (7/8s). ABA2 enrolled 142 recipients (8/8s, median follow-up = 716 days) and 43 recipients (7/8s, median follow-up = 708 days).

RESULTS

In 8/8s, grade 3-4 AGVHD was 6.8% (abatacept) versus 14.8% (placebo) (P = .13, hazard ratio = 0.45). SGFS was 93.2% (CNI/MTX plus abatacept) versus 82% (CNI/MTX plus placebo, P = .05). In the smaller 7/8 cohort, grade 3-4 AGVHD was 2.3% (CNI/MTX plus abatacept, intention-to-treat population), which compared favorably with a nonrandomized matched cohort of CNI/MTX (30.2%, P < .001), and the SGFS was better (97.7% v 58.7%, P < .001). Immunologic analysis revealed control of T-cell activation in abatacept-treated patients.

CONCLUSION

Adding abatacept to URD HCT was safe, reduced AGVHD, and improved SGFS. These results suggest that abatacept may substantially improve AGVHD-related transplant outcomes, with a particularly beneficial impact on HLA-mismatched HCT.

Scoring system for clinically significant CMV infection in seropositive recipients following allogenic hematopoietic cell transplant: an SFGM-TC study

In order to identify cytomegalovirus (CMV)-seropositive patients who are at risk of developing CMV infection following first allogeneic hematopoietic cell transplantation (allo-HCT), we built up a scoring system based on patient/donor characteristics and transplantation modalities. To this end, 3690 consecutive patients were chronologically divided into a derivation cohort (2010-2012, n = 2180) and a validation cohort (2013-2014, n = 1490). Haploidentical donors were excluded. The incidence of first clinically significant CMV infection (CMV disease or CMV viremia leading to preemptive treatment) at 1, 3, and 6 months in the derivation cohort was 13.8%, 38.5%, and 39.6%, respectively. CMV-seropositive donor, unrelated donor (HLA matched 10/10 or HLA mismatched 9/10), myeloablative conditioning, total body irradiation, antithymocyte globulin, and mycophenolate mofetil significantly and independently affected the incidence of 3-month infection. These six factors were selected to build up the prognostic model. Four risk groups were defined: low, intermediate-low, intermediate-high, and high-risk categories, with a 3-month predicted incidence of first clinically significant CMV infection in the derivation cohort of 22.2%, 31.1%, 45.4%, and 56.9%, respectively. This score represents a framework for the evaluation of patients who are at risk of developing clinically significant CMV infection following allo-HCT. Prospective studies using this score may be of benefit in assessing the value of anti-CMV prophylaxis in well-defined patient cohorts.

Toxoplasmosis in Pediatric Hematopoietic Stem Cell Transplantation Patients

Infection due to the protozoa Toxoplasma gondii can be life-threatening in hematopoietic stem cell transplantation (HSCT) recipients. Most cases of toxoplasmosis in HSCT recipients result from reactivation of latent infection in individuals who were Toxoplasma-seropositive before transplantation and did not receive appropriate prophylaxis. Pretransplantation screening with Toxoplasma IgG and IgM antibodies is suggested for all allogeneic HSCT recipients and their donors and all autologous HSCT recipients. Prevention of toxoplasmosis in T. gondii-seropositive HSCT recipients requires primary prophylaxis, preemptive screening, or both. Trimethoprim-sulfamethoxazole (TMP-SMX) is the preferred agent for Toxoplasma prophylaxis and should be continued for 6 months or until the patient is no longer receiving immunosuppression, whichever is longer, assuming that immune reconstitution has occurred. Preemptive weekly screening with whole blood Toxoplasma PCR should be considered for seropositive HSCT recipients if prophylaxis cannot be given or if prophylaxis other than TMP-SMX is used. The signs, symptoms, and radiographic findings of toxoplasmosis in HSCT recipients can be nonspecific, and the diagnosis requires a high degree of suspicion. Common presentations include fever, encephalopathy with mental status changes or seizures, and pneumonia. A Toxoplasma PCR analysis from whole blood (and other body fluids/tissues according to clinical symptoms) should be obtained in patients in whom there is a concern for toxoplasmosis. Treatment with oral pyrimethamine, sulfadiazine, and leucovorin for at least 6 weeks is the first-line therapy and should be followed by secondary prophylaxis. In this article, we review the published literature regarding the epidemiology, clinical presentation, treatment, and prevention of toxoplasmosis in HSCT recipients.

Impact of T Cell Repertoire Diversity on Mortality Following Cord Blood Transplantation

Introduction

Cord blood transplantation (CBT) recipients are at increased risk of mortality due to delayed immune recovery (IR). Prior studies in CBT patients have shown that recovery of absolute lymphocyte count is predictive of survival after transplant. However, there are no data on the association of T-cell receptor (TCR) and clinical outcomes after CBT. Here we retrospectively performed TCR beta chain sequencing on peripheral blood (PB) samples of 34 CBT patients.

Methods

All patients received a total body irradiation based conditioning regimen and cyclosporine and MMF were used for graft versus host disease (GvHD) prophylaxis. PB was collected pretransplant on days 28, 56, 80, 180, and 1-year posttransplant for retrospective analysis of IR utilizing high-throughput sequencing of TCRβ rearrangements from genomic DNA extracted from PB mononuclear cells. To test the association between TCR repertoire diversity and patient outcomes, we conducted a permutation test on median TCR repertoire diversity for patients who died within the first year posttransplant versus those who survived.

Results

Median age was 27 (range 1–58 years) and most of the patients (n = 27) had acute leukemias. There were 15 deaths occurring between 34 to 335 days after transplant. Seven deaths were due to relapse. Rapid turnover of T cell clones was observed at each time point, with TCR repertoires stabilizing by 1-year posttransplant. TCR diversity values at day 100 for patients who died between 100 and 365 days posttransplant were significantly lower than those of the surviving patients (p = 0.01).

Conclusions

Using a fast high-throughput TCR sequencing assay we have demonstrated that high TCR diversity is associated with better patient outcomes following CBT. Importantly, this assay is easily performed on posttransplant PB samples, even as early as day 28 posttransplant, making it an excellent candidate for early identification of patients at high risk of death.

The Identity Card of T Cells-Clinical Utility of T-cell Receptor Repertoire Analysis in Transplantation

There is a clear medical need to change the current strategy of "one-size-fits-all" immunosuppression for controlling transplant rejection to precision medicine and targeted immune intervention. As T cells play a key role in both undesired graft rejection and protection, a better understanding of the fate and function of both alloreactive graft-deteriorating T cells and those protecting to infections is required. The T-cell receptor (TCR) is the individual identity card of each T cell clone and can help to follow single specificities. In this context, tracking of lymphocytes with certain specificity in blood and tissue in clinical follow up is of especial importance. After overcoming technical limitations of the past, novel molecular technologies opened new avenues of diagnostics. Using advantages of next generation sequencing, a method was established for T-cell tracing by detection of variable TCR region as identifiers of individual lymphocyte clones. The current review describes principles of laboratory and computational methods of TCR repertoire analysis, and gives an overview on applications for the basic understanding of transplant biology and immune monitoring. The review also delineates methodological pitfalls and challenges. With the outlook on prediction of antigens in immune-mediated processes including those of unknown causative pathogens, monitoring the fate and function of individual T cell clones, and the adoptive transfer of protective effector or regulatory T cells, this review highlights the current and future capability of TCR repertoire analysis.

Assessment and streamlined preparation of low-cytotoxicity lentiviral vectors for mobilized human hematopoietic stem cell transduction

As important vectors for ectopic protein expression, gene silencing, and progenitor cell barcoding, lentiviruses continue to emerge as versatile research and clinical tools. For studies employing cell types that are relatively resistant to transduction, high-titer lentivirus preparations with low cytotoxicity are required. During lentivirus production, carryover plasmid DNA endotoxins, transfection reagents, damaged packaging cells, and virus concentration procedures are potential sources of cytotoxicity. As an often unevaluated property of lentivirus preparations, cytotoxicity can unwittingly skew estimates of functional titers and complicate interpretations of transduced cell phenotypes. By employing hematopoietic UT7epo cells cultured in erythropoietin (EPO) below maximal dosing, we first define a sensitive flow cytometric bioassay for critically assessing the cytotoxicity (and titers) of lentivirus preparations. Bioassay of custom preparations of research-grade lentiviruses from six commercial sources unexpectedly revealed substantial cytotoxicity (with certain preparations additionally registering titers several log below designated values). To overcome such limiting properties, we further report on unique, efficient workflows for reproducibly preparing and processing high-titer, low-cytotoxicity (HTLC) lentiviruses at research scale. These HTLC lentiviruses reliably transduce peripheral blood hematopoietic stem/progenitor cells (PB-HSPCs) at frequencies ≥40%, with low cytotoxicity. In addition, by employing cyclosporin H (to inhibit IFITM3), PB-HSPCs can be transduced at heightened efficiency with nominal cytotoxicity. Overall, this work provides straightforward approaches to (1) critical assessment of the cytotoxicity of lentivirus preparations; (2) reproducible generation (and concentration) of high-quality lentiviruses via a streamlined workflow; and (3) transduction of PB-HSPCs at benchmark levels with nominal cytotoxicity.

Clinical Relevance of Immunobiology in Umbilical Cord Blood Transplantation

Umbilical cord blood transplantation (UCBT) has been an important donor source for allogeneic hematopoietic stem cell transplantation, especially for patients who lack suitable matched donors. UCBT provides unique practical advantages, such as lower risks of graft-versus-host-disease (GVHD), permissive HLA mismatch, and ease of procurement. However, there are clinical challenges in UCBT, including high infection rates and treatment-related mortality in selected patient groups. These clinical advantages and challenges are tightly linked with cell-type specific immune reconstitution (IR). Here, we will review IR, focusing on T and NK cells, and the impact of IR on clinical outcomes. Better understanding of the immune biology in UCBT will allow us to further advance this field with improved clinical practice.

Umbilical cord blood transplantation and the impact of the CTLA4 genotype on outcomes

Background: Umbilical cord blood transplantation is an effective method of curing multiple diseases when there is no donor available for allogeneic hematopoietic stem cell transplantation (AHSCT). It has been recently suggested that polymorphisms in genes affecting antigen presentation could potentially affect cord blood transplantation (CBT) outcomes.Areas covered: In this review, we present the results of the latest studies investigating the link between CTLA4 gene variability and umbilical cord blood transplantation outcomes.Expert opinion: The search for genetic variants that influence the immune response, both innate and adaptive immunity, may lead to more optimal therapies. Promising candidate genes are those that regulate the expression of proteins associated with T-cell activation. Many genetic variants could be therapeutically important, including those related to innate and adaptive immunity, cytokines, chemokines, drug-metabolizing enzymes, drug transporters, and inflammatory enzymes. The development of an algorithm that includes the determination of selected genetic variants could be helpful for an appropriate donor-recipient CBT matching.

Cytomegalovirus (CMV) infection and risk of mortality in allogeneic hematopoietic stem cell transplantation (Allo-HSCT): A systematic review, meta-analysis, and meta-regression analysis

Controversy surrounds the potential association between cytomegalovirus (CMV) infection and increased risk of mortality after allogeneic hematopoietic stem cell transplantation (Allo-HSCT). A systematic literature search was conducted using the PubMed, EMBASE, and Web of Science databases, assessing the association between CMV infection, as documented by the pp65 antigenemia assay or by polymerase chain reaction (PCR) using blood specimens, and overall mortality (OM) and nonrelapse mortality (NRM) in the allo-HSCT setting. Pooled effects were estimated using the generic inverse variance random effects model. Heterogeneity was evaluated by Cochrane's Q test and I² statistics. The source of heterogeneity was investigated by meta-regression and subgroup analyses. Twenty-six of 1367 studies fulfilled eligibility criteria. CMV infection identified by PCR monitoring was significantly associated with an increased risk of OM and NRM (hazard ratio 1.47, 95% confidence interval [1.20-1.81], P ≤ .001; hazard ratio 1.68, 95% confidence interval [1.14-2.49], P = .05, respectively). In this setting, the use of preemptive antiviral therapy (PET) resulted in a twofold increased risk of OM and NRM. The estimated effect sizes were associated with allo-HSCT modalities. Although our analyses point to an association between CMV infection and an increased risk of OM and NRM in allo-HSCT recipients, the high heterogeneity across studies prevented drawing of robust conclusions on this matter.

Immune Reconstitution Disorders: Spotlight on Interferons

Three decades of research in hematopoietic stem cell transplantation and HIV/AIDS fields have shaped a picture of immune restoration disorders. This manuscript overviews the molecular biology of interferon networks, the molecular pathogenesis of immune reconstitution inflammatory syndrome, and post-hematopoietic stem cell transplantation immune restoration disorders (IRD). It also summarizes the effects of thymic involution on T cell diversity, and the results of the assessment of diagnostic biomarkers of IRD, and tested targeted immunomodulatory treatments.

Guidelines for the management of cytomegalovirus infection in patients with haematological malignancies and after stem cell transplantation from the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Cytomegalovirus is one of the most important infections to occur after allogeneic haematopoietic stem cell transplantation (HSCT), and an increasing number of reports indicate that cytomegalovirus is also a potentially important pathogen in patients treated with recently introduced drugs for hematological malignancies. Expert recommendations have been produced by the 2017 European Conference on Infections in Leukaemia (ECIL 7) after a review of the literature on the diagnosis and management of cytomegalovirus in patients after HSCT and in patients receiving other types of therapy for haematological malignancies. These recommendations cover diagnosis, preventive strategies such as prophylaxis and pre-emptive therapy, and management of cytomegalovirus disease. Antiviral drugs including maribavir and letermovir are in development and prospective clinical trials have recently been completed. However, management of patients with resistant or refractory cytomegalovirus infection or cytomegalovirus disease is a challenge. In this Review we summarise the reviewed literature and the recommendations of the ECIL 7 for management of cytomegalovirus in patients with haematological malignancies.

Immune reconstitution following hematopoietic stem cell transplantation using different stem cell sources

Introduction: Adequate immune reconstitution post-HSCT is crucial for the success of transplantation, and can be affected by both patient- and transplant-related factors. Areas covered: A systematic literature search in PubMed, Scopus, and abstracts of international congresses is performed to investigate immune recovery posttransplant. In this review, we discuss the pattern of immune recovery in the post-transplant period focusing on the impact of stem cell source (bone marrow, peripheral blood stem cells, and cord blood) on immune recovery and HSCT outcome. We examine the impact of serotherapy on immune reconstitution and the need to tailor dosing of serotherapy agents when using different stem cell sources. We discuss new techniques being used particularly with cord blood and haploidentical grafts to improve immune recovery in each scenario. Expert opinion: Cord blood T cells provide a unique CD4+ biased immune reconstitution. Initial studies using targeted serotherapy with cord grafts showed improved immune recovery with limited alloreactivity. Two competing haploidentical approaches have developed in recent years including TCRαβ/CD19 depleted grafts and post-cyclophosphamide haplo-HSCT. Both approaches have comparable survival rates with limited alloreactivity. However, delayed immune reconstitution is still an ongoing problem and could be improved by modified donor lymphocyte infusions from the same haploidentical donor.

Host and Graft Factors Impacting Infection Risk in Hematopoietic Cell Transplantation

Infection contributes significantly to morbidity and mortality in hematopoietic cell transplantation. A complex interplay of host, graft, and technical factors contributes to infectious risk in the recipient. Host factors such as age, underlying disease, and comorbidities; central venous access; and the preparative regimen contribute to mucosal disruption, organ dysfunction, and immunodeficiency before hematopoietic cell transplantation. Graft factors, including donor histocompatibility, cell source, and graft components, along with immunosuppression and graft-versus-host disease, contribute to the speed of immune reconstitution. Evaluation of these factors, plus previous and posttransplant exposure to pathogens, is necessary to best assess an individual recipient's infection risk.

Delayed immune reconstitution after allogeneic transplantation increases the risks of mortality and chronic GVHD

Slow immune reconstitution is a major obstacle to the successful use of allogeneic hematopoietic cell transplantation (allo-HCT). As matched sibling donor (MSD) allo-HCT is regarded as the gold standard, we evaluated the pace of immune reconstitution in 157 adult recipients of reduced-intensity conditioning followed by MSD peripheral blood HCT (n = 68) and compared these to recipients of umbilical cord blood (UCB; n = 89). At day 28, UCB recipients had fewer natural killer (NK) cells than MSD recipients, but thereafter, NK cell numbers (and their subsets) were higher in UCB recipients. During the first 6 months to 1 year after transplant, UCB recipients had slower T-cell subset recovery, with lower numbers of CD3⁺, CD8⁺, CD8⁺ naive, CD4⁺ naive, CD4⁺ effector memory T, regulatory T, and CD3⁺CD56⁺ T cells than MSD recipients. Notably, B-cell numbers were higher in UCB recipients from day 60 to 1 year. Bacterial and viral infections were more frequent in UCB recipients, yet donor type had no influence on treatment-related mortality or survival. Considering all patients at day 28, lower numbers of total CD4⁺ T cells and naive CD4⁺ T cells were significantly associated with increased infection risk, treatment-related mortality, and chronic graft-versus-host disease (GVHD). Patients with these characteristics may benefit from enhanced or prolonged infection surveillance and prophylaxis as well as immune reconstitution-accelerating strategies.

Infectious Complications After Umbilical Cord Blood Transplantation for Hematological Malignancy

Background

Umbilical cord blood transplant (UCBT) is used for patients who do not have a matched donor, but engraftment often takes longer than with a standard allogeneic transplant, likely increasing the risk for infection. We characterized specific infections and outcomes in adults undergoing UCBT at our 2 centers.

Methods

All adults who underwent UCBT between January 1, 2006 and December 31, 2015 were included. Infectious episodes from 6 months before to 2 years after UCBT were reviewed.

Results

Fifty-seven patients underwent UCBT; 47 had neutrophil engraftment. A total of 179 infectious episodes occurred in 55 patients, 73 (41%) within 30 days post-UCBT. Viruses caused 85 (47%) infections. Cytomegalovirus caused 32 infectious episodes and was most common from day 30 to 100. Human herpesvirus 6 occurred in 28 episodes, was most common within 30 days, and caused 1 death. Bacteria were responsible for 82 (46%) infections, most commonly bacteremias due to Staphylococcus spp, Enterococcus spp, and Enterobacteriaceae. Of 11 invasive fungal infections, 9 were aspergillosis, 4 of which were fatal. Overall mortality was 56% in the first year. Thirteen deaths were from infection; 11 occurred in the first 100 days and 7 in the first 30 days post-UCBT. Of 10 patients who never engrafted, 9 died, 6 from infection, within 100 days post-UCBT.

Conclusions

Infectious complications were common after UCBT, especially in the first 30 days. Deaths from viral infections were fewer than expected. Delayed engraftment and nonengraftment continue to convey increased risk for fatal bacterial and fungal infections post-UCBT.

Invasive fungal disease in patients undergoing umbilical cord blood transplantation after myeloablative conditioning regimen

OBJECTIVE

Characteristics and risk factors (RFs) of invasive fungal disease (IFD) have been little studied in the setting of umbilical cord blood transplantation (UCBT).

METHOD

We retrospectively included 205 single-unit myeloablative UCBT recipients with a median follow-up of 64 months.

RESULTS

Fifty-six episodes of IFD were observed in 48 patients (23%) at a median time of 123 days after stem cell infusion. Invasive mold disease (IMD) occurred in 42 cases, 38 of them (90%) caused by invasive aspergillosis whereas invasive yeast disease (IYD) occurred in 14 cases, most of them due to candidemia (n = 12, 86%). The 5-year cumulative incidence of IFD, IMDs, and IYDs was 24% 19%, and 7%, respectively. In multivariate analysis, three RFs for IMDs were identified: age >30 years (HR 3.5, P = 0.017), acute grade II-IV graft-versus-host disease (HR 2.3, P = 0.011), and ≥1 previous transplant (HR 3.1, P = 0.012). The probability of IMDs was 2.5%, 14%, and 33% for recipients with none, 1, or 2-3 RFs, respectively (P < 0.001). Among IFD, IMDs had a negative effect on non-relapse mortality in multivariate analysis (HR 1.6, P = 0.039). IMDs showed a negative impact on overall survival (HR 1.59, P = 0.018).

CONCLUSION

Invasive mold disease were very common and serious complication after UCBT.

Better outcomes of modified myeloablative conditioning without antithymocyte globulin versus myeloablative conditioning in cord blood transplantation for hematological malignancies: A retrospective (development) and a prospective (validation) study

Cord blood transplantation (CBT) is an effective option for treating hematological malignancies, but graft failure (GF) remains the primary cause of therapy failure. Thus, based on myeloablative conditioning (MAC) of busulfan with cyclophosphamide (Bu/Cy) or total body irradiation with Cy (TBI/Cy), fludarabine (Flu) was added to Bu/Cy and cytarabine (CA) to TBI/Cy for a modified myeloablative conditioning (MMAC). To compare the prognosis of MMAC with MAC, we conducted a retrospective study including 58 patients who underwent CBT with MAC or MMAC from 2000 to 2011. Neutrophil and platelet engraftment rate, overall survival (OS) and disease free survival (DFS) were significantly higher in the MMAC group (adjusted hazard ratio [HR], 2.58, 2.43, 0.36 and 0.37; p < 0.01, p = 0.01, p = 0.02 and p = 0.02, separately). Nonrelapse mortality (NRM) was comparable (p = 0.183). To validate the outcomes noted in the MMAC group, we conducted a prospective single‐arm clinical trial including 188 patients who underwent CBT with MMAC from 2011 to 2015. Engraftment rate, survival and NRM of the MMAC group in the prospective trail (MMAC‐P) were similar to the MMAC group in the retrospective study (MMAC‐R). This study is the first to demonstrate the superiority of MMAC to MAC in CBT for hematological malignancies.

What's new?

Cord blood transplants can help patients with blood cancer, but too often, the transplant fails due to immune rejection or other problems. Typically, patients receive myeloablative conditioning (MAC) prior to CBT, but more intense regimen might improve transplant success. Here, the authors compared the success of modified myeloablative conditioning (MMAC) with conventional MAC by looking at 58 patients over an 11‐year period. They then followed up with a four‐year prospective study, including 188 patients who received cord blood transplant with MMAC. The modified conditioning regimen boosted graft success and improved survival of patients with hematological cancers.

Reconstitution of adaptive immunity after umbilical cord blood transplantation: impact on infectious complications

In comparison with allogeneic stem cell transplantation (alloHSCT) with other stem cell sources, umbilical cord blood transplantation (UCBT) was traditionally associated with increased risk of infections, particularly during the first 3 months after transplantation. Longitudinal studies of immune monitoring reported peculiar patterns of T- and B-cell recovery in the peripheral blood of UCB recipients during the first months post-transplantation. Overall, current data suggest delayed reconstitution of naive and memory CD4⁺ and CD8⁺ T-cell pools after UCBT. This is particularly true for adult recipients and for patients who received in vivo T-cell depleting approaches before the transplantation. Such delayed T-cell recovery may increase susceptibility of UCB recipients for developing opportunistic infections and viral reactivations. Regarding B-cell recovery, UCBT was associated with accelerated B-lymphopoiesis. Recent studies also reported evidence for faster functional memory B-cell recovery in UCB recipients. In this article, we briefly review T- and B-cell reconstitution after alloHSCT, with emphasis on peculiarities observed after UCBT. We further put these data in lines with risks of infections after UCBT.

Optimal Practices in Unrelated Donor Cord Blood Transplantation for Hematologic Malignancies

Unrelated donor cord blood transplantation (CBT) results in disease-free survival comparable to that of unrelated adult donor transplantation in patients with hematologic malignancies. Extension of allograft access to racial and ethnic minorities, rapid graft availability, flexibility of transplantation date, and low risks of disabling chronic graft-versus-host disease (GVHD) and relapse are significant advantages of CBT, and multiple series have reported a low risk of late transplantation-related mortality (TRM) post-transplantation. Nonetheless, early post-transplantation morbidity and TRM and the requirement for intensive early post-transplantation management have slowed the adoption of CBT. Targeted care strategies in CBT recipients can mitigate early transplantation complications and reduce transplantation costs. Herein we provide a practical "how to" guide to CBT for hematologic malignancies on behalf of the National Marrow Donor Program and the American Society of Blood and Marrow Transplantation's Cord Blood Special Interest Group. It shares the best practices of 6 experienced US transplantation centers with a special interest in the use of cord blood as a hematopoietic stem cell source. We address donor search and unit selection, unit thaw and infusion, conditioning regimens, immune suppression, management of GVHD, opportunistic infections, and other factors in supportive care appropriate for CBT. Meticulous attention to such details has improved CBT outcomes and will facilitate the success of CBT as a platform for future graft manipulations.

Antithymocyte globulin improves the survival of patients with myelodysplastic syndrome undergoing HLA-matched unrelated donor and haplo-identical donor transplants

Significant advances have been achieved in the outcomes of patients with myelodysplastic syndromes (MDS) after both HLA-matched sibling donor transplants (MSDT) and non-MSDT, the latter including HLA-matched unrelated donor (MUDT) and haplo-identical donor transplants (HIDT). In this retrospective study, we analyzed the data of 85 consecutive patients with MDS who received allogeneic HSCT between Dec 2007 and Apr 2014 in our center. These patients comprised 38 (44.7%) who received MSDT, 29 (34.1%) MUDT, and 18 (21.2%) HIDT. The median overall survival (OS) was 60.2 months, the probabilities of OS being 63%, 57%, and 48%, at the first, second, and fifth year, respectively. Median OS post-transplant (OSPT) was 57.2 months, the probabilities of OSPT being 58%, 55%, and 48% at the first, second, and fifth year, respectively. The survival of patients receiving non-MSDT was superior to that of MSDT, median OSPT being 84.0 months and 23.6 months, respectively (P = 0.042); the findings for OS were similar (P = 0.028). We also found that using ATG in conditioning regimens significantly improved survival after non-MSDT, with better OS and OSPT (P = 0.016 and P = 0.025). These data suggest that using ATG in conditioning regimens may improve the survival of MDS patients after non-MSDT.

Early and Long-Term Impaired T Lymphocyte Immune Reconstitution after Cord Blood Transplantation with Antithymocyte Globulin

Immune reconstitution is crucial to the success of allogeneic hematopoietic stem cell transplantation. Umbilical cord blood transplantation (UCBT) has been associated with delayed immune reconstitution. We characterized the kinetics and investigated the risk variables affecting recovery of the main lymphocyte subsets in 225 consecutive pediatric and adult patients (males, n = 126; median age, 15; range, .3 to 60; interquartile range, 4 to 35) who underwent myeloablative single UCBT between 2005 and 2015 for malignant and nonmalignant disorders. Low CD4⁺ and CD8⁺ T cell counts were observed up to 12 months after UCBT. In contrast, B and natural killer cells recovered rapidly early after transplantation. In a multivariate regression model, factors favoring CD4⁺ T cell recovery ≥ 200 cells/µL were lower dose antithymocyte globulin (ATG) (hazard ratio [HR], 3.93; 95% confidence interval [CI], 2.3 to 5.83; P = .001), negative recipient cytomegalovirus (CMV) serostatus (HR, 3.76; 95% CI, 1.9 to 5.74; P = .001), and younger age (HR, 2.61; 95% CI, 1.01 to 3.47; P = .03). Factors favoring CD8⁺ T cell recovery ≥ 200 cells/µL were lower dose ATG (HR, 3.03; 95% CI, 1.4 to 5.1; P = .03) and negative recipient CMV serostatus (HR, 1.9; 95% CI, 1.63 to 2.15; P = .01). Our results demonstrate the significant negative impact of ATG on lymphocyte recovery. A reduction of the dose or omission of ATG could improve immune reconstitution and perhaps reduce opportunistic infections after UCBT.

Bacteremia during neutropenic episodes in children undergoing hematopoietic stem cell transplantation with ciprofloxacin and penicillin prophylaxis

Bacteremia during neutropenic episodes is a cause of morbidity and mortality in patients undergoing hematopoietic stem cell transplantation (HSCT). We have used oral ciprofloxacin and penicillin V, from the start of the conditioning regimen until engraftment, for the prophylaxis of bacterial infection. The objective of this study was to retrospectively analyze the prevalence of and risk factors for breakthrough bacteremia during neutropenic episodes in autologous and allogeneic HSCT patients. There were 215 patients enrolled, with a median age of 8.32 years (range 0.51-21.64 years) between 2002 and 2014. The common underlying diseases were thalassemia and acute leukemia. Bacteremia was documented in 33 patients (15.3 %), with 39 microorganisms isolated. Escherichia coli (28.2 %) and Streptococcus viridans (12.8 %) were the most commonly isolated Gram-negative and Gram-positive bacteria, respectively. Multidrug resistant strains were found in 32 and 14.3 % of Gram-negative and Gram-positive bacteria, respectively. Risk factors for bacteremia were receiving anti-thymocyte globulin (ATG) [odds ratio (OR) 2.44, 95 % confidence interval (CI) 1.06-5.65, P = 0.037] and umbilical cord blood as a stem cell graft (OR 6.60, 95 % CI 1.04-41.83, P = 0.045). In conclusion, the prevalence of bacteremia was 15.3 % and the use of ATG and cord blood were risk factors for bacteremia during neutropenic episodes.

Infectious Complications after Umbilical Cord-Blood Transplantation from Unrelated Donors

Umbilical cord-blood (UCB) is a well-recognized alternative source of stem cells for unrelated donor hematopoietic stem cell transplantation (HSCT). As compared with other stem cell sources from adult donors, it has the advantages of immediate availability of cells, absence of risk to the donor and reduced risk of graft-versus-host disease despite donor-recipient HLA disparity. However, the use of UCB is limited by the delayed post-transplant hematologic recovery due, at least in part, to the reduced number of hematopoietic cells in the graft and the delayed or incomplete immune reconstitution. As a result, severe infectious complications continue to be a leading cause of morbidity and mortality following UCB transplantation (UCBT). We will address the complex differences in the immune properties of UCB and review the incidence, characteristics, risk factors, and severity of bacterial, fungal and viral infectious complications in patients undergoing UCBT.

Chronic graft versus host disease burden and late transplant complications are lower following adult double cord blood versus matched unrelated donor peripheral blood transplantation

Adult umbilical cord blood transplantation (CBT) has emerged as an important option for patients lacking matched related (MRD) and matched unrelated donors (MUD). We compared chronic GVHD (cGVHD) incidence, immunosuppression burden and late infections and hospitalizations in consecutive patients undergoing CBT (n=51) versus peripheral blood MUD transplant (n=57) at our center between June 2009 and April 2014. At 3 years post transplantation, the cumulative incidence (CI) of moderate to severe cGVHD was 44% following MUD versus 8% following CBT (P=0.0006) and CI of any cGVHD was 68% following MUD versus 32% following CBT (P=0.0017). Median time to being off immunosuppression among CB patients was 268 days versus not reached among MUD patients (P<0.0001). Late infections and late hospitalized days were reduced in CB patients (P=0.1 and <0.001, respectively). Three-year CI of transplant-related mortality (TRM) and relapse as well as 3-year overall survival (OS) were similar following CB and MUD transplantation. We demonstrate a significantly lower incidence of cGVHD, immunosuppression burden and late complication rate following UCB versus peripheral blood MUD transplant without decreased OS, increased relapse or early TRM. Combined with the rapid availability of UCB, these findings have led our center to move primarily to UCB over peripheral blood MUD when a MRD is not available.

Immune reconstitution post allogeneic transplant and the impact of immune recovery on the risk of infection

Infection is the leading cause of non-relapse mortality after allogeneic haematopoietic cell transplantation (HCT). This occurs as a result of dysfunction to the host immune system from the preparative regimen used prior to HCT, combined with a delay in reconstitution of the donor-derived immune system after HCT. In this article, we elaborate on the process of immune reconstitution post-HCT that begins with the innate system and is followed by recovery of adaptive immunity. Simultaneously, we describe how the tempo of immune reconstitution influences the risk of various infections. We explain some of the key differences in immune reconstitution and the consequent risk of infections in recipients of peripheral blood stem cell, bone marrow or umbilical cord blood grafts. Other factors that impact on immune recovery are also highlighted. Finally, we allude to various strategies that are being tested to enhance immune reconstitution post-HCT.

Infection Rates among Acute Leukemia Patients Receiving Alternative Donor Hematopoietic Cell Transplantation

Alternative graft sources (umbilical cord blood [UCB], matched unrelated donors [MUD], or mismatched unrelated donors [MMUD]) enable patients without a matched sibling donor to receive potentially curative hematopoietic cell transplantation (HCT). Retrospective studies demonstrate comparable outcomes among different graft sources. However, the risk and types of infections have not been compared among graft sources. Such information may influence the choice of a particular graft source. We compared the incidence of bacterial, viral, and fungal infections in 1781 adults with acute leukemia who received alternative donor HCT (UCB, n= 568; MUD, n = 930; MMUD, n = 283) between 2008 and 2011. The incidences of bacterial infection at 1 year were 72%, 59%, and 65% (P < .0001) for UCB, MUD, and MMUD, respectively. Incidences of viral infection at 1 year were 68%, 45%, and 53% (P < .0001) for UCB, MUD, and MMUD, respectively. In multivariable analysis, bacterial, fungal, and viral infections were more common after either UCB or MMUD than after MUD (P < .0001). Bacterial and viral but not fungal infections were more common after UCB than MMUD (P = .0009 and <.0001, respectively). The presence of viral infection was not associated with an increased mortality. Overall survival (OS) was comparable among UCB and MMUD patients with Karnofsky performance status (KPS) ≥ 90% but was inferior for UCB for patients with KPS < 90%. Bacterial and fungal infections were associated with poorer OS. Future strategies focusing on infection prevention and treatment are indicated to improve HCT outcomes.

Higher Early Monocyte and Total Lymphocyte Counts Are Associated with Better Overall Survival after Standard Total Body Irradiation, Cyclophosphamide, and Fludarabine Reduced-Intensity Conditioning Double Umbilical Cord Blood Allogeneic Stem Cell Transplantation in Adults

This single-center retrospective study aimed to report the impact of early hematopoietic and immune recoveries after a standard total body irradiation, cyclophosphamide, and fludarabine (TCF) reduced-intensity conditioning (RIC) regimen for double umbilical cord blood (dUCB) allogeneic stem cell transplantation (allo-SCT) in adults. We analyzed 47 consecutive patients older than 17 years who engrafted after a dUCB TCF allo-SCT performed between January 2006 and April 2013 in our department. Median times for neutrophil and platelet recoveries were 17 (range, 6 to 59) and 37 days (range, 0 to 164), respectively. The 3-year overall (OS) and disease-free survivals, relapse incidence, and nonrelapse mortality were 65.7%, 57.2%, 27.1%, and 19%, respectively. In multivariate analysis, higher day +30 monocyte (≥615/mm(3); hazard ratio [HR], .04; 95% confidence interval [CI], .004 to .36; P < .01) and day +42 lymphocyte (≥395/mm(3); HR, .16; 95% CI, .03 to .78; P = .02) counts were independently associated with better OS. These results suggest that early higher hematopoietic and immune recovery is predictive of survival after dUCB TCF RIC allo-SCT in adults. Factors other than granulocyte colony-stimulating factor, which was used in all cases, favoring expansion of monocytes or lymphocytes, should be tested in the future as part of the UCB transplantation procedure.

Cord Blood Units with High CD3(+) Cell Counts Predict Early Lymphocyte Recovery After In Vivo T Cell-Depleted Single Cord Blood Transplantation

Although high absolute lymphocyte count (ALC) early after transplantation is a simple surrogate for immune reconstitution, few studies to date have established the predictive factors for ALC after umbilical cord blood transplantation (UCBT). We retrospectively studied the factors associated with early lymphocyte recovery and the impact of the ALC on day +42 (ALC42) of ≥300 × 10(6)/L on outcomes in 210 consecutive pediatric and adult patients (112 males; median age, 15 years; range, 0.3 to 60 years; interquartile range, 4 to 36 years) who underwent myeloablative in vivo T cell-depleted single UCBT between 2005 and 2014 for malignant and nonmalignant disorders. In a logistic multivariate regression model, factors favoring a higher ALC42 were higher infused CD3(+) cell dose (odds ratio [OR], 2.7; 95% CI, 1.4 to 5.2; P = .004), lower antithymocyte globulin dose (OR, 2.3; 95% CI, 1.2 to 4.5; P = .01), and better HLA match (OR, 2.1; 95% CI, 1.1 to 4.1; P = .03). In multivariate analysis, lower ALC42 was associated with higher nonrelapse mortality (hazard ratio [HR], 1.76; 95% CI, 1.34 to 2.32; P = .001), whereas a higher ALC42 was associated with better disease-free survival (HR, 2.03; 95% CI, 1.15 to 3.6; P < .001) and overall survival (HR, 2.03; 95% CI, 1.17 to 3.6; P < .001). Our study suggests that the selection of better HLA-matched cord blood units containing higher CD3(+) cell counts and the use of conditioning regimens with lower ATG doses could improve immune reconstitution after UCBT.

Immune reconstitution after cord blood transplantation: peculiarities, clinical implications and management strategies

Umbilical cord blood (UCB) is now widely used as an alternative hematopoietic stem cell source for patients lacking closely matched related or unrelated adult donors. UCB transplantation has traditionally been associated with delayed engraftment, poor immune reconstitution and consequent increased risk of infection. More recent clinical studies, however, suggest that conditioning regimens and in particular the omission of in vivo T-cell depletion may play a crucial role in post-transplant T-cell expansion, facilitating a uniquely rapid immune recovery after UCB transplantation. The peculiar characteristics of UCB cells, the importance of thymic function and the role of conditioning regimens and graft-versus-host disease influencing immune reconstitution are described. The last part of the review reports available data on UCB, as well as third-party peripheral blood derived anti-viral cell therapy, which provides a novel approach to rescue UCB recipients with viral complications in the post-transplant period.

[Efficacy analysis of unrelated cord blood transplantation for 58 acute myelogenous leukemia patients]

目的

探讨非血缘脐血移植(UCBT)治疗急性髓系白血病(AML)的疗效及影响疗效的相关因素。

方法

回顾性分析接受UCBT治疗58例AML患者的临床资料。中位年龄14.5(3~36)岁，中位体重45(12~90) kg。FAB分型：M₀ 1例、M₁ 1例、M₂ 35例(包括骨髓增生异常综合征转AML 1例)、M₄ 3例、M₅ 14例、M₆ 3例、混合细胞白血病1例。移植时处于第1次完全缓解期(CR₁)36例，第2次完全缓解期(CR₂)14例，未缓解(NR) 8例，其中高危难治患者43例(74.1%)。单份UCBT 49例(84.5%)，双份UCBT 9例(15.5%)。所有患者均采用强化清髓预处理方案，采用环孢素联合霉酚酸酯预防移植物抗宿主病(GVHD)。

结果

全部58例患者中56例(96.6%)获得造血重建，中性粒细胞植入、血小板植入的中位时间分别为17(12~37) d、33(17~140) d。24例(42.9%)患者发生急性GVHD，其中Ⅱ~Ⅳ度急性GVHD的发生率为30.4%(17/56)。在可评估的49例患者中，7例(14.3%)出现慢性GVHD(均为局限型)。预期3年累积总体生存(OS)率和无病生存(DFS)率分别为(60.3±6.4)％和(60.1±6.5)%。3年非复发死亡率为33.3%，复发率为9.1%。UCBT时疾病为CR患者(50例)的3年OS率高于NR患者(8例)[(66.0±6.7)％对(25.0±15.3)%，P=0.013]。

结论

UCBT治疗AML安全有效，慢性GVHD发生率和复发率较低。

Severe infections after single umbilical cord blood transplantation in adults with or without the co-infusion of CD34+ cells from a third-party donor: results of a multicenter study from the Grupo Español de Trasplante Hematopoyético (GETH)

BACKGROUND

Umbilical cord blood transplantation (CBT) is an established alternative source of stem cells in the setting of unrelated transplantation. When compared with other sources, single-unit CBT (sCBT) is associated with a delayed hematologic recovery, which may lead to a higher infection-related mortality (IRM). Co-infusion with the sCBT of CD34+ peripheral blood stem cells from a third-party donor (TPD) (sCBT + TPDCD34+) has been shown to markedly accelerate leukocyte recovery, potentially reducing the IRM. However, to our knowledge, no comparative studies have focused on severe infections and IRM with these 2 sCBT strategies.

METHODS

A total of 148 consecutive sCBT (2000-2010, median follow-up 4.5 years) were included in a multicenter retrospective study to analyze the incidence and risk factors of IRM and severe viral and invasive fungal infections (IFIs). Neutrophil engraftment occurred in 90% of sCBT (n = 77) and 94% sCBT + TPDCD34+ (n = 71) recipients at a median of 23 and 12 days post transplantation, respectively (P < 0.01).

RESULTS

The 4-year IRM was 24% and 20%, respectively (P = 0.7), with no differences at day +30 (5% and 4%, respectively) and day +100 (10% and 8%, respectively). In multivariate analysis early status of the underlying malignancy, cytomegalovirus (CMV)-seronegative recipient and high CD34+ cell content in the cord blood unit before cryostorage (≥1.4 × 10(5) /kg) were protective of IRM. Among the causes of IRM, bacterial infections and IFIs were more common in sCBT (15% vs. 4%), while CMV disease and parasitic infections were more common in the sCBT + TPDCD34+ cohort (5% vs. 16%).

CONCLUSION

These data show that sCBT supported with TPDCD34(+) cells results in much shorter periods of post-transplant leukopenia, but the short- and long-term rates of IRM were comparable to those of sCBT, presumably because immune recovery is equally delayed in both graft types.

Robust Vaccine Responses in Adult and Pediatric Cord Blood Transplantation Recipients Treated for Hematologic Malignancies

Because cord blood (CB) lacks memory T and B cells and recent decreases in herd immunity to vaccine-preventable diseases in many developed countries have been documented, vaccine responses in CB transplantation (CBT) survivors are of great interest. We analyzed vaccine responses in double-unit CBT recipients transplanted for hematologic malignancies. In 103 vaccine-eligible patients, graft-versus-host disease (GVHD) most commonly precluded vaccination. Sixty-five patients (63%; engrafting units median HLA-allele match 5/8; range, 2 to 7/8) received protein conjugated vaccines, and 63 patients (median age, 34 years; range, .9 to 64) were evaluated for responses. Median vaccination time was 17 months (range, 7 to 45) post-CBT. GVHD (n = 42) and prior rituximab (n = 13) delayed vaccination. Responses to Prevnar 7 and/or 13 vaccines (serotypes 14, 19F, 23F) were seen in children and adults (60% versus 49%, P = .555). Responses to tetanus, diphtheria, pertussis, Haemophilus influenzae, and polio were observed in children (86% to 100%) and adults (53% to 89%) even if patients had prior GVHD or rituximab. CD4(+)CD45RA(+) and CD19(+) cell recovery significantly influenced tetanus and polio responses. In a smaller cohort responses were seen to measles (65%), mumps (50%), and rubella (100%) vaccines. No vaccine side effects were identified, and all vaccinated patients survived (median follow-up, 57 months). Although GVHD and rituximab can delay vaccination, CBT recipients (including adults and those with prior GVHD) have similar vaccine response rates to adult donor allograft recipients supporting vaccination in CBT recipients.

Topping it up: methods to improve cord blood transplantation outcomes by increasing the number of CD34+ cells

Cord blood is increasingly recognized for its excellent stem cell potential, lenient matching criteria, instant availability and clinical behavior in transplants when cell dose criteria can be met. However with 1-2 log fewer total (stem cell) numbers in the graft compared with other cell sources, the infused cell dose per kilogram is critical for engraftment and outcome, creating the need for development of stem cell support platforms. The co-transplant platforms of haplo cord and double unit cord blood (DUCB) transplantation are aimed toward increasing stem cell dose. Together with the optimization of reduced-intensity protocols, long-term sustained engraftment using cord blood has become available to most patients, including elderly patients. Haplo cord has a low incidence of both acute and chronic graft-versus-host disease but may require anti-thymocyte globulin ATG for effective neutrophil recovery. DUCB can be performed without anti-thymocyte globulin with excellent immune reconstitution and disease-free survival, but engraftment is considerably slower, and graft-versus-host disease incidence significant. Both haplo-cord and DUCB transplantation appear to both be valid alternatives to matched unrelated donors in adults.

Comparison of conditioning regimens with or without antithymocyte globulin for unrelated cord blood transplantation in children with high-risk or advanced hematological malignancies

The role and potential efficacy of antithymocyte globulin (ATG) in patients receiving cord blood transplantation (CBT) remain controversial. We retrospectively evaluated the effect of ATG on patient outcomes in 207 children with high-risk or advanced hematological malignancies at 8 child blood disease centers in China. The cumulative incidence of platelet recovery on day 100 was significantly lower in the ATG cohort compared with the non-ATG cohort (77.3% versus 89.8%) (P = .046). There was no significant difference in the incidence of grade II to IV acute and chronic graft-versus-host disease (GVHD), and transplantation-related mortality (TRM) between the 2 groups (P = .76, P = .57, and P = .46, respectively). The incidence of CMV infection was significantly higher among the ATG group compared with that among the non-ATG group (P = .003). The 5-year cumulative incidence of relapse was significantly higher in the ATG cohort (30.7% versus 15.4%) (P = .009). Overall survival in the non-ATG group was slightly higher than that of the ATG cohort (64.1% versus 52.1%, P = .093) and leukemia-free survival in the non-ATG cohort was significantly higher than in the ATG cohort (56.6% versus 37.7%, P = .015). Our study demonstrated that, for high-risk or advanced childhood hematological malignancies receiving unrelated CBT, patients who received conditioning that omitted ATG had a faster platelet recovery, a comparable GVHD and TRM, a significantly lower relapse risk, and an improved long-term survival compared with those patients who received ATG in the conditioning.