Double unrelated reduced-intensity umbilical cord blood transplantation in adults

Umbilical Cord Blood Transplantation: Connecting Its Origin to Its Future

Transplantation of umbilical cord blood (UCB) is an attractive alternative source of hematopoietic stem cells (HSCs). The unique properties of cord blood and its distinct immune tolerance and engraftment kinetics compared to bone marrow (BM) and peripheral blood progenitor cells, permit a wider disparity in human leukocyte antigen levels between a cord blood donor and recipient after an unrelated umbilical cord blood transplant (UCBT). In addition, it is readily available and has a lowered risk of graft-versus-host disease (GvHD), with similar long-term clinical outcomes, compared to BM transplants. However, the relatively low number of cells administered by UCB units, as well as the associated delayed engraftment and immune reconstitution, pose limitations to the wide application of UCBT. Research into several aspects of UCBT has been evaluated, including the ex vivo expansion of cord blood HSCs and the process of fucosylation to enhance engraftment. Additionally, UCB has also been used in the treatment of several neurodegenerative and cardiovascular disorders with varying degrees of success. In this article, we will discuss the biology, clinical indications, and benefits of UCBT in pediatric and adult populations. We will also discuss future directions for the use of cord blood.

Transplant for non-malignant disorders: an International Society for Cell & Gene Therapy Stem Cell Engineering Committee report on the role of alternative donors, stem cell sources and graft engineering

Hematopoietic stem cell transplantation (HSCT) is curative for many non-malignant disorders. As HSCT and supportive care technologies improve, this life-saving treatment may be offered to more and more patients. With the development of new preparative regimens, expanded alternative donor availability, and graft manipulation techniques, there are many options when choosing the best regimen for patients. Herein the authors review transplant considerations, transplant goals, conditioning regimens, donor choice, and graft manipulation strategies for patients with non-malignant disorders undergoing HSCT.

Current status of umbilical cord blood storage and provision to private biobanks by institutions handling childbirth in Japan

Background

The Act Regarding the Promotion of the Appropriate Supply of Hematopoietic Stem Cells for Transplant regulates only how public banks store and provide umbilical cord blood (UCB) for research or transplantation. Japan had no laws to regulate how the private banks manage the procedures, harvesting, preparation, and storage of such blood. As a result, the status of UCB distribution remains unknown. We conducted a survey to investigate the current status of UCB storage and provision to private biobanks by Japanese institutions that handle childbirth.

Methods

Questionnaire forms were mailed to 3,277 facilities handling childbirth that were registered in the Japan Council for Quality Health Care website.

Results

Of the 1,192 institutions handling childbirth that participated in the survey (response rate: 36.7%), 34.4% responded that they currently provide UCB to private biobanks, while 16.1% of facilities did so in the past. Moreover, some institutions currently provide or formerly provided UCB to medical treatment facilities (2.6%), research institutions (5.9%), companies (2.2%), or overseas treatment facilities, research institutions, or companies (0.3%). A certain number of institutions handling childbirth did not even provide explanations or obtain consent when the UCB was harvested from private bank users.

Conclusions

This is the first study to determine the status of UCB provision to private banks by Japanese institutions handling childbirth. Future studies will need to examine in detail how institutions handling childbirth provide explanations to private bank users and UCB providers as well as how these institutions obtain consent.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12910-022-00830-8.

Primary graft failure, but not relapse, may be identified by early chimerism following double cord unit transplantation

Primary graft failure may be identified by early chimerism analysis after DUCBT with RIC.

Chimerism does not appear to be useful in predicting relapse.

Umbilical cord blood transplantation (UCBT) has increased access to potentially curative therapy for patients with life-threatening disorders of the bone marrow and immune system. The introduction of reduced intensity conditioning (RIC) regimens and double umbilical cord unit infusions (DUCBT) has broadened the applicability of UCBT to more frail or larger recipients. The kinetics of chimerism after RIC DUCBT and their clinical utility are poorly understood. The RIC CBT trial reported here sought to prospectively evaluate the role of lineage-specific chimerism after DUCBT in adult patients with hematologic malignancies in the United Kingdom. Fifty-eight patients with a median age of 52 years were recruited, with overall and progression-free survivals of 59% (95% confidence interval [CI], 45%-71%) and 52% (95% CI, 39%-64%), respectively, at 2 years. Nonrelapse mortality was 4% (95% CI, 1%-13%) at day 100, and the relapse rate was 31% (95% CI, 21%-45%) at 1 year. Peripheral blood lineage-specific chimerism was feasible from day 7 after transplant onward. Five patterns of chimerism were observed including (1) complete single unit dominance (39 patients), (2) sustained donor-donor mixed chimerism (3 patients), (3) sustained donor-recipient mixed chimerism (5 patients), (4) dominance reversion (1 patient), and (5) primary graft failure (4 patients). The RIC CBT trial enabled adult patients with high-risk hematologic malignancies to safely access UCBT in the United Kingdom and provided novel insights into the kinetics of donor and recipient chimerism after RIC DUCBT that are clinically relevant. This trial was registered at https://www.clinicaltrialsregister.eu/ctr-search/trial/2004-003845-41/GB as #NCT00959231 and EudraCT 2004-003845-41.

First-Line Unrelated Double-Unit Umbilical Cord Blood Transplantation for Acquired Severe Aplastic Anemia

We analyzed the outcomes of 14 patients with severe aplastic anemia (SAA) who received first-line double-unit cord blood transplantation (dUCBT). Patients' median age was 24.5 years (range, 10-44 years). The median numbers of infused nucleated and CD34⁺ cells were 5.48 × 10⁷/kg (range, 3.33-7.96 × 10⁷/kg) and 2.30 × 10⁵/kg (range, 0.86-3.97 × 10⁵/kg), respectively. One patient died 5 days after transplantation. Three of the 13 patients acquired autologous myeloid recovery. Neutrophil engraftment was observed in 10 patients (76.29%), and the median time of neutrophil recovery was 19 days (range, 15-40 days). Platelet engraftment was observed in 7 cases (53.8%), and 3 patients experienced platelet graft failure. The median time of platelet recovery was 32 days (range, 22-80 days). The cumulative incidence of grade II-IV acute graft-vs-host disease (GVHD) was 38.5%. One patient demonstrated mild chronic GVHD. After a median follow-up of 61 months (range, 18-102 months), 6 patients were alive. The predicted 5-year overall survival and GVHD-free, failure-free survival rates were 42.9% ± 13.2% and 14.3% ± 9.4%, respectively. The first-line dUCBT for SAA is still primarily evaluated through multicenter prospective clinical trials by an optimal conditioning regimen, cell dose, and other graft and transplantation-related factors.

Guidelines for Adult Patient Selection and Conditioning Regimens in Cord Blood Transplant Recipients with Hematologic Malignancies and Aplastic Anemia

For cord blood transplantation (CBT), appropriate patient and conditioning regimen selection is necessary to achieve long-term disease-free survival. This review aims to provide comprehensive guidelines on these issues using evidence from the literature and experience at dedicated CBT centers. Topics include patient and disease characteristics that make CBT a good or poor choice and a review of outcomes in commonly used conditioning regimens in CBT. This is accompanied with recommendations on regimen intensity based on disease, organ function, and patient performance status and age. In addition, the use of antithymocyte globulin in CBT is discussed, as is the choice of conditioning in aplastic anemia patients who have access to acceptable CB units.

Treosulfan-based conditioning is feasible and effective for cord blood recipients: a phase 2 multicenter study

Although the use of treosulfan (TREO) in conventional donor hematopoietic cell transplantation (HCT) has been extensively evaluated, its use in cord blood transplantation (CBT) for hematologic malignancies has not been reported. Between March 2009 and October 2019, 130 CBT recipients were enrolled in this prospective multicenter phase 2 study. The conditioning regimen consisted of TREO, fludarabine, and a single fraction of 2 Gy total-body irradiation. Cyclosporine and mycophenolate mofetil were used for graft-versus-host disease prophylaxis. The primary end point was incidence of graft failure (GF), and based on risk of GF, patients were classified as low risk (arm 1, n = 66) and high risk (arm 2, n = 64). The median age was 45 years (range, 0.6-65 years). Disease status included acute leukemias in first complete remission (CR; n = 56), in ≥2 CRs (n = 46), and myelodysplastic (n = 25) and myeloproliferative syndromes (n = 3). Thirty-five patients (27%) had received a prior HCT. One hundred twenty-three patients (95%) engrafted, with neutrophil recovery occurring at a median of 19 days for patients on arm 1 and 20 days for patients on arm 2. The 3-year overall survival, relapse-free survival (RFS), transplant-related mortality, and relapse for the combined groups were 66%, 57%, 18%, and 24%, respectively. Among patients who had a prior HCT, RFS at 3 years was 48%. No significant differences in clinical outcomes were seen between the 2 arms. Our results demonstrate that TREO-based conditioning for CBT recipients is safe and effective in promoting CB engraftment with favorable clinical outcomes. This trial was registered at www.clinicaltrials.gov as #NCT00796068.

Blood type change identifies late dominance reversal of chimerism after double umbilical cord blood transplantation with review of the literature

BACKGROUND

A 30-year-old man underwent double umbilical cord blood transplantation (UCBT) for acute myeloid leukemia (AML) with reduced intensity conditioning. The cords had identical HLA types and were each a 5/6 match to the patient. Following transplantation, cord 2 initially dominated all tested cell populations. At day +306, we observed an unusual reversal of dominance chimerism pattern in which cord 1 instead dominated all tested populations.

STUDY DESIGN & METHODS

Polymerase chain reaction (PCR)-based short tandem repeat (STR) assays were performed on the peripheral blood and bone marrow samples. The white blood cell (WBC) populations from the peripheral blood were manipulated for testing to create subpopulations enriched for CD3, CD33, and CD56.

RESULTS

Chimerism studies on day +77 showed the following: cord 1: 44%-CD3; 0%-CD33; 16%-CD56; cord 2: 56%-CD3; 100%-CD33; 84%-CD56. Cord 2 initially dominated in all tested cell populations. Chimerism studies performed on post-transplantation day +306 uncovered a reversal of dominance chimerism pattern in which cord 1 now dominated in all cell populations (cord 1: 82%-CD3; >95%-CD33; 67%-CD56; cord 2: 18%-CD3; <5%-CD33; 33%-CD56). Between days +127 and  +244, the patient's blood type shifted from B Rh-positive to A Rh-negative.

CONCLUSION

The change in the patient's blood type identified a late reversal of dominance chimerism pattern. This is a rare occurrence, previously cited only once, which is inconsistent with published data that early high CD3 counts and unseparated bone marrow chimerism predominance at day +100 predict long-term cord dominance in double UCBT in the vast majority of cases.

A Review of Evaluating Hematopoietic Stem Cells Derived from Umbilical Cord Blood's Expansion and Homing

Transplantation of hematopoietic stem cells (HSCs) derived from umbilical cord blood (UCB) has been taken into account as a therapeutic approach in patients with hematologic malignancies. Unfortunately, there are limitations concerning HSC transplantation (HSCT), including (a) low contents of UCB-HSCs in a single unit of UCB and (b) defects in UCB-HSC homing to their niche. Therefore, delays are observed in hematopoietic and immunologic recovery and homing. Among numerous strategies proposed, ex vivo expansion of UCB-HSCs to enhance UCB-HSC dose without any differentiation into mature cells is known as an efficient procedure that is able to alter clinical treatments through adjusting transplantation-related results and making them available. Accordingly, culture type, cytokine combinations, O2 level, co-culture with mesenchymal stromal cells (MSCs), as well as gene manipulation of UCB-HSCs can have effects on their expansion and growth. Besides, defects in homing can be resolved by exposing UCB-HSCs to compounds aimed at improving homing. Fucosylation of HSCs before expansion, CXCR4-SDF-1 axis partnership and homing gene involvement are among strategies that all depend on efficiency, reasonable costs, and confirmation of clinical trials. In general, the present study reviewed factors improving the expansion and homing of UCB-HSCs aimed at advancing hematopoietic recovery and expansion in clinical applications and future directions.

Therapeutic Potential of Umbilical Cord Stem Cells for Liver Regeneration

The liver is a vital organ for life and the only internal organ that is capable of natural regeneration. Although the liver has high regeneration capacity, excessive hepatocyte death can lead to liver failure. Various factors can lead to liver damage including drug abuse, some natural products, alcohol, hepatitis, and autoimmunity. Some models for studying liver injury are APAP-based model, Fas ligand (FasL), D-galactosamine/endotoxin (Gal/ET), Concanavalin A, and carbon tetrachloride-based models. The regeneration of the liver can be carried out using umbilical cord blood stem cells which have various advantages over other stem cell types used in liver transplantation. UCB-derived stem cells lack tumorigenicity, have karyotype stability and high immunomodulatory, low risk of graft versus host disease (GVHD), low risk of transmitting somatic mutations or viral infections, and low immunogenicity. They are readily available and their collection is safe and painless. This review focuses on recent development and modern trends in the use of umbilical cord stem cells for the regeneration of liver fibrosis.

Optimizing Preparative Regimen for Umbilical Cord Blood Transplantation in Adult Acute Leukemia Patients: Acute Lymphoblastic Leukemia Requires Myeloablative Conditioning but Not Acute Myeloid Leukemia

Cord blood transplantation (CBT) is a valuable alternative to bone marrow transplantation in adults without readily available donors. We conducted this study to investigate the feasibility of CBT for adult patients with acute leukemia with regards to impact of different conditioning and graft-versus-host disease (GVHD) prophylaxis regimens on clinical outcomes. From 16 centers in Korea, 41 acute myeloid leukemia (AML) and 29 ALL (acute lymphoblastic leukemia) patients undergoing CBT were enrolled. For AML patients, the neutrophil engraftment was observed in 87.5% of reduced intensity conditioning (RIC) and 72.0% of myeloablative conditioning (MAC) (p = 0.242). The median RFS was 5 months and OS 7 months. Conditioning regimen did not affect relapse free survival (RFS) or overall survival (OS). GVHD prophylaxis using calcineurin inhibitors (CNI) plus methotrexate was associated with better RFS compared to CNI plus ATG (p = 0.032). For ALL patients, neutrophil engraftment was observed in 55.6% of RIC and 90.0% of MAC (p = 0.034). The median RFS was 5 months and OS 19 months. MAC regimens, especially total body irradiation (TBI)-based regimen, were associated with both longer RFS and OS compared to other conditioning regimens. In conclusion, individualized conditioning regimens will add value in terms of enhancing safety and efficacy of CBT.

Engraftment kinetics after transplantation of double unit cord blood grafts combined with haplo-identical CD34+ cells without antithymocyte globulin

Double unit cord blood (dCB) transplantation (dCBT) is associated with high engraftment rates but delayed myeloid recovery. We investigated adding haplo-identical CD34+ cells to dCB grafts to facilitate early haplo-identical donor-derived neutrophil recovery (optimal bridging) prior to CB engraftment. Seventy-eight adults underwent myeloablation with cyclosporine-A/mycophenolate mofetil immunoprophylaxis (no antithymocyte globulin, ATG). CB units (median CD34+ dose 1.1 × 10⁵/kg/unit) had a median 5/8 unit-recipient human leukocyte antigen (HLA)-match. Haplo-identical grafts had a median CD34+ dose of 5.2 × 10⁶/kg. Of 77 evaluable patients, 75 had sustained CB engraftment that was mediated by a dominant unit and heralded by dominant unit-derived T cells. Optimal haplo-identical donor-derived myeloid bridging was observed in 34/77 (44%) patients (median recovery 12 days). Other engrafting patients had transient bridging with second nadir preceding CB engraftment (20/77 (26%), median first recovery 12 and second 26.5 days) or no bridge (21/77 (27%), median recovery 25 days). The 2 (3%) remaining patients had graft failure. Higher haplo-CD34+ dose and better dominant unit-haplo-CD34+ HLA-match significantly improved the likelihood of optimal bridging. Optimally bridged patients were discharged earlier (median 28 versus 36 days). ATG-free haplo-dCBT can speed neutrophil recovery but successful bridging is not guaranteed due to rapid haplo-identical graft rejection.

What have we learned from transplanting older patients?

Aggressive curative therapies have now been extended to patients older than 65 years, a fast-growing segment of the population. As the number of allogeneic transplants in patients older than age 65 is increasing, attention is now focused on improving outcomes in this group. This paper discusses important aspects of allogeneic transplant in the older patient, focusing on donor and patient selection, choice of conditioning regimen and graft source, and the importance of timely access to a transplant center.

Small-molecule nicotinamide for ex vivo expansion of umbilical cord blood

Umbilical cord blood transplant is an alternative graft source for patients lacking a human leukocyte antigen-matched donor; however, delayed engraftment times have historically resulted in transplant-related morbidity and mortality from complications such as infections and ineffective hematopoiesis. Recent advances in ex vivo expansion techniques have successfully augmented the initial cell dose delivered from an umbilical cord blood graft, leading to improved immune reconstitution, durable hematopoiesis, decreased transplant-related morbidity and mortality, and better outcomes. Herein we review the data for existing and developing ex vivo expansion techniques, with a focus on the preclinical and clinical data for nicotinamide-mediated cord blood expansion across both malignant and benign hematologic indications.

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.

Effects of Haplotype Matching on Outcomes after Adult Single-Cord Blood Transplantation

It remains unclear whether the HLA haplotype of unrelated cord blood (UCB) should be matched to that of the patient in single UCB transplantation. Thus, using data from a Japanese registry, we analyzed the effect of haplotype matching on outcomes. Patients with hematologic diseases aged 16 years or older who had undergone their first transplant were included (N = 1347). The effects of haplotype matching and high-frequency HLA haplotype on outcomes were analyzed. Median patient age was 55 years. The cumulative incidences of neutrophil engraftment among groups with 0, 1, and 2 HLA haplotype matches were 79%, 82%, and 88%, respectively (P = .008). In a multivariate analysis, the group with 0 haplotype matches was marginally associated with worse neutrophil engraftment (P = .087) and significantly associated with platelet engraftment (P = .044) compared with the group with 1 haplotype match. Two-haplotype matches were associated with a higher risk of relapse. In the group with 1 haplotype match, the top 3 shared haplotypes were "A*24:02-B*52:01-C*12:02-DRB1*15:02" (HP-P1), "A*33:03-B*44:03-C*14:03-DRB1*13:02" (HP-P2), and "A*24:02-B*07:02-C*07:02-DRB1*01:01" (HP-P3). The presence of HP-P2 but not HP-P1 or HP-P3 was associated with a decreased risk of grades II to IV acute graft-versus-host disease (hazard ratio, .56; P = .001) but an increased risk of relapse (hazard ratio, 1.35; P = .045). HLA haplotype matching might be considered to improve engraftment. Two-haplotype matches should be avoided if the relapse risk is high. The haplotype itself may have an effect on the risk of acute graft-versus-host disease and relapse.

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.

Concepts, Utility and Limitations of Cord Blood Banking: What Clinicians Need to Know

Stem cell transplantation and cord blood banking have received much popularity among general public and medical professionals in the recent past. But information about the scientific aspects, its utility and limitations is incomplete amongst laypersons as well as many medical practitioners. Stem cells differ from all other types of cells in the human body because of their ability to multiply in order to self perpetuate and differentiate into specialized cells. Stems cells could be totipotent, multipotent, pluripotent, oligopotent or unipotent depending on the type of cells that can arise or differentiate from them. Umbilical cord blood serves as a potent source of hematopoeitic stem cells and is being used to treat various disorders like blood cancers, hemoglobinopathies and immunodeficiency disorders for which hematological stem cell transplantation is the standard of care. Cord blood can be collected at ease, without any major complications and has a lower incidence of graft vs. host reaction compared to bone marrow cells or peripheral blood cells. Both public and private banks have been established for collection and storage of umbilical cord blood. However, false claims and misleading commercial advertisements about the use of umbilical cord blood stem cells for the treatment of a variety of conditions ranging from neuromuscular disorders to cosmetic benefits are widespread and create unrealistic expectations in laypersons and clinicians. Many clinicians and laypersons are unaware of the limitations of cord blood banking, as in treating a genetic disorder by autologous cord blood transplant. Knowledge and awareness about the scientific indications of cord blood stem cell transplantation and realistic expectations about the utility of cord blood among medical practitioners are essential for providing accurate information to laypersons before they decide to preserve umbilical cord blood in private banks and thus prevent malpractice.

Hematopoietic stem cell transplant with HLA-mismatched grafts: impact of donor, source, conditioning, and graft versus host disease prophylaxis

INTRODUCTION

Allogeneic hematopoietic cell transplantation is frequently used to treat malignant and non-malignant conditions, and many patients lack a human leukocyte antigen (HLA) matched related or unrelated donor. For those patients, available alternative graft sources include HLA mismatched unrelated donors, cord blood, or haplo-identical donors. These graft sources have unique characteristics and associated outcomes requiring graft-specific variations to conditioning regimens, graft-versus-host disease prophylaxis, and post-transplant care. Areas covered: This manuscript will cover approaches in selecting donors, conditioning regimens, graft versus host disease prophylaxis, post-transplant care, and ongoing clinical trials related to mismatched grafts. Expert commentary: In the setting, haplo-identical grafts are increasingly popular due to low graft versus host disease (GVHD) risk and control of cellular dose. We recommend young male donors, utilizing bone marrow with post-transplant cyclophosphamide for GVHD prophylaxis. Cord blood transplant is appropriate for young healthy patients, and we recommend 6/8 HLA matched grafts with at least 2.0 × 10⁷/kg total nucleated cell dose. For mismatched unrelated donors we recommend young male donors, utilizing bone marrow with in vivo T-cell conditioning with post-transplant cyclophosphamide, alemtuzumab, or ATG. With these transplants, significant post-transplant surveillance and infectious prophylaxis is key to reducing treatment-related mortality.

Factors Influencing the Umbilical Cord Blood Stem Cell Industry: An Evolving Treatment Landscape

Hematopoietic stem cell transplantation (HSCT) is common practice today for life threatening malignant and non-malignant diseases of the blood and immune systems. Umbilical cord blood (UCB) is rich in hematopoietic stem cells (HSCs) and is an attractive alternative to harvesting HSCs from bone marrow or when mobilized into peripheral blood. One of the most appealing attributes of UCB is that it can be banked for future use and hence provides an off-the-shelf solution for patients in urgent need of a transplantation. This has led to the establishment of publicly funded and private UCB banks, as seen by the rapid growth of the UCB industry in the early part of this century. However, from about 2010, the release of UCB units for treatment purposes plateaued and started to decrease year-on-year from 2013 to 2016. Our interest has been to investigate the factors contributing to these changes. Key drivers influencing the UCB industry include the emergence of haploidentical HSCT and the increasing use of UCB units for regenerative medicine purposes. Further influencing this dynamic is the high cost associated with UCB transplantation, the economic impact of sustaining public bank operations and an active private UCB banking sector. We foresee that these factors will continue in a tug-of-war fashion to shape and finally determine the fate of the UCB industry. Stem Cells Translational Medicine 2018 Stem Cells Translational Medicine 2018;7:643-650.

Stable mixed double donor chimerism: Absence of war doesn't necessarily mean peace

Double cord blood transplantation has successfully been introduced to remedy the obstacle of a limited stem cell dose in a single cord blood graft. After a short initial period, the sustained hematopoiesis is derived almost exclusively from one of the donated units. In a recent publication in Clinical and Experimental Immunology we investigated two rare individuals in which both cord blood units co-existed for more than two years after transplantation.

Reduced-Intensity Allogeneic Transplant for Acute Myeloid Leukemia and Myelodysplastic Syndrome Using Combined CD34-Selected Haploidentical Graft and a Single Umbilical Cord Unit Compared with Matched Unrelated Donor Stem Cells in Older Adults

Haplo/cord transplantation combines an umbilical cord blood (UCB) graft with CD34-selected haploidentical cells and results in rapid hematopoietic recovery followed by durable UCB engraftment. We compared outcomes of transplants in older patients with acute myeloid leukemia (AML) or high-risk myelodysplastic syndromes (MDS) who received either HLA-matched unrelated donor (MUD) cells or haplo/cord grafts. Between 2007 and 2013, 109 adults ages 50 and older underwent similar reduced-intensity conditioning with fludarabine and melphalan and antibody-mediated T cell depletion for AML (n = 83) or high-risk MDS (n = 26) followed by either a MUD (n = 68) or haplo/cord (n = 41) graft. Patient characteristics were similar for each graft source except for more minority patients receiving a haplo/cord transplant (P = .01). One half of the AML patients were not in remission. Two-year progression-free survival (PFS), overall survival (OS), and graft-versus-host disease-free relapse-free survival were 38%, 48%, and 32.1% for MUD and 33%, 48%, and 33.8% for haplo/cord transplants (P = .62 for PFS; P = .97 for OS; P= .84), respectively. Acute grades II to IV and chronic graft-versus-host-disease rates did not differ at 19.5% and 4.9% in haplo/cord compared with 25% and 7.4% after MUD (P = .53 and P = .62, respectively). Multivariate analysis confirmed no significant differences in transplant outcomes by donor type. Haplo/cord reduced-intensity transplantation achieves similar outcomes relative to MUD in older AML and MDS patients, making this a promising option for those without matched donors.

Neurologic complications after allogeneic hematopoietic stem cell transplantation: risk factors and impact

Neurologic complications (NCs) may be a significant source of morbidity and mortality after hematopoietic cell transplantation (HCT). We performed a retrospective study of 263 consecutive patients undergoing allogeneic HCT for hematological malignancies to determine the incidence, risk factors and clinical impact of NCs in the first 5 years after HCT. We determined the incidence of central nervous system (CNS) infection, intracranial hemorrhage, ischemic stroke, metabolic encephalopathy, posterior reversal encephalopathy syndrome, seizure and peripheral neuropathy. In all, 50 patients experienced 63 NCs-37 early (⩽day +100), 21 late (day +101 to 2 years) and 5 very late (2 to 5 years). The 1- and 5-year cumulative incidences of all NCs were 15.6% and 19.2%, respectively, and of CNS complication (CNSC; all of the above complications except peripheral neuropathy) were 12.2 and 14.5%. Risk factors for CNSC were age (hazard ratio (HR)=1.06 per year, P=0.0034), development of acute GvHD grade III-IV (HR=2.78, P=0.041), transfusion-dependent thrombocytopenia (HR=3.07, P=0.025) and delayed platelet engraftment (>90th centile; HR=2.77, P=0.043). CNSCs negatively impacted progression-free survival (HR=2.29, P=0.0001), overall survival (HR=2.63, P<0.0001) and non-relapse mortality (HR=8.51, P<0.0001). NCs after HCT are associated with poor outcomes, and usually occur early after HCT.

Haploidentical hematopoietic cell transplantation for adult acute myeloid leukemia: a position statement from the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Allogeneic blood or marrow hematopoietic cell transplantation continues to be the most potent anti-leukemic treatment for adult patients with standard, high-risk, or chemo-refractory acute myeloid leukemia. Until recently, this procedure was generally limited to those recipients who had an available matched-sibling donor or matched-unrelated donor. Technical advances in graft cell processing and manipulation, control of bidirectional T cell alloreactivity, graft-versus-host disease prophylaxis, and other supportive measures in haploidentical transplantation now enable nearly all patients with acute myeloid leukemia to benefit from the graft-versus-leukemia effect with substantial reduction in procedure-related mortality. Over recent years, haploidentical donors have been increasingly adopted as a valid donor source in allogeneic hematopoietic cell transplantation for acute myeloid leukemia in the absence of an HLA-matched donor. Among centers of the European Society for Blood and Marrow Transplantation, the use of haploidentical related donor transplantation has increased by 250% since 2010, and 291% since 2005. On behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation, we summarize recent utilization trends in haploidentical transplantation for acute myeloid leukemia and describe the transformative changes in haploidentical hematopoietic cell transplantation techniques over the past decade, which have led to the current widespread use of this procedure. Furthermore, we review the efficacy of haploidentical hematopoietic cell transplantation for acute myeloid leukemia from available studies, including preliminary comparative studies, and bring attention to remaining unanswered questions and directions for future research. We conclude this report with our recommendations for the role of haploidentical hematopoietic cell transplantation in acute myeloid leukemia.

Update on umbilical cord blood transplantation

Allogeneic hematopoietic cell transplant is a curative procedure for many patients with leukemia, lymphoma, myelodysplasia, myeloproliferative neoplasms, and genetic disorders. Umbilical cord blood transplantation is a graft source for patients who do not have a matched donor in their family or in the unrelated registry. It is particularly difficult for Black, Hispanic, and White patients of non-Western European background to find fully matched adult volunteer donors. An estimated 700,000 umbilical cord blood units have been donated for public use, and over 40,000 umbilical cord blood transplantations have been performed. Over 25,000 patients have been cured with this approach.

Adult Umbilical Cord Blood Transplantation Using Myeloablative Thiotepa, Total Body Irradiation, and Fludarabine Conditioning

Treatment-related mortality (TRM) remains elevated in adult patients undergoing umbilical cord blood transplantation (UCBT), including an early rise in TRM suggestive of excessive toxicity associated with the standard myeloablative total body irradiation (TBI), fludarabine, and cyclophosphamide regimen. In an attempt to reduce regimen-related toxicity, we previously studied a modified myeloablative regimen with TBI (1350 cGy) and fludarabine (160 mg/m²); TRM was decreased, but neutrophil engraftment was suboptimal. Therefore, to improve engraftment while still minimizing regimen-related toxicity, we piloted a myeloablative regimen with the addition of thiotepa (10 mg/kg) to TBI and fludarabine conditioning. Thirty-one adult patients (median age, 46 years; range, 19 to 65) with hematologic malignancies (acute leukemia/myelodysplastic syndrome, 77%; lymphoid malignancy, 23%) underwent single (n = 1) or double (n = 30) UCBT from 2010 to 2015 at our institution. The cumulative incidence of neutrophil engraftment was 90% (95% confidence interval [CI], 70% to 97%) by 60 days, with a median time to engraftment of 21 days (95% CI, 19 to 26). The cumulative incidence of platelet engraftment was 77% (95% CI, 57% to 89%) by 100 days, with a median time to engraftment of 47 days (95% CI, 37 to 73). Cumulative incidences of grades II to IV and grades III to IV acute graft-versus-host disease (GVHD) at day 100 were 45% (95% CI, 27% to 62%) and 10% (95% CI, 2% to 23%), respectively. The overall incidence of chronic GVHD at 2 years was 40% (95% CI, 22% to 57%), with 17% of patients (95% CI, 6% to 33%) experiencing moderate to severe chronic GVHD by 2 years. TRM at 180 days was 13% (95% CI, 4% to 27%), at 1 year 24% (95% CI, 10% to 41%), and at 3 years 30% (95% CI, 13% to 49%). Relapse at 1 year was 13% (95% CI, 4% to 27%) and at 3 years 19% (95% CI, 6% to 38%). With a median follow-up of 35.5 months (95% CI, 12.7 to 52.2), disease-free and overall survival at 3 years were 51% (95% CI, 29% to 69%) and 57% (95% CI, 36% to 73%), respectively. This regimen represents a reasonable alternative to myeloablative conditioning with TBI, fludarabine, and cyclophosphamide and warrants further study.

A multicenter, retrospective, case-cohort study of the epidemiology and risk factors for Clostridium difficile infection among cord blood transplant recipients

BACKGROUND

Clostridium difficile infection (CDI) is the leading cause of health-care associated infectious diarrhea. The aim of this study was to evaluate the epidemiology and risk factors for CDI in the 100 days following umbilical cord blood transplantation (UCBT) at three Boston hospitals.

METHODS

We performed a multicenter, retrospective, case-cohort study of 226 UCBT recipients at Beth Israel Deaconess Medical Center, Massachusetts General Hospital, and Dana Farber/Brigham and Women's Cancer Center from 2003 to 2012. CDI was defined as diarrhea (≥3 unformed bowel movements for at least 2 days) plus a positive stool test for toxinogenic C. difficile and not attributed to any other cause.

RESULTS

Among 226 UCBT recipients, 22 patients (9.7%) developed CDI within the first 100 days of transplant (corresponding to an infection rate of 10.8 cases per 10 000 person-days). The 100-day and 1-year rates were stable across the time period and between institutions. UCBT recipients with CDI were more likely than non-CDI patients to be older, with higher body mass indices, and to have received an antipseudomonal penicillin agent. In a time-dependent case-cohort analysis of the risk factors associated with CDI in the first 100 days after UCBT, bacterial infection after UCBT was the strongest risk factor for CDI (hazard ratio 2.8; 95% confidence interval 1.08-7.24; P=.03), after adjustment for transplant variables including antibiotic exposure.

CONCLUSION

This study verifies the previously reported risk factors for CDI including older age and antibiotic exposure and identifies a novel association between bacterial infections and risk for CDI.

Graft predominance after double umbilical cord blood transplantation: a review

Several parameters are involved in graft predominance after double umbilical cord blood transplantation (dUCBT), of which T-cell alloreactivity between the grafts is now considered to be the major denominator. We recently showed that alloreactive CD4+ T-cells originating from the predominant CBU recognize HLA-class II allele mismatches and can readily be detected in the majority of patients. In addition, it was shown that HLA-class II allele-specific CD4+ T-cells were able to recognize primary leukemic cells when the mismatched HLA-class II allele was shared between the rejected CBU and the patient. These results further underscored the role of alloreactive T-cells, notably class II specific CD4+ T-cells, in graft-versus-graft reactions and in graft-versus-leukemia after dUCBT.

Ex Vivo Mesenchymal Precursor Cell-Expanded Cord Blood Transplantation after Reduced-Intensity Conditioning Regimens Improves Time to Neutrophil Recovery

We previously showed the safety of using cord blood (CB) expanded ex vivo in cocultures with allogeneic mesenchymal precursor cells (MPC) after myeloablative conditioning with faster recovery of neutrophils and platelets compared with historical controls. Herein, we report the transplantation outcomes of 27 patients with hematologic cancers who received 1 CB unit expanded ex vivo with MPCs in addition to an unmanipulated CB (MPC group) after reduced-intensity conditioning (RIC). The results in this group were compared with 51 historical controls who received 2 unmanipulated CB units (control group). The analyses were stratified for 2 RIC treatment groups: (1) total body irradiation 200 cGy + cyclophosphamide + fludarabine) (TCF), and (2) fludarabine + melphalan  (FM). Coculture of CB with MPCs led to an expansion of total nucleated cells by a median factor of 12 and of CD34⁺ cells by a median factor of 49. In patients in whom engraftment occurred, the median time to neutrophil engraftment was 12 days in the MPC group, as compared with 16 days in controls (P = .02). The faster neutrophil engraftment was observed in both RIC groups. The cumulative incidence of neutrophil engraftment on day 26 was 75% with expansion versus 50% without expansion in patients who received FM as the RIC regimen (P = .03). Incidence of neutrophil engraftment was comparable in MPC and control groups if treated with TCF (82% versus 79%, P = .40). Transplantation of CB units expanded with MPCs is safe and effective with faster neutrophil engraftment even after RIC regimens.

Lack of impact of umbilical cord blood unit processing techniques on clinical outcomes in adult double cord blood transplant recipients

BACKGROUND AIMS

Despite widespread use of umbilical cord blood (UCB) transplantation and distinct practice preferences displayed by individual UCB banks and transplant centers, little information exists on how processing variations affect patient outcomes.

METHODS

We reviewed 133 adult double UCB transplants performed at a single center: 98 after reduced-intensity and 35 after myeloablative conditioning. Processing associated with contributing UCB banks and units was surveyed to identify differences in practice. We analyzed effect of selected variables on clinical outcomes of engraftment, dominance, transplant-related mortality, and survival.

RESULTS

Eighty-eight percent of banks queried currently practice red blood cell (RBC) depletion before cryopreservation. This reflects a shift in practice because previously 65% of banks employed RBC-replete processing methods (i.e., cryopreservation or plasma/volume reduction). Neither neutrophil nor platelet engraftment was affected by processing conditions analyzed. RBC depletion was not associated with clinical outcomes, except in 17 recipients of 2 RBC-replete units, where survival was better than that observed in 116 recipients of ≥1 RBC-depleted units (hazard ratio 3.26, P = 0.004). When analyzed by attributes of the dominant unit, RBC depletion, time in storage, bank years in existence, and inventory size did not affect clinical outcomes. Postthaw viability and CD34 dose were factors impacting engraftment. Notably, all RBC-replete units in this cohort were washed in dextran-human serum albumin before infusion.

DISCUSSION

These findings support continued utilization of the entire existing pool of cord blood units, despite recent trends in processing, and have important implications for banking resources and UCB selection practices.

Decitabine prior to salvaged unrelated cord blood transplantation for refractory or relapsed childhood acute leukemia

No clinical studies have investigated the role of decitabine as a part of the myeloablative conditioning regimen prior to UCBT for refractory or relapsed childhood AL in patients in NR status. The aim of this study was to identify the potential benefits of decitabine as a prior therapy before salvaged unrelated UCBT for refractory or relapsed childhood AL. Eight consecutive patients with childhood refractory/relapsed AL were enrolled in our study between 2013 and 2014. All patients were in NR status before the time of transplant and had features associated with poor outcomes, such as CNSL, MDS-AML, high WBC count at diagnosis, and hypodiploid status (FLT3+/ITD+). Additionally, all patients had one of the following disease statuses: PIF, multiple relapse, or early relapse. All transplants were performed with decitabine as part of the myeloablative conditioning regimen, which was decitabine+Flu/Bu/CY±BCNU or decitabine+Ara-c/BU/CY2±BCNU. A total of seven patients (7 of 8) achieved neutrophil engraftment and platelet engraftment, and one patient experienced primary graft failure. All eight patients (100%) developed PES at a median of 7 days. Three patients developed stage II-IV acute GVHD at a median of 18 days. Additionally, three patients developed chronic GVHD, but it was not extensive in any of those three patients. The median follow-up time after CBT was 19.9 months (range, 9.2-30.7 months). The estimated probability of OS was 75%. Two patients (2 of 8) experienced a testis relapse, and two patients (2 of 8) died. Our experience suggests that the additional application of decitabine as part of the myeloablative conditioning regimen prior to UCBT for refractory or relapsed childhood AL among patients who are not in remission is safe and might be an effective treatment option.

Matching at Human Leukocyte Antigen-C Improved the Outcomes after Double Umbilical Cord Blood Transplantation for Recipients of Two to Four of Six Human Leukocyte Antigen-Matched Grafts

We studied the effect of HLA-C matching in 515 patients after double umbilical cord blood (UCB) transplantation. After HLA matching HLA-A, -B, and -DRB1 at the allele level, we scored patients according to number of donor-recipient HLA-C matches at 4 possible loci: 2 from each donor unit, at the allele level. Given a direct interaction between HLA-A, -B, and -DRB1 matching and HLA-C score, we analyzed HLA-C matching in those receiving at least 1 2/6 to 4/6 HLA-matched unit (n = 389) versus those receiving only 5/6 or 6/6-matched units (n = 126). In those with at least 1 2/6 to 4/6 HLA-matched unit, a better HLA-C matching score was associated with significantly lower risk of death of any cause and nonrelapse mortality and better disease-free survival. There was no association with the risk of relapse, acute and chronic graft-versus-host disease, and hematopoietic recovery. In contrast, among patients receiving only allele-level 5/6 or 6/6 HLA-matched UCB units, HLA-C match had no demonstrable effect on any outcome. For patients receiving at least 1 allele-level 2/6 to 4/6 HLA-matched UCB unit, matching at HLA-C reduces nonrelapse mortality and improves survival.

Angiogenic Factors Correlate with T Cell Immune Reconstitution and Clinical Outcomes after Double-Unit Umbilical Cord Blood Transplantation in Adults

Umbilical cord blood (UCB) is a valuable graft source for allogeneic hematopoietic stem cell transplantation (HSCT) in patients who lack adult donors. UCB transplantation (UCBT) in adults results in delayed immune reconstitution, leading to high infection-related morbidity and mortality. Angiogenic factors and markers of endothelial dysfunction have biologic and prognostic significance in conventional HSCT, but their role in UCBT has not been investigated. Furthermore, the interplay between angiogenesis and immune reconstitution has not been studied. Here we examined whether angiogenic cytokines, angiopoietin-1 (ANG-1) and vascular endothelial growth factor (VEGF), or markers of endothelial injury, thrombomodulin (TM) and angiopoietin-2 (ANG-2), associate with thymic regeneration as determined by T cell receptor excision circle (TREC) values and recovery of T cell subsets, as well as clinical outcomes in adult recipients of UCBT. We found that plasma levels of ANG-1 significantly correlated with the reconstitution of naive CD4⁺CD45RA⁺ and CD8⁺CD45RA⁺ T cell subsets, whereas plasma levels of VEGF displayed a positive correlation with CD4⁺CD45RO⁺ T cells and regulatory T cells and a weak correlation with TRECs. Assessment of TM and ANG-2 revealed a strong inverse correlation of both factors with naive T cells and TRECs. The angiogenic capacity of each patient's plasma, as determined by an in vitro angiogenesis assay, positively correlated with VEGF levels and with reconstitution of CD4⁺ T cell subsets. Higher VEGF levels were associated with worse progression-free survival and higher risk of relapse, whereas higher levels of TM were associated with chronic graft-versus-host disease and nonrelapse mortality. Thus, angiogenic factors may serve as valuable markers associated with T cell reconstitution and clinical outcomes after UCBT.

Erythropoietin modulation is associated with improved homing and engraftment after umbilical cord blood transplantation

Umbilical cord blood (UCB) engraftment is in part limited by graft cell dose, generally one log less than that of bone marrow (BM)/peripheral blood (PB) cell grafts. Strategies toward increasing hematopoietic stem/progenitor cell (HSPC) homing to BM have been assessed to improve UCB engraftment. Despite recent progress, a complete understanding of how HSPC homing and engraftment are regulated is still elusive. We provide evidence that blocking erythropoietin (EPO)-EPO receptor (R) signaling promotes homing to BM and early engraftment of UCB CD34⁺ cells. A significant population of UCB CD34⁺ HSPC expresses cell surface EPOR. Exposure of UCB CD34⁺ HSPC to EPO inhibits their migration and enhances erythroid differentiation. This migratory inhibitory effect was reversed by depleting EPOR expression on HSPC. Moreover, systemic reduction in EPO levels by hyperbaric oxygen (HBO) used in a preclinical mouse model and in a pilot clinical trial promoted homing of transplanted UCB CD34⁺ HSPC to BM. Such a systemic reduction of EPO in the host enhanced myeloid differentiation and improved BM homing of UCB CD34⁺ cells, an effect that was overcome with exogenous EPO administration. Of clinical relevance, HBO therapy before human UCB transplantation was well-tolerated and resulted in transient reduction in EPO with encouraging engraftment rates and kinetics. Our studies indicate that systemic reduction of EPO levels in the host or blocking EPO-EPOR signaling may be an effective strategy to improve BM homing and engraftment after allogeneic UCB transplantation. This clinical trial was registered at www.ClinicalTrials.gov (#NCT02099266).

Impact of graft-versus-host disease on outcomes after unrelated cord blood transplantation

The effect of graft-versus-host disease (GVHD) on transplant outcomes after unrelated cord blood transplantation (UCBT) has not been fully elucidated. We analyzed the impact of acute and chronic GVHD on outcomes in adult patients with acute leukemia or myelodysplastic syndrome who underwent their first UCBT (n=2558). The effect of GVHD on outcomes was analyzed after adjusting for other significant variables. The occurrence of GVHD was treated as a time-dependent covariate. The occurrence of grade 1-2 or 3-4 acute GVHD was significantly associated with a lower relapse rate. Grade 3-4 acute GVHD was associated with a higher risk of non-relapse and overall mortality than no acute GVHD, whereas grade 1-2 acute GVHD was associated with a lower risk of non-relapse and overall mortality than no acute GVHD. Limited or extensive chronic GVHD was significantly associated with a lower relapse rate. Limited chronic GVHD was associated with a lower overall and non-relapse mortality than no chronic GVHD. In conclusion, mild acute or chronic GVHD was associated not only with a low risk of relapse but also with a low risk of non-relapse mortality, and provides a survival benefit in UCBT.

CD4+ T-cell alloreactivity toward mismatched HLA class II alleles early after double umbilical cord blood transplantation

Although double umbilical cord blood transplantation (dUCBT) in adult patients may be associated with less graft failure compared with single UCBT, hematopoietic recovery generally originates from a single cord blood unit (CBU). CBU predominance is still incompletely understood. We recently showed that blood CD4⁺ T-cell numbers rapidly increase after dUCBT, and early CD4⁺ T-cell chimerism predicts for graft predominance. Given the frequent HLA class II allele mismatches between CBUs in dUCBT, we hypothesized that alloreactive HLA class II-specific CD4⁺ T cells from the "winning" CBU may contribute to rejection of the "loser" CBU. We evaluated whether CD4⁺ T cells originating from the predominant (PD)-CBU would recognize HLA class II allele mismatches, expressed by the nonengrafting (NE)-CBU. Alloreactive effector CD4⁺ T cells toward 1 or more mismatched HLA class II alleles of the NE-CBU were detected in 11 of 11 patients, with reactivity toward 29 of 33 (88%) tested mismatches, and the strongest reactivity toward DR and DQ alleles early after dUCBT. Mismatched HLA class II allele-specific CD4⁺ T cells recognized primary leukemic cells when the mismatched HLA class II allele was shared between NE-CBU and patient. Our results suggest that cytotoxicity exerted by CD4⁺ T cells from the PD-CBU drives the rapid rejection of the NE-CBU, whose alloreactive effect might also contribute to graft-versus-leukemia.

IL-10+ regulatory B cells are enriched in cord blood and may protect against cGVHD after cord blood transplantation

Cord blood (CB) offers a number of advantages over other sources of hematopoietic stem cells, including a lower rate of chronic graft-versus-host disease (cGVHD) in the presence of increased HLA disparity. Recent research in experimental models of autoimmunity and in patients with autoimmune or alloimmune disorders has identified a functional group of interleukin-10 (IL-10)-producing regulatory B cells (Bregs) that negatively regulate T-cell immune responses. At present, however, there is no consensus on the phenotypic signature of Bregs, and their prevalence and functional characteristics in CB remain unclear. Here, we demonstrate that CB contains an abundance of B cells with immunoregulatory function. Bregs were identified in both the naive and transitional B-cell compartments and suppressed T-cell proliferation and effector function through IL-10 production as well as cell-to-cell contact involving CTLA-4. We further show that the suppressive capacity of CB-derived Bregs can be potentiated through CD40L signaling, suggesting that inflammatory environments may induce their function. Finally, there was robust recovery of IL-10-producing Bregs in patients after CB transplantation, to higher frequencies and absolute numbers than seen in the peripheral blood of healthy donors or in patients before transplant. The reconstituting Bregs showed strong in vitro suppressive activity against allogeneic CD4(+) T cells, but were deficient in patients with cGVHD. Together, these findings identify a rich source of Bregs and suggest a protective role for CB-derived Bregs against cGVHD development in CB recipients. This advance could propel the development of Breg-based strategies to prevent or ameliorate this posttransplant complication.

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.

Umbilical cord blood graft engineering: challenges and opportunities

We are entering a very exciting era in umbilical cord blood transplantation (UCBT), where many of the associated formidable challenges may become treatable by ex vivo graft manipulation and/or adoptive immunotherapy utilizing specific cellular products. We envisage the use of double UCBT rather than single UCBT for most patients; this allows for greater ability to treat larger patients as well as to manipulate the graft. Ex vivo expansion and/or fucosylation of one cord will achieve more rapid engraftment, minimize the period of neutropenia and also give certainty that the other cord will provide long-term engraftment/immune reconstitution. The non-expanded (and future dominant) cord could be chosen for characteristics such as better HLA matching to minimize GvHD, or larger cell counts to enable part of the unit to be utilized for the development of specific cellular therapies such as the production of virus-specific T-cells or chimeric-antigen receptor T-cells which are reviewed in this study.

Frequency and Risk Factors Associated with Cord Graft Failure after Transplant with Single-Unit Umbilical Cord Cells Supplemented by Haploidentical Cells with Reduced-Intensity Conditioning

Delayed engraftment and cord graft failure (CGF) are serious complications after unrelated cord blood (UCB) hematopoietic stem cell transplantation (HSCT), particularly when using low-cell-dose UCB units. The haplo-cord HSCT approach allows the use of a lower dose single UCB unit by co-infusion of a CD34(+) selected haploidentical graft, which provides early transient engraftment while awaiting durable UCB engraftment. We describe the frequency, complications, and risk factors of CGF after reduced-intensity conditioning haplo-cord HSCT. Among 107 patients who underwent haplo-cord HSCT, 94 were assessable for CGF, defined as <5% cord blood chimerism at day 60 in the myeloid and CD3 compartments, irrespective of neutrophil and platelet counts. CGF occurred in 14 of 94 assessable patients (15%). Median survival after CGF was 12.7 months with haploidentical or mixed haploidentical-autologous hematopoiesis persisting in the 7 surviving. Median progression-free survival after CGF was 7.7 months and was not statistically different from those without CGF (10.47 months; P = .18). In univariate analyses, no UCB factors were associated with CGF, including cell dose, cell viability, recipient major ABO mismatch against the UCB unit, or degree of HLA match. We also found no association of CGF with recipient cytomegalovirus serostatus, haploidentical donor age, or day 30 haploidentical chimerism. However, higher haploidentical total nucleated and CD34(+) cell doses and day 30 UCB chimerism < 5% in either the myeloid or CD3 compartments were associated with greater risk of CGF. We conclude that assessing chimerism at day 30 may foretell impending CGF, and avoidance of high haploidentical cell doses may reduce risk of CGF after haplo-cord HSCT. However, long-term survival is possible after CGF because of predominant haploidentical or mixed chimerism and hematopoietic function.