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

Haplo-cord transplant. Realizing the potential of umbilical cord blood grafts. - A review of techniques and analysis of outcomes

The combination of cord blood transplant with progenitor cells from partially HLA-matched adult donors (haplo-cord transplant) has been used over the past two decades. In Europe and the US the adult donor graft is CD34 selected and provides early hematopoiesis, but durable engraftment derives from the cord blood graft (CD34 selected haplo-cord). Neutrophil recovery is prompt and rates of acute and chronic GVHD are low. Recent Chinese studies combine cord blood grafts with T-replete haplo-identical grafts (unmodified haplo-cord). The haplo graft usually establishes dominance and UCB chimerism is rarely detected. Comparison studies suggest considerably decreased rates of relapse and improved outcomes, compared with either haplo-identical transplant or CBU transplant, particularly in patients with advanced leukemia. A recent prospective randomized study confirms this. Haplo-cord mitigates the engraftment delay of UCB transplant. The unique biology of UCB grafts results in low GVHD and improved GVL especially beneficial in high-risk disease.

Impact of COVID-19 pandemic on cord blood banking and transplantation

Umbilical cord blood is a rich source of hematopoietic stem cells that has been used for transplantation for over 30 years, especially when there is no compatible hematopoietic stem cell donor available. Its use has decreased more recently, since the development of methods to improve haploidentical transplants has allowed the use of mobilized peripheral blood as a source of hematopoietic stem cells. Public cord blood banks collect, process and store cord blood samples from voluntary donations. In addition, many public banks are involved in research to enhance hematopoietic stem cell therapies and develop new treatments for haematological and genetic diseases. The COVID-19 pandemic, which emerged in 2019, has had a profound and wide-ranging impact on human health and treatment. The area of hematopoietic stem cell transplantation was deeply affected by reductions in bone marrow, peripheral blood and cord blood donations; logistical challenges; exposure of healthcare workers and other challenges. The present study reviews the impact of the COVID-19 pandemic on cord blood banking and transportation around the world with a special focus on Brazil.

Feasibility and safety of the discontinuation of systemic immunosuppressive treatment after single-unit cord blood transplantation in adults

We retrospectively evaluated the incidence, factors, and clinical outcomes of the discontinuation of immunosuppressive treatment (IST) after single-unit unrelated cord blood transplantation (CBT) in adults receiving cyclosporine-based graft-versus-host disease (GVHD) prophylaxis at our institute. Among the 309 patients who achieved engraftment, 247 were able to discontinue IST with a median follow-up of 121 months for survivors. The cumulative incidence of the discontinuation of IST was 46.2% at 180 days, 72.8% at 2 years, and 79.3% at 5 years post-CBT. In the multivariate analysis, discontinuation of IST after CBT was significantly associated with the requirement for steroid therapy (hazard ratio [HR]: 0.46; P < 0.001) and the recent calendar year of CBT (HR: 1.79; P < 0.001). In the conditional landmark analysis at 180 days, discontinuation of IST was not associated with the development of extensive chronic GVHD (HR: 1.00; P = 0.989), non-relapse mortality (HR: 0.49; P = 0.122), relapse (HR: 1.46; P = 0.388), or overall survival (HR: 1.91; P = 0.065). Our data showed that successful discontinuation of IST is common after single-unit CBT in adults. Discontinuation of IST did not affect subsequent outcomes, suggesting that discontinuation of IST is both feasible and safe in adults undergoing single-unit CBT.

Effect of fetal distress on viability and yield of umbilical cord blood stem cells-a prospective comparative study

INTRODUCTION

Different factors affect the quality and viability of cord blood stem cells, and therefore the efficacy of umbilical cord stem cell transplantation. Fetal distress is one factor affecting the quantity of CD34+ cells in cord blood. This study was designed to compare the viability and yield of the umbilical cord blood stem cells of women who have undergone emergency lower segment caesarean section for fetal distress or for other causes.

MATERIALS AND METHODS

This cross-sectional analytical study was performed at a tertiary care hospital facility with a total sample size of 68: 34 participants had undergone emergency C-section for fetal distress, and 34 had undergone emergency C-section for other causes. Umbilical cord blood was collected ex-utero in a 350 mL bag with citrate-phosphate-dextrose solution with adenine. Three milliliter of blood were transferred to an ethylenediaminetetraacetic acid (EDTA) tube for cell counts and flow cytometry testing for CD34+. The chi-square test was used to compare the total mononuclear cell, CD34+, and viability between the groups.

RESULTS

The CD34+ count [mean 4.9 versus 1.1 (× 106 cells/unit)] and total nucleated cell count [mean 14.2 versus 7.5 (× 108/unit)] were significantly higher in cord blood units collected from women who delivered by C-section for fetal distress (p-value <0.05). However, the volume of umbilical cord stem cells and viability of stem cells did not vary significantly based on the presence or absence of fetal distress (p-value >0.05).

CONCLUSION

The current study shows that umbilical cord blood collected during fetal distress has a significantly higher content of stem cells and total nucleated cells than the non-fetal distress group.

Mechanisms of resistance to chimeric antigen receptor-T cells in haematological malignancies

Chimeric antigen receptor (CAR)-T cells have recently emerged as a powerful therapeutic approach for the treatment of patients with chemotherapy-refractory or relapsed blood cancers, including acute lymphoblastic leukaemia, diffuse large B cell lymphoma, follicular lymphoma, mantle cell lymphoma and multiple myeloma. Nevertheless, resistance to CAR-T cell therapies occurs in most patients. In this Review, we summarize the resistance mechanisms to CAR-T cell immunotherapy by analysing CAR-T cell dysfunction, intrinsic tumour resistance and the immunosuppressive tumour microenvironment. We discuss current research strategies to overcome multiple resistance mechanisms, including optimization of the CAR design, improvement of in vivo T cell function and persistence, modulation of the immunosuppressive tumour microenvironment and synergistic combination strategies.

Validated graft-specific biomarkers identify patients at risk for chronic graft-versus-host disease and death

BACKGROUNDChronic graft-versus-host disease (cGVHD) is a serious complication of allogeneic hematopoietic cell transplantation (HCT). More accurate information regarding the risk of developing cGVHD is required. Bone marrow (BM) grafts contribute to lower cGVHD, which creates a dispute over whether risk biomarker scores should be used for peripheral blood (PB) and BM.METHODSDay 90 plasma proteomics from PB and BM recipients developing cGVHD revealed 5 risk markers that were added to 8 previous cGVHD markers to screen 982 HCT samples of 2 multicenter Blood and Marrow Transplant Clinical Trials Network (BMTCTN) cohorts. Each marker was tested for its association with cause-specific hazard ratios (HRs) of cGVHD using Cox-proportional-hazards models. We paired these clinical studies with biomarker measurements in a mouse model of cGVHD.RESULTSSpearman correlations between DKK3 and MMP3 were significant in both cohorts. In BMTCTN 0201 multivariate analyses, PB recipients with 1-log increase in CXCL9 and DKK3 were 1.3 times (95% CI: 1.1-1.4, P = 0.001) and 1.9 times (95%CI: 1.1-3.2, P = 0.019) and BM recipients with 1-log increase in CXCL10 and MMP3 were 1.3 times (95%CI: 1.0-1.6, P = 0.018 and P = 0.023) more likely to develop cGVHD. In BMTCTN 1202, PB patients with high CXCL9 and MMP3 were 1.1 times (95%CI: 1.0-1.2, P = 0.037) and 1.2 times (95%CI: 1.0-1.3, P = 0.009) more likely to develop cGVHD. PB patients with high biomarkers had increased likelihood to develop cGVHD in both cohorts (22%-32% versus 8%-12%, P = 0.002 and P < 0.001, respectively). Mice showed elevated circulating biomarkers before the signs of cGVHD.CONCLUSIONBiomarker levels at 3 months after HCT identify patients at risk for cGVHD occurrence.FUNDINGNIH grants R01CA168814, R21HL139934, P01CA158505, T32AI007313, and R01CA264921.

Venetoclax is safe and tolerable as post-transplant maintenance therapy for AML patients at high risk for relapse

Relapse is the most common cause of mortality in acute myeloid leukemia (AML) patients after allogeneic stem cell transplant (SCT). Post-SCT maintenance strategies that prevent relapse are desirable but must be well tolerated and convenient to administer. We hypothesized single agent venetoclax (ven) may be an effective maintenance therapy among high relapse risk patients. Between February 2019 and December 2021, we administered post-SCT ven maintenance to 49 AML patients at high-risk for relapse as a prospectively defined off-label practice at our institution. Ven was planned to be administered until 1-year post-SCT. While temporary interruptions were common (67.3% of all patients), of those with >1 year follow up, 22/25 (88%) completed the full year of planned therapy. Cytopenias (40.8%) and gastrointestinal adverse events (34.7%) were the most common toxicities. At 1-year post-SCT, overall survival (OS) and relapse-free survival (RFS) were 70% and 67% respectively. Our experience demonstrates single agent ven is a safe, tolerable, and feasible maintenance therapy that may improve RFS and OS in high relapse risk post-SCT patients.

T-cell replete cord transplants give superior outcomes in high-risk and relapsed/refractory pediatric myeloid malignancy

Stem cell transplant (SCT) outcomes in high-risk and relapsed/refractory (R/R) pediatric acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) have been historically poor. Cord blood (CB) allows T-cell replete CB transplant (TRCB), enabling enhanced graft-versus-leukemia. We consecutively collected data from 367 patients undergoing TRCB (112 patients) or other cell source (255 patients) SCT for pediatric AML/MDS in the United Kingdom and Ireland between January 2014 and December 2021. Data were collected about the patient's demographics, disease, and its treatment; including previous transplant, measurable residual disease (MRD) status at transplant, human leukocyte antigen-match, relapse, death, graft versus host disease (GvHD), and transplant-related mortality (TRM). Univariable and multivariable analyses were undertaken. There was a higher incidence of poor prognosis features in the TRCB cohort: 51.4% patients were MRD positive at transplant, 46.4% had refractory disease, and 21.4% had relapsed after a previous SCT, compared with 26.1%, 8.6%, and 5.1%, respectively, in the comparator group. Event free survival was 64.1% within the TRCB cohort, 50% in MRD-positive patients, and 79% in MRD-negative patients. To allow for the imbalance in baseline characteristics, a multivariable analysis was performed where the TRCB cohort had significantly improved event free survival, time to relapse, and reduced chronic GvHD, with some evidence of improved overall survival. The effect appeared similar regardless of the MRD status. CB transplant without serotherapy may be the optimal transplant option for children with myeloid malignancy.

Unrelated Donor Cord Blood Transplantation in Children: Lessons Learned Over 3 Decades

Four decades ago, Broxmeyer et al. demonstrated that umbilical cord blood (CB) contained hematopoietic stem cells (HSC) and hypothesized that CB could be used as a source of donor HSC for rescue of myeloablated bone marrow. In 1988, Gluckman et al. reported the first successful matched sibling cord blood transplant (CBT) in a child with Fanconi Anemia. In 1991, Rubinstein et al. established an unrelated donor CB bank, and in 1993, the first unrelated CBT used a unit from this bank. Since that time, >40 000 CBTs have been performed worldwide. Early outcomes of CBT were mixed and demonstrated the importance of cell dose from the CB donor. We hypothesized that improvements in CB banking and transplantation favorably impacted outcomes of CBT today and performed a retrospective study combining data from Eurocord and Duke University in 4834 children transplanted with a single unrelated CB unit (CBU) from 1993 to 2019. Changes in standard transplant outcomes (overall survival [OS], disease free survival [DFS], acute and chronic graft-versus-host disease [GvHD], treatment related mortality [TRM], and relapse) over 3 time periods (1: <2005; 2: 2005 to <2010; and 3: >2010 to 2019) were studied. Increased cell dose and degree of HLA matching were observed over time. OS, times to engraftment, and DFS improved over time. The incidence of TRM and GvHD decreased while the incidence of relapse remained unchanged. Relative contributions of cell dose and HLA matching to transplant outcomes were also assessed and showed that HLA matching was more important than cell dose in this pediatric cohort.

Incidence and risk factors for graft failure in the modern era of cord blood transplantation

BACKGROUND AND OBJECTIVES

Graft failure (GF) after cord blood transplant (CBT) has decreased with improved supportive care and cord selection strategies. We aimed to evaluate cord blood selection and factors associated with retransplantation on the incidence of GF, determine risk factors for GF including host antibodies to Kell antigen and evaluate survival after GF.

MATERIALS AND METHODS

We retrospectively reviewed 84 patients who underwent CBT at the University of Oklahoma between 2000 and 2016 and compared outcomes in patients with/without engraftment by Day 28. The nonengraftment cohort was further divided into patients who underwent retransplantation. Kaplan-Meier curves with log-rank tests were calculated to assess the association between mortality and engraftment.

RESULTS

Engraftment following CBT was high at 81%, with 52% engrafting by Day 28 and an additional 29% engrafting by a median of 36 days. Retransplantation led to 88% engraftment at a median of 53 days. Overall, 75% of the 40 patients who did not engraft by Day 28 died. Female sex and total nucleated cell count < 3.5/kg were significantly associated with lack of engraftment and higher mortality. Antibodies to Kell fetal antigen were not identified. Retransplantation by Day 28 for primary GF conferred a survival advantage.

CONCLUSION

This study demonstrates that failure to engraft by 28 days was associated with increased mortality, and risk was mitigated with early retransplantation. Female sex and low total cell dose were associated with increased mortality. Early identification of GF coupled with early retransplantation can reduce mortality in CBT.

Umbilical cord blood: an undervalued and underutilized resource in allogeneic hematopoietic stem cell transplant and novel cell therapy applications

PURPOSE OF REVIEW

The purpose of this review is to primarily discuss the unwarranted decline in the use of umbilical cord blood (UCB) as a source of donor hematopoietic stem cells (HSC) for hematopoietic cell transplantation (HCT) and the resulting important implications in addressing healthcare inequities, and secondly to highlight the incredible potential of UCB and related birthing tissues for the development of a broad range of therapies to treat human disease including but not limited to oncology, neurologic, cardiac, orthopedic and immunologic conditions.

RECENT FINDINGS

When current best practices are followed, unrelated donor umbilical cord blood transplant (CBT) can provide superior quality of life-related survival compared to other allogeneic HSC donor sources (sibling, matched or mismatched unrelated, and haploidentical) through decreased risks of relapse and chronic graft vs. host disease. Current best practices include improved UCB donor selection criteria with consideration of higher resolution human leukocyte antigen (HLA) typing and CD34+ cell dose, availability of newer myeloablative but reduced toxicity conditioning regimens, and rigorous supportive care in the early posttransplant period with monitoring for known complications, especially related to viral and other infections that may require intervention. Emerging best practice may include the use of ex vivo expanded single-unit CBT rather than double-unit CBT (dCBT) or 'haplo-cord' transplant, and the incorporation of posttransplant cyclophosphamide as with haploidentical transplant and/or incorporation of novel posttransplant therapies to reduce the risk of relapse, such as NK cell adoptive transfer. Novel, non-HCT uses of UCB and birthing tissue include the production of UCB-derived immune effector cell therapies such as unmodified NK cells, chimeric antigen receptor-natural killer cells and immune T-cell populations, the isolation of mesenchymal stem cells for immune modulatory treatments and derivation of induced pluripotent stem cells haplobanks for regenerative medicine development and population studies to facilitate exploration of drug development through functional genomics.

SUMMARY

The potential of allogeneic UCB for HCT and novel cell-based therapies is undervalued and underutilized. The inventory of high-quality UCB units available from public cord blood banks (CBB) should be expanding rather than contracting in order to address ongoing healthcare inequities and to maintain a valuable source of cellular starting material for cell and gene therapies and regenerative medicine approaches. The expertise in Good Manufacturing Practice-grade manufacturing provided by CBB should be supported to effectively partner with groups developing UCB for novel cell-based therapies.

Venetoclax and azacitidine followed by allogeneic transplant results in excellent outcomes and may improve outcomes versus maintenance therapy among newly diagnosed AML patients older than 60

The combination of venetoclax (ven) and azacitidine (aza) has resulted in high response rates in the upfront treatment of AML in patients age > 75 and patients unfit for intensive chemotherapy. Given the poor historical outcomes in patients age ≥ 60 treated with induction chemotherapy, ven/aza has become our institutional preference for the initial treatment of non-core binding factor (CBF) AML patients age ≥ 60. The benefit of allogeneic stem cell transplant (SCT) in patients who achieve response to ven/aza is uncertain. We report outcomes of SCT-eligible patients treated at our center. Between 1/2015 and 1/2020, 119 newly diagnosed non-CBF AML patients age ≥ 60 received ven/aza as initial therapy. 21 patients underwent SCT; 31 additional patients were potentially SCT eligible but deferred SCT. Overall survival (OS) was significantly greater among SCT patients (median survival not reached) versus potentially SCT eligible patients not undergoing SCT (median 518 days) (p = 0.01). Our data suggest that ven/aza followed by SCT in newly diagnosed AML patients older than ≥ 60 results in excellent outcomes and likely improves outcomes over maintenance therapy. Ongoing investigation will further refine the optimal timing of and selection of patients for SCT based on prognostic disease features and response assessments.

Umbilical cord blood transplants facilitated by the French cord blood banks network. On behalf of the Agency of Biomedicine, Eurocord and the French society of bone marrow transplant and cell therapy (SFGM-TC)

The public French Cord Blood Banks Network was established in 1999 with the objective of standardizing the practices governing umbilical cord blood (UCB) banking in France. The Network adopted a strategy to optimize its inventory and improve the quality of its banked units based on a quality improvement process using outcome data regularly provided by Eurocord. This study aimed to describe the results, over 10 years, of UCBT facilitated by a national network that used the same criteria of UCB collection and banking and to assess how modifications of banking criteria and unit selection might influence transplant outcomes. Nine hundred and ninety-nine units (593 single-unit and 203 double-unit grafts) were released by the Network to transplant 796 patients with malignant (83%) and non-malignant (17%) diseases. Median cell dose exceeded 3.5 × 107 TNC/kg in 86%. There was a trend to select units more recently collected and with higher cell dose. Neutrophil engraftment was 88.2% (85.7-90.7) and 79.3% (72.6-86.5) respectively for malignant and non-malignant diseases with a trend to faster recovery with higher cell doses. The respective 3-year transplant-related mortality were 31.1% (27.5-35.1) and 34.3% (27.0-43.5). OS was 49% ± 4 in malignant and 62% ± 4 in non-malignant disorders. In multivariate analysis, cell dose was the only unit-related factor associated with outcomes. Our results reflect the benefit on clinical outcomes of the strategy adopted by the Network to bank units with higher cell counts.

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.

CMV viral load kinetics as surrogate endpoints after allogeneic transplantation

BACKGROUNDViral load (VL) surrogate endpoints transformed development of HIV and hepatitis C therapeutics. Surrogate endpoints for CMV-related morbidity and mortality could advance development of antiviral treatments. Although observational data support using CMV VL as a trial endpoint, randomized controlled trials (RCTs) demonstrating direct associations between virological markers and clinical endpoints are lacking.METHODSWe performed CMV DNA PCR on frozen serum samples from the only placebo-controlled RCT of ganciclovir for early treatment of CMV after hematopoietic cell transplantation (HCT). We used established criteria to assess VL kinetics as surrogates for CMV disease or death by weeks 8, 24, and 48 after randomization and quantified antiviral effects captured by each marker. We used ensemble-based machine learning to assess the predictive ability of VL kinetics and performed this analysis on a ganciclovir prophylaxis RCT for validation.RESULTSVL suppression with ganciclovir reduced cumulative incidence of CMV disease and death for 20 years after HCT. Mean VL, peak VL, and change in VL during the first 5 weeks of treatment fulfilled the Prentice definition for surrogacy, capturing more than 95% of ganciclovir's effect, and yielded highly sensitive and specific predictions by week 48. In the prophylaxis trial, the viral shedding rate satisfied the Prentice definition for CMV disease by week 24.CONCLUSIONSOur results support using CMV VL kinetics as surrogates for CMV disease, provide a framework for developing CMV preventative and therapeutic agents, and support reductions in VL as the mechanism through which antivirals reduce CMV disease.FUNDINGMerck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.

Guidelines for the Prevention and Management of Graft-versus-Host Disease after Cord Blood Transplantation

The incidence of graft-versus-host disease (GVHD) after cord blood (CB) transplantation (CBT) is lower than expected given the marked degree of human leukocyte antigen (HLA)-mismatch of CB grafts. While the exact mechanism that underlies this biology remains unclear, it is hypothesized to be due to the low number of mostly immature T-cells infused as part of the graft1,2, and increased tolerance of CB-derived lymphocytes induced by the state of pregnancy. Nevertheless, acute GVHD (aGVHD) is a significant complication of CBT. In contrast, the incidence of chronic GVHD (cGVHD) following CBT is lower than what is observed following matched related or unrelated donor HSC transplantation (HSCT)3-6. This review outlines the guidelines for the prevention and management of acute and chronic GVHD following CBT.

Adult cord blood transplant results in comparable overall survival and improved GRFS vs matched related transplant

We compared outcomes among adult matched related donor (MRD) patients undergoing peripheral blood stem cell transplantation and adult patients undergoing double unit cord blood transplantation (CBT) at our center between 2010 and 2017. A total of 190 CBT patients were compared with 123 MRD patients. Median follow-up was 896 days (range, 169-3350) among surviving CBT patients and 1262 days (range, 249-3327) among surviving MRD patients. Comparing all CBT with all MRD patients, overall survival (OS) was comparable (P = .61) and graft-versus-host disease (GVHD) relapse-free survival (GRFS) was significantly improved among CBT patients (P = .0056), primarily because of decreased moderate to severe chronic GVHD following CBT (P < .0001; hazard ratio [HR], 3.99; 95% confidence interval [CI], 2.26-7.04). Among patients undergoing our most commonly used MRD and umbilical cord blood (CB) myeloablative regimens, OS was comparable (P = .136) and GRFS was significantly improved among CBT patients (P = .006). Cumulative incidence of relapse trended toward decreased in the CBT group (P = .075; HR, 1.85; CI 0.94-3.67), whereas transplant-related mortality (TRM) was comparable (P = .55; HR, 0.75; CI, 0.29-1.95). Among patients undergoing our most commonly used nonmyeloablative regimens, OS and GRFS were comparable (P = .158 and P = .697). Cumulative incidence of both relapse and TRM were comparable (P = .32; HR, 1.35; CI, 0.75-2.5 for relapse and P = .14; HR, 0.482; CI, 0.18-1.23 for TRM). Our outcomes support the efficacy of CBT and suggest that among patients able to tolerate more intensive conditioning regimens at high risk for relapse, CB may be the preferred donor source.

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.

Decreased Mortality in 1-Year Survivors of Umbilical Cord Blood Transplant vs. Matched Related or Matched Unrelated Donor Transplant in Patients with Hematologic Malignancies

Allogeneic hematopoietic stem cell transplantation (HCT) has the potential to cure hematologic malignancies but is associated with significant morbidity and mortality. Although deaths during the first year after transplantation are often attributable to treatment toxicities and complications, death after the first year may be due to sequelae of accelerated aging caused by cellular senescence. Cytotoxic therapies and radiation used in cancer treatments and conditioning regimens for HCT can induce aging at the molecular level; HCT patients experience time-dependent effects, such as frailty and aging-associated diseases, more rapidly than people who have not been exposed to these treatments. Consistent with this, recipients of younger cells tend to have decreased markers of aging and improved survival, decreased graft-versus-host disease, and lower relapse rates. Given that umbilical cord blood (UCB) is the youngest donor source available, we studied the outcomes after the first year of UCB transplantation versus matched related donor (MRD) and matched unrelated donor (MUD) transplantation in patients with hematologic malignancies over a 20-year period. In this single-center, retrospective study, we examined the outcomes of all adult patients who underwent their first allogeneic HCT through the Duke Adult Bone Marrow Transplant program from January 1, 1996, to December 31, 2015, to allow for at least 3 years of follow-up. Patients were excluded if they died or were lost to follow-up before day 365 after HCT, received an allogeneic HCT for a disease other than a hematologic malignancy, or received cells from a haploidentical or mismatched adult donor. UCB recipients experienced a better unadjusted overall survival than MRD/MUD recipients (log rank P = .03, median overall survival: UCB not reached, MRD/MUD 7.4 years). After adjusting for selected covariates, UCB recipients who survived at least 1 year after HCT had a hazard of death that was 31% lower than that of MRD/MUD recipients (hazard ratio, 0.69; 95% confidence interval, 0.47-0.99; P = .049). This trend held true in a subset analysis of subjects with acute leukemia. UCB recipients also experienced lower rates of moderate or severe chronic graft-versus-host disease (GVHD) and nonrelapse mortality, and slower time to relapse. UCB and MRD/MUD recipients experienced similar rates of grade 2-4 acute GVHD, chronic GHVD, secondary malignancy, and subsequent allogeneic HCT. UCB is already widely used as a donor source in pediatric HCT; however, adult outcomes and adoption have historically lagged behind in comparison. Recent advancements in UCB transplantation such as the implementation of lower-intensity conditioning regimens, double unit transplants, and ex vivo expansion have improved early mortality, making UCB an increasingly attractive donor source for adults; furthermore, our findings suggest that UCB may actually be a preferred donor source for mitigating late effects of HCT.

Allogeneic CAR T Cells: An Alternative to Overcome Challenges of CAR T Cell Therapy in Glioblastoma

Chimeric antigen receptor (CAR) T cell therapy has emerged as one of the major breakthroughs in cancer immunotherapy in the last decade. Outstanding results in hematological malignancies and encouraging pre-clinical anti-tumor activity against a wide range of solid tumors have made CAR T cells one of the most promising fields for cancer therapies. CAR T cell therapy is currently being investigated in solid tumors including glioblastoma (GBM), a tumor for which survival has only modestly improved over the past decades. CAR T cells targeting EGFRvIII, Her2, or IL-13Rα2 have been tested in GBM, but the first clinical trials have shown modest results, potentially due to GBM heterogeneity and to the presence of an immunosuppressive microenvironment. Until now, the use of autologous T cells to manufacture CAR products has been the norm, but this approach has several disadvantages regarding production time, cost, manufacturing delay and dependence on functional fitness of patient T cells, often reduced by the disease or previous therapies. Universal “off-the-shelf,” or allogeneic, CAR T cells is an alternative that can potentially overcome these issues, and allow for multiple modifications and CAR combinations to target multiple tumor antigens and avoid tumor escape. Advances in genome editing tools, especially via CRISPR/Cas9, might allow overcoming the two main limitations of allogeneic CAR T cells product, i.e., graft-vs.-host disease and host allorejection. Here, we will discuss how allogeneic CAR T cells could allow for multivalent approaches and alteration of the tumor microenvironment, potentially allowing the development of next generation therapies for the treatment of patients with GBM.

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.

Outcomes of chronic graft-versus-host disease following matched sibling donor versus umbilical cord blood transplant

We compared chronic graft-versus-host disease (cGvHD) following umbilical cord blood (UCBT) and matched sibling donor peripheral blood transplant (MSD). 145 patients (2010-2017) with cGvHD after MSD (n = 104) and UCBT (n = 41) were included. Prior acute GvHD was less frequent in MSD (55% vs. 85%; p = 0.01). Severe cGvHD (32% vs. 15%, p = 0.01) and de-novo onset (45% vs. 15%, p < 0.01) were more frequent following MSD. Liver was more frequently involved in MSD recipients (38% vs. 6%); and GI in UCBT (33% vs. 63%), both p < 0.01. Overall response (CR + PR) was similar between both cohorts. 2-year CR was higher in UCBT (14% vs 33%, p = 0.02). Karnofsky score (KPS) ≥ 90 at cGvHD diagnosis was associated with higher odds of response (95%CI: 1.42-10, p < 0.01). The cumulative incidence of durable discontinuation of immune-suppressive therapy, failure-free survival (FFS) and NRM at 2-years were similar between cohorts. KPS < 90 (95%CI: 3.1-24.9, p < 0.01) and platelets <100 × 10e9/L (95%CI: 1.25-10, p = 0.01) were associated with higher risk of NRM. UCBT patients were more likely to have a prior acute GvHD, less severe cGvHD and more likely to attain CR. Despite differences, both cohorts had similar NRM and FFS. High-risk groups, including those with platelets <100 × 10e9/L and KPS < 90, need careful monitoring and intensified therapy.

Intestinal CD8+ T cell responses are abundantly induced early in human development but show impaired cytotoxic effector capacities

Gastrointestinal viral infections are a major global cause of disease and mortality in infants. Cytotoxic CD8⁺ T cells are critical to achieve viral control. However, studies investigating the development of CD8⁺ T cell immunity in human tissues early in life are lacking. Here, we investigated the maturation of the CD8⁺ T cell compartment in human fetal, infant and adult intestinal tissues. CD8⁺ T cells exhibiting a memory phenotype were already detected in fetal intestines and increased after birth. Infant intestines preferentially harbored effector CCR7^-CD45RA^-CD127^-KLRG1^+/- CD8⁺ T cells compared to tissue-resident memory CD69⁺CD103⁺CD8⁺ T cells detected in adults. Functional cytotoxic capacity, including cytokine and granzyme B production of infant intestinal effector CD8⁺ T cells was, however, markedly reduced compared to adult intestinal CD8⁺ T cells. This was in line with the high expression of the inhibitory molecule PD-1 by infant intestinal effector CD8⁺ T cells. Taken together, we demonstrate that intestinal CD8⁺ T cell responses are induced early in human development, however exhibit a reduced functionality. The impaired CD8⁺ T cell functionality early in life contributes to tolerance during foreign antigen exposure after birth, however functions as an immune correlate for the increased susceptibility to gastrointestinal viral infections in infancy.

Haploidentical Hematopoietic Stem Cell Transplantation Versus Umbilical Cord Blood Transplantation in Hematologic Malignancies: A Systematic Review and Meta-Analysis

Haploidentical hematopoietic stem cell transplantation (Haplo-SCT) and umbilical cord blood transplantation (UCBT) are two important alternatives when a matched sibling donor is unavailable. Several studies have reported inconsistent clinical outcomes comparing Haplo-SCT and UCBT. Therefore, it is necessary to synthesize the existing evidence regarding outcomes of stem cell transplantations comparing Haplo-SCT with UCBT. We searched article titles that compared transplantation with Haplo-SCT and UCBT in MEDLINE (PubMed), Cochrane library, and EMBASE database. To compare clinical outcomes between Haplo-SCT and UCBT, we performed a meta-analysis of 12 studies and reported the pooled odds ratios (ORs) of 6 end points including overall survival (OS), progression-free survival (PFS), nonrelapse mortality (NRM), relapse rate (RR), acute graft-versus-host disease (aGVHD), and chronic graft-versus-host disease (cGVHD). We found that Haplo-SCT was associated with a significantly superior OS (pooled OR of 0.74, 95% confidence interval [CI] 0.68 to 0.80) and PFS (0.77, 95% CI 0.72 to 0.83), as well as a lower NRM (0.72, 95% CI 0.64 to 0.80) and aGVHD (0.87, 95% CI 0.77 to 0.98) compared to the UCBT group. We also found a significantly increased risk of cGVHD in Haplo-SCT group (1.40, 95% CI 1.22 to 1.62). In terms of RR, Haplo-SCT was comparable to UCBT (0.91, 95% CI 0.79 to 1.05). Results of this meta-analysis demonstrate that Haplo-SCT results in better clinical outcomes compared to UCBT in terms of OS, PFS, TRM, and aGVHD, but is inferior to UCBT in terms of increased cGVHD risk. Further prospective comparisons between Haplo-SCT and UCBT are needed.

The influence of stem cell source on transplant outcomes for pediatric patients with acute myeloid leukemia

When hematopoietic stem cell transplant (HSCT) is necessary for children with acute myeloid leukemia (AML), there remains debate about the best stem cell source. Post-HSCT relapse is a common cause of mortality, and complications such as chronic graft versus host disease (cGVHD) are debilitating and life-threatening. To compare post-HSCT outcomes of different donor sources, we retrospectively analyzed consecutive transplants performed in several international centers from 2005 to 2015. A total of 317 patients were studied: 19% matched sibling donor (MSD), 23% matched unrelated donor (MUD), 39% umbilical cord blood (UCB), and 19% double UCB (dUCB) recipients. The median age at transplant was 10 years (range, 0.42-21 years), and median follow-up was 4.74 years (range, 4.02-5.39 years). Comparisons were made while controlling for patient, transplant, and disease characteristics. There were no differences in relapse, leukemia-free survival, or nonrelapse mortality. dUCB recipients had inferior survival compared with matched sibling recipients, but all other comparisons showed similar overall survival. Despite the majority of UCB transplants being HLA mismatched, the rates of cGVHD were low, especially compared with the well-matched MUD recipients (hazard ratio, 0.3; 95% confidence interval, 0.14-0.67; P = .02). The composite measure of cGVHD and leukemia-free survival (cGVHD-LFS), which represents both the quality of life and risk for mortality, was significantly better in the UCB compared with the MUD recipients (HR, 0.56; 95% confidence interval, 0.34-1; P = .03). In summary, the use of UCB is an excellent donor choice for pediatric patients with AML when a matched sibling cannot be identified.

Umbilical cord blood: The promise and the uncertainty

Unfortunately, many patients referred for hematopoietic cell transplant will not have a fully matched related donor, and finding matched unrelated donors through the registry may be difficult, especially if the recipient is not of Northern European descent [N Engl J Med 2014;371:339‐348]. Umbilical cord blood (UCB) has been an available graft source for hematopoietic cell transplant for more than 30 years, since the first UCB transplant was performed in the late 1980s [N Engl J Med 1989;321:1174‐1178]. UCB is readily available, has low immunogenicity, and does not require as strict of human leukocyte antigen (HLA) matching compared to other graft sources [N Engl J Med 2004;351:2265‐2275]. According to data from the Center for International Blood and Marrow Transplant Research (CIBMTR), an estimated 500 patients in the US will have received a UCB transplant in 2018. Since 2014, haploidentical transplants have surpassed UCB transplants performed in the United States (CIBMTR Summary Slides, 2018, available at https://www.cibmtr.org). Increased use of haploidentical transplants has brought to light concerns about UCB transplants, including delayed engraftment and graft failure, increased nonrelapse mortality, increased infection risk, and UCB acquisition costs [Lancet Oncol 2010;11:653‐660; Biol Blood Marrow Transplant 2019;1456‐1464]. These concerns will need to be addressed for UCB to remain a viable option as a graft source for hematopoietic cell transplant. Other promising therapeutic benefits for UCB, in addition to hematopoietic cell transplant, is its use in regenerative medicine and immune modulation, which is currently being evaluated in ongoing clinical trials.

Cord blood transplants supported by unrelated donor CD34+ progenitor cells

Alternative donor transplantation with the haplo-cord platform allows the use of a lower-dose single umbilical cord blood unit (CBU) by co-infusion of third-party CD34⁺-selected cells from a haploidentical relative, which provides early transient engraftment while awaiting durable CBU engraftment. In our experience, ~15% of patients lack a suitable haploidentical donor. Here we report 26 patients who underwent haplo-cord transplant using CD34⁺-selected partially matched unrelated donor grafts. Twenty-four were conditioned with fludarabine/melphalan +/- low-dose TBI (n = 16). Twenty-five received ATG and all received posttransplant tacrolimus and mycophenolate mofetil. Median time to neutrophil and platelet recovery was 11 and 18 days. CBU engraftment, with CD33 and CD3 >5% cord chimerism in the myeloid/lymphoid compartment by day +60, occurred in 20 of 24 patients (83%). Incidence of grade 2-4 acute graft-versus-host disease (GVHD) was 27% at day +100, and chronic GVHD was 4% at 1 year. Overall survival at 1 year was 54%. For patients in need of an alternative transplant who lack a haploidentical donor, haplo-cord transplantation using CD34⁺-selected partially matched unrelated donor grafts results in rapid engraftment with no increased rate of cord graft failure or GVHD.

Post transplant cyclophosphamide based haplo-identical transplant versus umbilical cord blood transplant; a meta-analysis

OBJECTIVES

Both haplo-identical transplant (haplo) and umbilical cord transplant (UC) are valuable graft options for patients without available matched relative. Previous studies showed inconsistent outcomes comparing Post transplant Cyclophosphamide based haplo (PTCy-haplo) and UC; therefore, we attempt to compare the studies by mean of meta-analysis.

METHODS

We searched for titles of articles in MEDLINE (PubMed), Cochrane library, EMBASE database and Google scholar that compared transplantation with PTCy-haplo versus UC. We conducted a random-effect meta-analysis of seven studies involving a total of 3434 participants and reported the pooled odd ratios (OR) of acute graft-versus-host disease (aGVHD), chronic graft-versus-host disease (cGVHD), relapse and overall survival (OS) between PTCy-haplo and UC groups.

RESULTS

We found a significantly decreased risk of aGVHD and relapse in the PTCy-haplo group compared to the UC group with a pooled OR of 0.78, 95% Confidence Interval (CI) 0.67-0.92, I2=0%, and 0.74, 95% CI 0.57-0.97, I2=23.9% respectively. We also found a significantly increased rate of cGVHD and OS with a pooled OR of 1.41, 95% CI 1.02-1.95, I2=56.8%, and 1.77, 95% CI 1.1-2.87, I2=82.5%, respectively.

CONCLUSION

Our meta-analysis of clinical trials demonstrated superior outcome from PTCy-haplo group compared to the UC group in terms of decreased rate of aGVHD and relapse as well as the increased rate of OS but inferior in terms of increased cGVHD risk compared to UC transplant.

Unlicensed Umbilical Cord Blood Units Provide a Safe and Effective Graft Source for a Diverse Population: A Study of 2456 Umbilical Cord Blood Recipients

Umbilical cord blood (UCB) transplantation (UCBT) is a curative procedure for patients with hematologic malignancies and genetic disorders and expands access to transplantation for non-Caucasian patients unable to find a fully matched unrelated donor. In 2011, the US Food and Drug Administration required that unrelated UCBT be performed using either licensed UCB or unlicensed UCB under the Investigational New Drug (IND) program. The National Marrow Donor Program manages an IND under which 2456 patients (1499 adults and 957 children, 564 with malignant diseases and 393 with nonmalignant diseases) underwent single or double UCBT between October 2011 and December 2016. The median patient age was 31 years (range, <1 to 81 years), and 50% of children and 36% of adults were non-Caucasian. The median time to neutrophil engraftment (ie, absolute neutrophil count ≥500/mm³) was 22 days for adults, 20 days for pediatric patients with malignant diseases, and 19 days for pediatric patients with nonmalignant diseases, with corresponding rates of engraftment at 42 days of 89%, 88%, and 90%. In these 3 groups of patients, the incidence of acute graft-versus-host disease (GVHD) grade II-IV was 35%, 32%, and 24%; the incidence of chronic GVHD was 24%, 26%, and 24%; and 1-year overall survival (OS) was 57%, 71%, and 79%, respectively. In multivariate analysis, younger age, lower Hematopoietic Cell Transplantation-Specific Comorbidity Index, early-stage chemotherapy-sensitive disease, and higher performance score were predictive of improved OS for adults. In a subset analysis of children with malignancies undergoing single UCBT, the use of either licensed UCB (n = 48) or unlicensed UCB (n = 382) was associated with similar engraftment and survival. The use of unlicensed UCB units is safe and effective and provides an important graft source for a diverse population.

Human multipotent hematopoietic progenitor cell expansion is neither supported in endothelial and endothelial/mesenchymal co-cultures nor in NSG mice

Endothelial and mesenchymal stromal cells (ECs/MSCs) are crucial components of hematopoietic bone marrow stem cell niches. Both cell types appear to be required to support the maintenance and expansion of multipotent hematopoietic cells, i.e. hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs). With the aim to exploit niche cell properties for experimental and potential clinical applications, we analyzed the potential of primary ECs alone and in combination with MSCs to support the ex vivo expansion/maintenance of human hematopoietic stem and progenitor cells (HSPCs). Even though a massive expansion of total CD34⁺ HSPCs was observed, none of the tested culture conditions supported the expansion or maintenance of multipotent HSPCs. Instead, mainly lympho-myeloid primed progenitors (LMPPs) were expanded. Similarly, following transplantation into immunocompromised mice the percentage of multipotent HSPCs within the engrafted HSPC population was significantly decreased compared to the original graft. Consistent with the in vitro findings, a bias towards lympho-myeloid lineage potentials was observed. In our conditions, neither classical co-cultures of HSPCs with primary ECs or MSCs, even in combination, nor the xenograft environment in immunocompromised mice efficiently support the expansion of multipotent HSPCs. Instead, enhanced expansion and a consistent bias towards lympho-myeloid committed LMPPs were observed.

Clinical Features of Chronic Graft-Versus-Host Disease Following Haploidentical Transplantation Combined with Infusion of a Cord Blood

Our previous studies demonstrated promising outcomes after haploidentical donor transplant combined with unrelated umbilical cord blood (haplo-cord- hematopoietic stem cell transplantation [HSCT]) for hematological disorders. However, clinical profiling regarding chronic graft-versus-host disease (cGVHD) has not yet been fully described under this protocol. This study analyzed the clinical characteristics of cGVHD among 300 patients with hematological malignancies who received haplo-cord-HSCT between January 2012 and July 2016 at our center. During the follow-up, the 5-year cumulative incidence of cGVHD based on the National Institutes of Health (NIH) consensus criteria was 32.2% (95% confidence interval [CI], 28.7-35.7); the 5-year cumulative incidence of moderate to severe cGVHD was 11.4% (95% CI, 9.4-13.4). After the multivariate analysis, the GVHD overall survival (GOS) was associated with relapse, thrombocytopenia, bronchiolitis obliterans syndrome, and steroid-refractory cGVHD. The infused CD34⁺ cells (≥3.46 × 10⁶/kg) from haploidentical grafts were a protective factor affecting GOS. This study proposed a nomogram for predicting GOS using the aforementioned five variables. The concordance index was 0.877 (95% CI, 0.859-0.895) for the accuracy evaluation of the nomogram. Our results suggested that the 5-year cumulative incidence of NIH-defined cGVHD after haplo-cord-HSCT was 32.2%, and this nomogram may help clinicians select reasonable treatment strategies.

Allogeneic Hematopoietic Cell Transplantation for Older Adults with Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a disease that affects adults aged 65 years and above, and survival in this population is poor. Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapy for these patients but is underutilized due to frequent comorbidities and perceived higher risk of treatment-related mortality and non-relapse mortality. Increasing data supports the utility of allo-HCT in fit older patients after intensive chemotherapy resulting in improvement of outcomes. With the development of reduced intensity and non-myeloablative conditioning regimens that are associated with lower rates of treatment-related toxicity and mortality, this has allowed more older patients with AML to receive allo-HCT. In this review, we provide some guidance on appropriate selection of older patients as transplant candidates, benefits and risks associated with allo-HCT, conditioning regimen choice, and stem cell transplant sources as they relate to the conduct of stem cell transplantation in older patients.

Foxp3 expression in induced T regulatory cells derived from human umbilical cord blood vs. adult peripheral blood

Foxp3 is essential for T regulatory cell (Treg) function. Broad complex-Tramtrack-Bric-a-brac domain (BTB) and Cap'n'collar (CNC) homology 1, transcription factor 2 (BACH2) stabilizes Treg immune homeostasis in murine studies. However, little is known regarding what role, if any, BACH2 may have in Foxp3 regulation in human-induced Treg (iTreg). We examined Foxp3 expression and regulation comparing iTreg differentiated from umbilical cord blood (UCB) vs. adult blood (AB) naive CD4⁺ T-cells. Foxp3 expression was higher in UCB vs. AB-derived iTreg, and was sustained during 21-day expansion in vitro. The number of Foxp3⁺ iTreg generated from UCB vs. AB naive CD4⁺ T-cells was higher in iTreg differentiation conditions. In addition, UCB iTreg were more potent in suppressing T-cell proliferation compared to AB iTreg. Naive UCB CD4⁺ T-cells highly expressed BACH2 protein compared to AB. Putative transcriptional BACH2 binding sites were identified at the Foxp3 promoter, using BACH2 consensus sequence. Cross-linking chromatin immunoprecipitation (ChIP) showed that BACH2 binds to the Foxp3 proximal promoter in UCB iTreg, but not AB iTreg. BACH2 was transcriptionally active, as shRNA-mediated BACH2 knockdown resulted in reduction of Foxp3 gene transcription in UCB CD4⁺ T-cells. In summary, BACH2 serves to stabilize robust Foxp3 expression in UCB CD4⁺ T-cell-derived iTreg.

Thiotepa-Based Intensified Reduced-Intensity Conditioning Adult Double-Unit Cord Blood Hematopoietic Stem Cell Transplantation Results in Decreased Relapse Rate and Improved Survival Compared with Transplantation Following Standard Reduced-Intensity Conditioning: A Retrospective Cohort Comparison

The "Minnesota" reduced-intensity conditioning (RIC) cord blood transplantation (CBT) regimen (standard RIC) of fludarabine (Flu) (200 mg/m²), cyclophosphamide (Cy) (50 mg/kg), and 200- or 300-cGy total body irradiation (TBI) is the most published RIC CBT regimen. Though well tolerated, high relapse rates remain a concern with this regimen. Intensification of conditioning may reduce relapse without increasing transplant-related mortality (TRM). We performed a retrospective cohort comparison of outcomes in adult patients who underwent first double-unit CBT with standard RIC as compared with the intensified regimen of Flu 150 mg/m², Cy 50 mg/kg, thiotepa 10 mg/kg, and 400-cGy TBI (intensified RIC). Of the 99 patients studied, 47 received intensified RIC. Acute myelogenous leukemia was the major indication for transplant. The median age at transplant was 67 years (range, 24 to 74 years) and 54 years (range, 25 to 67 years) in standard RIC and intensified RIC, respectively. Median hematopoietic stem cell transplantation comorbidity index was 3 (range, 0 to 5) and 1 (range, 0 to 6) in the standard RIC and intensified RIC groups, respectively. Median follow-up among survivors was 22 months (range, 3.7 to 79 months) following standard RIC and 15 months (range, 2.8 to 36 months) following intensified RIC. The cumulative incidence (CI) of relapse was significantly lower following intensified RIC compared with standard RIC (P = .0013); this finding maintained significance in multivariate analysis (P = .045). TRM was comparable between the 2 groups (P = .99). Overall survival (OS) was significantly improved following intensified RIC as compared with standard RIC (P = .03). Median OS was 17 months following standard RIC versus not reached followed intensified RIC. The CI of grade II to IV acute graft-versus-host disease (GVHD) was significantly higher in the intensified RIC cohort than the standard RIC-cohort (P = .007), while CI of grade III to IV acute GVHD, any chronic GVHD, and moderate-to-severe chronic GVHD was comparable in each cohort (P = .20, P = .21, and P = .61, respectively). This retrospective analysis shows an improvement in OS and decreased relapse without increase in TRM in patients receiving intensified RIC as compared with standard RIC. Our data suggest that consideration of thiotepa-based intensified RIC may improve outcomes in fit, older patients undergoing double-unit CBT.

Recombinant TAT-BMI-1 fusion protein induces ex vivo expansion of human umbilical cord blood-derived hematopoietic stem cells

Transplantation of hematopoietic stem cells (HSCs) is a well-established therapeutic approach for numerous disorders. HSCs are typically derived from bone marrow or peripheral blood after cytokine-induced mobilization. Umbilical cord blood (CB) represents an appealing alternative HSC source, but the small amounts of the individual CB units have limited its applications. The availability of strategies for safe ex vivo expansion of CB-derived HSCs (CB-HSCs) may allow to extend the use of these cells in adult patients and to avoid the risk of insufficient engraftment or delayed hematopoietic recovery.

Here we describe a system for the ex vivo expansion of CB-HSCs based on their transient exposure to a recombinant TAT-BMI-1 chimeric protein. BMI-1 belongs to the Polycomb family of epigenetic modifiers and is recognized as a central regulator of HSC self-renewal. Recombinant TAT-BMI-1 produced in bacteria was able to enter the target cells via the HIV TAT-derived protein transduction peptide covalently attached to BMI-1, and conserved its biological activity. Treatment of CB-CD34⁺ cells for 3 days with repeated addition of 10 nM purified TAT-BMI-1 significantly enhanced total cell expansion as well as that of primitive hematopoietic progenitors in culture. Importantly, TAT-BMI-1-treated CB-CD34⁺ cells displayed a consistently higher rate of multi-lineage long-term repopulating activity in primary and secondary xenotransplants in immunocompromised mice. Thus, recombinant TAT-BMI-1 may represent a novel, effective reagent for ex vivo expansion of CB-HSC for therapeutic purposes.

Transplants of unrelated cord blood or sibling allogeneic peripheral blood stem cells/bone marrow in adolescent and young adults with chronic myeloid leukemia: comparable outcomes but better chronic GVHD-free and relapse-free survival among survivors with cord blood

Adolescent and young adult (AYA) patients with hematological malignancy aged 15 to 39 years are recognized as a separate entity, and the efficacy and safety of unrelated cord blood transplantation (CBT) for chronic myeloid leukemia (CML) in AYA patients has not been reported. From March 2002 to June 2015, total of 106 CML patients received allogeneic hematopoietic cell transplantation (allo-HCT) in our center. Included in the present study were CML patients aged 15 to 39 years who received unrelated CBT or sibling allo-HCT, and 74 consecutive AYA patients with CML enrolled in this analysis. The day-100 cumulative incidences of grade 2–4 aGVHD and grade 3–4 aGVHD were similar following CBT and sibling-PBSCT/BMT. The cumulative incidences of cGVHD and extensive cGVHD were 21.7% and 5.3% in the CBT cohort, which were significantly lower than those in the sibling-PBSCT/BMT cohort (58.0% and 45.5%), respectively (p = 0.046, 0.008). There was no significant difference between the two cohorts in terms of transplant-related mortality (TRM), relapse, and long-term survival (overall survival and leukemia-free survival). The 5-year probability of GVHD-free/relapse-free survival (GRFS) was 47.9% and 33.4% in the CBT and the sibling-PBSCT/BMT cohorts, respectively (p = 0.632); among patients who survived more than 100 days after transplantation (n = 61), the 5-year probability of chronic GVHD-free, relapse-free survival (CRFS) was 66.2% in the CBT cohort, which was significantly higher than that in the sibling-PBSCT/BMT cohort (37.4%) (p = 0.037). Our study suggests that for AYA patients with CML, transplantation using unrelated CB offers comparable outcomes to sibling -PBSCT/BMT, including similar aGVHD, TRM, relapse, and long-term survival; however, from the perspective of quality of life, unrelated CBT have a lower incidence of cGVHD and a higher CRFS among survivors.

Awareness of cord blood collection and the impact on banking

BACKGROUND

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells for transplantation especially in minority populations with limited chances of finding a histocompatible volunteer donor in the registry. UCB has the advantages of early availability, successful outcomes despite some histocompatibility mismatch, and low incidence of chronic graft-versus-host disease. Public cord blood banks that disseminate UCB products for transplant depend on voluntary donation at participating hospitals and obstetrical providers for collection.

PROCEDURE

Using survey questionnaires, we evaluated attitudes toward UCB donation, the frequency of donation, and provider opinions on UCB collection in the greater St. Louis metropolitan area that caters to minority ethnicities in significant numbers.

RESULTS

Our data suggest that nervousness and lack of information regarding the donation and utility of the product were ubiquitous reasons for not donating. Additionally, irrespective of age or level of education, women relied on healthcare providers for information regarding UCB donation. Providers reported primarily time constraints to discussing UCB donation at prenatal visits (54%). Of the interviewees, 62% donated UCB. Fallout due to refusal or preferring private banking was miniscule.

CONCLUSIONS

These results suggest that dedicated personnel focused on disseminating information, obtaining consent, and collecting the UCB product at major hospitals can enrich cord blood banks especially with minority cords. Sustained and focused efforts could improve upon a relatively high wastage rate and ensure a robust supply of UCB products at local public banks.

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.