Cost-Effectiveness of Unrelated Umbilical Cord Blood vs. HLA Haploidentical Related Bone Marrow Transplant: Evidence from BMT CTN 1101

BACKGROUND

BMT CTN 1101 was a Phase III randomized controlled trial comparing reduced intensity conditioning followed by double unrelated umbilical cord blood (UCB) versus HLA-haploidentical related donor bone marrow (haplo-BM) transplantation for patients with high-risk hematologic malignancies.

OBJECTIVE

The objective of this study is to report the results of a parallel cost-effectiveness analysis.

STUDY DESIGN

Three hundred sixty-eight patients were randomized to unrelated UCB (n=186) or haplo-BM (n=182) transplant. We estimated healthcare utilization and costs using propensity score-matched BMT patients from the OptumLabs^Ⓡ Data Warehouse for trial participants <65 years and Medicare claims for participants ≥65 years. Weibull models were used to estimate 20-year survival. EQ-5D surveys by trial participants were used estimate Quality-Adjusted Life Years (QALYs).

RESULTS

At 5-year follow-up, survival was 42% for haplo-BM versus 36% for UCB (P=.06). Over a 20-year time horizon, haplo-BM is expected to be more effective (+0.63 QALY) and more costly +$118,953) for persons under 65. For those over 65, haplo-BM is expected to be more effective and less costly. In one-way uncertainty analyses, for persons <65, the cost per QALY result was most sensitive to life years and health state utilities. For persons ≥65, life years were more influential than costs and health state utilities.

CONCLUSION

Compared to UCB, haplo-BM was moderately cost-effective for patients aged <65 years, and less costly and more effective for persons ≥65 years. Haplo-BM is a fair value choice for commercially insured patients with high-risk leukemia and lymphoma who require HCT. For Medicare enrollees, haplo-BM is a preferred choice when considering costs and outcomes.

Cytomegalovirus-Specific Immunity Recovers More Slowly after Cord Blood Transplantation Compared with Matched Sibling Donor Allogeneic Transplantation

BACKGROUND

Rapid quantitative recovery of NK cells but slower recovery of T-cell subsets along with frequent viral infections are reported after umbilical cord blood (UCB) compared with matched sibling donor (MSD) hematopoietic cell transplantation (HCT). However, it remains unclear whether increased propensity for viral infections is also a result of slower recovery of virus-specific immunity after UCB as compared to MSD HCT.

OBJECTIVES

We examined the differences in the function of virus-specific peripheral blood mononuclear cells (PBMC) after UCB (N=17) vs. MSD (N=9) using previously collected patient blood samples at various time points after HCT.

METHODS

Interferon-gamma (IFN-γ) enzyme-linked immune absorbent spot (ELISpot) assay was used to quantify the PBMC frequencies that secrete IFN-γ in response to 11 immunopeptides from 5 common viruses. We included the patients who received the same reduced intensity conditioning regimen without ATG, no systemic glucocorticoids and had no relapse or acute/chronic graft-versus-host disease within 1 year after HCT.

RESULTS

The CMV-reactive PBMC frequencies were higher in CMV seropositive vs. seronegative patients after HCT. Among CMV seropositive patients, the frequency of CMV-reactive PBMC was lower after UCB compared to MSD throughout one year of HCT. We observed no differences in virus-specific PBMC responses towards HHV6, EBV, BK, and adenovirus antigens between UCB and MSD.

CONCLUSION

Our data demonstrate that the reconstitution of CMV-specific immunity is slower in CMV seropositive recipients of UCB vs. MSD HCT in contrast to other viruses which had similar recoveries. These study findings support implementation of more potent prophylactic strategies for preventing CMV reactivation in CMV seropositive patients receiving UCB HCT.

CD56dimCD57+NKG2C+ NK cell expansion is associated with reduced leukemia relapse after reduced intensity HCT

We have recently described a specialized subset of human natural killer (NK) cells with a CD56^dimCD57⁺NKG2C⁺ phenotype that expand specifically in response to cytomegalovirus (CMV) reactivation in hematopoietic cell transplant (HCT) recipients and exhibit properties characteristic of adaptive immunity. We hypothesize that these cells mediate relapse protection and improve post-HCT outcomes. In 674 allogeneic HCT recipients, we found that those who reactivated CMV had lower leukemia relapse (26% [17–35%], p=0.05) and superior disease-free survival (DFS) (55% [45–65%] p=0.04) 1 year after reduced intensity conditioning (RIC) compared to CMV seronegative recipients who experienced higher relapse rates (35% [27–43%]) and lower DFS (46% [38–54%]). This protective effect was independent of age and graft-versus-host disease (GvHD) and was not observed in recipients who received myeloablative (MA) regimens. Analysis of the reconstituting NK cells demonstrated that CMV reactivation is associated with both higher frequencies and greater absolute numbers of CD56^dimCD57⁺NKG2C⁺ NK cells, particularly after RIC HCT. Furthermore, expansion of these cells at 6 months post-transplant independently trended toward a lower 2-year relapse risk. Together, our data suggest that the protective effect of CMV reactivation on post-transplant relapse is in part driven by adaptive NK cell responses.

Factors predicting single-unit predominance after double umbilical cord blood transplantation

Double umbilical cord blood transplantation (dUCBT), developed as a strategy to treat larger patients with hematologic malignancies, frequently leads to the long-term establishment of a new hematopoietic system maintained by cells derived from a single UCB unit. However, predicting which unit will predominate has remained elusive. This retrospective study examined risk factor associated with unit predominance in 262 patients with hematologic malignancies who underwent dUCBT with subsequent hematopoietic recovery and complete chimerism between 2001–2009. Dual chimerism was detected at day 21–28, with subsequent single chimerism in 97% of cases by day +100 and beyond. Risk factors included nucleated cell dose, CD34+ and CD3+ cell dose, colony forming units-granulocyte macrophage dose, donor-recipient human leukocyte antigen (HLA) match, sex and ABO match, order of infusion, and cell viability. In the myeloablative setting, CD3+ cell dose was the only factor associated with unit predominance (OR 4.4, 95%CI, 1.8–10.6; p<0.01), but in the non-myeloablative setting, CD3+ cell dose (OR 2.1, 95%CI, 1.0–4.2; p=0.05) and HLA match (OR 3.4, 95%CI, 1.0–11.4; p=0.05) were independent factor associated with unit predominance. Taken together, these findings suggest that immune reactivity plays a role in unit predominance and should be considered during graft selection and graft manipulation.

Reduced-intensity hematopoietic cell transplantation in older patients with AML/MDS: umbilical cord blood is a feasible option for patients without HLA-matched sibling donors

Umbilical cord blood (UCB) has increased access to hematopoietic cell transplantation (HCT) for patients without HLA-matched sibling donors (MSD). We compared outcomes of HCT using MSD (N=38) or UCB (N=60) among older patients (age ≥ 55 years) with AML or myelodysplastic syndromes (MDS). All patients received a reduced intensity regimen consisting of CY, fludarabine and 200 cGy TBI. Median age at HCT was 63 years for MSD and 61 years for UCB recipients. Among UCB recipients, 95% received two UCB units and 88% received 1-2 locus HLA-mismatched units to optimize cell dose. OS at 3-years was 37% for MSD and 31% for UCB recipients (P=0.21). On multivariate analysis, donor source (MSD vs UCB) did not impact risks of OS, leukemia-free survival and relapse or treatment-related mortality. UCB is feasible as an alternative donor source for reduced-intensity conditioning HCT among older patients with AML and MDS who do not have a suitable MSD.

Umbilical cord blood: current status and future directions

Once considered biological waste, umbilical cord blood (UCB) has become an accepted source of haematopoietic stem cells (HSCs). With initial success in the pediatric setting, UCB transplantation continues to gain favor in the adult patient population. Novel approaches to UCB transplantation include use of two units and a variety of graft manipulations. Additional uses for UCB are currently being explored and include applications in regenerative medicine and immunotherapy.

Delayed platelet recovery after allogeneic transplantation: a predictor of increased treatment-related mortality and poorer survival

Delayed platelet recovery (DPR) is common after allo-SCT. Insufficient data on risk factors and association with OS and TRM are available. We conducted a retrospective analysis of all allografts at the University of Minnesota between 2000 and 2005 to characterize the frequency of DPR (platelets <50 000/μL by day 60), risk factors and related complications. A total of 850 patients with hematological malignancies and benign disorders were included. Myeloablative (MA) conditioning was used in 65% of the patients and 45% received umbilical cord blood (UCB) grafts. The 60-day cumulative incidence of platelet recovery was 40% in UCB, 57% in unrelated donor (URD) and 74% in sibling donor. Multivariate analysis confirmed that the variables associated with DPR were MA (versus reduced intensity) conditioning, graft source other than sibling donor, ABO major mismatch, recipient CMV-positive serostatus, the presence of grade II-IV acute GVHD and slower neutrophil recovery. These data demonstrate that DPR is frequent after allogeneic hematopoietic cell transplantation, especially after UCB. DPR is a significant independent risk factor for increased TRM and poorer OS along with HLA-mismatched URD, but not UCB, grade II-IV acute GVHD, old age and advanced disease stage.

Infectious complications following unrelated cord blood transplantation

INTRODUCTION

Infections following cord blood transplantation are just beginning to be defined in the literature. This review will outline infections at death, the epidemiology of individual infections, and the impact of stem cell source.

METHODS

A review of studies published since 2000.

RESULTS

Based on registry data, most studies demonstrate an approximate rate of infection at death of 30-40% among cord blood recipients. Bacterial infections often occur prior to engraftment and increase among patients with graft failure. In addition, there is delayed recovery of the immune response among patients with graft-versus-host disease that leads to viral infections at later time points. The risk of serious infection among children receiving umbilical cord blood (UCB) grafts is comparable to that of children receiving unmanipulated marrow and is lower than that of recipients of a T-cell-depleted stem cell source. Among adult patients, despite an overall higher incidence of serious infections after UCB transplantation as compared with unrelated donor grafts, non-relapse mortality and overall survival were not significantly different between haematopoietic stem cell sources.

CONCLUSIONS

Further studies are needed to confirm these observations and determine whether the risk of infection for cord blood recipients is comparable to that of recipients of unmanipulated marrow.

Leukemia in donor cells after allogeneic hematopoietic stem cell transplant

The development of leukemia in donor cells after allogeneic hematopoietic stem cell transplant is an extremely rare event. We report here the case of a patient who developed myelodysplastic syndrome/acute myeloid leukemia, in cells of donor origin 3.5 years after related donor HSCT for refractory chronic lymphocytic leukemia and therapy-induced myelodysplastic syndrome. The origin of the leukemia was determined by analysis of minisatillite polymorphism tested on CD34(+) cells.

Non-leukemic autologous reconstitution after allogeneic bone marrow transplantation for Ph-positive chronic myelogenous leukemia: extended remission preceding eventual relapse

Autologous reconstitution is the recovery of autologous hematopoietic function after failure of an allogeneic graft to establish sustained hematopoiesis either with or without preceding donor engraftment. We reviewed 9 years experience of the University of Minnesota and identified 10 of 291 patients who underwent allogeneic BMT for Ph-positive CML and developed non-leukemic autologous reconstitution. All patients received the same preparative regimen with cyclophosphamide and total body irradiation. Eight patients had a 6/6-antigen matched donor. Eight patients received their graft from an unrelated donor. In five cases the graft was T cell-depleted. Non-malignant autologous reconstitution initially manifested as mixed chimerism in nine of 10 patients and lasted for a median of 11 (3-41) months. Eight patients have relapsed and four are still alive. The two relapse-free patients have died 24 and 48 months post transplant. Of the four surviving patients, two are in interferon-induced cytogenetic remission at 53+ and 101+ months of follow-up. Autologous non-leukemic reconstitution is uncommon, but appears to be a distinct clinical syndrome, perhaps occurring more frequently after unrelated donor BMT. Although usually followed by relapse, relapse-free survival may be prolonged.