Double Unrelated Reduced-Intensity Umbilical Cord BloodTransplantation in Adults

Karen K. Ballen1, Thomas R. Spitzer1, Beow Y. Yeap1, Steven McAfee1, Bimalangshu R.Dey1, Eyal Attar1, Richard Haspel2, Grace Kao3, Deborah Liney3, Edwin Alyea3, StephanieLee3, Corey Cutler3, Vincent Ho3, Robert Soiffer3, and Joseph H. Antin31 Division of Hematology/Oncology, Department of Medicine, Massachusetts General Hospital,Boston, Massachusetts2 Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts3 Division of Hematologic Malignancies, Dana-Farber Cancer Institute, Boston, Massachusetts

AbstractUmbilical cord blood (UBC) stem cells are a useful stem cell source for patients without matchedrelated or unrelated donors. Adult transplantation with single UBC units is associated with hightransplantation-related mortality (TRM). In most cases, mortality is due to infection related to slowengraftment and immunoincompetence. In this study, we used a reduced-intensity conditioningregimen of fludarabine, melphalan, and antithymocyte globulin followed by 2 partially matched UBCunits. The UBC units were a 4/6 HLA match or better with each other and with the patient andachieved a minimum precryopreservation cell dose of 3.7 × 107 nucleated cells/kg. A total of 21patients (median age, 49 years) were treated. The median time to an absolute neutrophil count > 0.5× 109/L was 20 days, and the median time to an unsupported platelet count > 20 × 109/L was 41 days.Two patients experienced primary graft failure and underwent a second UBC transplantation. Onepatient had a late graft failure. Acute graft-versus-host disease (GVHD) grade II–IV occurred in 40%of patients. The 100-day TRM was 14%, and the 1-year disease-free survival was 67%. Mixedchimerism was associated with a higher risk of chronic GVHD. Our findings indicate that adultpatients can tolerate double UBC transplantation well and achieve sustained antitumor responsesusing this reduced-intensity conditioning regimen.

INTRODUCTIONUmbilical cord blood (UCB) has been shown to contain sufficient progenitor cells to providedurable engraftment in children, and it provides an alternative stem cell source for patientswithout matched related or unrelated donors [1,2]. Trials of UCB transplantation in childrenhave shown a 30%–80% disease-free survival (DFS), depending on patient age and diseasestatus [3,4]. However, in adults, the results of single UCB transplantation have been lesspromising because of high transplantation-related mortality due to a low infused cell dose andthe subsequent risk of infection associated with prolonged cytopenia [5–7].

The results of both pediatric and adult UBC transplantation studies suggest improved survivalwith UBC grafts of higher cell dose [3,4,8]. Barker and colleagues reported that outcomes maybe improved with 2 UBC units in both the nonmyeloablative and ablative setting [9,10].Preliminary data from the same group indicates a reduction in relapse with transplantation of

Correspondence and reprint requests: Karen K. Ballen, MD, Division of Hematology/Oncology, Massachusetts General Hospital, Cox640, 100 Blossom Street, Boston, MA 02114 (kballen@partners.org).

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Published in final edited form as:Biol Blood Marrow Transplant. 2007 January ; 13(1): 82–89. doi:10.1016/j.bbmt.2006.08.041.

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2 UBC units [11]. In an effort to increase the cell dose and decrease transplantation-relatedtoxicity, we treated 21 patients with a reduced-intensity conditioning regimen followed bysequential infusion of 2 partially matched UBC units.

PATIENTS AND METHODSPatients

Patients were eligible for UCB transplant if they had no 5/6 or 6/6 HLA-A, -B, or -DR allele-matched related donor or no 6/6 HLA-A, -B, or -DR allele-matched unrelated donor available.Patients were age 18–65 years and met standard transplantation eligibility criteria, includingejection fraction > 45%, diffusing capacity of the lung for carbon monoxide > 50% predicted,and European Cooperative Oncology Group performance status of 0–2. Patients with acuteleukemia were eligible if they were in second or subsequent complete remission or in firstremission with high-risk cytogenetics or an antecedent hematologic disorder. Patients withrefractory leukemia or leukemia in relapse were not eligible. Patients with chronic lymphocyticleukemia progressive after at least 2 chemotherapy regimens, myelodysplasia with life-threatening cytopenia, aplastic anemia, and non-Hodgkin’s lymphoma or Hodgkin’slymphoma refractory to chemotherapy or relapse were eligible. We limited our study to areduced-intensity conditioning regimen, because it was anticipated that the lower risk ofmucositis would be preferable in patients with a high probability for delayed engraftment. Theprotocol was reviewed and approved by the Institutional Review Board of the Dana-Farber/Harvard Cancer Center. Written informed consent was obtained from all patients beforeparticipation.

HLA TypingConfirmatory HLA typing was performed on all UCB units before transplantation. Moleculartyping was performed for both class I (HLA-A, -B, -C) and class II (HLA-DR and -DQ) alleles.Information was recorded on all of these alleles, but only HLA-A, -B, and -DR were used inthe search strategy. HLA typing was performed by polymerase chain reaction and sequence-specific primer technology (One Lambda, Canoga Park, CA).

UBC Unit SelectionUCB units were obtained from a various national and international registries. UBC units hadto meet a minimum combined precryopreservation cell dose of 3.7 × 107 nucleated cells/kgrecipient. A minimum cell dose per UCB unit was not required. UCB units were required tobe a 4/6 or better allele-level HLA-A, -B, and -DR match with each other and with the patient.Typing at HLA-C and -DQ was obtained but not used in the match strategy. The choice ofUCB when multiple units were available was based on higher cell dose and greater HLAcompatibility, in that order.

Treatment PlanPatients received conditioning with fludarabine 30 mg/m2/day on days −8 through −3 (totaldose, 180 mg/m2), melphalan 100 mg/m2/day on day −2, and rabbit antithymocyte globulin(Sangstat, Fremont, CA) 1.5 mg/kg/day on days −7, −5, −3, and −1 (total dose, 6.0 mg/kg).GVHD prophylaxis consisted of continuous intravenous infusion cyclosporine starting on day−3 and mycophenolate mofetil (MMF) 15 mg/kg intravenously twice daily starting on day 0.Cyclosporine and MMF were given orally when the patient was able to tolerate oralmedications. In the absence of GVHD, the MMF was tapered between days +30 and +60posttransplantation, and the cyclosporine was tapered between days +100 and +180. Stem cellswere infused on day 0. UCB units were thawed according to the methods of Rubinstein et al[12], and administered sequentially on the same day 1–6 hours apart. After transplantation,

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patients received supportive care with transfusion support; prophylactic antibacterial,antifungal, antiviral, and antipneumocystis therapy; and filgrastim 5 μg/kg/day from day +5until the absolute neutrophil count was > 2.0 × 109 cells/L for 2 consecutive days. Neutrophilengraftment was defined as the first of 3 consecutive days with neutrophil recovery to at least0.5 × 109 cells/L. Platelet engraftment was defined as the first day of an unsupported plateletcount > 20 × 109 cells/L (no platelet transfusion within 7 days). Early graft failure was definedas absence of neutrophil recovery by day +35 after transplantation. Late graft failure wasdefined as the presence of neutrophil engraftment by day +35, followed by a decline of theneutrophil count to < 0.5 × 109 cells/L after day +42, and the loss of donor chimerism. GVHDwas graded according to the consensus criteria [13].

Donor Chimerism AnalysisDonor chimerism was determined from the peripheral blood at posttransplantation weeks 2, 4,6, 8, 10, and 12 and months 6, 12, and 24. Bone marrow samples were also obtained atposttransplantation months 3, 6, 12, and 24. Chimerism assays were performed by short tandemrepeat analysis using a multiplex kit with primers for 10 different loci (Profiler Plus, AppliedBiosystems, Foster City, CA) and an Applied Biosystems ABI-310 genetic analyzer. Pre-transplantation samples from the recipient and both UBC donors were tested to identify allelesat each locus that would be specific for each of them. When possible, recipient blood was testedwith unseparated cells as well as CD3+- and CD33+-enriched populations, separated using anegative selection assay (RosetteSep; StemCell Technologies, Vancouver, Canada) [14].

Statistical AnalysisTime for the engraftment and survival outcomes was measured from day 0 of stem cell infusionand estimated by the Kaplan-Meier method. The engraftment time of a hematopoieticparameter was censored at the time of relapse, or time of death if the event occurred beforeengraftment. Patients who had not died were censored at their last follow-up date in the analysisof overall survival (OS). Patients who were still alive without relapse were censored at thesame time with respect to DFS. Wilcoxon’s rank-sum test was used to determine the associationbetween CD4 count at day +100 and likelihood of infection. Mc-Nemar’s test and Wilcoxon’ssigned-rank test were used to identify UBC factors associated with the predominating unit atday +100 among the evaluable patients, excluding primary graft failures and early deaths duringthe first month posttransplantation. The rates of acute grade II–IV GVHD and chronic GVHDwere analyzed actuarially, treating graft failure and non-GVHD death as independentcompeting risks. The log-rank test was used to compare OS and GVHD incidence betweengroups. All P values were based on 2-sided hypothesis tests, with the exact inference computedusing StatXact Version 6 (Cytel Software Corp, Cambridge, MA).

UBC SearchDuring the study period, UBC searches were undertaken for 60 patients, who lacked a suitablymatched related or unrelated donor. In 48 patients (80%), the searches resulted in identificationof an appropriate matched pair. Twenty-seven patients did not proceed to reduced-intensitydouble UBC transplantation because another donor source was identified, the patient electednot to undergo transplantation, the disease relapsed, or insurance approval could not beobtained. UBC searches were unsuccessful for 12 patients; 9 of these patients were non-Caucasian. Five patients would have had 4/6 UBC matches if antigen level, rather than allele-level matching, were used for class I. The median number of confirmatory testings performedto locate a suitable UBC pair was 6 (range, 2–37).

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RESULTSPatient Characteristics

Patient characteristics are listed in Table 1. A total of 21 patients (median age, 49 years)underwent transplantation in this study between October 2003 and May 2005. The medianrecipient weight was 78 kg (range, 58–111 kg). Four patients were non-Caucasian. Acutemyelogeneous leukemia was the most common diagnosis. Five patients (24%) had undergoneprevious autologous stem cell transplantation.

Graft CharacteristicsCharacteristics of the UBC graft are displayed in Table 2. Allele-level typing for HLA-A, -B,and -DR were used in the matching strategy. Fourteen patients (67%) received 2 4/6 matchedUBC units, 5 patients received 1 4/6 and 1 5/6 HLA-matched unit, and 2 patients received 25/6 matched units. Most of the UBC pairs (76%) were 4/6 matches. Allele-level typing forHLA-C and -DQ were performed for 15 patients and corresponding UBC pairs and aredisplayed in Table 2. Matching ranged from 8/10 alleles to 5/10 alleles for patients and UBCunits, and 10/10 to 5/10 alleles between UBC units; for example, 4/6 HLA-A, -B, and -DRallele matches corresponded to 5/10, 6/10, or 7/10 HLA-A, -B, -C, -DR, and -DQ allelematches. The median infused cell doses were 4.0 × 107 nucleated cells/kg (range, 2.9–5.1) and1.9 × 105 CD34+ cells/kg (range, 0.6–9.7) for the 2 UBC units combined. The median infusedcell doses for each individual UBC unit were 2.0 × 107 nucleated cells/kg (range, 1.1–3.4) and0.9 × 105 CD34+ cells/kg (range, 0.1–8.6).

Engraftment and GVHDTwo patients had primary graft failure and received a second double UBC transplant with adifferent conditioning regimen of low-dose total body radiation, cyclophosphamide, andfludarabine on days +39 and +50 after the first transplantation. Both of these patients hadaplastic anemia with late transformation to myelodysplastic syndrome after failing to respondto antithymocyte serum and calcineurin inhibitor therapy. Neither had received previouscytotoxic therapy. Before the second transplantation, the patients remained neutropenic andthrombocytopenic, with no evidence of autologous reconstitution. One patient died ofzygomycetes infection 8 months after the first transplantation, and the other patient wassurviving at 19 months after the first transplantation. Among the remaining 19 patients, themedian time to an absolute neutrophil count > 0.5 × 109 cells/L was 20 days (range, 15–34days). Two patients did not recover to a platelet count > 100 × 109 cells/L by day +100. Amongthe remaining patients, the median time to a platelet count > 20 × 109 cells/L unsupported was41 days (range, 21–55 days), and the median time to a platelet count > 100 × 109 cells/L was63 days (range, 34–91 days). One patient experienced late graft failure 3 monthsposttransplantation, after a rapid early taper of cyclosporine in the context of severe adenovirusinfection. He underwent infusion of previously stored autologous stem cells at 4 monthsposttransplantation and relapsed 18 months posttransplantation. Acute GVHD grade I–IV wasseen in 58% of patients (40% grade II–IV), but only 1 patient had grade III GVHD and nopatients had grade IV GVHD. There were no deaths attributable to acute GVHD. Sixteenpatients were evaluable for chronic GVHD; 5 of these 16 patients developed chronic GVHD,2 with extensive disease. There was 1 death from chronic GVHD complicated by vancomycin-resistant enterococcus (VRE) sepsis.

Relapse and SurvivalTransplantation-related (nonrelapse) mortality was 14% at 100 days and 19% at 6 months. Onepatient with CLL had progressive disease and 2 patients (1 with AML as discussed above and1 with NHL) relapsed. The median follow-up of survivors was 18 months (range, 11–30

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months). OS was 71% and DFS was 67%, as illustrated in Figure 1. The projected 2-year OSand DFS are 71% and 55%, respectively. Causes of death occurring before day +100 includedcentral nervous system hemorrhage, staphylococcal sepsis with cerebral edema, andposttransplantation lymphoproliferative disease. There were 3 deaths after day +100, 1 fromchronic GVHD with VRE sepsis, 1 from disseminated fungal infection after a second doubleUBC transplantation in a patient with primary graft failure, and 1 from posttransplantationlymphoproliferative disorder. Other nonfatal infections included cytomegalovirus reactivation,disseminated adenovirus, mucor, and human herpes virus 6 encephalitis.

Immune ReconstitutionPeripheral blood was analyzed by flow cytometry for T-cell, B-cell, and natural killer cellmarkers at 100 days and 1 year posttransplantation; the results are displayed in Table 3. Earlygraft failures were excluded from these analyses, and the patient with late graft failure wasexcluded from the 1-year analysis. The median total CD4 count at 100 days posttransplantationwas 90 cells/μL (range, 18–425 cells/μL). By 1-year posttransplantation, the median CD4 counthad risen to 518 cells/μL (range, 21–1785 cells/μL), consistent with immune system recovery.Severe and life-threatening infections were more common in the patients with a lower CD4count at day +100 but did not reach statistical significance.

Chimerism DataExcluding the 2 early graft failures and 2 early deaths within 1 month of transplantation,chimerism was evaluable in 17 patients. By day +28, a single UBC unit predominated in 8patients. In 6 patients, a combination of both UBC units was detected, ranging from 50%5–0% to 80%–20%. Three patients had persistent host hematopoiesis; 2 of these patients haddetectable donor cells from only 1 UBC unit. Three patterns of chimerism emerged by 12 weeksposttransplantation (Fig 2). Group 1 comprised 10 patients with evidence of only a single UBCengraftment by 6 weeks posttransplantation; the same pattern was seen at week 12. Group 2comprised 4 patients in whom both UBC donors were initially identified, but in 3 of 4 patients,only a single donor predominated by week 12. In the other patient, both donors were presentin a 69/31 ratio at week 12. Group 3 (3 patients) consisted of patients with a mixed chimera ofrecipient blood and a single UBC unit.

In 76% of patients (13 of 17), the predominant UBC unit at 3 months posttransplantation wasthe first UBC unit infused (P = .049). There was a trend toward the predominant UBC unithaving a higher nucleated cell dose (P = .071) and CD34 count (P = .120). The median celldoses of the predominant UBC unit were higher than those of the minor UBC unit by 0.4 ×107 nucleated cells/kg and 0.3 × 105 CD34 cells/kg. A closer HLA match, ABO match, or sexagreement did not correlate with the predominant cord. Some ninety percent of the UBC unitpairs were infused 3.5–4.5 hours apart. There was no correlation between time between unitinfusions and graft failure.

PREDICTORS FOR SURVIVAL AND GVHDPatient age, HLA match, cell doses infused, and chimerism pattern at day +100 were analyzedto determine predictive factors for OS and DFS, as well as acute GVHD (grade II–IV) andchronic GVHD (Table 4). The limited patient numbers precluded the fitting of a multivariatemodel; thus, the univariate numbers must be interpreted cautiously. At 1 yearposttransplantation, DFS was 44% and OS was 56% respectively for patients over age 50 (n= 9). Younger patients achieved 83% DFS and OS. There was a trend toward improved survivalin patients with a higher CD34 count in the predominant UBC unit. No patients have diedamong those who received a predominant UBC unit with a CD34 dose/kg above the medianof 1.9 × 105. A higher nucleated cell dose or closer HLA match between the patient and the 2

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UBC units was not associated with better survival. The HLA match of the predominating UBCunit did not correlate with survival or with GVHD. There was a trend toward less chronicGVHD in the patients infused with lower CD34 doses; however, there were only 5 patientswith chronic GVHD, and the median follow-up of the study is 18 months. In addition, thechimerism pattern (chimerism groups 2 and 3) was also strongly associated with the presenceof chronic GVHD. The actuarial rate of chronic GVHD rate at 1 year posttransplantation was100% in patients who had mixed chimera of either 2 UBC units or 1 UBC unit and recipientblood at 6 weeks posttransplantation, but 0% in patients who had evidence of only 1 cordengraftment (P < .001). The strong association between chimerism and GVHD remained highlysignificant even after adjusting for potential confounding by each of the factors in Table 4.However, these numbers should be interpreted cautiously, given the small number of patientswith chronic GVHD.

DISCUSSIONIn this study, we report a low TRM and encouraging DFS using a reduced-intensity regimenfollowed by sequential UBC transplantation. These findings are consistent with the favorableexperiences of nonmyeloablative and reduced-intensity regimens after related and unrelatedadult donor transplantation [15–17]. Reduced-intensity regimens have been used with singleUBC transplantation; however, TRM was high even with a reduced-intensity regimen [18,19].

The sequential or double UBC transplantation approach was built on the observation that celldose is an important prognostic factor for engraftment and survival [6,20]. An early report ofpatients infused with multiple mismatched units suggested that crossed immunologic rejectionwould not occur [21]. Moreover, recent studies by Barker et al [9] at the University ofMinnesota demonstrated that reliable engraftment can occur using 2 UCB products.

In our study, the 100-day TRM was remarkably low, at 14%. The low TRM might beattributable to patient selection (patients with active leukemia were excluded), high infusedcell dose (all patients received 2 UBC units, with a median nucleated cell dose of 4.0 × 107

cells/kg), allele-level matching, and a low incidence of GVHD disease. Younger patients hada better outcome than patients over age 50. Because there are no objective data demonstratingbetter outcomes for myeloablative therapy in UBC transplantation, we chose to focus ourattention on reduced-intensity transplantation, because it was anticipated that the lowerincidence of mucositis would be preferable in patients with a high probability of havingprolonged neutrophil nadirs.

The relapse rate was low, suggesting preservation of the graft-versus-leukemia after UBCtransplantation. The 2 patients with graft failure had aplastic anemia/MDS and had not receivedprevious cytotoxic chemotherapy. Each had primary graft failure but engrafted satisfactorilyafter the subsequent administration of a more intensive conditioning regimen, followed by asecond double UBC transplant. We have previously shown that lack of previous intensivetherapy is a risk factor for graft failure in nonmyeloablative unrelated transplants or relateddonor transplants with very-low-dose conditioning [22,23]. Two patients died ofposttransplantation lymphoproliferative disorder (PTLD), on days 41 and 216posttransplantation. In both of these patients, recurrent disease was suspected, andposttransplantation lymphoma was diagnosed late in the course. The greaterimmunosuppressive activity of thymoglobulin may also be a contributing factor to the PTLDseen in our study.

Future studies include monthly Epstein-Barr virus (EBV) monitoring. The risk of EBV viremiaor EBV posttransplantation lymphoproliferative disorder has been reported to be 20% in UBC

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recipients conditioned with nonmyeloablative regimens containing antithymocyte globulin and7% in UBC recipients conditioned with an ablative regimen containing antithymocyte globulin[24]. The median time to development of PTLD was 133 days, and 5 of 9 patients with PTLDsurvived.

In all of our patients, chimerism analyses indicated the predominance of 1 cord by 3 monthsposttransplantation. Patients who were mixed chimeras at 6 weeks posttransplantation had ahigher incidence of developing chronic GVHD. The explanation for this observation is unclear;a hypothesis may be ongoing graft-versus-graft interactions. This finding will need to beconfirmed in larger trials.

In our series, with a limited number of patients, the first UBC unit infused was more often thechimerism “winner.” One possible explanation for this is that there may be limitedopportunities to fill the hematopoietic stem cell niche after conditioning, and that the first UBCinfused may be more likely to fill this niche [25]. Scadden et al have demonstrated that thecapacity of the stem cell niche is limited; in a murine system, osteoblastic cells form a regulatorycomponent of the stem cell niche [26], and the osteoblast product, osteopontin, may provide aconstraint against stem cell numbers in this niche [27]. Also in a murine model, Nilsson hasshown that nonlineage-committed hematopoetic stem cells redistributed to the endostealhematopoietic niche region by 4 hours [28]. Our UCB units were infused 1–6 hours apart, withmost units infused 4 hours apart. It is possible that in a competitive niche repopulation model,even a short interval (2–4 hours) may be sufficient to confer an advantage to the first infusedunit. The Minnesota group did not report this finding; however, in that analysis, UBC unitswere administrated directly after one another, which may not have allowed sufficient time forthe first unit to populate the niche [9,10]. These observations need to be tested in a larger patientpopulation.

Our study is the first double UBC study to carefully evaluate high-resolution HLA typing andmatching between the 2 UBC units. Preliminary data using antigen-level typing for class Isuggest higher posten-graftment mortality in mismatched UBC transplantation recipients[29]. The use of allele-level typing has resulted in improved outcomes in the unrelated bonemarrow transplantation setting compared with antigen-level typing [30]. Therefore, selectedUBC products had to be a 4/6 HLA-A, -B, and -DR allele-level match or better with each otherand with the patient. There was no obvious relationship between the degree ofhistocompatibility between the patient and UBC units and the risk of acute or chronic GVHD,but small numbers limited the ability to detect such a relationship. Mismatching at HLA-C hasbeen associated with worse outcomes after adult unrelated-donor reduced-intensitytransplantation [31]. HLA-C and -DQ typing were obtained but were not used in the matchingstrategy. In the UBC setting, the use of allele-level typing may have limited the degree ofmismatch and excluded 5 patients from transplantation. In contrast, the NETCORD group didnot find a benefit of high-resolution typing for HLA-A, -B, -C, -DR, and -DQ in single UBCtransplantation outcomes [32]. Although allele-level matching might not be important forsingle UBC transplantation, allele-level typing might decrease the risk of GVHD or graft failurein the double UBC setting. The role of allele-level typing in double UBC transplantation willneed to be clarified as more of these transplants are performed.

We have demonstrated that the double UBC transplantation strategy is an important advancein adult UBC transplantation. TRM is low, suggesting that this approach is an acceptablealternative approach for patients without sibling donors.

AcknowledgmentsThis work was supported in part by National Heart, Lung, and Blood Institute grant PO1 HL070149.

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28. Nilsson SK, Johnson HM, Coverdale JA, et al. Spatial localization of transplanted hemopoietic stemcells: inferences for the localization of stem cell niches. Blood 2001;97:2293–2299. [PubMed:11290590]

29. Barker JN, Scaradavou A, Stevens CE, et al. Analysis of 608 umbilical cord blood transplants. HLAmatch is a critical determinant of transplant-related mortality in the post-engraftment period even inthe absence of graft-vs-host disease [abstract]. Blood 2005;106:303a.

30. Flomenberg N, Baxter-Lowe LA, Confer D, et al. Impact of HLA class I and class II high-resolutionmatching on outcomes of unrelated donor bone marrow transplantation. HLA-C mismatching isassociated with a strong adverse effect on transplantation outcome. Blood 2004;104:1923–1930.[PubMed: 15191952]

31. Ho VT, Kim HT, Liney D, et al. HLA-C mismatch is associated with inferior survival after unrelateddonor non-myeloablative hematopoietic stem cell transplantation. Bone Marrow Transplant2006;37:845–50. [PubMed: 16532020]

32. Kogler G, Enczmann J, Rocha V, et al. High-resolution HLA typing by sequencing for HLA-A, -B,-C, -DR, and -DQ in 122 unrelated cord blood/patient pair transplants hardly improves long-termclinical outcome. Bone Marrow Transplant 2005;36:1033–1041. [PubMed: 16247425]

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Figure 1.OS for all patients undergoing sequential UBC transplantation (A) and DFS for all patientsundergoing sequential UBC transplantation (B).

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Figure 2.Chimerism studies: emergence of 3 patterns of chimerism by week 12. The bars represent meanpercent hematopoiesis for each group.

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Table 1

Patient characteristics

Median Range

Age (years) 49 24–63

Weight (kg) 78 58–111

Time from diagnosis to transplantation (months) 22 4–106

Sex (n)

Male 15

Female 6

Diagnosis (n)

Acute myeloid leukemia 8 (4 CR1, 4 CR2 and greater)

Acute lymphocytic leukemia 1 (CR1)

Myelodysplastic syndrome 1

Chronic lymphocytic leukemia 2

Non-Hodgkin’s lymphoma 5 (2 CR2, 3 PR)

Hodgkin’s lymphoma 2

Aplastic anemia 2

Race/ethnicity

White, non-Hispanic 17

White, Hispanic 2

Black 1

Asian 1

Previous autologous transplantation 5

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Table 2

Cord blood characteristics

n %

Allele-level HLA match (-A, -B, -DR) patient and cords

4/6, 4/6 14 67

4/6, 5/6 5 24

5/6, 5/6 2 10

Allele-level HLA match (-A, -B, -DR) cord and cord

4/6 16 76

5/6 3 14

6/6 2 10

Allele-level HLA match (-A, -B, -C, -DR, -DQ) patient and cords

8/10, 8/10 1 5

8/10, 6/10 1 5

7/10, 7/10 2 10

7/10, 6/10 5 24

6/10, 6/10 3 14

6/10, 5/10 3 14

HLA-C and -DQ Not available 6 29

Allele-level HLA match (-A, -B, -C, -DR, -DQ) cord and cord

10/10 2 10

8/10 2 10

7/10 3 14

6/10 7 33

5/10 1 5

HLA-C and -DQ not available 6 29

Median Range

Combined cell doses/kg

Total nucleated cells prethawing × 107 4.8 3.5–7.2

Total nucleated cells infused × 107 4.0 2.9–5.1

Total CD34+ cells infused × 105 1.9 0.6–9.7

Predominating UBC unit cell doses/kg

Total nucleated cells infused × 107 2.2 1.6–3.4

CD34+ cells infused × 105 1.1 0.3–8.6

Nonpredominating UBC unit cell doses/kg

Total nucleated cells infused × 107 1.8 1.1–2.7

Total CD34+ cells infused × 105 0.7 0.1–6.6

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Table 3

Immune reconstitution after UCB transplantation

Day + 100 (n = 11) Year + 1 (n = 11)

Median Range Median Range

CD4 90 (18–425) 518 (21–1785)

CD4/CD8 3.4 (0.23–27.0) 2 (0.1–31.0)

CD16+56 269 (34–764) 228 (105–2190)

CD19 360 (0–4458) 614 (0–1088)

Numbers of cells/μL obtained from peripheral blood flow cytometry are expressed as the median and range; n refers to the number of patient samplesanalyzed.

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Table 4

Univariate predictors for survival and GVHD

Patient and UCB factors

P values

OS aGVHD cGVHD

Age: ≤ 50 vs >50 years .165 .991 0.073

Total infused nucleated cells/kg: ≤ vs > 4.0 × 107 .149 .969 .537

Total infused CD34+ cells/kg: ≤ vs >1.9 × 105 .635 .385 .106

Predominating cord nucleated cells/kg: ≤ vs > 2.15 × 107 1.000 .995 .504

Predominating cord CD34+ cells/kg: ≤ vs >1.0 × 105 .082 .269 .160

HLA-A, -B, -DR patient–cord: > 4/6,4/6 vs 4/6,4/6 .378 .538 .577

HLA-A, -B, -DR cord–cord: 5/6,6/6 vs 4/6 .553 .343 .862

HLA A,B,C,DR,DQ patient–cord: >6/10,6/10 vs 6/10,6/10 .420 .688 .303

HLA-A, -B, -C, -DR, -DQ cord–cord: >6/10 vs 6/10 .928 .969 .859

Chimerism day + 100: group 1 vs groups 2 and 3 .537 .347 <.001

aGHVD, acute graft-versus-host disease; cGHVD, chronic graft-versus-host disease.

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