Volume 14, Issue 12 , Pages 1341-1347, December 2008
Unrelated Cord Blood Transplantation after Myeloablative Conditioning in Adults with Acute Myelogenous Leukemia
Article Outline
Abstract
We analyzed the disease-specific outcomes of adult acute myelogenous leukemia (AML) patients treated with unrelated cord blood transplantation (CBT) after myeloablative conditioning. Between August 1998 and February 2008, 77 adult patients with AML were treated with unrelated CBT. All patients received 4 fractionated 12 Gy total body irradiation (TBI) and chemotherapy as myeloablative conditioning. The median age was 45 years, the median weight was 55 kg, the median number of nucleated cells was 2.44 × 107/kg, and the median number of CD34-positive cells was 1.00 × 105/kg. All patients received a single and HLA mismatched cord blood unit. The cumulative incidence of neutrophil recovery at day 50 and platelet recovery at day 200 was 94.8% and 91.7%, respectively. A higher CD34-positive cell dose was associated with faster hematopoietic recovery. The cumulative incidence of grade III to IV acute graft-versus-host disease (aGVHD) and extensive-type chronic GVHD (cGVHD) was 25.1% and 28.6%, respectively. With a median follow-up of 78 months, the probability of event-free survival (EFS) at 5 years was 62.8%. The 5-year cumulative incidence of treatment related-mortality (TRM) and relapse was 9.7%, 25.8%, respectively. In multivariate analyses, the risk factor identified for event free survival (EFS) was disease status and cytogenetics. These results suggest that unrelated CBT after myeloablative conditioning could be safely and effectively used for adult patients with AML.
Key Words: Cord blood transplantation, Adult, Acute myelogenous leukemia, Myeloablative conditioning
Introduction
Although allogeneic stem cell transplantation from a human leukocyte antigen (HLA)-identical related donor offers a potential cure for patients with acute myelogenous leukemia (AML), a suitably matched related donor is unavailable for approximately two-thirds of patients. Recently, umbilical cord blood from unrelated donors has been used as an alternative stem cell source for adult patients 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13. However, reports of disease-specific outcomes for adult patients with AML after cord blood transplantation (CBT) are still limited. We have previously reported the results of a group of adult patients with AML who received unrelated CBT 7, 8. Here, we updated the results of unrelated CBT after myeloablative conditioning for 77 adult patients with AML. The main purpose of this retrospective single center study was to confirm the safety and efficacy of unrelated CBT for adult AML patients after myeloablative conditioning as well as to identify pretransplant factors related to the transplant outcomes on long-term follow-up.
Patients and Methods
Patients
This was a retrospective single center analysis. The study included the data from 77 consecutively treated AML patients, 18 years of age or older, who received a single unit CBT after myeloablative conditioning between August 1998 and February 2008, at the Institute of Medical Science, University of Tokyo. Diagnoses at transplantation included de novo AML (n = 57) and myelodysplastic syndrome (MDS)-related secondary AML (n = 20). The diagnosis of AML was made for all patients according to the French-American-British (FAB) Cooperative Group criteria 14, 15. MDS-related secondary AML was defined as AML that developed during the follow-up period of MDS. Patients qualified as being standard risk if they were in first or second complete remission (CR). Patients in third CR, in relapse, or in refractory disease were classified as being high risk. The cytogenetic subgroups according to the SWOG/ECOG criteria [16] were favorable in 11 patients, intermediate in 43 patients, unfavorable in 21 patients, and unknown in 2 patients. Patients were eligible for allogeneic transplantation in CR1 if they had intermediate and unfavorable cytogenetic abnormalities. Twenty-nine patients included in our previous study were also included and extended the follow-up 7, 8. Written informed consent for treatment was obtained from all patients.
Cord Blood Unit Selection
HLA-A and HLA-B antigens were identified by serological typing. HLA-DRB1 alleles were determined by high-resolution molecular typing using polymerase chain reaction sequence-specific primers (PCR-SSP). Patients without a suitable closely HLA-matched family donor were eligible for CBT, if a matched unrelated bone marrow donor was unavailable as a first treatment option. If there was insufficient time for an unrelated bone marrow donor search because of disease status or the preliminary search indicated a low likelihood of obtaining a matched unrelated bone marrow donor, we attempted to locate cord blood grafts. Preferred cord blood units matched 3 or more of 6 HLA loci and contained a minimal cell count of 1.5 × 107 nucleated cells/kg before freezing. All but 1 cord blood units were obtained from cord blood banks in the Japan Cord Blood Bank Network.
Conditioning
Seventy-two patients received 4 fractionated 12 Gy total body irradiation (TBI) on days −9, −8 or days −8 and −7, recombinant human granulocyte colony-stimulating factor (G-CSF) combined cytosine arabinoside (Ara-C) and cyclophosphamide (Cy). Ara-C was administered intravenously over 2 hours at a dose of 3 g/m2 every 12 hours on days −6 and −5 or days −5 and −4 (total dose 12 g/m2). G-CSF was administered by continuous infusion at a dose of 5 μg/kg/day. Infusion of G-CSF was started 12 hours before the first dose of Ara-C and stopped at the completion of the last dose. Cy was administered intravenously over 2 hours at a dose of 60 mg/kg once daily on days −4 and −3 or days −3 and −2 (total dose 120 mg/kg). Five patient who had a cardiac damage as a result of extensive prior therapies, received 4 fractionated 12 Gy TBI on days –9 and –8, G-CSF combined Ara-C 3 g/m2 every 12 hours on days –6 to –3 (total dose 24 g/m2), and fludarabine 30 mg/m2 once daily on days –5 to –3. Two days or 3 days after the completion of conditioning, patients received a CBT.
GVHD Prophylaxis
Seventy-four patients received standard cyclosporine (CsA) and methotrexate (MTX), and 3 patients received CsA only as a graft-versus-host disease (GVHD) prophylaxis. CsA was given intravenously every day starting on day −1 at a dose of 3 mg/kg/day. MTX (15 mg/m2 intravenously) was given on day 1, and 10 mg/m2 on days 3 and 6. Once oral intake could be tolerated, patients were administered oral CsA at a dose of 1:2-2.5 based on the last intravenous dose. In the absence of GVHD, CsA was tapered beginning between weeks 6 and 9 until it could be discontinued in the absence of chronic GVHD (cGVHD) between 6 and 12 months after transplantation. CsA was reduced when serum creatinine levels rose above 1.5 times baseline or other serious agent-associated toxicities occurred. Physicians could freely modify the CsA dose for patients experiencing severe acute GVHD (aGVHD) risk for disease relapse. Corticosteroid-based treatment was considered when grade II or higher severe aGVHD occurred (0.5 to 2 mg/kg).
Supportive Care
All patients received G-CSF by intravenous infusion starting on day 1 until durable granulocyte recovery was achieved. The supportive care regimen, including prophylaxis for infection was the same as previously reported [10].
End Points and Definitions
Myeloid engraftment was defined as the first of 3 consecutive days during which the absolute neutrophil count was at least 0.5 × 109/L. Platelet recovery time was achieved on the first of 3 days when the platelet count higher than 5 × 109/L without transfusion support. The chimerism status after CBT was determined either by fluorescein in situ hybridization (FISH) with a Y chromosome probe for sex-mismatched CBT or by quantitative PCR analysis for microsatellite DNA markers. Primary engraftment failure was defined as the absence of donor-derived myeloid cells on the day of death, the day of relapse, or the day 60 in patients surviving after CBT. A second allogeneic transplantation or autologous hematopoietic reconstitution before donor-derived myeloid recovery was considered as primary engraftment failure. Both aGVHD and cGVHD were graded according to the previously published criteria 17, 18. Treatment-related mortality (TRM) was defined as death from any cause except relapse. Relapse was defined by morphologic evidence of disease in peripheral blood, bone marrow, or extramedullary sites. Event-free survival (EFS) was defined as the time from CBT to graft failure, relapse, death, or the last observation.
Statistical Analysis
Cumulative incidences were estimated for hematopoietic recovery, GVHD, TRM, and relapse to take competing risks into account. The probability of EFS was estimated from the time of CBT according to the Kaplan-Meier method. Variables considered in univariate analysis were: body weight, age, recipient sex, degree of ABO matching, degree of HLA matching, recipient cytomegalovirus (CMV) serology, type of AML (de novo AML or MDS/AML), cytogenetic subgroups, disease status at transplant (standard or high risk), total nucleated cell (TNC) dose, CD34-positive cell dose, and year of transplant. Variables with a value of P < .05 for each end point were tested in multivariate analysis using Cox proportional hazards models. R version 2.4.1 was used for all analysis. End points were calculated at the last contact, the date of the last follow-up being August 1, 2008.
Results
Characteristics of Patients and Cord Blood Units
The characteristics of 77 patients and cord blood units are shown in Table 1.
Table 1. Characteristics of Patients and Cord Blood Units
| Characteristics | |
|---|---|
| Patients, n | 77 |
| Male/female, n | 40/37 |
| Median age, years (range) | 45 (18-55) |
| Median weight, kg (range) | 55 (36-76) |
| Median number of cryopreserved nucleated cells, ×107/kg (range) | 2.44 (1.16-5.29) |
| Median number of cryopreserved CD34 positive cells, ×105/kg (range) | 1.00 (0.15-8.97) |
| Median time from diagnosis to transplantation, months (range) | 17.1 (2-103) |
| Recipient CMV status, positive/negative, n | 64/13 |
| Diagnosis | |
 De novo AML, n | 57 |
| MDS-related secondary AML, n | 20 |
| Cytogenetic subgroups | |
| Favorable, n | 11 |
| t(8;21), n | 4 |
| t(15;17), n | 4 |
| inv(16)/t(16;16), n | 3 |
| Intermediate, n | 43 |
| Normal, n | 39 |
| +8, n | 4 |
| Unfavorable, n | 21 |
| Complex, n | 5 |
| −7, n | 4 |
| t(6;11), n | 4 |
| t(11;17), n | 2 |
| t(9;11), n | 1 |
| t(11;19), n | 1 |
| abn 11q23, n | 1 |
| abn 3q, n | 1 |
| abn 20q, n | 1 |
| del (9q), n | 1 |
| Unknown, n | 2 |
| Disease status at transplant | |
| Standard risk (CR1 or CR2), n | 31 |
| High-risk (More advanced phase), n | 46 |
| Conditioning regimen | |
| TBI+Ara-C/G-CSF+CY, n | 72 |
| TBI+Ara-C/G-CSF+Flu, n | 5 |
| GVHD prophylaxis | |
| CyA+MTX, n | 74 |
| CyA, n | 3 |
| No. of HLA-A,B,DRB1 mismatches | |
| 1, n | 16 |
| 2, n | 34 |
| 3, n | 23 |
| 4, n | 4 |
| ABO compatibility | |
| Match, n | 23 |
| Mismatch, n | 54 |
| Year of transplant | |
| 1998-2002, n | 32 |
| 2003-2008, n | 45 |
Among the patients the median age was 45 years (range: 18-55 years), the median weight was 55 kg (range: 36-76 kg), the median number of cryopreserved nucleated cells was 2.44 × 107/kg (range: 1.16-5.29 × 107/kg), and the median number of cryopreserved CD34 positive cells was 1.00 × 105/kg (range: 0.15-8.97 × 105/kg). All patients received a single and HLA mismatched cord blood unit.
Hematopoietic Recovery
Seventy-three patients had myeloid reconstitution and the median time to more than 0.5 × 109/L absolute neutrophil count was 21 days (range: 16-41 days). All but 1 patients with myeloid reconstitution showed full donor chimerism at first bone marrow analysis around 4-6 weeks after CBT. Four patients experienced primary engraftment failure. Of the 4 patients, 1 relapsed at day 53, and 3 died at days 21, 24, and 49 without myeloid engraftment. No patients experienced secondary engraftment failure. The cumulative incidence of neutrophil recovery at day 50 was 94.8% (95% confidence interval [CI], 89.5% to 100%) (Figure 1A). In multivariate analysis, a higher CD 34-positive cell dose was significantly associated with faster neutrophil recovery (Table 2). A self-sustained platelet counts more than 50 × 109/L was achieved in 69 patients at a median time of 40 days (range: 30-263). The cumulative incidence of platelet recovery at day 200 was 91.7% (95% CI, 85.7% to 97.7%) (Figure 1B). In multivariate analysis, a higher CD 34-positive cell dose and lower body weight were significantly associated with faster platelet recovery (Table 2).
Figure 1
Cumulative incidence of neutrophil recovery and platelet recovery. (A) Neutrophil recovery. (B) Platelet recovery.
Table 2. Multivariate Analysis of Factors Associated with Hematopoietic Recovery, Acute GVHD, and EFS
| Outcome/variables | Hazard Ratio (95% CI) | P |
|---|---|---|
| Neutrophil recovery | ||
| CD34 (+) cell dose (×105/kg) | ||
| ≥1.0 | 2.45 (2.03-2.87) | <.0001 |
| <1.0 | 1 | |
| Platelet recovery | ||
| CD34 (+) cell dose (×105/kg) | ||
| ≥1.0 | 2.12 (1.61-2.63) | .0036 |
| <1.0 | 1 | |
| Body weight (kg) | ||
| ≥55 | 0.48 (0.01-0.95) | .0022 |
| <55 | 1 | |
| Acute GVHD (grade III-IV) | ||
| Cytogenetics | ||
| Unfavorable | 4.94 (3.59-6.29) | .02 |
| Others | 1 | |
| EFS | ||
| Disease status | ||
| High risk | 2.86 (1.04-7.86) | .042 |
| Standard risk | 1 | |
| Cytogenetics | ||
| Unfavorable | 4.94 (1.01-5.04) | .048 |
| Others | 1 |
aGVHD and cGVHD
aGVHD occurred in 69 of 73 evaluable patients. The grading of aGVHD was grade I in 19 patients, grade II in 41, grade III in 7, and grade IV in 2. The cumulative incidence of grade II to IV and grade III to IV aGVHD at day 100 after CBT was 81.5% (95% CI, 70.6% to 92.4%) and 25.1% (95% CI, 6.9% to 43.3%), respectively. No factor was associated with the incidence of grade II to IV aGVHD; however, unfavorable cytogenetics risk status was associated with the incidence of grade III to IV aGVHD (Table 2). cGVHD occurred in 63 of 68 evaluable patients. Among 63 cGVHD patients, 21 patients were extensive type. Of the 21 patients, leukemia relapse after CBT was detected in 3 patients only. Although many patients responded to cGVHD treatment including CsA and/or corticosteroids, 3 patients died of cGVHD. The cumulative incidence of overall and extensive-type cGVHD at day 500 after CBT was 84.0% (95% CI, 74.4% to 93.6%) and 28.6% (95% CI, 17.7% to 39.5%), respectively. No factor was associated with the incidence of overall and extensive-type cGVHD.
Relapse
The cumulative incidence of relapse at 5 years was 25.8% (95% CI, 15.1% to 36.5%) (Figure 2A). No factor was associated with the incidence of relapse. Eighteen patients relapsed after CBT. Of these patients, 13 patients had active disease at the time of transplant. The cumulative incidence of relapse at 5 years of MDS/AML and de novo AML was 26.4% (95% CI, 5.6% to 47.2%) and 25.8% (95% CI, 12.9% to 38.7%), respectively (P = .747). In subgroup analysis according to disease status at transplant, no factor was associated with the incidence of relapse in patients with standard risk AML.
Figure 2
Cumulative incidence of relapse and TRM. (A) Relapse. (B) TRM.
TRM and Causes of Death
The cumulative incidence of TRM at day 100 and at 5 years was 9.1% (95% CI, 2.6% to 15.6%) and 9.7% (95% CI, 1.8% to 16.6%) (Figure 2B), respectively. No factor was associated with TRM. Nineteen patients died. Of 19 patients, 11 patients died of relapse. In 8 patients the causes of death were treatment-related (organ failure n = 2, infection n = 3, cGVHD with or without infection n = 3).
EFS
Of 77 patients, 51 are alive and event-free after CBT. Median follow-up of event-free survivor was 78 months (range: 5-121 months). The probability of EFS at 2 years and 5 years was 73.5% (95% CI, 64.2% to 84.2%) and 62.8% (95% CI, 52.1% to 75.7%), respectively (Figure 3). The probability of EFS at 5 years of standard risk patients and high-risk patients was 82.7% (95% CI, 69.9% to 97.9%) and 49.1% (95% CI, 35.5% to 67.9%), respectively (P = .0065). The probability of EFS at 5 years of MDS/AML and de novo AML was 67.4% (95% CI, 48.9% to 93.0%) and 61.1% (95% CI, 48.6% to 76.8%), respectively (P = .749). In multivariate analysis, high-risk disease at transplant and unfavorable cytogenetics risk status at diagnosis were significantly associated with worse EFS (Table 2). In subgroup analysis according to disease status at transplant, no factor was associated with EFS in patients with standard risk AML.
Figure 3
Probability of EFS after CBT.
Discussion
Several studies have suggested the promising results of unrelated CBT after myeloablative conditioning for adult patients 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13. However, the factors associated with hematopoietic recovery were not fully described. In the report of Laughlin et al. [1] 68 adult patients received CBT after myeloablative conditioning. The estimated probability of neutrophil recovery during the first 42 days was 90% and the median time to neutrophil recovery was 27 days. Although CD34 positive cell dose after thawing and the closeness of HLA matching were not related to the speed of neutrophil recovery, a higher number of nucleated cells in the cord blood before freezing was associated with faster neutrophil recovery. Because CD34 cell dose was not always measured before freezing, the impact of CD34-positive cell dose before freezing on the speed of neutrophil recovery was unclear. However, they found the number of nucleated cells before freezing correlated with the number of CD34-positive cells present after thawing. Recently, Arcese et al. [12] reported the updated results of a large series of adult patients with different hematopoietic malignancies transplanted in 63 centers of the Eurocord group. One hundred seventy-one adult patients received CBT after myeloablative conditioning. They analyzed outcomes and risk factors after CBT. The cumulative incidence of neutrophil recovery at day 60 was 72% and the median time to neutrophil recovery was 28 days. In multivariate analysis, the number of nucleated cells at collection or freezing and the use of hematopoietic growth factors within 1 week after transplant were associated with faster neutrophil recovery. In our study, the cumulative incidence of neutrophil recovery at day 50 was 94.8% and the median time to neutrophil recovery was 21 days. A higher CD 34-positive cell dose before freezing was significantly associated with faster neutrophil recovery in multivariate analysis and all patients received G-CSF by intravenous infusion starting on day 1 until durable granulocyte recovery was achieved. Therefore, a higher number of CD34 positive cells before freezing and the use of hematopoietic growth factors may be associated with neutrophil recovery after CBT in adult settings. Additionally, although use of CsA and MTX as GVHD prophylaxis in adult CBT has been avoided in several centers because of concerns regarding engraftment, this GVHD prophylaxis regimen in our study does not appear to have negatively influenced rates and kinetics of engraftment.
In our study, the cumulative incidence of grade II to IV aGVHD, grade III to IV aGVHD, overall and extensive-type cGVHD was 81.5%, 25.1%, 84.0%, and 28.6%, respectively. Although the incidence of aGVHD and cGVHD was relatively higher than other reports of adult CBT 1, 2, 3, 4, 5, 6, 12, the cumulative incidence of TRM at day 100 and at 5 years was very low (9.1% and 9.7%, respectively). Therefore, aGVHD and cGVHD were not related to TRM in this study. As described before [10], immunosuppressants for CBT recipients tendted to be discontinued faster in our institution. This may be 1 of the reasons of the relatively higher incidence of GVHD. Also, we found no effect of HLA matching on aGVHD as other reports of adult CBT 1, 12.
In the report of Rocha et al. [6], 98 adult patients received CBT. Among the 98 patients, 45 were AML and 2-year leukemia-free survival was 32%. Because this report was registry-based retrospective studies comparing the results of unrelated CBT and unrelated bone marrow transplantation in adults, the details of outcomes of AML were not described. Recently, Brunstein et al. [13] reported the results of 33 adult patients with AML who received CBT after myeloablative conditioning at the University of Minnesota. The overall survival is 58% and leukemia-free survival is 54%. However, the details of transplant procedures and outcomes were not described. Although we have previously reported the results of 29 adult patients with AML (11 with MDS-related secondary AML, 18 with de novo AML) who received CBT after myeloablative conditioning 7, 8, the follow-up duration after CBT was short and risk factors associated with transplant outcomes were not analyzed. Our recent report compared unrelated CBT and related donor grafts in adult patients [11], including 57 patients with AML who received CBT. However, the details of outcomes of AML were not analyzed. At present, therefore, there have been no reports detailing the long-term follow-up results of disease-specific outcomes of adult AML patients treated with CBT after myeloablative conditioning. In this analysis, unrelated CBT after myeloablative conditioning can cure approximately 65% adult patients with AML. As previously described 10, 11, a lower TRM rate and the use of a G-CSF-combined preparative regimen [19], which was capable of reducing the posttransplant relapse rate in refractory myeloid malignancies, may be associated with encouraging outcomes in this study.
In summary, these results suggest that unrelated CBT after myeloablative conditioning could be safely and effectively used for adult patients with AML. A higher CD34-positive cell dose was associated with faster hematopoietic recovery. We found no impact of HLA matching on engraftment, GVHD, and survival. Disease status at transplant and cytogenetics risk status at diagnosis were significantly associated with EFS.
Acknowledgments
Financial disclosure: The authors have nothing to disclose.
The authors would like to thank the physicians and nurses who cared for patients in this study.
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Financial disclosure: See Acknowledgments on page 1346.
PII: S1083-8791(08)00397-2
doi:10.1016/j.bbmt.2008.09.007
© 2008 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.
Volume 14, Issue 12 , Pages 1341-1347, December 2008
