Stem Cell Transplantation |
1 Division of Hematology and Cellular Therapies Unit Carlo Melzi, Dept. of Morphological and Medical Research, University of Udine
2 II Hematology Division, San Martino Hospital, Genoa
3 Statistics Institute, Dept. of Morphological and Medical Research, University of Udine
4 Hematology Division, La Sapienza University, Rome
5 Hematology Department, Pescara Hospital, Oncohematology Unit
6 La Maddalena Hospital, Palermo
7 Internal Medicine and Hematology Division, S. Gerardo de Tintori Hospital, Monza
8 Division of Hematology, Pesaro Hospital
9 Division of Hematology, Reggio Calabria Hospital
10 Hematology Division, Azienda Ospedaliera Careggi, University of Florence, Italy
Correspondence: Francesca Patriarca, MD, Division of Hematology and Cellular Therapies Unit Carlo Melzi, Azienda Ospedaliera-Universitaria p.zale S. Maria della Misericordia 1, 33100 Udine, Italy. E-mail:patriarca.francesca{at}aoud.sanita.fvg.it
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Design and Methods: One hundred patients were transplanted in 26 Italian centers between 1986 and 2006. We analyzed the influence of the patients characteristics and the clnical features of their disease before stem cell transplantation and of transplant procedures on transplant-related mortality, overall survival, and relapse-free survival by means of univariate and multivariate analyses.
Results: The median age of the patients at the time of stem cell transplantation was 49 years (range, 21–68) and 90% of them had an intermediate or high Dupriez score. Forty-eight percent received a myeloablative conditioning regimen and 78% received stem cells from matched sibling donors. The cumulative incidence of engraftment at day 90 after transplant was 87% (95% CI, 0.87–0.97). The cumulative 1-year and 3-year incidences of transplant-related mortality were 35% and 43%, respectively. The estimated 3-year overall and relapse-free survival rates after stem cell transplantation were 42% and 35%, respectively. In multivariate analysis, negative predictors of transplant-related mortality were year of stem cell transplantation before 1995, unrelated donor, and a long interval between diagnosis and transplantation. There was a trend towards longer overall and relapse-free survival in patients receiving peripheral blood stem cells rather than bone marrow as the source of their graft (p=0.070 and p=0.077, respectively). The intensity of the conditioning regimen (myeloablative versus reduced intensity regimens) did not significantly influence the outcome.
Conclusions: We conclude that the outcome of myelofibrosis patients who underwent allogeneic stem cell transplantation significantly improved after 1996 due to the reduction in transplant-related mortality. We observed that a reduction in transplant-related mortality was associated with the choice of a matched sibling donor, whereas longer overall survival was associated with the use of peripheral blood as the source of stem cells.
Key words: primary myelofibrosis, allogeneic stem cell transplantation, prognostic factors, reduced-intensity regimens.
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In order to identify prognostic factors influencing the outcome after HSCT, we retrospectively analyzed the influence of patients characteristics and the clinical features of their disease before HSCT and of transplant procedures on TRM and OS in 100 patients with myelofibrosis who underwent allogeneic HSCT in 26 Italian transplant centers that are part of the Gruppo Italiano Trapianto Midollo Osseo (GITMO).
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The information required for entry into the study was as follows: demographic data of the recipient, date of transplant, cell source, donor, type of conditioning regimen (myeloablative or reduced intensity), engraftment, follow-up to December 2006, date of relapse, date and cause of death, and development of acute and chronic graft-versus-host disease (GVHD). A total of 100 HSCT recipients from 26 transplant centers met these eligibility criteria.
Further data collected were: date of diagnosis of myelofibrosis, previous treatment, clinical, hematologic and cytogenetic characteristics of the disease before transplantation, Dupriez score5 at transplant, combinations of drugs, drug doses and irradiation dose delivered during the conditioning regimen, and GVHD prophylaxis. These data were not considered essential for participation in the study and were provided by 20 out the 26 centers.
Patients
Twenty-one centers transplanted five or fewer patients each, whereas the centers in Palermo, Pescara, Udine, Rome and Genoa performed 7, 7, 8, 9 and 26 transplants, respectively.
Informed consent was signed before transplantation and the procedures were performed according to each centers protocol. The protocol for each institution was approved by the institutional review board. The results of 15 patients included in this study have been previously reported7,13 and are here updated with a longer follow-up. Patient and disease characteristics are presented in Table 1. At the time of HSCT, the patients median age was 49 years (range, 21–68), 13% of them were 60 years or older, 65% were male, the median time between diagnosis and HSCT was 14 months (range, 3–300), and one-third of the procedures were performed 3 or more years after diagnosis. Eighty-two percent of the patients had primary myelofibrosis and 57% had previously received chemotherapy, mainly hydroxyurea or busulfan. Ninety percent of the patients had an intermediate or high Dupriez score, 54% had previously received red cell transfusions, 24% had circulating blasts in the peripheral blood, 56% had splenomegaly, and 38% had previously undergone splenectomy. Abnormal karyotypes were detected in 24% of the patients. Nine patients with a low Dupriez score were considered eligible for transplantation: these patients were agend between 34 and 55 years, all had splenomegaly, five had a hemoglobin concentration <11 g/dL, and three had bone marrow cytogenetic abnormalities.
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Table 1. Clinical and hematologic characteristics of the patients at allogeneic stem cell transplantation.
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Table 2. Transplant-related characteristics.
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Statistical analysis
Data were collected in an XLS database and imported into Stata/SE 9.0 for Windows for the statistical analysis. The close-out date for analysis was December, 2006.
The end-points were engraftment, acute and chronic GVHD, relapse, TRM, OS, and relapse-free survival (RFS). TRM was defined as death due to all causes not related to myelofibrosis. The cumulative incidence method was used to estimate the rate of engraftment, acute and chronic GVHD, TRM, and relapse. OS was defined as the time (in months) from the date of transplant to either death or last observation. RFS was defined as the time from the date of transplant to relapse, death or last observation. OS and RFS were described using the Kaplan-Meier approach. Survival was analyzed using Cox proportional hazard models, after the proportional hazard assumption had been verified. In univariate analysis, variables considered as possible prognostic factors were: primary diagnosis (primary or secondary myelofibrosis), Dupriez score at transplant (low, intermediate, or high), transplant time (before 1995, 1996–2000, after 2001), interval between diagnosis and transplantation (months), transfusions before transplant, hemoglobin levels, white cell counts, circulating blasts, karyotype, previous splenectomy, splenomegaly at transplantation, age at transplantation, intensity of conditioning regimen (standard myeloablative or reduced intensity), donor (matched sibling or mismatched sibling and unrelated), source of stem cells (bone marrow or peripheral blood), acute GVHD (grade 0-I or grade II-IV), and chronic GVHD (absent or present).
Acute and chronic GVHD were treated as time-dependent variables. Multivariate stepwise analyses included all variables significant at p
0.10 in univariate analysis. Retention in the stepwise model required that the variable be significant at p
0.05 in a multivariate analysis.
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Figure 1. Cumulative incidence of engraftment at +90 days.
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Patients outcome: transplant-related mortality and causes of death
Overall, 38 patients died at a median time of 4.5 months (range, 1–48) after transplantation because of transplant-related causes: acute GVHD (13 patients), infections (13 patients), bleeding (6 patients), veno-occlusive disease (2 patients), transplant-related microangiopathy (1 patient), second cancer (1 patient), and heart failure (2 patients). The 1-year and 3-year TRM cumulative incidence rates were 35% and 43%, respectively (Figure 2). Seventeen patients (45%) died within 100 days after transplantation and 32 (89%) within 1 year. The prognostic factors that showed a significant (p
0.10) association with TRM in the univariate proportional hazard model were: transplant time, interval between diagnosis and transplantation, and type of donor (Table 3). These variables comprised the eligible pool of predictors for multivariate, stepwise proportional hazards models used to predict TRM.
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Figure 2. Cumulative incidence of transplant- related mortality.
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Table 3. Univariate analysis of transplant-related mortality data.
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Table 4. Multivariate analysis of transplant-related mortality (TRM) data and overall survival data.
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0.10) associated with RFS in the univariate proportional hazard model were: transplant time, interval between diagnosis and transplantation, and source of stem cells (Table 5). In the univariate analysis, transplantation after 2001 favorably affected RFS (p=0.038). There was a trend for the use of peripheral blood as compared to bone marrow to have a favorable impact on RFS (p=0.077). The final survival model did not show any significant prognostic factor for RFS. |
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Table 5. Univariate analysis of relapse-free survival data.
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0.10) associated with survival in the univariate proportional hazard model were: transplant time, interval between diagnosis and transplantation, and source of stem cells (Table 6). In the univariate analysis, transplantation after 2001 significantly reduced the hazard of mortality (p=0.022), whereas there was a trend for the use of peripheral blood as compared to bone marrow to have a favorable impact on OS (p=0.070). However, there was a borderline significant trend towards shorter OS for patients whose transplant was performed a long time after diagnosis (p=0.058). The final survival model did not show any significant prognostic factor for OS. At the last follow-up, with a median survival follow-up of 34 months (range, 14–234), 39 patients were alive and free of disease after the first SCT and another 4 patients, previously described, were in remission after a second SCT. Among the survivors who had not undergone splenectomy, the spleen was of normal size in all patients. The median white cell count was 5.2x109/L (range, 3.7–15.0x109), median hemoglobin level was 13.7 g/dL (11.7–16.3) and the median platelet count was 250x109/L (range, 105–422x109). |
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Table 6. Univariate analysis of overall survival data.
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Table 7. Summary of the results of previous reports and of the present study with regard to allogeneic stem cell transplantation (SCT) in myelofibrosis.
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We found a progressive improvement of outcomes during the 20-year period analyzed. The most impressive result was the significant reduction in TRM rate after 1996, which emerged from the multivariate analysis. However, a trend towards improvements in both OS and RFS was observed in the periods 1996–2000 and 2001–2006. Of the transplant-related variables, transplants from unrelated or mismatched sibling donors were associated with a higher TRM, whereas there was a trend for the use of peripheral blood instead of bone marrow to have a favorable impact on both RFS and OS. There was only a minority of unrelated or mismatched transplants in previous reports, and the outcomes observed were very different, varying from a high TRM described by Snyder15 and a high risk of graft failure observed by Deeg8 to outcomes equivalent to those of transplants from matched sibling donors in the most recent report of the Seattle group.9 Our negative results could be, in part, due to the lack of a homogeneous policy of HLA matching of unrelated donors.
In our study, we did not observe an advantage in terms of decreased TRM and prolongation of OS after RIC transplants in comparison with myeloablative transplants. Previous studies13,14 reported encouraging TRM rates below 15% and OS rates of around 80% in small series of 20–25 patients transplanted with different RIC regimens, but there was no comparison with other preparative regimens. It has to be underlined that in our series, conditioning regimens were heterogeneous, including truly myeloablative regimens as well as different kinds of RIC regimens. The distinction between the two categories was sometimes quite difficult; for example, thiotepa–cyclophosphamide was classified as myeloablative or as RIC on the basis of the drug doses delivered to the patient. The great heterogeneity of drugs and doses received by the patients could partly explain the failure to detect any difference in outcomes after these two procedures. However, in our series RIC regimens tended to be associated with a higher rate of engraftment failure in comparison with myeloablative transplants. Moreover, it could be hypothesized that the reduction of TRM observed after 1996 was not due to the introduction of RIC transplants, but rather to a general improvement of supportive, anti-infectious and immunosuppressive procedures and treatments.
We reported the first series of second transplants for myelofibrosis (8 cases). Second transplants were successful in four out of five cases when they were performed because of relapse, whereas they did not achieve hematologic reconstitution when they followed a previously failed graft.
This study has several limitations. It is retrospective, like all the previous published studies; it is multicenter, with the participation of numerous transplant centers, the majority of which included one or two patients; and it covers a 20-year period, during which policies and strategies for transplantation in myelofibrosis have changed. Moreover, the study does not report information on biological factors that have recently been shown to have an important role in assessing risk before transplantation or on minimal residual disease in the follow-up, such as histopathological evaluation of the degree of marrow fibrosis,7,12 percentage of circulating CD34-positive cells,20 and molecular assessment of JAK2-V617F mutations.21
Despite these limitations, our results confirm that allogeneic HSCT may be an attractive treatment approach for patients with high-risk myelofibrosis. The outcome of such patients has improved significantly since 1996 due to the reduction of TRM. Since the TRM rate increases as the duration of disease before transplant is prolonged, the biological factors mentioned above should to be taken into consideration in the initial history of the disease to plan early transplantation in selected patients. Future prospective trials should address the issue of the choice of conditioning regimen, the source of stem cells, and the type of donor. Some suggestions emerging from our results are that peripheral blood should be preferred to bone marrow as the source of stem cells and the need for full HLA matching (10 out of 10 identical loci) for unrelated donors, which may overcome the increase in TRM observed in our series in comparison with the outcome following grafts from matched sibling donors. RIC transplants tended to be associated with a higher rate of graft failure than myeloablative procedures, but the impact of this type of conditioning on outcome should be evaluated further in prospective trials.
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Figure 3. Kaplan-Meier estimate of relapse-free survival.
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Figure 4. Kaplan-Meier estimate of overall survival.
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FP: conception and design of the study, literature search, collection of data, writing the article; AB: design of the study, interpretation of data, collaboration in writing the article; AS: collection and interpretation of the data; MI, FS: statistical analysis; BB: collection of the data and organization of database; MTvL, API, PDB, FP, PP, GV, PI: collection of clinical data; RF, AB: interpretation of the data and revision of the final version of the article. The authors reported no potential conflicts of interest.
Received for publication January 31, 2008. Revision received May 27, 2008. Accepted for publication May 28, 2008.
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