Sequential Regimen of Chemotherapy, Reduced-Intensity Conditioning for Allogeneic Stem-Cell Transplantation, and Prophylactic Donor Lymphocy
http://www.100md.com
《临床肿瘤学》
the José Carreras Unit for Hematopoietic Stem Cell Transplantation, Department of Medicine III, Ludwig-Maximilians-University Hospital, Munich
the Stem Cell Transplantation Unit, Deutsche Klinik für Diagnostik, Wiesbaden, Germany
ABSTRACT
PURPOSE: To improve the effect of allogeneic stem-cell transplantation by sequential use of intensive chemotherapy, reduced-intensity conditioning (RIC), and prophylactic donor lymphocyte transfusions (pDLTs) in high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).
PATIENTS AND METHODS: In a prospective study of 75 consecutive patients (median age, 52.3 years), high risk was defined by progressive or refractory disease (n = 59), second remission after early relapse (n = 8), or first remission with poor prognosis based on cytogenetics or delayed response to induction therapy (n = 8). Unfavorable karyotypes were found in 49% of informative patients, and 68 patients had medical contraindications against standard conditioning. Fludarabine (30 mg/m2), cytarabine (2 g/m2), and amsacrine (100 mg/m2) for 4 days were used for cytoreduction. After 3 days of rest, RIC consisted of 4 Gy total-body irradiation, antithymocyte globulin, and 80 to 120 mg/kg cyclophosphamide. Thirty-one patients had an HLA-identical sibling donor; 44 patients had an unrelated and/or HLA-mismatched donor. pDLT was given from day +120 in patients who were not receiving immunosuppression and were free of graft-versus-host disease (GvHD).
RESULTS: Complete remission was induced in 66 patients (88%). With a median follow-up of 35.1 months (range, 13.6 to 47.6 months), 2-year overall and leukemia-free survival were 42% and 40%, respectively. Outcome of patients with refractory disease or with complex cytogenetic aberrations was identical to that of better prognostic subgroups. Survival was best in patients who received high CD34+ cell numbers, and in patients with limited GvHD.
CONCLUSION: Sequential use of intensive chemotherapy, RIC transplantation, and pDLT represents a promising approach to the treatment of high-risk AML and MDS, particularly in patients with most unfavorable prognoses.
INTRODUCTION
Advances in chemotherapy have improved the prognosis of patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, patients with refractory disease or early relapse still have a poor outcome.1-3 High-risk disease can be defined further by delayed response to chemotherapy,4 unfavorable karyotype,5-7 and a history of preceding neoplasia and/or chemotherapy.8,9
Allogeneic hematopoietic stem-cell transplantation (HSCT) is the most effective antileukemic treatment.10 Nevertheless, because of relapse and treatment-related complications, long-term survival is rare in advanced disease.11 Particularly in elderly patients, patients with secondary AML, and patients with advanced disease, nonrelapse mortality (NRM) may reach more than 70%.12-15
During recent years, the role of high-dose chemoradiotherapy for the elimination of leukemia in allogeneic HSCT has been questioned. Instead, the graft-versus-leukemia (GvL) effect seems to play a major role. GvL reactions are known from animal studies16 and clinical trials.17,18 In AML, evidence comes from the lower relapse rates and improved progression-free survival after allogeneic as compared with autologous HSCT,10,19 and from the higher risk of relapse in patients receiving a T-cell–depleted transplant or in patients who do not develop graft-versus-host disease (GvHD).18
Reduced-intensity conditioning (RIC) regimens have been advocated to reduce transplantation-associated toxicity in elderly or medically unfit patients.20-22 However, in progressive leukemia, RIC may not sufficiently control the disease to allow a GvL effect to occur. The intensity of the preparative regimen has been shown to directly influence relapse incidence and leukemia-free survival after allografting for AML and MDS,23 and disappointing results are reported from RIC transplantations in advanced disease.24 Recently, a study on nonmyeloablative transplantation for AML in first complete remission (CR1) was published.25 However, the relapse rate was 41%, and 1-year progression-free survival was only 42%. Therefore, it is uncertain to what extent the conditioning regimen can be reduced without jeopardizing the efficacy of the entire procedure.
Therefore, we studied the possibility of combining a short, intensive course of chemotherapy aimed to reduce the leukemic burden, with RIC for allogeneic HSCT in patients with high-risk AML and MDS, and to reinforce the GvL effect by prophylactic transfusion of donor lymphocytes.
PATIENTS AND METHODS
Patients
A prospective pilot trial for 75 consecutive patients with high-risk AML and MDS was conducted from October 1999 until December 2002 at the Ludwig-Maximilians-University Hospital (Munich, Germany). The study was approved by the local ethical review board and written informed consent was obtained from each patient. Patients were included if they fulfilled at least one of the following criteria defining high-risk disease: primary or secondary refractory leukemia (as defined by persisting disease following one course of high-dose cytarabine); delayed response to induction chemotherapy; relapse within 3 months from induction or consolidation therapy; second relapse, or relapse after autologous HSCT; unfavorable cytogenetics6; AML secondary to MDS or other malignancies; or progressive MDS and/or refractory anemia with excess myeloblasts. Additional inclusion criteria were age (18 to 70 years) and the availability of a family or unrelated stem-cell donor (10-HLA match or one major mismatch). Serologic typing was used for major histocompatibility complex I; molecular typing was used for major histocompatibility complex II. Exclusion criteria were creatinine clearance less than 50 mL/min, bilirubin or aminotransferases more than 3x the upper limit of normal, cardiac ejection fraction less than 30%, and pregnancy.
Treatment
For cytoreduction, patients received fludarabine 30 mg/m2, high-dose cytarabine 2 g/m2, and amsacrine 100 mg/m2 from days –12 to –9 (FLAMSA regimen). After 3 days of rest, RIC consisted of 4 Gy total-body irradiation (TBI) on day –5, cyclophosphamide (40 mg/kg with HLA-identical sibling, 60 mg/kg for unrelated or mismatched donors) on days –4 and –3, and rabbit antithymocyte globulin (10 mg/kg for HLA-identical sibling, 20 m/kg for unrelated or mismatched donors) from days –4 to day –2. For transplantation, granulocyte colony-stimulating factor mobilized peripheral-blood stem cells (PBSCs) were preferred; bone marrow (BM) was accepted at the donor’s preference. GvHD prophylaxis consisted of cyclosporine from day –1, and mycophenolate mofetil (15 mg/kg bid), starting from day 0.26 In the absence of GvHD, mycophenolate mofetil was discontinued by day +50 and cyclosporine was tapered from days +60 to +90. Standard infection prophylaxis was used.25 Patients received prophylactic donor lymphocyte transfusions (pDLTs) if they were in CR without evidence of GvHD at day +120 or 30 days after discontinuation of immunosuppression. The initial dose was 1 x 106 CD3+ cells/kg; it could be increased to 5 x 106 CD3+ cells/kg in patients without a history of acute GvHD (aGvHD). In the absence of GvHD, pDLT was repeated up to three times, using escalating cell doses (five- to 10-fold increase/transfusion) at 4- to 6-week intervals.
Evaluation
At day +30, hematopoietic reconstitution, disease response, and chimerism were assessed. Given that thrombocytic regeneration could be postponed by factors other than leukemia and cytotoxic therapy (ie, GvHD, virus, drugs), CR was defined as less than 5% blasts without evidence of dysplasia in BM, and more than 1,500 neutrophils/μL in PB. Donor chimerism among peripheral CD3+ cells and in unfractionated BM was studied at days +30 and +90 using fluorescent in situ hybridization in sex-mismatched27 and short tandem repeat analysis in sex-matched transplantations.28 Regimen-related toxicity and GvHD were graded as described.29,30
Leukemia-free survival (LFS) at 2 years from transplantation was the primary end point. Secondary end points included overall survival (OS), the number of patients achieving complete donor chimerism and CR, treatment-related toxicity and mortality, aGvHD and chronic GvHD (cGvHD), and feasibility and toxicity of pDLT.
Statistics
Using SPSS software (SPSS Inc, Chicago, IL), 2 test, Student’s t test, and Fisher’s exact test were applied for univariate analysis; stepwise logistic regression was applied for multivariate analysis. OS and LFS were estimated by Kaplan-Meier plots. Log-rank test and a Cox proportional hazards regression model were used for risk factor analysis for survival. Factors showing a P < .01 in univariate tests were included in multivariate analyses. Data were analyzed by December 10, 2003.
RESULTS
Patients
October 1999 to December 2002, 75 consecutive high-risk patients (de novo AML, n = 50; progressive MDS and sAML/MDS, n = 15; secondary AML [sAML] after other hematologic malignancies, n = 10) were included (Table 1). Twenty-seven patients had refractory leukemia, as defined by persistent disease after at least one course of high-dose cytarabine. Twenty-two patients had untreated relapse, 10 had progressive MDS, and 16 were in remission. Among 30 patients who were in relapse or CR2 before transplantation, 25 had recurrent disease after high-dose cytarabine and eight had received autologous HSCT. According to the Southwest Oncology Group/Eastern Cooperative Oncology Group criteria,6 the karyotype of 71 informative patients was favorable in three, intermediate in 30, unfavorable in 35 (including 19 with complex abnormalities), and of unknown significance in three patients.
Although the study was not aimed to define a protocol for patients ineligible for standard conditioning, all but seven patients fulfilled exclusion criteria for conventional allografts as defined by the Seattle/Leipzig group,26 because of age (older than 50 years), extensive pretreatment, and/or concomitant disease (Table 2). Median age was 52.3 years (range, 18.5 to 65.8 years). Thirty-seven patients had a related donor (31 matched, six mismatched); 38 patients had an unrelated donor (30 matched, eight mismatched). Sixty-one patients received PBSCs (CD34+ cells/kg, 9.6 x 106 [range, 1.6 to 23.1 x 106] and mononuclear cells/kg: 9.7 x108 [range, 1.6 to 35.4 x108]); 14 received BM (CD34+ cells/kg, 4.0 x 106 [range, 2.9 to 10.2 x 106] and mononuclear cells/kg, 3.3 x108 [range, 2 to 14 x 108]).
Cytoreduction, Engraftment, and Chimerism
The FLAMSA regimen induced effective cytoreduction. After conditioning, all patients developed pancytopenia. Seventy patients engrafted and five died in aplasia. Median time to engraftment (> 500 neutrophils/μL on 3 consecutive days) was 14 days (range, 8 to 29 days). Secondary graft rejection was suspected in two patients with otherwise unexplained pancytopenia. However, hematopoiesis could be reconstituted by donor cell transfusion. Chimerism was analyzed on days +30 and +90 in the BM of all patients and in the T-cell compartment of patients who underwent transplantation after December 2000. More than 90% of donor cells were found in the vast majority of patients at both times and in both compartments (Table 3).
GvHD
Acute GvHD developed in 46 patients (61%), reaching grade 2, 3, and 4 in 19 (25%), 12 (16%), and six (8%) patients, respectively. The median day of onset was +17 (range, +7 to +51) Skin, liver, and gut were affected in 43, 13, and 19 patients, respectively. Acute GvHD was controlled by corticosteroids in 22 patients; eight patients required monoclonal antibodies, rapamycin, or daclizumab; and seven had refractory aGvHD.
cGvHD developed in 26 (45%; 19 de novo, seven from aGvHD) of those patients alive at day +100. The median interval from transplantation to onset of cGvHD was 211 days (range, 101 to 673 days). Fifteen patients had limited disease and 11 had extensive disease. Patients with an HLA-identical sibling donor had a lower risk of grade II-IV acute and of chronic GvHD (P = .039 and P = .003). In PBSC recipients, cGvHD was associated with higher doses of transfused CD34+ cells (P = .02).
Regimen-Related Toxicity and Infections
Cytoreductive chemotherapy and conditioning were well tolerated; no patient was lost before transplantation. Acute regimen-related toxicity was moderate: grade I/II mucositis was seen in 21 patients and grade II GI toxicity was seen in four patients. Overall, 26 episodes of grade III/IV regimen-related toxicity, including five deaths, were observed. Affected organs were liver (n = 13), kidneys (n = 4), heart (n = 4), CNS and bladder (n = 2 each), and lung (n = 1).
Septicemias were encountered in 37 patients. Radiologically documented pneumonia occurred in 31 patients, and was caused by bacteria in four patients, Aspergillus spp in 10 patients, Candida spp in three patients, virus in five patients, and of unknown etiology in nine patients. Other relevant infections were gastroenteritis (Clostridium difficile; n = 4; virus, n = 9), soor esophagitis (n = 3), herpes zoster (n = 1), and HHV6-associated meningoencephalitis (n = 1).
Disease Response and Survival
At day +30, five patients had died in aplasia, 65 patients were in CR, and five had persisting leukemia. Among the latter patients, one achieved a CR after immediate discontinuation of immunosuppression, bringing the CR rate up to 88%. By December 10, 2003, 29 patients were alive and in continuous CR. Median follow-up of survivors was 31.5 months (range, 13.6 to 47.6 months). Leukemic death occurred in 17 patients: four died as a result of refractory leukemia early after transplantation; 13 died as a result of relapse. Having an HLA-identical family donor was a risk factor for leukemic death (Table 4). Overall, relapse occurred in 15 patients at a median of 149 days (range, 65 to 770 days) from transplantation.
The overall NRM, including deaths related to concomitant disease, was 20% at day +100% and 33% at 1 year. Causes of death were sepsis (n = 3); GvHD alone (n = 3) or in combination with infections (n = 9); pneumonia (n = 7); hemorrhage (n = 2); chronic hepatitis (n = 2); and bronchiolitis obliterans, renal failure, and myocarditis (n = 1 each). Patients with an HLA-identical family donor and PBSC recipients receiving higher CD34+ cell doses had less NRM (Table 4).
OS and LFS were 42% and 40% at 2 years, respectively (Fig 1). A higher number of CD34+ cells in PBSC recipients was the only pretransplantation variable associated with better outcome, whereas all other variables, including cytogenetics and disease stage at transplantation, were not significant (Table 4; Fig 2). The influence of GvHD is listed in Table 5 and Fig 3: severe forms were associated with high NRM and were deleterious for outcome, whereas patients with mild GvHD had a significantly better outcome.
Prophylactic DLT
Twelve patients fulfilled the criteria for prophylactic DLT (ie, they were free of immunosuppressive medication for at least 30 days without developing GvHD (Table 6). Median time from transplantation to first pDLT was 160 days (range, 120 to 294 days). Two patients received one, five patients received two, and five patients received three transfusions in escalating doses, containing a median of 1 x 106, 1 x 107, and 3 x 107 CD3+ cells/kg at pDLT 1, 2, and 3, respectively. Reasons for administering fewer than three transfusions were GvHD, relapse, or refusal by the patient.
So far, two of 12 patients have experienced disease relapse. One died as a result of refractory leukemia, whereas one achieved a stable secondary CR after adoptive immunotherapy. At present, 11 patients are alive in continuous CR; LFS at 3 years from transplantation is 92%. Nine patients were complete chimeras when receiving pDLT; pDLT converted mixed chimerism into complete chimerism in one patient, but failed in two patients. Minimal residual disease (MRD) was not observed systematically; however, in one patient with persisting MRD after transplantation, CBF?/MYH11 nested polymerase chain reaction became negative for the first time ever after the third pDLT. GvHD was the main complication; aGvHD III° developed in one patient and cGvHD developed in three patients. Thirty-eight patients alive at day +120 did not receive pDLT because of cGvHD (n = 22), continued immunosuppression (n = 3), refusal by donor or patient (n = 3 each), infections (n = 3), a history of aGvHD IV° (n = 2), relapse (n = 1), or interstitial pneumonitis (n = 1).
DISCUSSION
The concept of the FLAMSA-RIC protocol was to minimize the leukemic burden by intensive chemotherapy before reduced conditioning for allogeneic HSCT. For cytoreduction, we applied a fludarabine- and high-dose cytarabine-based regimen. Similar protocols were effective in high-risk AML and advanced CML.31 Instead of anthracyclines, amsacrine was introduced. This drug has shown to be similarly effective in poor-prognosis AML, and it also is less cardiotoxic.32 AML patients have been treated regularly with considerable doses of anthracyclines before transplantation. Therefore, the use of a different drug seemed reasonable to prevent chemotherapy resistance. Within our cohort, the regimen was well tolerated and nevertheless ensured effective cytoreduction.
Sustained engraftment was achieved in all but those patients dying in aplasia. These results are in line with other studies using a reduced, but myeloablative regimen,33,34 whereas other studies on nonmyeloablative regimen reported graft injections of 7% to 20%.22,26 The induction of donor chimerism was successful and occurred early after transplantation; at day +30, donor chimerism was 95% in BM and peripheral CD3+ cells in the majority of patients. Engraftment and chimerism seemed to be stable, given that only two patients had secondary graft failure. Therefore, the regimen can be classified as myeloablative despite the reduced radiation dose.
An overall CR rate of 88% was achieved, thereby demonstrating a superior antileukemic efficacy of the protocol as compared with nonmyeloablative procedures, after which CR rates in the range of 45% have been observed.26 In addition, the relatively low relapse rate within our high-risk cohort, which included 49% of patients with unfavorable cytogenetics and 36% with refractory disease, indicates the potential of the FLAMSA-RIC protocol to eradicate leukemia.
The 2-year OS and LFS were 42% and 40%, respectively. To identify patients who might or might not benefit from our approach, we analyzed the influence of established risk factors on outcome. Interestingly, neither cytogenetics nor the stage of the disease at transplantation had a significant influence on outcome. No difference was seen in terms of survival between the intermediate and the poor prognostic cytogenetic subgroups (Fig 2A). This seems remarkable, given that the prognostic value of cytogenetics had been preserved in various studies using allogeneic HSCT with standard conditioning in CR1.5 So far, there are no reliable data on the role of cytogenetics in allogeneic transplantation beyond CR1. Therefore, it could be argued that the advanced stage per se might be a stronger risk factor, thereby overcoming the prognostic value of cytogenetic subgroups. Conversely, karyotype was the most important prognostic factor in relapsed or refractory AML using conventional chemotherapy.35 Among the patients with unfavorable cytogenetics, the group with complex abnormalities showed the most encouraging results: of 19 patients, seven underwent transplantation in untreated relapse, and six had primarily refractory disease. Fourteen patients achieved a CR, two patients experienced relapse, and six died as a result of nonleukemic causes. The 2-year OS was 42%, thereby equalizing the outcome of the entire cohort.
Regarding the stage of the disease at transplantation, patients in remission showed a trend toward better results. Interestingly, the group of patients with refractory disease did not have a significantly inferior outcome, although at least one course of high-dose cytarabine had been administered to all patients before they were declared refractory (Fig 2B). In light of the extremely poor outcome patients suffering from refractory or complex karyotype leukemia have with conventional chemotherapy,1,6,35 our results may give hope to a subgroup of patients with otherwise limited options.
Our overall results compare favorably to the results reported after standard conditioning, showing high NRM and a 2-year OS of 20% or less in advanced AML.11-15,36 In contrast, similar results have been observed by several groups using reduced but still myeloablative fludarabine-based regimens.34,37,38 These studies reported on a remarkably low rate of 1-year NRM of 5% to 20%. Recently, de Lima et al39 used targeted intravenous busulfan/fludarabine for allografting in 96 high-risk patients with AML/MDS. With a 12-month median follow-up, NRM, OS, and EFS were 3%, 65%, and 52%, respectively. However, this cohort contained 20% of patients in CR1, 54% with active disease, and 29% with unfavorable cytogenetics, compared with 11%, 79%, and 49%, respectively, in our group. In addition, median age was younger (45 v 52 years), more patients had a family donor (62% v 41%), inclusion criteria relating to organ dysfunction and HLA matching in unrelated donors were stricter, and no data were reported on comorbidities and pretransplantation therapy. Therefore, it is difficult to compare the results directly, although the low NRM is impressive. Within our cohort, all but seven patients fulfilled the exclusion criteria for conventional allografts,26 which might have contributed to the relatively high NRM. Nevertheless, completely avoiding TBI might further reduce NRM, and targeted intravenous busulfan, as suggested by de Lima et al39, might be a possible substitute for TBI. Conversely, highly aggressive leukemia, as refractory or poor cytogenetic disease, may require an intensive approach, including chemotherapy and TBI. This is supported by the data by de Lima et al,39 who, in contrast to our study, showed high relapse rates and a significantly inferior outcome in patients with active disease, as compared with patients who underwent transplantation in remission.
In line with another recent study,40 HLA-identical family donor transplants and higher numbers of infused CD34+ cells were associated with less NRM within our trial. The role of higher cell doses might be explained by a shorter period of neutropenia (P = .005), although no direct correlation with infections was observed. Nevertheless, the relatively long duration of the preparative regimen might have increased NRM. The relevance of cell doses for outcome has been shown in BMT for AML in CR1.41 It is less clear in PBSC transplantation, where it may be most important in high-risk disease.42,43 In our cohort, higher CD34+ doses were associated with better survival in PBSC recipients (Table 4).
In patients with an HLA-identical family donor, reduced NRM was due mainly to a lower risk of GvHD. However, this did not influence survival because of an increased risk of death from leukemia, possibly indicating an inferior GvL reaction in genotypically identical donor-recipient combinations. Reduction or avoidance of antithymocyte globulin might allow for more alloreactivity in HLA-identical transplants.
aGvHD grade II to IV developed in 49% of our patients, and chronic GvHD was seen in 45% of patients alive at day 100, including three with cGvHD after pDLT. Several RIC investigators have reported similar results,22,26,40 whereas a lower incidence, particularly of aGvHD, was seen by others.33,38,39 These differences have been explained in part by a delayed achievement of full donor chimerism in cohorts with less GvHD, in particular with respect to the T-cell compartment.38 Within the Seattle study, the risk of aGvHD increased with T-cell chimerism at day +28.22 In other studies, high numbers of CD34+ cells were associated with complete T-cell chimerism by day +28, and with increased incidence of cGvHD.43,44 This might be confirmed by our results. However, the variety in GvHD incidence after RIC is not completely understood.
aGvHD limited to the skin and limited cGvHD were associated with better OS and LFS, compared with the results of patients without GvHD. In contrast, severe forms of GvHD contributed considerably to NRM, thereby leading to inferior results in affected patients. These data demonstrate the two sides of GvHD as a surrogate marker for a GvL effect on one hand, and a life-threatening complication on the other. Better prevention and treatment of severe GvHD will improve the results.
pDLT to eliminate potential MRD was an integral part of the treatment for patients without GvHD after immunosuppression was discontinued for 30 days. In fact, 24% of the patients alive at day +120 proceeded to pDLT, whereas the majority could not be transfused because of GvHD or continued immunosuppression. Therefore, reducing the incidence of GvHD might increase the number of candidates for pDLT.
Several studies on pDLT have been published that report on high rates of clinical response at the expense of severe GvHD.45,46 In contrast, GvHD incidence was low in our study. This might be explained by the delay of pDLT until day +120, whereas it was given between days +30 and +90 in other studies. Delay of pDLT is supported by animal data, suggesting that one must allow time for the development of tolerance before DLT can be performed safely.47 Using an escalating cell dose regimen with an initial dose as low as 1 x 106 CD3+ cells/kg might be another way to avoid GvHD, as has been demonstrated after DLT for relapsed CML.48 Aside from GvHD, no relevant adverse effects were observed.
The influence of pDLT on outcome in AML and MDS remains uncertain. In our study, an antileukemic effect was supported by a low relapse rate and excellent survival in patients receiving pDLT, and by the disappearance of the so far persisting CBF?/MYH11 transcript in one patient after pDLT. In lymphoid malignancies, clinical response has been reported in 70% of patients.49 The results of our small cohort are encouraging. However, patients alive and free of GvHD at day +120 may represent a positive selection. Therefore, broader experience is warranted.
Our results and those from other pilot studies demonstrate the efficacy of RIC protocols in high-risk AML and MDS. However, the optimal balance between antileukemic activity and toxicity still has to be defined. Patients with extremely poor prognosis (eg, with a complex karyotype leukemia or refractory disease) seemed to benefit from the combined strategy of intensive chemotherapy, RIC, and prolonged allogeneic immune reaction, either by repeated pDLT or cGvHD. However, the toxicity of the regimen is still considerable, and a less aggressive regimen might be preferable for chemotherapy-sensitive or less advanced disease.
Authors' Disclosures of Potential Conflicts of Interest
The authors indicated no potential conflicts of interest.
Acknowledgment
We thank all of the nurses on the wards and the outpatient clinic of the José Carreras Transplantation Unit for their dedicated work.
NOTES
Presented in part as a preliminary analysis at the Annual Meeting of the German Society of Hematology and Oncology, October 29, 2002, Munich, Germany, and the Annual Meeting of the European Group of Blood and Marrow Transplantation, July 22, 2003, Istanbul, Turkey.
C.S. and M.S. contributed equally to this work.
Authors' disclosures of potential conflicts of interest are found at the end of this article.
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Parker JE, Pagliuca A, Mijovic A, et al: Fludarabine, cytarabine, G-CSF and idarubicin (FLAG-IDA) for the treatment of poor-risk myelodysplastic syndromes and acute myeloid leukaemia. Br J Haematol 99:939-944, 1997
Watson AM, Seymour J, Lee N, et al: An effective age-unrestricted m-AMSA-based second-line regimen for poor prognosis acute myeloid leukaemia. Eur J Haematol 52:80-86, 1994
Nagler A, Aker M, Or R, et al: Low-intensity conditioning is sufficient to ensure engraftment in matched unrelated bone marrow transplantation. Exp Hematol 29:362-370, 2001
Martino R, Caballero MD, Simon JA, et al: Evidence for a graft-versus-leukemia effect after allogeneic peripheral blood stem cell transplantation with reduced-intensity conditioning in acute myelogenous leukemia and myelodysplastic syndromes. Blood 100:2243-2245, 2002
Kern W, Schoch C, Haferlach T, et al: Multivariate analysis of prognostic factors in patients with refractory and relapsed acute myeloid leukemia undergoing sequential high-dose cytosine arabinoside and mitoxantrone (S-HAM) salvage therapy: Relevance of cytogenetic abnormalities. Leukemia 14:226-231, 2000
Sierra J, Storer B, Hansen JA, et al: Transplantation of marrow cells from unrelated donors for treatment of high-risk acute leukemia: The effect of leukemic burden, donor HLA-matching, and marrow cell dose. Blood 89:4226-4235, 1997
Bertz H, Potthoff K, Finke J: Allogeneic stem-cell transplantation from related and unrelated donors in older patients with myeloid leukemia. J Clin Oncol 21:1480-1484, 2003
Taussig DC, Davies AJ, Cavenagh JD, et al: Durable remissions of myelodysplastic syndrome and acute myeloid leukemia after reduced-intensity allografting. J Clin Oncol 21:3060-3065, 2003
de Lima M, Couriel D, Thall PF, et al: Once-daily intravenous busulfan and fludarabine: Clinical and pharmacokinetic results of a myeloablative, reduced-toxicity conditioning for allogeneic stem cell transplantation in AML and MDS. Blood 104:857-864, 2004
Wong R, Giralt SA, Martin T, et al: Reduced-intensity conditioning for unrelated donor hematopoietic stem cell transplantation as treatment for myeloid malignancies in patients older than 55 years. Blood 102:3052-3059, 2003
Rocha V, Labopin M, Gluckman E, et al: Relevance of bone marrow cell dose on allogeneic transplantation outcomes for patients with acute myeloid leukemia in first complete remission: Results from an European survey. J Clin Oncol 20:4324-4330, 2002
Urbano-Ispizua A, Carreras E, Marin P, et al: Allogeneic transplantation of CD34(+) selected cells from peripheral blood from human leukocyte antigen-identical siblings: Detrimental effect of a high number of donor CD34(+) cells ? Blood 98:2352-2357, 2001
Perez-Simon JA, Diez-Campelo M, Martino R, et al: Impact of CD34+ cell dose on the outcome of patients undergoing reduced-intensity-conditioning allogeneic peripheral blood stem cell transplantation. Blood 102:1108-1113, 2003
Przepiorka D, Smith TL, Folloder J, et al: Risk factors for acute GvHD after allogeneic blood stem cell transplantation. Blood 94:1465-1470, 1999
De Lima M, Bonamino M, Vasconcelos Z, et al: Prophylactic donor lymphocyte infusions after moderately ablative chemotherapy and stem cell transplantation for hematological malignancies: High remission rate among poor prognosis patients at the expense of graft-versus-host disease. Bone Marrow Transplant 27:73-78, 2001
Massenkeil G, Nagy M, Lawang M, et al: Reduced intensity conditioning and prophylactic DLI can cure patients with high-risk acute leukaemias if complete donor chimerism can be achieved. Bone Marrow Transplant 31:339-345, 2003
Kolb HJ, Gunther W, Schumm M, et al: Adoptive immunotherapy in canine chimeras. Transplantation 63:430-436, 1997
Guglielmi C, Arcese W, Dazzi F, et al: Donor lymphocyte infusion for relapsed chronic myelogenous leukemia: Prognostic relevance of the initial cell dose. Blood 100:397-405, 2002
Peggs KS, Thomson K, Hart DP, et al: Dose-escalated donor lymphocyte infusions following reduced intensity transplantation: Toxicity, chimerism, and disease responses. Blood 103:1548-1556, 2004(Christoph Schmid, Michael)
the Stem Cell Transplantation Unit, Deutsche Klinik für Diagnostik, Wiesbaden, Germany
ABSTRACT
PURPOSE: To improve the effect of allogeneic stem-cell transplantation by sequential use of intensive chemotherapy, reduced-intensity conditioning (RIC), and prophylactic donor lymphocyte transfusions (pDLTs) in high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS).
PATIENTS AND METHODS: In a prospective study of 75 consecutive patients (median age, 52.3 years), high risk was defined by progressive or refractory disease (n = 59), second remission after early relapse (n = 8), or first remission with poor prognosis based on cytogenetics or delayed response to induction therapy (n = 8). Unfavorable karyotypes were found in 49% of informative patients, and 68 patients had medical contraindications against standard conditioning. Fludarabine (30 mg/m2), cytarabine (2 g/m2), and amsacrine (100 mg/m2) for 4 days were used for cytoreduction. After 3 days of rest, RIC consisted of 4 Gy total-body irradiation, antithymocyte globulin, and 80 to 120 mg/kg cyclophosphamide. Thirty-one patients had an HLA-identical sibling donor; 44 patients had an unrelated and/or HLA-mismatched donor. pDLT was given from day +120 in patients who were not receiving immunosuppression and were free of graft-versus-host disease (GvHD).
RESULTS: Complete remission was induced in 66 patients (88%). With a median follow-up of 35.1 months (range, 13.6 to 47.6 months), 2-year overall and leukemia-free survival were 42% and 40%, respectively. Outcome of patients with refractory disease or with complex cytogenetic aberrations was identical to that of better prognostic subgroups. Survival was best in patients who received high CD34+ cell numbers, and in patients with limited GvHD.
CONCLUSION: Sequential use of intensive chemotherapy, RIC transplantation, and pDLT represents a promising approach to the treatment of high-risk AML and MDS, particularly in patients with most unfavorable prognoses.
INTRODUCTION
Advances in chemotherapy have improved the prognosis of patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, patients with refractory disease or early relapse still have a poor outcome.1-3 High-risk disease can be defined further by delayed response to chemotherapy,4 unfavorable karyotype,5-7 and a history of preceding neoplasia and/or chemotherapy.8,9
Allogeneic hematopoietic stem-cell transplantation (HSCT) is the most effective antileukemic treatment.10 Nevertheless, because of relapse and treatment-related complications, long-term survival is rare in advanced disease.11 Particularly in elderly patients, patients with secondary AML, and patients with advanced disease, nonrelapse mortality (NRM) may reach more than 70%.12-15
During recent years, the role of high-dose chemoradiotherapy for the elimination of leukemia in allogeneic HSCT has been questioned. Instead, the graft-versus-leukemia (GvL) effect seems to play a major role. GvL reactions are known from animal studies16 and clinical trials.17,18 In AML, evidence comes from the lower relapse rates and improved progression-free survival after allogeneic as compared with autologous HSCT,10,19 and from the higher risk of relapse in patients receiving a T-cell–depleted transplant or in patients who do not develop graft-versus-host disease (GvHD).18
Reduced-intensity conditioning (RIC) regimens have been advocated to reduce transplantation-associated toxicity in elderly or medically unfit patients.20-22 However, in progressive leukemia, RIC may not sufficiently control the disease to allow a GvL effect to occur. The intensity of the preparative regimen has been shown to directly influence relapse incidence and leukemia-free survival after allografting for AML and MDS,23 and disappointing results are reported from RIC transplantations in advanced disease.24 Recently, a study on nonmyeloablative transplantation for AML in first complete remission (CR1) was published.25 However, the relapse rate was 41%, and 1-year progression-free survival was only 42%. Therefore, it is uncertain to what extent the conditioning regimen can be reduced without jeopardizing the efficacy of the entire procedure.
Therefore, we studied the possibility of combining a short, intensive course of chemotherapy aimed to reduce the leukemic burden, with RIC for allogeneic HSCT in patients with high-risk AML and MDS, and to reinforce the GvL effect by prophylactic transfusion of donor lymphocytes.
PATIENTS AND METHODS
Patients
A prospective pilot trial for 75 consecutive patients with high-risk AML and MDS was conducted from October 1999 until December 2002 at the Ludwig-Maximilians-University Hospital (Munich, Germany). The study was approved by the local ethical review board and written informed consent was obtained from each patient. Patients were included if they fulfilled at least one of the following criteria defining high-risk disease: primary or secondary refractory leukemia (as defined by persisting disease following one course of high-dose cytarabine); delayed response to induction chemotherapy; relapse within 3 months from induction or consolidation therapy; second relapse, or relapse after autologous HSCT; unfavorable cytogenetics6; AML secondary to MDS or other malignancies; or progressive MDS and/or refractory anemia with excess myeloblasts. Additional inclusion criteria were age (18 to 70 years) and the availability of a family or unrelated stem-cell donor (10-HLA match or one major mismatch). Serologic typing was used for major histocompatibility complex I; molecular typing was used for major histocompatibility complex II. Exclusion criteria were creatinine clearance less than 50 mL/min, bilirubin or aminotransferases more than 3x the upper limit of normal, cardiac ejection fraction less than 30%, and pregnancy.
Treatment
For cytoreduction, patients received fludarabine 30 mg/m2, high-dose cytarabine 2 g/m2, and amsacrine 100 mg/m2 from days –12 to –9 (FLAMSA regimen). After 3 days of rest, RIC consisted of 4 Gy total-body irradiation (TBI) on day –5, cyclophosphamide (40 mg/kg with HLA-identical sibling, 60 mg/kg for unrelated or mismatched donors) on days –4 and –3, and rabbit antithymocyte globulin (10 mg/kg for HLA-identical sibling, 20 m/kg for unrelated or mismatched donors) from days –4 to day –2. For transplantation, granulocyte colony-stimulating factor mobilized peripheral-blood stem cells (PBSCs) were preferred; bone marrow (BM) was accepted at the donor’s preference. GvHD prophylaxis consisted of cyclosporine from day –1, and mycophenolate mofetil (15 mg/kg bid), starting from day 0.26 In the absence of GvHD, mycophenolate mofetil was discontinued by day +50 and cyclosporine was tapered from days +60 to +90. Standard infection prophylaxis was used.25 Patients received prophylactic donor lymphocyte transfusions (pDLTs) if they were in CR without evidence of GvHD at day +120 or 30 days after discontinuation of immunosuppression. The initial dose was 1 x 106 CD3+ cells/kg; it could be increased to 5 x 106 CD3+ cells/kg in patients without a history of acute GvHD (aGvHD). In the absence of GvHD, pDLT was repeated up to three times, using escalating cell doses (five- to 10-fold increase/transfusion) at 4- to 6-week intervals.
Evaluation
At day +30, hematopoietic reconstitution, disease response, and chimerism were assessed. Given that thrombocytic regeneration could be postponed by factors other than leukemia and cytotoxic therapy (ie, GvHD, virus, drugs), CR was defined as less than 5% blasts without evidence of dysplasia in BM, and more than 1,500 neutrophils/μL in PB. Donor chimerism among peripheral CD3+ cells and in unfractionated BM was studied at days +30 and +90 using fluorescent in situ hybridization in sex-mismatched27 and short tandem repeat analysis in sex-matched transplantations.28 Regimen-related toxicity and GvHD were graded as described.29,30
Leukemia-free survival (LFS) at 2 years from transplantation was the primary end point. Secondary end points included overall survival (OS), the number of patients achieving complete donor chimerism and CR, treatment-related toxicity and mortality, aGvHD and chronic GvHD (cGvHD), and feasibility and toxicity of pDLT.
Statistics
Using SPSS software (SPSS Inc, Chicago, IL), 2 test, Student’s t test, and Fisher’s exact test were applied for univariate analysis; stepwise logistic regression was applied for multivariate analysis. OS and LFS were estimated by Kaplan-Meier plots. Log-rank test and a Cox proportional hazards regression model were used for risk factor analysis for survival. Factors showing a P < .01 in univariate tests were included in multivariate analyses. Data were analyzed by December 10, 2003.
RESULTS
Patients
October 1999 to December 2002, 75 consecutive high-risk patients (de novo AML, n = 50; progressive MDS and sAML/MDS, n = 15; secondary AML [sAML] after other hematologic malignancies, n = 10) were included (Table 1). Twenty-seven patients had refractory leukemia, as defined by persistent disease after at least one course of high-dose cytarabine. Twenty-two patients had untreated relapse, 10 had progressive MDS, and 16 were in remission. Among 30 patients who were in relapse or CR2 before transplantation, 25 had recurrent disease after high-dose cytarabine and eight had received autologous HSCT. According to the Southwest Oncology Group/Eastern Cooperative Oncology Group criteria,6 the karyotype of 71 informative patients was favorable in three, intermediate in 30, unfavorable in 35 (including 19 with complex abnormalities), and of unknown significance in three patients.
Although the study was not aimed to define a protocol for patients ineligible for standard conditioning, all but seven patients fulfilled exclusion criteria for conventional allografts as defined by the Seattle/Leipzig group,26 because of age (older than 50 years), extensive pretreatment, and/or concomitant disease (Table 2). Median age was 52.3 years (range, 18.5 to 65.8 years). Thirty-seven patients had a related donor (31 matched, six mismatched); 38 patients had an unrelated donor (30 matched, eight mismatched). Sixty-one patients received PBSCs (CD34+ cells/kg, 9.6 x 106 [range, 1.6 to 23.1 x 106] and mononuclear cells/kg: 9.7 x108 [range, 1.6 to 35.4 x108]); 14 received BM (CD34+ cells/kg, 4.0 x 106 [range, 2.9 to 10.2 x 106] and mononuclear cells/kg, 3.3 x108 [range, 2 to 14 x 108]).
Cytoreduction, Engraftment, and Chimerism
The FLAMSA regimen induced effective cytoreduction. After conditioning, all patients developed pancytopenia. Seventy patients engrafted and five died in aplasia. Median time to engraftment (> 500 neutrophils/μL on 3 consecutive days) was 14 days (range, 8 to 29 days). Secondary graft rejection was suspected in two patients with otherwise unexplained pancytopenia. However, hematopoiesis could be reconstituted by donor cell transfusion. Chimerism was analyzed on days +30 and +90 in the BM of all patients and in the T-cell compartment of patients who underwent transplantation after December 2000. More than 90% of donor cells were found in the vast majority of patients at both times and in both compartments (Table 3).
GvHD
Acute GvHD developed in 46 patients (61%), reaching grade 2, 3, and 4 in 19 (25%), 12 (16%), and six (8%) patients, respectively. The median day of onset was +17 (range, +7 to +51) Skin, liver, and gut were affected in 43, 13, and 19 patients, respectively. Acute GvHD was controlled by corticosteroids in 22 patients; eight patients required monoclonal antibodies, rapamycin, or daclizumab; and seven had refractory aGvHD.
cGvHD developed in 26 (45%; 19 de novo, seven from aGvHD) of those patients alive at day +100. The median interval from transplantation to onset of cGvHD was 211 days (range, 101 to 673 days). Fifteen patients had limited disease and 11 had extensive disease. Patients with an HLA-identical sibling donor had a lower risk of grade II-IV acute and of chronic GvHD (P = .039 and P = .003). In PBSC recipients, cGvHD was associated with higher doses of transfused CD34+ cells (P = .02).
Regimen-Related Toxicity and Infections
Cytoreductive chemotherapy and conditioning were well tolerated; no patient was lost before transplantation. Acute regimen-related toxicity was moderate: grade I/II mucositis was seen in 21 patients and grade II GI toxicity was seen in four patients. Overall, 26 episodes of grade III/IV regimen-related toxicity, including five deaths, were observed. Affected organs were liver (n = 13), kidneys (n = 4), heart (n = 4), CNS and bladder (n = 2 each), and lung (n = 1).
Septicemias were encountered in 37 patients. Radiologically documented pneumonia occurred in 31 patients, and was caused by bacteria in four patients, Aspergillus spp in 10 patients, Candida spp in three patients, virus in five patients, and of unknown etiology in nine patients. Other relevant infections were gastroenteritis (Clostridium difficile; n = 4; virus, n = 9), soor esophagitis (n = 3), herpes zoster (n = 1), and HHV6-associated meningoencephalitis (n = 1).
Disease Response and Survival
At day +30, five patients had died in aplasia, 65 patients were in CR, and five had persisting leukemia. Among the latter patients, one achieved a CR after immediate discontinuation of immunosuppression, bringing the CR rate up to 88%. By December 10, 2003, 29 patients were alive and in continuous CR. Median follow-up of survivors was 31.5 months (range, 13.6 to 47.6 months). Leukemic death occurred in 17 patients: four died as a result of refractory leukemia early after transplantation; 13 died as a result of relapse. Having an HLA-identical family donor was a risk factor for leukemic death (Table 4). Overall, relapse occurred in 15 patients at a median of 149 days (range, 65 to 770 days) from transplantation.
The overall NRM, including deaths related to concomitant disease, was 20% at day +100% and 33% at 1 year. Causes of death were sepsis (n = 3); GvHD alone (n = 3) or in combination with infections (n = 9); pneumonia (n = 7); hemorrhage (n = 2); chronic hepatitis (n = 2); and bronchiolitis obliterans, renal failure, and myocarditis (n = 1 each). Patients with an HLA-identical family donor and PBSC recipients receiving higher CD34+ cell doses had less NRM (Table 4).
OS and LFS were 42% and 40% at 2 years, respectively (Fig 1). A higher number of CD34+ cells in PBSC recipients was the only pretransplantation variable associated with better outcome, whereas all other variables, including cytogenetics and disease stage at transplantation, were not significant (Table 4; Fig 2). The influence of GvHD is listed in Table 5 and Fig 3: severe forms were associated with high NRM and were deleterious for outcome, whereas patients with mild GvHD had a significantly better outcome.
Prophylactic DLT
Twelve patients fulfilled the criteria for prophylactic DLT (ie, they were free of immunosuppressive medication for at least 30 days without developing GvHD (Table 6). Median time from transplantation to first pDLT was 160 days (range, 120 to 294 days). Two patients received one, five patients received two, and five patients received three transfusions in escalating doses, containing a median of 1 x 106, 1 x 107, and 3 x 107 CD3+ cells/kg at pDLT 1, 2, and 3, respectively. Reasons for administering fewer than three transfusions were GvHD, relapse, or refusal by the patient.
So far, two of 12 patients have experienced disease relapse. One died as a result of refractory leukemia, whereas one achieved a stable secondary CR after adoptive immunotherapy. At present, 11 patients are alive in continuous CR; LFS at 3 years from transplantation is 92%. Nine patients were complete chimeras when receiving pDLT; pDLT converted mixed chimerism into complete chimerism in one patient, but failed in two patients. Minimal residual disease (MRD) was not observed systematically; however, in one patient with persisting MRD after transplantation, CBF?/MYH11 nested polymerase chain reaction became negative for the first time ever after the third pDLT. GvHD was the main complication; aGvHD III° developed in one patient and cGvHD developed in three patients. Thirty-eight patients alive at day +120 did not receive pDLT because of cGvHD (n = 22), continued immunosuppression (n = 3), refusal by donor or patient (n = 3 each), infections (n = 3), a history of aGvHD IV° (n = 2), relapse (n = 1), or interstitial pneumonitis (n = 1).
DISCUSSION
The concept of the FLAMSA-RIC protocol was to minimize the leukemic burden by intensive chemotherapy before reduced conditioning for allogeneic HSCT. For cytoreduction, we applied a fludarabine- and high-dose cytarabine-based regimen. Similar protocols were effective in high-risk AML and advanced CML.31 Instead of anthracyclines, amsacrine was introduced. This drug has shown to be similarly effective in poor-prognosis AML, and it also is less cardiotoxic.32 AML patients have been treated regularly with considerable doses of anthracyclines before transplantation. Therefore, the use of a different drug seemed reasonable to prevent chemotherapy resistance. Within our cohort, the regimen was well tolerated and nevertheless ensured effective cytoreduction.
Sustained engraftment was achieved in all but those patients dying in aplasia. These results are in line with other studies using a reduced, but myeloablative regimen,33,34 whereas other studies on nonmyeloablative regimen reported graft injections of 7% to 20%.22,26 The induction of donor chimerism was successful and occurred early after transplantation; at day +30, donor chimerism was 95% in BM and peripheral CD3+ cells in the majority of patients. Engraftment and chimerism seemed to be stable, given that only two patients had secondary graft failure. Therefore, the regimen can be classified as myeloablative despite the reduced radiation dose.
An overall CR rate of 88% was achieved, thereby demonstrating a superior antileukemic efficacy of the protocol as compared with nonmyeloablative procedures, after which CR rates in the range of 45% have been observed.26 In addition, the relatively low relapse rate within our high-risk cohort, which included 49% of patients with unfavorable cytogenetics and 36% with refractory disease, indicates the potential of the FLAMSA-RIC protocol to eradicate leukemia.
The 2-year OS and LFS were 42% and 40%, respectively. To identify patients who might or might not benefit from our approach, we analyzed the influence of established risk factors on outcome. Interestingly, neither cytogenetics nor the stage of the disease at transplantation had a significant influence on outcome. No difference was seen in terms of survival between the intermediate and the poor prognostic cytogenetic subgroups (Fig 2A). This seems remarkable, given that the prognostic value of cytogenetics had been preserved in various studies using allogeneic HSCT with standard conditioning in CR1.5 So far, there are no reliable data on the role of cytogenetics in allogeneic transplantation beyond CR1. Therefore, it could be argued that the advanced stage per se might be a stronger risk factor, thereby overcoming the prognostic value of cytogenetic subgroups. Conversely, karyotype was the most important prognostic factor in relapsed or refractory AML using conventional chemotherapy.35 Among the patients with unfavorable cytogenetics, the group with complex abnormalities showed the most encouraging results: of 19 patients, seven underwent transplantation in untreated relapse, and six had primarily refractory disease. Fourteen patients achieved a CR, two patients experienced relapse, and six died as a result of nonleukemic causes. The 2-year OS was 42%, thereby equalizing the outcome of the entire cohort.
Regarding the stage of the disease at transplantation, patients in remission showed a trend toward better results. Interestingly, the group of patients with refractory disease did not have a significantly inferior outcome, although at least one course of high-dose cytarabine had been administered to all patients before they were declared refractory (Fig 2B). In light of the extremely poor outcome patients suffering from refractory or complex karyotype leukemia have with conventional chemotherapy,1,6,35 our results may give hope to a subgroup of patients with otherwise limited options.
Our overall results compare favorably to the results reported after standard conditioning, showing high NRM and a 2-year OS of 20% or less in advanced AML.11-15,36 In contrast, similar results have been observed by several groups using reduced but still myeloablative fludarabine-based regimens.34,37,38 These studies reported on a remarkably low rate of 1-year NRM of 5% to 20%. Recently, de Lima et al39 used targeted intravenous busulfan/fludarabine for allografting in 96 high-risk patients with AML/MDS. With a 12-month median follow-up, NRM, OS, and EFS were 3%, 65%, and 52%, respectively. However, this cohort contained 20% of patients in CR1, 54% with active disease, and 29% with unfavorable cytogenetics, compared with 11%, 79%, and 49%, respectively, in our group. In addition, median age was younger (45 v 52 years), more patients had a family donor (62% v 41%), inclusion criteria relating to organ dysfunction and HLA matching in unrelated donors were stricter, and no data were reported on comorbidities and pretransplantation therapy. Therefore, it is difficult to compare the results directly, although the low NRM is impressive. Within our cohort, all but seven patients fulfilled the exclusion criteria for conventional allografts,26 which might have contributed to the relatively high NRM. Nevertheless, completely avoiding TBI might further reduce NRM, and targeted intravenous busulfan, as suggested by de Lima et al39, might be a possible substitute for TBI. Conversely, highly aggressive leukemia, as refractory or poor cytogenetic disease, may require an intensive approach, including chemotherapy and TBI. This is supported by the data by de Lima et al,39 who, in contrast to our study, showed high relapse rates and a significantly inferior outcome in patients with active disease, as compared with patients who underwent transplantation in remission.
In line with another recent study,40 HLA-identical family donor transplants and higher numbers of infused CD34+ cells were associated with less NRM within our trial. The role of higher cell doses might be explained by a shorter period of neutropenia (P = .005), although no direct correlation with infections was observed. Nevertheless, the relatively long duration of the preparative regimen might have increased NRM. The relevance of cell doses for outcome has been shown in BMT for AML in CR1.41 It is less clear in PBSC transplantation, where it may be most important in high-risk disease.42,43 In our cohort, higher CD34+ doses were associated with better survival in PBSC recipients (Table 4).
In patients with an HLA-identical family donor, reduced NRM was due mainly to a lower risk of GvHD. However, this did not influence survival because of an increased risk of death from leukemia, possibly indicating an inferior GvL reaction in genotypically identical donor-recipient combinations. Reduction or avoidance of antithymocyte globulin might allow for more alloreactivity in HLA-identical transplants.
aGvHD grade II to IV developed in 49% of our patients, and chronic GvHD was seen in 45% of patients alive at day 100, including three with cGvHD after pDLT. Several RIC investigators have reported similar results,22,26,40 whereas a lower incidence, particularly of aGvHD, was seen by others.33,38,39 These differences have been explained in part by a delayed achievement of full donor chimerism in cohorts with less GvHD, in particular with respect to the T-cell compartment.38 Within the Seattle study, the risk of aGvHD increased with T-cell chimerism at day +28.22 In other studies, high numbers of CD34+ cells were associated with complete T-cell chimerism by day +28, and with increased incidence of cGvHD.43,44 This might be confirmed by our results. However, the variety in GvHD incidence after RIC is not completely understood.
aGvHD limited to the skin and limited cGvHD were associated with better OS and LFS, compared with the results of patients without GvHD. In contrast, severe forms of GvHD contributed considerably to NRM, thereby leading to inferior results in affected patients. These data demonstrate the two sides of GvHD as a surrogate marker for a GvL effect on one hand, and a life-threatening complication on the other. Better prevention and treatment of severe GvHD will improve the results.
pDLT to eliminate potential MRD was an integral part of the treatment for patients without GvHD after immunosuppression was discontinued for 30 days. In fact, 24% of the patients alive at day +120 proceeded to pDLT, whereas the majority could not be transfused because of GvHD or continued immunosuppression. Therefore, reducing the incidence of GvHD might increase the number of candidates for pDLT.
Several studies on pDLT have been published that report on high rates of clinical response at the expense of severe GvHD.45,46 In contrast, GvHD incidence was low in our study. This might be explained by the delay of pDLT until day +120, whereas it was given between days +30 and +90 in other studies. Delay of pDLT is supported by animal data, suggesting that one must allow time for the development of tolerance before DLT can be performed safely.47 Using an escalating cell dose regimen with an initial dose as low as 1 x 106 CD3+ cells/kg might be another way to avoid GvHD, as has been demonstrated after DLT for relapsed CML.48 Aside from GvHD, no relevant adverse effects were observed.
The influence of pDLT on outcome in AML and MDS remains uncertain. In our study, an antileukemic effect was supported by a low relapse rate and excellent survival in patients receiving pDLT, and by the disappearance of the so far persisting CBF?/MYH11 transcript in one patient after pDLT. In lymphoid malignancies, clinical response has been reported in 70% of patients.49 The results of our small cohort are encouraging. However, patients alive and free of GvHD at day +120 may represent a positive selection. Therefore, broader experience is warranted.
Our results and those from other pilot studies demonstrate the efficacy of RIC protocols in high-risk AML and MDS. However, the optimal balance between antileukemic activity and toxicity still has to be defined. Patients with extremely poor prognosis (eg, with a complex karyotype leukemia or refractory disease) seemed to benefit from the combined strategy of intensive chemotherapy, RIC, and prolonged allogeneic immune reaction, either by repeated pDLT or cGvHD. However, the toxicity of the regimen is still considerable, and a less aggressive regimen might be preferable for chemotherapy-sensitive or less advanced disease.
Authors' Disclosures of Potential Conflicts of Interest
The authors indicated no potential conflicts of interest.
Acknowledgment
We thank all of the nurses on the wards and the outpatient clinic of the José Carreras Transplantation Unit for their dedicated work.
NOTES
Presented in part as a preliminary analysis at the Annual Meeting of the German Society of Hematology and Oncology, October 29, 2002, Munich, Germany, and the Annual Meeting of the European Group of Blood and Marrow Transplantation, July 22, 2003, Istanbul, Turkey.
C.S. and M.S. contributed equally to this work.
Authors' disclosures of potential conflicts of interest are found at the end of this article.
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