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1 (2004) 34, & 2004 Nature Publishing Group All rights reserved /04 $ Graft-versus-myeloma following antithymocyte globulin-based reduced intensity conditioning allogeneic stem cell transplantation M Mohty 1, JM Boiron 2, G Damaj 3, AS Michallet 4, JO Bay 5, C Faucher 1, V Perreau 2, K Bilger 1, D Coso 3, AM Stoppa 3, R Tabrizi 2, JA Gastaut 3,6, M Michallet 4, D Maraninchi 3,6 and D Blaise 1,3,6 1 Unité de Transplantation et de Thérapie Cellulaire (UTTC), Institut Paoli-Calmettes, Marseille, France; 2 Centre Hospitalier Universitaire (CHU) de Bordeaux, Bordeaux, France; 3 Département d Hématologie, Institut Paoli-Calmettes, Marseille, France; 4 CHU Edouard Herriot, Lyon, France; 5 Centre Jean-Perrin, Clermont-Ferrand, Marseille, France; and 6 Université de la Méditerranée, Marseille, France Summary: In all, 41 multiple myeloma (MM)patients received an antithymocyte globulin (ATG), fludarabine, and busulfanbased reduced intensity conditioning (RIC)for allogeneic stem cell transplantation (allo-sct)from HLA-identical siblings. In total, 29 patients (70%)were in partial remission, one patient in complete remission, and 11 (27%)with progressive disease at the time of allo-sct. Median time between diagnosis and allo-sct was 24 months. The cumulative incidences of grade II IV and grade III IV acute graft-versus-host disease (GVHD) were 36% (95% CI, 21 51%)and 7% (95% CI, 2 20%), respectively. Overall, 10 patients developed limited chronic GVHD, whereas seven developed an extensive form (cumulative incidence, 41% (95% CI, 26 56%)at 2 years). With a median follow-up of 389 days, the overall cumulative incidence of transplant-related mortality (TRM)was 17% (95% CI, 6 28%). In all, 11 patients (27%)are in continuous complete remission, and the Kaplan Meier estimates of overall survival (OS)and progression-free survival (PFS)at 2 years were 62% (95% CI, 47 76%)and 41% (95% CI, 23 62%), respectively. PFS and OS were significantly higher in patients with chronic GVHD as compared to patients without chronic GVHD (P ¼ for PFS and P ¼ 0.01 for OS). Collectively, these data demonstrate that RIC allo-sct can mediate a potentially curative graft-versusmyeloma effect with an acceptable incidence of toxicity and TRM. (2004) 34, doi: /sj.bmt Published online 10 May 2004 Correspondence: Dr M Mohty, Unite de Transplantation et de The rapie Cellulaire (UTTC), Institut Paoli-Calmettes and Universite de la Me diterrane e, 232 Bd. Ste Marguerite, Marseille Cedex 09, France. mohtym@marseille.fnclcc.fr Received 30 November 2003; accepted 3 February 2004 Published online 10 May 2004 Keywords: Allogeneic stem cell transplantation; multiple myeloma; reduced intensity preparative regimen, graftversus-tumor effect Multiple myeloma (MM) is a lymphoid malignancy with a median survival of 3 years. 1 Despite the development of numerous conventional chemotherapy regimens, there has been little progress in improving the survival of patients with MM. 1 High-dose chemotherapy with autologous stem cell transplantation (SCT) can result in prolonged response duration and survival. 2 9 Unfortunately, few, if any, patients with MM who receive high-dose therapy are cured. 10 On the other hand, extensive clinical and experimental data support an important role for a graft-versustumor (GVT) effect in eradicating a number of different tumor cells in patients who receive allogeneic stem cell transplantation (allo-sct). 11,12 Specifically, it has been shown that a graft-versus-myeloma (GVM) effect can be induced against MM even in patients who have been heavily pretreated or who relapse after high-dose therapy However, these promising results are often achieved at the cost of high treatment-related morbidity and mortality, considered as a contraindication to the use of standard myeloablative allo-sct as a classical treatment strategy for MM patients. 17,18 As a possible less toxic alternative to standard myeloablative allo-sct, reduced intensity conditioning (RIC) regimens for allo-sct, combining highly immunosuppressive drugs or using low-dose total body irradiation, have been shown to induce durable donor cell engraftment with a relatively low rate of procedure-related toxicity and clinically effective GVT effect in some cases Recently, it has been shown that application of RIC allo-sct for MM, may temper the frequency of transplant-related toxicities, and allow a sustained disease-free survival in a significant proportion of patients However, specific data on the potential benefit of RIC allo-sct for MM are still sparse and poorly defined. This report describes the results of 41 consecutive MM patients who received an antithymocyte globulin (ATG), fludarabine, and busulfan-based RIC for allo-sct from HLA-identical siblings.

2 78 Patients and methods Patients and donors Study design. In all, 41 consecutive patients who received an RIC allo-sct from HLA-identical donors for MM were included in this study. Patients were treated in a joint program between the Institut Paoli-Calmettes (Marseille), the CHU de Bordeaux (Bordeaux), the CHU Edouard Herriot (Lyon), and the Centre Jean-Perrin (Clermont- Ferrand) between June 1999 and March Approval for the study was obtained from institutional review boards at the four participating centers and corresponding local ethical committees. Written informed consent was obtained from each patient and donor. All donors were HLA-A-, HLA-B-, and HLA-DR-identical siblings. The primary aim of the study was to analyze engraftment and transplantrelated mortality (TRM). Other objectives included determining the incidence of GVHD and disease response. Conditioning regimen. The preparative regimen was adapted from that reported by Slavin et al, 21 with fludarabine (Fludara; Schering AG, Lys-Lez-Lannoy, France) 30 mg/m 2 for 6 or 5 consecutive days, oral busulfan 4 mg/kg/day for 2 consecutive days and ATG (Thymoglobuline; Sangstat, Lyon, France) 2.5 mg/kg/day for 5, 4, 3, or 1 day as indicated hereinafter. As part of the protocol, the ATG dose administered during conditioning was progressively decreased from 12.5 to 2.5 mg/kg. 19 The first 24 patients received the higher total ATG dose of 12.5 mg/ kg (n ¼ 11), 10 mg/kg (n ¼ 3) and 7.5 mg/kg (n ¼ 10), while the next 17 patients received the lower total ATG dose of 5 mg/kg (n ¼ 5) and 2.5 mg/kg (n ¼ 12). Supportive care. Patient management (antibacterial and antiviral prophylaxis, transfusion policy) was performed according to the standard procedures of each center and was expected to be the same in all patients for a given center. GVHD prophylaxis. In total, 13 patients received cyclosporine A (CsA) and short-course methotrexate (15 mg/m 2 on day 1 and 10 mg/m 2 on days 3 and 6) as GVHD prophylaxis. 32 The remaining 28 patients received CsA alone at a dose of 3 mg/kg/day by continuous intravenous infusion, and changed to twice daily oral dosing as soon as tolerated. The CsA doses were adjusted to achieve blood levels between 150 and 250 ng/ml and to prevent renal dysfunction. CsA was tapered starting on day 90 if no GVHD appeared. Graft source. In total, 14 patients (34%) received a bone marrow (BM) graft collected under general anesthesia, whereas 27 patients (66%) received peripheral blood stem cells (PBSC). For PBSC collection, donors were treated with granulocyte-colony-stimulating factor (G-CSF) (Filgrastim, Amgen, Neuilly-sur-Seine, France) at a dose of 10 mg/kg/day for 5 days. The day of BM or PBSC infusion was designated as day 0. The graft was analyzed for content of hematopoietic progenitors (CD34 þ cells) and CD3 þ lymphoid cells using standard flow cytometry procedures. Clinical outcomes and GVHD assessment Clinical outcomes after allo-sct that were recorded included time of neutrophil and platelet engraftment, time to start, and severity of acute GVHD (agvhd); chronic GVHD (cgvhd); disease relapse or progression, progression-free survival (PFS), and overall survival (OS). Time to neutrophil engraftment was defined as the first of 3 consecutive days in which the ANC exceeded 500/ml. Time to platelet engraftment was defined as the first of 3 days a platelet count was /ml without a need for platelet transfusion during a 5-day period. Acute and chronic GVHD were graded according to standard criteria Chronic GVHD was defined as any GVHD developing after day 100 including the progressive form if it followed as a direct extension of agvhd. Other forms of cgvhd included the quiescent (onset after the resolution of agvhd) and the de novo (not preceded by agvhd) forms. Donor leukocyte infusions (DLI) Patients who relapsed after allo-sct or who showed evidence of disease progression or had persistent disease without any sign of GVHD after immunosuppressive therapy withdrawal, were candidates for DLI ranging between and CD3 þ cells/kg. Patients with mixed hematopoietic chimerism beyond 3 months after allo-sct were also candidates for pre-emptive DLI. Donors underwent a leukapheresis without cytokine mobilization for donor lymphocyte procurement. Assessment of response Disease progression was defined as re-emergence of MM (if a complete remission had been reached), or implied at least a 25% increase in M-protein from a prior stable condition, or development of new extramedullary disease. 28 TRM was defined as death without evidence of disease progression. The response to treatment was defined according to the European Group for Blood and Marrow Transplantation (EBMT) criteria. 37 Statistics All data were computed using SPSS for Windows (SPSS, Inc, Chicago, IL, USA) and SEM software (SILEX, Mirefleurs, France). The Mann Whitney test was used for comparison of continuous variables. Categorical variables were compared using the w 2 test. The probability of developing agvhd or cgvhd was depicted by calculating the cumulative incidence with relapse and death without relapse or agvhd or cgvhd as competing risks. 38 Cumulative incidence estimates were also used to measure the probability of relapse or progression. 38 Probabilities of PFS and OS were estimated from the time of allo-sct using the Kaplan Meier product-limit estimates. 39 Differences between groups were tested using the log-rank test when Kaplan Meier analysis was performed.

3 Results Patients and disease characteristics Patients and disease baseline characteristics are shown in Table 1. Briefly, the median age of recipients was 52 (range, 35 61) years. In all, 24 donor recipient pairs (58%) were sex mismatched. Totally, 29 patients (70%) were in partial remission after salvage therapy given before allo-sct, whereas only one patient was in complete remission. The remaining 11 patients (27%) were in refractory or progressive disease stage at the time of allo-sct. In total, 34 patients (83%) received at least one autologous SCT in the course of their disease prior to entering this study. In patients who received an autologous SCT, the median time between allo-sct and autologous transplantation was 4 (range, 2 57) months. Median time between the initial diagnosis of MM and allo-sct was 24 (range, 6 146) Table 1 Patient and disease characteristics n(%) Age (years) Recipient, median (range) 52 (35 61) Donor, median (range) 51 (28 73) Female donor 15 (37) Time (months) from diagnosis to transplantation, 24 (6 146) median (range) Disease status at time of transplantation Complete remission 1 (2) Partial remission 29 (70) Progressive disease 11 (27) Monoclonal component Ig G 19 (46) Ig A 12 (29) Light chain 9 (22) Plasmocytoma only 1 (2) Disease stage a I 2 (5) II 5 (12) III 33 (80) Plasmocytoma 1 (3) No. of prior autologous stem cell transplantation 0 7 (17) 1 23 (56) 2 10 (24) 3 1 (2) Cytomegalovirus status Seronegative, with seronegative donor 12 (29) ABO mismatch 22 (54) Graft source Bone marrow 14 (34) Peripheral blood stem cells 27 (66) GVHD prophylaxis Cyclosporine b 28 (68) Cyclosporine + methotrexate 13 (32) Median ATG-dose infused during conditioning 7.5 mg/kg ( ) (range) a According to Salomon and Durie classification. b One patient was rapidly switched to mycophenolate mofetil because of intolerance to cyclosporine; because of rounding, not all percentages total 100. Cytogenetics data were not available from patients included in this study. months. Patients were not treated in a combined autologous/allo-sct strategy. Patients in this series received a median ATG dose of 7.5 (range, ) mg/kg. Engraftment and GVHD Table 2 summarizes transplant-related events. In this series, two patients died at days 5 and 7 after allo-sct from a severe respiratory distress syndrome associated with septicemia. Another patient had a cerebral hemorrhage during conditioning, likely due to a cerebral vascular malformation. A fourth patient had persistent cytopenia with recurrent infections and died at day 69 post-allo-sct of disease progression. The remaining 37 patients reached a sustained ANC of more than 500/ml at a median of 17 (range, 0 27) days. Platelet engraftment occurred at a median of 10 (range, 0 32) days. In all, 37 patients (90%) were evaluable for agvhd. Two patients (5%; 95% confidence interval (CI), 1 18%) developed grade I agvhd. The cumulative incidences of grade II IV and grade III IV agvhd were 36% (95% CI, 21 51%) and 7% (95% CI, 2 20%), respectively (Figure 1a). The median time to onset of agvhd was 34 (range, 14 85) days. The skin was the most common target of agvhd, being involved in 13 of the 17 patients (76%) developing agvhd; the gastrointestinal tract was involved in seven of these patients (41%) and the liver in five patients (29%). Over all, 33 patients (80%; 95% CI, 66 94%) survived beyond day 100 and were evaluable for cgvhd. Overall, cgvhd developed in 17 patients at a median time of 105 (range, ) days after allo-sct. In the 33 patients evaluable for cgvhd, 10 developed limited cgvhd, whereas seven developed clinical extensive cgvhd. The cumulative incidence of cgvhd (both limited and extensive cgvhd) was 41% (95% CI, 26 56%) (Figure 1b). Immunosuppressive treatments duration and Table 2 Transplant-related events n(%) Median time (days) to ANC 4500/ml (range) 17 (0 27) Median time (days) to platelets /ml (range) 10 (0 32) Acute GVHD 37 No. evaluable Grade 20 (54) a 0 2 (6) a I 12 (32) a II 3 (8) a III IV Median time (days) to onset of acute GVHD (range) 34 (14 85) Chronic GVHD No. evaluable 33 (80) Chronic GVHD 17 (51) a Extensive chronic GVHD 7 (21) a Limited chronic GVHD 10 (30) a Median time (days) to onset of chronic GVHD 105 ( ) ANC ¼ absolute neutrophil count; GVHD ¼ graft-versus-host disease. Because of rounding, not all percentages total 100. a % of evaluable patients. 79

4 80 a Cumulative incidence of acute GVHD (%) b Cumulative incidence of chronic GVHD (%) Figure 1 GVHD Days post-transplantation Months post-transplantation types were assessed in all patients included in this study. At time of last follow-up, 29 patients (71%) were off all immunosuppressive therapy, and the median time for immunosuppressive therapy discontinuation was 86 days post-allo-sct (range, ). Among patients who experienced agvhd, four patients needed high-dose steroids (prednisone, 2 mg/kg/day or above). Moreover, four GVHD patients needed a second-line immunosuppressive regimen (mycophenolate mofetil, n ¼ 2; ATG, n ¼ 1; and total lymphoid irradiation, n ¼ 1) replacing or being in addition to first-line salvage therapy, because of CsA and steroid-refractory or clinically worsening GVHD. Donor leukocyte infusions Grade 3-4 agvhd Grade 2-4 agvhd Extensive cgvhd Limited+Extensive Cumulative incidence of GVHD. (a) Acute GVHD; (b) chronic Overall, 14 patients (34%) in this series received up to four escalating doses of DLI starting at a median time of 145 (range, ) days post-allo-sct. DLI were given to establish full donor chimerism (n ¼ 3) or to patients who relapsed or who showed evidence of disease progression or had persistent disease without any sign of GVHD after immunosuppressive therapy withdrawal (n ¼ 11). GVHD occurred in two patients among the 14 who received DLI (one grade I and one grade III). Among patients receiving DLI for disease progression, four (36%) subsequently achieved partial remission. Transplant-related mortality, disease response, and outcome Of the 41 patients included in this study, 21 patients (53%; 95% CI, 38 68%) achieved an objective disease response during the follow-up period [complete remission (CR), n ¼ 10; partial remission, n ¼ 11], in addition to the one patient who was already in CR at the time of allo-sct. The median follow-up of patients in CR was 12 (median, 2 33) months. Among patients in CR, eight experienced cgvhd (three extensive and five limited), of whom two are still under immunosuppressive therapy at time of last follow-up. Interestingly, three patients needed DLI to establish full donor chimerism before achieving CR. Two patients had stable disease, three were not assessable for disease response because of early death, and 14 (34%; 95% CI, 20 48%) did not have any detectable disease response and progressed after allo-sct (Table 3). Among the patients who survived beyond day 100 after allo-sct and who had an objective disease response, 13 (65%) experienced limited or extensive cgvhd as compared to only four (31%) in those who did not respond (P ¼ 0.05). At time of last follow-up, 18 patients (44%) had died and 23 (56%) are still alive with a Table 3 Disease response and outcome n(%) Disease response after allo-sct Complete remission 11 (27) Partial remission 11 (27) Stable disease 2 (5) Progressive disease 14 (34) Not assessable 3 (7) Progression or relapse 21 (51) Median time (days) to progression or relapse (range) 131 ( ) Median follow-up (days) of surviving patients (range) 389 ( ) Patients surviving in Complete remission 10 (24) Partial remission 8 (20) Stable disease 1 (2) Progressive disease 4 (10) Deaths 18 (44) Causes of death Disease 11 (61) Transplant-related mortality Acute GVHD 1 (6) Chronic GVHD 0 Infections 4 (22) Other 2 (11) Because of rounding, not all percentages total 100. GVHD, graft-versushost disease.

5 median follow-up of 389 (range, ) days, of whom 18 have responded, 10 in CR and eight in PR (Table 3). Overall, disease progression or relapse occurred in 21 patients (51%; 95% CI, 36 66%) at a median time of 131 (range, ) days post-allo-sct. The majority of deaths (n ¼ 11; 61% of all deaths) were directly attributed to disease progression or relapse. One death was attributed to severe agvhd, while four patients died of infections. Overall cumulative incidence of TRM (n ¼ 7) was 17% (95% CI, 6 28%) occurring at a median of 68 (range, 1 122) days post-allo-sct. Interestingly, the cumulative incidence of TRM (n ¼ 5) was 18% (95% CI, 6 38%) in the 27 patients aged over 50 years, and 14% (95% CI, 2 44%) in the 14 patients aged under 50 (P ¼ NS). The Kaplan Meier estimate of OS and PFS at 2 years were 62% (95% CI, 47 76%) and 41% (95% CI, 23 62%), respectively. Interestingly, PFS and OS were significantly higher in patients with cgvhd (n ¼ 17) as compared to patients without (n ¼ 16) cgvhd (P ¼ for PFS and P ¼ 0.01 a % 100 Progression-free survival b % 100 Overall survival 25 Without chronic GVHD With chronic GVHD P = Months post-transplantation Without chronic GVHD With chronic GVHD P = Months post-transplantation Figure 2 Progression-free and overall survival according to chronic GVHD. (a) Progression-free survival after allo-sct in patients with (n ¼ 17) and without (n ¼ 16) chronic GVHD (whatever its form); (b) overall survival after allo-sct in patients with (n ¼ 17) and without (n ¼ 16) (whatever its form). for OS) (Figure 2a and b). Thus, because cgvhd by definition begins on day 100 following allo-sct, we attempted to detect prognostic factors for better OS in patients who survived beyond day 100. When comparing the group of patients with cgvhd and the group of patients without cgvhd, all relevant prognostic factors (age, gender, CMV serostatus, disease status at allo-sct, time from diagnosis to allo-sct, monoclonal component type, disease stage, autologous SCT prior to allo-sct, stem cell source, stem cell dose, ATG dose, GVHD prophylaxis, acute GVHD, DLI, overall follow-up) were not significantly different between the two groups (data not shown), further supporting the protective effect of cgvhd on disease progression or relapse. Discussion In this study, we have analyzed the outcome of 41 high-risk MM patients given HLA-identical allo-sct following ATG-based RIC. Although 66% of the patients in this study were aged over 50 years, overall TRM did not exceed 17% confirming the significantly lower TRM associated with RIC when compared to TRM rates reported with conventional myeloablative allo-sct. 17,40 42 Our results suggest that in a busulfan, fludarabine, and ATG-based RIC, an objective GVM effect can be achieved without an increased risk of GVHD-related mortality. Allo-SCT for MM using myeloablative conditioning regimens has been the subject of controversy over the years because of the high rate of GVHD and TRM without a clear benefit from a GVM effect. 43,44 As of June 2002, 105 MM patients who received a RIC allo-sct have been reported, 45 with further evidence in other publications that the use of RIC allo-sct for MM is rapidly growing. 30,46 48 However, issues related to TRM rate, GVHD incidence, and proof of a GVM effect are still unresolved because of considerable heterogeneity in patient selection criteria, conditioning regimens, timing of RIC allo-sct (after autologous transplantation, in complete or partial remission, or after relapse), and comorbid conditions (age and exclusion criteria due to other organ dysfunction). In the series of RIC allo-sct for MM reported by Badros et al, 28 TRM in the first 100 days was 10% comparing favorably with results obtained in the myeloablative setting from the same institution. However, in that study, the cumulative incidence of agvhd was relatively high (58%). Moreover, a more recent report from the same group (likely representing an update) included 45 patients, with 17 patients reported to have died from transplant-related complications giving an overall incidence of TRM of 38%, 49 in line with other results from Majolino et al 50 showing a 30% rate of TRM. In contrast to Majolino et al, 50 who used a full dose of busulfan and melphalan regimen, the RIC regimen used by Badros et al (melphalan 100 mg/m 2 ) is clearly of low intensity decreasing the risk of early TRM. Such a high long-term incidence of TRM might be explained by the systematic use of early preemptive DLI and a very short duration of immunosuppressive therapy. 28 In our series, DLI were only administered to patients who had mixed donor recipient chimerism or to patients who relapsed or who showed evidence of 81

6 82 disease progression or had persistent disease without any sign of GVHD after immunosuppressive therapy withdrawal. Moreover, the overall GVHD-related mortality was impressively low (only one patient in this series). It is likely that the incorporation of ATG as part of the RIC regimen provided a powerful tool of in vivo T-cell depletion significantly decreasing the risk of deleterious GVHD without compromising the GVM effect. 51 In this regard, we have previously shown a significant impact of ATG on GVHD, related to a dose-dependent in vivo T-cell depletion, effectively modulating the risk of GVHD after RIC allo-sct. 19 Although containing an intermediate dose of an alkylating agent (busulfan), it is unlikely that our ATG-based conditioning regimen alone could result in a long-term disease control because the majority of patients had relapsed after multiple chemotherapy regimens including autologous SCT with high-dose alkylating agents. However, such a regimen allows durable engraftment, and possibly, some level of disease control until the GVM could be mounted. At present, the immunosuppressive dose of the most commonly used agents necessary to allow engraftment of allogeneic stem cells is not well defined. Also, it is likely that patients heavily immunocompromised by prior therapy (different lines of prior chemotherapy including high-dose chemotherapy) are most likely to engraft, develop GVHD, allowing for establishment of the GVM effect and long term disease control. Although myelomaspecific cytotoxic T lymphocytes have been described in different settings, and a GVT effect has been observed in some hematological malignancies without clinically significant GVHD, 55,56 and although a longer follow-up is still needed, the GVM effect in our study, as in most other studies, was closely related to cgvhd. The latter is in line with previous data from both the myeloablative and RIC allogeneic transplantation settings 12,19,57 59 showing that despite important efforts to separate immune effectors responsible for GVHD and GVT, the allogeneic GVT effect cannot yet be reliably dissociated from GVHD that is the major determinant associated with lower progression and better survival. In this study, the impact of stem cell source or ATG dose on GVHD incidence and outcome could not be assessed as it has been already shown in our previous studies, 19,60 likely because of the limited number of patients. Alternatively, we could not detect a significant impact of other factors such as disease status before allo-sct or the number of prior autologous transplantations that influenced the final outcome separate from GVHD. This might be also due to the relatively small number of patients in this study. Thus, further large studies with a longer follow-up are needed to identify potential disease characteristics impacting outcome and the most suitable allo-sct timing that is more likely to induce a beneficial and durable GVM effect. In this regard, Maloney et al 31 have recently shown that a combination of planned autologous transplantation immediately followed by RIC allo-sct after recovery is feasible and may result in a high rate of objective disease responses and low TRM in the first 100 days after allo- SCT. 31 We conclude that in addition to a decreased rate of procedure-related toxicities, the relatively high response rate observed in our series warrants developing a global RIC approach designed to enhance the GVM effect of allo- SCT. Assessment of the potential morbidity associated with cgvhd adjusted for quality of life may be crucial determinants for the ultimate outcome and are obvious targets of investigations into improving the safety of RIC allo-sct approaches for MM. Acknowledgements M Mohty was supported by grants from the Association Me diterrane enne pour le De veloppement, de la Transplantation (Marseille, France) and from the Ligue contre le Cancer du Gard (Nimes, France). We thank FB Petersen, MD (University of Utah Health Sciences Center, Salt Lake City, Utah) for critical reading of the manuscript. We thank the nursing staff for providing excellent care for our patients. We also thank the following physicians for their dedicated patient care and important study contributions: N Vey, RT Costello, R Bouabdallah, A Charbonnier, JM Schiano de Collela, C Chabannon, PLadaique (Institut Paoli-Calmettes); and B Choufi, O Tournilhac (Centre Jean Perrin). References 1 Hahn T, Wingard JR, Anderson KC et al. The role of cytotoxic therapy with hematopoietic stem cell transplantation in the therapy of multiple myeloma: an evidence-based review. Biol Blood Marrow Transplant 2003; 9: Attal M, Harousseau JL, Stoppa AM et al. A prospective, randomized trial of autologous bone marrow transplantation and chemotherapy in multiple myeloma. Intergroupe Francais du Myelome. N Engl J Med 1996; 335: Child JA, Morgan GJ, Davies FE et al. High-dose chemotherapy with hematopoietic stem-cell rescue for multiple myeloma. N Engl J Med 2003; 348: Barlogie B, Jagannath S, Vesole DH et al. Superiority of tandem autologous transplantation over standard therapy for previously untreated multiple myeloma. Blood 1997; 89: Gianni AM, Tarella C, Bregni M et al. High-dose sequential chemoradiotherapy, a widely applicable regimen, confers survival benefit to patients with high-risk multiple myeloma. J Clin Oncol 1994; 12: Lenhoff S, Hjorth M, Holmberg E et al. Impact on survival of high-dose therapy with autologous stem cell support in patients younger than 60 years with newly diagnosed multiple myeloma: a population-based study. Nordic Myeloma Study Group. Blood 2000; 95: Palumbo A, Triolo S, Argentino C et al. Dose-intensive melphalan with stem cell support (MEL100) is superior to standard treatment in elderly myeloma patients. Blood 1999; 94: Gertz MA, Lacy MQ, Inwards DJ et al. Early harvest and late transplantation as an effective therapeutic strategy in multiple myeloma. Bone Marrow Transplant 1999; 23: Alexanian R, Weber D, Giralt S et al. Impact of complete remission with intensive therapy in patients with responsive multiple myeloma. Bone Marrow Transplant 2001; 27: Bensinger WI. Hematopoietic cell transplantation for multiple myeloma. Cancer Control 1998; 5:

7 11 Weiden PL, Flournoy N, Thomas ED et al. Antileukemic effect of graft-versus-host disease in human recipients of allogeneic-marrow grafts. N Engl J Med 1979; 300: Horowitz MM, Gale RP, Sondel PM et al. Graft-versusleukemia reactions after bone marrow transplantation. Blood 1990; 75: Tricot G, Vesole DH, Jagannath S et al. Graft-versus-myeloma effect: proof of principle. Blood 1996; 87: Mehta J, Singhal S. Graft-versus-myeloma. Bone Marrow Transplant 1998; 22: Lokhorst HM, Schattenberg A, Cornelissen JJ et al. Donor lymphocyte infusions for relapsed multiple myeloma after allogeneic stem-cell transplantation: predictive factors for response and long-term outcome. J Clin Oncol 2000; 18: Salama M, Nevill T, Marcellus D et al. Donor leukocyte infusions for multiple myeloma. Bone Marrow Transplant 2000; 26: Bensinger WI, Buckner CD, Anasetti C et al. Allogeneic marrow transplantation for multiple myeloma: an analysis of risk factors on outcome. Blood 1996; 88: Gahrton G, Svensson H, Cavo M et al. Progress in allogenic bone marrow and peripheral blood stem cell transplantation for multiple myeloma: a comparison between transplants performed and at European Group for Blood and Marrow Transplantation centres. Br J Haematol 2001; 113: Mohty M, Bay JO, Faucher C et al. Graft-versus-host disease following allogeneic transplantation from HLA-identical sibling with antithymocyte globulin-based reduced-intensity preparative regimen. Blood 2003; 102: Giralt S, Estey E, Albitar M et al. Engraftment of allogeneic hematopoietic progenitor cells with purine analog-containing chemotherapy: harnessing graft-versus-leukemia without myeloablative therapy. Blood 1997; 89: Slavin S, Nagler A, Naparstek E et al. Nonmyeloablative stem cell transplantation and cell therapy as an alternative to conventional bone marrow transplantation with lethal cytoreduction for the treatment of malignant and nonmalignant hematologic diseases. Blood 1998; 91: Khouri IF, Keating M, Korbling M et al. Transplant-lite: induction of graft-versus-malignancy using fludarabine-based nonablative chemotherapy and allogeneic blood progenitorcell transplantation as treatment for lymphoid malignancies. J Clin Oncol 1998; 16: Carella AM, Cavaliere M, Lerma E et al. Autografting followed by nonmyeloablative immunosuppressive chemotherapy and allogeneic peripheral-blood hematopoietic stem-cell transplantation as treatment of resistant Hodgkin s disease and non-hodgkin s lymphoma. J Clin Oncol 2000; 18: Kottaridis PD, Milligan DW, Chopra R et al. In vivo CAMPATH-1 H prevents graft-versus-host disease following nonmyeloablative stem cell transplantation. Blood 2000; 96: McSweeney PA, Niederwieser D, Shizuru JA et al. Hematopoietic cell transplantation in older patients with hematologic malignancies: replacing high-dose cytotoxic therapy with graftversus-tumor effects. Blood 2001; 97: Giralt S, Thall PF, Khouri I et al. Melphalan and purine analog-containing preparative regimens: reduced-intensity conditioning for patients with hematologic malignancies undergoing allogeneic progenitor cell transplantation. Blood 2001; 97: Childs R, Chernoff A, Contentin N et al. Regression of metastatic renal-cell carcinoma after nonmyeloablative allogeneic peripheral-blood stem-cell transplantation. N Engl J Med 2000; 343: Badros A, Barlogie B, Siegel E et al. Improved outcome of allogeneic transplantation in high-risk multiple myeloma patients after nonmyeloablative conditioning. J Clin Oncol 2002; 20: Badros A, Barlogie B, Morris C et al. High response rate in refractory and poor-risk multiple myeloma after allotransplantation using a nonmyeloablative conditioning regimen and donor lymphocyte infusions. Blood 2001; 97: Kroger N, Schwerdtfeger R, Kiehl M et al. Autologous stem cell transplantation followed by a dose-reduced allograft induces high complete remission rate in multiple myeloma. Blood 2002; 100: Maloney DG, Molina AJ, Sahebi F et al. Allografting with non-myeloablative conditioning following cytoreductive autografts for the treatment of patients with multiple myeloma. Blood 2003; First: Edition Paper. 32 Storb R, Deeg HJ, Whitehead J et al. Methotrexate and cyclosporine compared with cyclosporine alone for prophylaxis of acute graft versus host disease after marrow transplantation for leukemia. N Engl J Med 1986; 314: Przepiorka D, Weisdorf D, Martin P et al Consensus Conference on Acute GVHD Grading. Bone Marrow Transplant 1995; 15: Shulman HM, Sullivan KM, Weiden PL et al. Chronic graft-versus-host syndrome in man. A long-term clinicopathologic study of 20 Seattle patients. Am J Med 1980; 69: Farmer ER. The histopathology of graft-versus-host disease. Adv Dermatol 1986; 1: Sullivan KM, Agura E, Anasetti C et al. Chronic graft-versushost disease and other late complications of bone marrow transplantation. Semin Hematol 1991; 28: Blade J, Samson D, Reece D et al. Criteria for evaluating disease response and progression in patients with multiple myeloma treated by high-dose therapy and haemopoietic stem cell transplantation. Myeloma Subcommittee of the EBMT. European Group for Blood and Marrow Transplant. Br J Haematol 1998; 102: Gooley TA, Leisenring W, Crowley J, Storer BE. Estimation of failure probabilities in the presence of competing risks: new representations of old estimators. Stat Med 1999; 18: Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc 1958; 53: Bjorkstrand BB, Ljungman P, Svensson H et al. Allogeneic bone marrow transplantation versus autologous stem cell transplantation in multiple myeloma: a retrospective casematched study from the European Group for Blood and Marrow Transplantation. Blood 1996; 88: Varterasian M, Janakiraman N, Karanes C et al. Transplantation in patients with multiple myeloma: a multicenter comparative analysis of peripheral blood stem cell and allogeneic transplant. Am J Clin Oncol 1997; 20: Couban S, Stewart AK, Loach D, Panzarella T, Meharchand J. Autologous and allogeneic transplantation for multiple myeloma at a single centre. Bone Marrow Transplant 1997; 19: Bensinger WI. Recent developments in hematopoietic stem cell transplantation for multiple myeloma. Int J Hematol 2003; 77: Lokhorst HM, Segeren CM, Verdonck LF et al. Partially T- cell-depleted allogeneic stem-cell transplantation for first-line treatment of multiple myeloma: a prospective evaluation of patients treated in the phase III study HOVON 24 MM. J Clin Oncol 2003; 21:

8 84 45 Djulbegovic B, Seidenfeld J, Bonnell C, Kumar A. Nonmyeloablative allogeneic stem-cell transplantation for hematologic malignancies: a systematic review. Cancer Control 2003; 10: Gratwohl A, Baldomero H, Passweg J et al. Hematopoietic stem cell transplantation for hematological malignancies in Europe. Leukemia 2003; 17: Kroger N, Sayer HG, Schwerdtfeger R et al. Unrelated stem cell transplantation in multiple myeloma after a reducedintensity conditioning with pretransplantation antithymocyte globulin is highly effective with low transplantation-related mortality. Blood 2002; 100: Einsele H, Schafer HJ, Hebart H et al. Follow-up of patients with progressive multiple myeloma undergoing allografts after reduced-intensity conditioning. Br J Haematol 2003; 121: Lee CK, Badros A, Barlogie B et al. Prognostic factors in allogeneic transplantation for patients with high-risk multiple myeloma after reduced intensity conditioning. Exp Hematol 2003; 31: Majolino I, Corradini P, Scime R et al. High rate of remission and low rate of disease recurrence in patients with multiple myeloma allografted from their HLA-identical sibling donors. Bone Marrow Transplant 2003; 31: Kroger N, Zabelina T, Kruger W et al. In vivo T cell depletion with pretransplant anti-thymocyte globulin reduces graftversus-host disease without increasing relapse in good risk myeloid leukemia patients after stem cell transplantation from matched related donors. Bone Marrow Transplant 2002; 29: Orsini E, Bellucci R, Alyea EP et al. Expansion of tumorspecific CD8+ T cell clones in patients with relapsed myeloma after donor lymphocyte infusion. Cancer Res 2003; 63: Lim SH, Badros A, Lue C, Barlogie B. Distinct T-cell clonal expansion in the vicinity of tumor cells in plasmacytoma. Cancer 2001; 91: Chiriva-Internati M, Du J, Cannon M, Barlogie B, Yi Q. Myeloma-reactive allospecific cytotoxic T lymphocytes lyse target cells via the granule exocytosis pathway. Br J Haematol 2001; 112: Kolb HJ, Schattenberg A, Goldman JM et al. Graft-versusleukemia effect of donor lymphocyte transfusions in marrow grafted patients. European Group for Blood and Marrow Transplantation Working Party Chronic Leukemia. Blood 1995; 86: Slavin S, Naparstek E, Nagler A et al. Allogeneic cell therapy with donor peripheral blood cells and recombinant human interleukin-2 to treat leukemia relapse after allogeneic bone marrow transplantation. Blood 1996; 87: Kersey JH, Weisdorf D, Nesbit ME et al. Comparison of autologous and allogeneic bone marrow transplantation for treatment of high-risk refractory acute lymphoblastic leukemia. N Engl J Med 1987; 317: Sullivan KM, Weiden PL, Storb R et al. Influence of acute and chronic graft-versus-host disease on relapse and survival after bone marrow transplantation from HLA-identical siblings as treatment of acute and chronic leukemia. Blood 1989; 73: Gratwohl A, Hermans J, Apperley J et al. Acute graft-versushost disease: grade and outcome in patients with chronic myelogenous leukemia. Working Party Chronic Leukemia of the European Group for Blood and Marrow Transplantation. Blood 1995; 86: Mohty M, Kuentz M, Michallet M et al. Chronic graft versus host disease after allogeneic blood stem cell transplantation: long term results of a randomized study. Blood 2002; 100: