Volume 16, Issue 8 , Pages 1122-1129, August 2010
Reduced-Intensity Allogeneic Hematopoietic Stem Cell Transplantation for Relapsed Multiple Myeloma
Article Outline
Despite recent advances, multiple myeloma (MM) remains incurable, and most patients eventually develop progressive disease. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) offers a potentially curative option in 10%-20% of patients with relapsed or refractory disease. We evaluated the outcome of patients undergoing allo-HSCT with reduced-intensity conditioning (RIC) for relapsed and/or refractory MM at our institution. The study cohort included 51 patients with heavily pretreated, relapsed MM who underwent RIC allo-HSCT between 1996 and 2006. The median time from diagnosis to allo-HSCT was 34 months, and median follow-up in surviving patients was 27 months (range, 3-98 months). Cumulative transplantation-related mortality at 1 year was 25%. Progression-free survival (PFS) and overall survival (OS) at 2 years were 19% and 32%, respectively. The incidences of grade II-IV acute and chronic graft-versus-host disease were 27% and 47%, respectively. At the time of this analysis, 12 patients (24%) were alive, 7 of whom (14%) were in remission for up to 6 years after allo-HSCT. A lower β2 microglobulin level (<3.3) and previous autologous HSCT were predictive of lower nonrelapse mortality and longer PFS and OS. Our findings indicate that allo-HSCT with RIC is associated with acceptable toxicity and durable remission and survival in relapsed or refractory MM. The use of RIC allo-HSCT earlier in the course of the disease may offer the greatest benefit.
Key Words: Reduce intensity allogeneic transplant, Multiple myeloma, Relapse/refractory
Introduction
Multiple myeloma (MM) represents approximately 10% of all hematologic malignancies. The treatment of newly diagnosed MM has improved remarkably with the introduction of the novel therapies thalidomide, lenalidomide, and bortezomib 1, 2, 3, 4, 5, 6. High-dose therapy followed by single or tandem autologous hematopoietic stem cell transplantation (auto-HSCT) is a treatment option for patients under the age of 65 years 7, 8. Despite these advances, however, MM remains incurable, and most patients develop progressive disease (PD) within 5 years of auto-HSCT [9].
Allogeneic HSCT (allo-HSCT) offers a potentially curative option in 10%-20% of patients with relapsed or refractory MM 10, 11, 12, 13, mainly because of a tumor-free graft and a graft-versus-myeloma (GVM) effect. The GVM effect has been well documented and is thought to be mediated by donor-derived T lymphocytes 10, 11, 12. However, the high treatment-related mortality (TRM) with myeloablative (MA) conditioning regimens (up to 55%) neutralizes any potential benefit in terms of progression-free survival (PFS) and overall survival (OS), and limits the use of allo-HSCT in patients with advanced MM 12, 14, 15.
Reduced intensity conditioning (RIC) allo-HSCT offers the potential advantage of decreased TRM, whereas it preserves the GVM effect 16, 17. Only limited information is available on the outcomes of RIC allo-HSCT in patients with advanced and heavily pretreated MM. In this retrospective single-center study, we evaluated the outcomes of RIC allo-HSCT in 51 heavily pretreated patients with relapsed and/or refractory disease.
Patients and Methods
Patients
The study cohort included 51 patients with MM who had relapsed disease and underwent RIC allo-HSCT from a matched related or unrelated donor between 1996 and 2006. Patients were eligible for allo-HSCT if they were aged 18-70 years and had a performance status of 0 or 1, adequate organ function, and no uncontrolled infection.
Hematopoietic Stem Cell Collection
Donor bone marrow (BM) or granulocyte colony-stimulating factor (G-CSF)–primed peripheral blood (PB) progenitor cells were collected using standard mobilization protocols and apheresis techniques. BM from unrelated donors was obtained through the National Marrow Donor Program (NMDP) according to standard guidelines. All patients provided written informed consent in accordance with guidelines of the University of Texas M.D. Anderson Cancer Center (MDACC) and the NMDP. The study design was reviewed and approved by the MDACC's Institutional Review Board.
Preparative Regimen and Supportive Care
The RIC regimen consisted of fludarabine (Flu) 90-120 mg/m2 and melphalan 90-140 mg/m2. The definition of RIC conditioning was based on published guidelines and recommendations [18]. All patients receiving unrelated donor progenitor cells also received antithymocyte globulin (ATG) as part of their preparative regimen [19]. Graft-versus-host disease (GVHD) prophylaxis consisted of a combination of tacrolimus and methotrexate. Patients received infection prophylaxis with levaquin or ciprofloxacin, voriconazole or fluconazole, and acyclovir or valacyclovir. Filgrastim 5 μg/kg was administered s.c. daily from day 7 after allo-HSCT until the recovery of absolute neutrophil count (ANC) to >1.5 × 109/L for 3 days. Blood products were irradiated and filtered to remove leukocytes before transfusion. After recovery of ANC, patients received prophylaxis against Pneumocystis jiroveci (formerly Pneumocystis carini) infection with oral sulfamethoxazole-trimethoprim twice weekly or i.v. pentamidine every 3 weeks.
Engraftment and Chimerism
Engraftment was defined as the first of 3 consecutive days with an ANC ≥0.5 × 109/L. Failure to engraft by day 30 was considered primary graft failure. Platelet engraftment was defined as the first of 7 consecutive days with a platelet count ≥20 × 109/L without transfusion support. PB or BM donor–recipient chimerism was performed on days 30 and 100 posttransplantation, and as clinically indicated thereafter, through analysis of DNA microsatellite polymorphisms by polymerase chain reaction with D6S264, D3S1282, D18S62, and D3S1300 fluorescence-labeled primers and through conventional cytogenetic analysis by G-banding or fluorescent in situ hybridization studies for the Y chromosome in sex-mismatched cases.
Response and Outcome
Response, relapse, and disease progression were defined based on the international uniform response criteria for MM [20]. Complete response (CR) was defined as negative immunofixation on the serum and urine, <5% plasma cells in BM, and absence of any plasmacytomas or soft tissue lesions. Very good partial response or major response (VGPR/MR) was serum and urine monoclonal protein (M-protein) detectable by immunofixation but not by electrophoresis, or at least a 90% reduction in serum M-protein, and urine M-protein <100 mg/24 hours. Partial response (PR) was defined as at least a 50% reduction of serum M-protein, at least a 50% reduction in the size of soft tissue plasmacytomas if present at baseline, and at least a 90% reduction in 24-hour urinary M-protein. Response criteria had to be met on at least 2 assessments at least 6 weeks apart. PD was defined as an increase in serum M-protein or urine light chains of ≥20% in patients with refractory or stable disease (SD). Relapse was defined the reappearance of serum M-protein, urine light chains, or BM infiltration in patients in previous CR, or at least a 25% increase in any marker in patients in PR. SD was defined as not meeting the criteria for CR, VGPR, PR, or PD.
Statistical Methods
Primary endpoints were Kaplan-Meier estimates of OS and PFS. Secondary endpoints were TRM, relapse, and incidence of acute and chronic GVHD (aGVHD, cGVHD). OS was measured from the day of allo-HSCT (day 0) to death from any cause, with censoring performed at the date of last contact. PFS was determined from the day of stem cell infusion to the day of documented relapse or progression. Death from any cause other than relapse was classified as TRM. GVHD occurring any time after day 90 posttransplantation was considered cGVHD; otherwise, it was aGVHD. Standard criteria were used for the diagnosis and grading of aGVHD and cGVHD [21]. The incidences of disease progression, TRM, aGVHD, and cGVHD were estimated using the cumulative incidence method, accounting for competing risk. Statistical significance was determined at P = .05. Analysis was performed using Stata 7.0 (StataCorp, College Station, TX).
Results
Patient Characteristics
Between 1996 and 2006, 51 patients with relapsed or refractory multiple myeloma underwent allo-HSCT using an RIC regimen at MDACC. Patient characteristics are summarized in Table 1. At the time of transplantation, 55% of the patients were in at least partial remission (CR, 4%; VGPR, 6%; PR, 45%). The median patient age was 51 years (range, 32-65 years), and median time from diagnosis to transplantation was 34 months (range, 9-232 months). Thirty-six patients (70%) had undergone previous auto-HSCT, including 5 (10%) with 2 previous auto-HSCTs. The median number of previous regimens was 5 (range, 1-10). The stem cell source was PB in 41 patients (80%) and matched related donor stem cells in 40 patients (78%). Chromosomal analysis results were available for 40 of the 51 patients before allo-HSCT. Twelve patients had cytogenetic abnormalities (3 patients with 13p deletion, 2 patients with 1q abnormality, 2 patients with 17p deletion and the rest having complex abnormalities), and 28 patients had normal cytogenetics.
Table 1. Patient Characteristics
| Age, years, median (range) | 51 (32-65) |
| Females/males, n | 24/27 |
| Immunoglobulin class, n (%) | |
 IgG | 29 (57) |
| IgA | 8 (16) |
| IgM | 1 |
| Light chain only | 10 (20) |
| Nonsecretory | 2 |
| Unknown | 1 |
| Stage at initial diagnosis, n (%) | |
| I | 5 |
| II | 14 (27) |
| III | 30 (59) |
| Unknown | 2 |
| Disease status at transplantation, n (%) | |
| Complete response | 2 (4) |
| Very good partial response | 3 (6) |
| Partial response | 23 (45) |
| Stable disease | 14 (27) |
| Progressive disease | 8 (16) |
| Unknown/not evaluated | 1 (2) |
| Previous regimens, median (range) | 5 (1-10) |
| Previous auto-HSCT, n (%) | 36 (70) |
| One | 31 |
| Two | 5 |
| Time from diagnosis to allo-HSCT, months, median (range) | 34.4 (9.8-232.2) |
| HSCT source, n (%) | |
| Peripheral blood | 41 (80) |
| Bone marrow | 10 (20) |
| Donor type, n (%) | |
| Related donor | 40 (78) |
| Unrelated donor | 11 (22) |
| Year of allo-HSCT, n (%) | |
| 1996-2000 | 15 (29) |
| Beyond 2000 | 36 (71) |
| DLIs, n (%) | 12 (22) |
Engraftment
All 51 patients (100%) achieved engraftment. The median times to neutrophil and platelet engraftment were 13 days (range, 9-25 days) and 15 days (range, 10-28 days), respectively. The median percentage of donor cells at day 30 posttransplantation was 100% (range, 95%-100%).
Response
Overall, 12 patients (23%) achieved CR and 26 patients (51%) achieved PR, with an overall response rate of 74% after RIC allo-HSCT. Three patients (6%) had minimal response (<50%), and 4 patients (8%) had SD. Two of the 3 patients with a VGPR before transplantation achieved CR after RIC allo-HSCT. Of the 23 patients in PR before allo-HSCT, 4 (17%) achieved CR, 1 developed PD, and the rest remained in PR. Of the 14 patients in SD before allo-HSCT, 3(21%) achieved CR and 7 (50%) achieved PR/VGPR. Of the 8 patients with PD at allo-HSCT, 1 achieved CR and 3 achieved PR, with an overall response of 50% in this group. Seven patients who underwent allo-HSCT from a matched related donor received a total of 12 donor lymphocyte infusions (DLIs) for persistent disease, PD, or relapse after allo-HSCT. One patient with persistent disease achieved CR, and 1 patient with PD achieved VGPR after a single DLI; the rest had no response. Table 2 summarizes cell doses, intervals between HSCT and DLI, intervals between DLIs, and responses.
Table 2. DLI and Outcome
| Patient | DLIs, n | Cell Dose (CD3+ × 107/kg) | Reason for DLI Post-HSCT | Interval from HSCT to DLI, Days | Interval Between DLIs, Days | Response Status Post- DLI |
|---|---|---|---|---|---|---|
| 1 | 2 | 1.0; 3.85 | Persistent disease; PD | 391 | 478 | PD |
| 2 | 4 | Unknown; 0.3; 3.0; unknown | Persistent disease; PD | 97 | 197 | PD |
| 3 | 1 | Unknown | Persistent disease; PD | 132 | - | CR |
| 4 | 2 | Unknown | Relapse | 338 | 77 | PD |
| 5 | 1 | Unknown | VGPR | 109 | - | VGPR |
| 6 | 1 | 3.3 | PD | 198 | - | PD |
| 7 | 1 | 1.4 | PD | 450 | - | VGPR |
GVHD
The cumulative incidence of grade II-IV aGVHD was 27% (Table 3). Grade II aGVHD was seen in 16%; grade III-IV aGVHD, in 11%. The cumulative incidence of cGVHD was 47%, with limited cGVHD seen in 23% of patients. The use of unrelated donor or PB stem cells (PBSCs) as the graft source did not increase the incidence of aGVHD or cGVHD, possibly due to the small number of patients with unrelated donors (n = 11) and BM stem cells (n = 10).
Table 3. Response Rate, TRM, Relapse, and GVHD
| Time to neutrophil engraftment, days, median (range) | 13 (9-25) |
| Time to platelet engraftment, days, median (range) | 15 (10-28) |
| 100-day TRM, n (%) | 6 (12) |
| Cumulative 1-year TRM, n (%) | 13 (25) |
| Overall response rate | 74% (CR, 23%; PR, 51%) |
| Relapse at 2 years, n (%) | 25 (49) |
| Median PFS, months | 6.8 |
| 2 year PFS, % | 19 |
| Median OS, months | 13.9 |
| 2-year OS, % | 32 |
| Acute GVHD grade II-IV, n (%) | 14 (27) |
| Chronic GVHD, limited or extensive, % | 47% |
| Deaths, n (%) | 39 (76) |
| Disease recurrence | 22 (43) |
| Acute or chronic GVHD | 10 (20) |
| Infection | 3 (6) |
| Other | 4 (8) |
TRM
The 100-day TRM was 12%, and the 1-year TRM was 25%. At the time of this analysis, 12 patients (24%) were still alive; of these, 7 (14%) had been in remission for up to 6 years after allo-HSCT. The most common causes of death were recurrent disease (22 patients; 43%), aGVHD or cGVHD (10 patients; 20%), and opportunistic infections (3 patients; 6%) (Table 3).
Survival and Prognostic Features
The median follow-up for surviving patients was 27 months (range, 3-98 months). Twenty-five patients (49%) had relapsed at 2 years. Seven patients had received a total of 12 DLIs. The use of DLI did not contribute to improved PFS and OS on multivariate and univariate analyses, perhaps because of the small number of patients who received DLI. The 2-year PFS and OS were 19% and 32%, respectively (Figure 1). On univariate analyses, a lower β2 microglobulin (<3.3mg/L) and previous auto-HSCT predicted longer PFS and OS (Table 4). These 2 factors also emerged as predictors of longer PFS and OS on multivariate analysis (Table 5). Age, immunoglobulin subtype, serum lactate dehydrogenase (LDH) level, serum albumin level, stem cell source, donor type, use of DLI, interval between diagnosis and allo-HSCT, and interval between auto-HSCT and allo-HSCT did not emerge as statistically significant predictors of outcome.
Figure 1
PFS and OS of patients undergoing RIC allo-HSCT.
Table 4. Univariate Factors Affecting NRM, PFS, and OS in the RIC Group
| NRM | OS | PFS | ||||
|---|---|---|---|---|---|---|
| Pre-HSCT Factors | HR (95% CI) | P | HR (95% CI) | P | HR (95% CI) | P |
| Age at HSCT, years | ||||||
| ≤50 | ||||||
| >50 | 0.3 (0.1-1.6) | .2 | 0.8 (0.4-1.7) | .6 | 0.8 (0.4-1.5) | .4 |
| IgG(mg/dL) | ||||||
| ≤1600 | ||||||
| >1600 | 1.1 (0.2-5.5) | .9 | 1.4 (0.7-2.9) | .3 | 1.4 (0.7-2.8) | .3 |
| β2m(mg/L) | ||||||
| ≤3.3 | ||||||
| >3.3 | 7 NRM | .01 | 3.1 (1.5-6.4) | .002 | 2.6 (1.3-5.1) | .005 |
| LDH(U/L) | ||||||
| ≤618 | ||||||
| >618 | 0.5 (0.1-4.6) | .6 | 0.7 (0.3-1.8) | .5 | 0.9 (0.4-1.9) | .8 |
| Albumin(g/dL) | ||||||
| ≤3.5 | ||||||
| >3.5 | 0.6 (0.1-2.6) | .5 | 0.7 (0.3-1.4) | .3 | 0.7 (0.4-1.4) | .4 |
| Response pre-HSCT | ||||||
| CR/PR | 0.7 (0.2-3.2) | .6 | 1.1 (0.6-2.2) | .7 | 1.1 (0.6-2.1) | .7 |
| Other | ||||||
| Cytogenetics pre-HSCT | ||||||
| High risk | 1.9 (0.4-11) | .4 | 2.1 (0.9-4.7) | .08 | 1.8 (0.8-3.9) | .1 |
| Other | ||||||
| Previous auto-HSCT | ||||||
| No | 17 (2.0-142) | .009 | 2.2 (1.1-4.5) | .03 | 1.8 (0.9-3.4) | .08 |
| Yes | ||||||
| Donor type | ||||||
| Related | 0.3 (0.1-1.5) | .1 | 0.7 (0.3-1.6) | .5 | 0.9 (0.4-1.9) | .9 |
| Unrelated | ||||||
| Graft source | ||||||
| Peripheral blood | 1.5 (0.2-12) | .7 | 0.9 (0.4-2.1) | .9 | 1.1 (0.5-2.3) | .9 |
| Bone marrow | ||||||
| Months from diagnosis to HSCT | ||||||
| ≤24 | ||||||
| >24 | 0.4 (0.1-1.8) | .2 | 0.5 (0.2-1.1) | .07 | 0.6 (0.3-1.1) | .1 |
| Months from auto-HSCT to allo-HSCT | ||||||
| ≤24 | ||||||
| >24 | 0.9 (0.3-2.1) | .8 | 0.6 (0.3-1.4) | .2 | ||
Table 5. Multivariate Factors Affecting OS and PFS in the RIC Group
| OS | PFS | |||
|---|---|---|---|---|
| Factors | HR (95% CI) | P | HR (95% CI) | P |
| β2m | ||||
| ≤3.3 | ||||
| >3.3 | 3.3 (1.6-6.9) | .002 | 2.7 (1.4-5.3) | .004 |
| Previous auto-HSCT | ||||
| No | 2.8 (1.3-5.9) | .01 | 1.9 (0.9-3.9) | .06 |
| Yes | ||||
The major differences between the long-term survivors (12 patients) and others were a lower β2 microglobulin level (median, 2.45 vs 3.5; P = .01) and more previous auto-HSCTs (92% vs 64%; P = .08) in the long-term survivor group (Table 6).
Table 6. Characteristics of Long-Term Survivors and Others
| Long-Term Survivors (n = 12) | Others (n = 39) | |
|---|---|---|
| Age, years, median (range) | 51 (32-55) | 52 (41-65) |
| Females/males | 6/6 | 18/21 |
| Immunoglobulin class, n (%) | ||
| IgG | 6 (50) | 23 (59) |
| IgA | 2 (17) | 6 (15) |
| IgM | 1 | 0 |
| Light chain only | 3 (25) | 7 (18) |
| Nonsecretory | 0 | 2 |
| Unknown | 0 | 1 |
| Stage at initial diagnosis, n (%) | ||
| I | 0 | 5 (19) |
| II | 4 (33) | 10 (25) |
| III | 7 (58) | 23 (59) |
| Unknown | 1 | 1 |
| Cytogenetics | ||
| Normal | 4 (33) | 24 (62) |
| 13p deletion | 0 | 3 (8) |
| 1q abnormality | 0 | 2 (5) |
| 17p deletion | 0 | 2 (5) |
| Other | 3 | 2 |
| Unknown | 5 | 6 |
| B2m, median (range) | 2.45 (1.8-4.9) | 3.5 (1.0-8.2) |
| Disease status at HSCT, n (%) | ||
| CR | 2 (17) | 0 |
| VGPR | 1 (8) | 2 (5) |
| PR | 4 (33) | 19 (49) |
| SD | 2 (17) | 12 (31) |
| PD | 2 (17) | 6 (15) |
| Unknown/not evaluated | 1 | 0 |
| Previous regimens, n, median (range) | 5 (2-10) | 5 (1-10) |
| Previous auto-HSCT, n (%) | 11 (92) | 25 (64) |
| One | 8 | 23 |
| Two | 3 | 2 |
| Performance status | 0-1 | 0-1 |
| Time from diagnosis to allo-HSCT, months, median (range) | 40.2 (19.8-89.1) | 34.0 (9.8-232.2) |
| HSCT source, n (%) | ||
| Peripheral blood | 9 (75) | 32 (82) |
| Bone marrow | 3 (25) | 7 (18) |
| Donor type, n (%) | ||
| Related donor | 9 (75) | 31 (79) |
| Unrelated donor | 3 (25) | 8 (21) |
| Year of allo-HSCT, n (%) | ||
| 1996-2000 | 2 (17) | 13 (33) |
| Beyond 2000 | 10 (83) | 26 (66) |
| DLIs, n (%) | 2 (17) | 10 (25) |
Discussion
Despite recent progress in the treatment of MM, the disease remains incurable. The response duration decreases with each successive relapse and salvage, reflecting acquired drug resistance. Before the advent of novel therapies, event-free survival (EFS) was 7 months for patients undergoing a second-line regimen and 3 months for those undergoing a sixth-line regimen [22]. Novel therapies have improved this dismal outcome. In 289 relapsed patients who had received thalidomide, lenalidomide, or bortezomib at some point after relapse, the median and 2-year OS were 23.9 months and 49%, compared with 11.8 months and 24% in 98 patients who had not received these drugs at relapse [6]. Despite this improvement, however, EFS in most patients with persistent or refractory disease is only 6-14 months 23, 24, 25, 26. These numbers highlight the need for more effective therapy, especially in patients with good performance status.
Allografting is a potentially curative option for selected patients with relapsed or refractory multiple myeloma, in part because of a tumor-free graft and a GVM effect 10, 11, 12, 27, 28. The increased TRM achieved using MA regimens offsets any improvement in EFS and OS 12, 14, 15, 29. Randomized studies using RIC allo-HSCT in combination with autologous transplant (auto-RIC allo-HSCT) have been performed mainly in newly diagnosed patients with a matched related donor 30, 31, 32. These studies compared tandem auto-HSCT and auto-RIC allo-HSCT. Although the auto-RIC allo-HSCT group had a higher rate of CR, 2 of the 3 studies found no difference in EFS and OS between the 2 groups, mainly because of increased TRM 30, 32. The discrepant results might be explained by differences in study design. In the Spanish trial, only patients failing to achieve near CR after a first auto-HSCT were included, and the conditioning regimen comprised Flu and melphalan [30]. In the Italian study, all patients were included regardless of prognostic factors and disease status after a first auto-HSCT, and the conditioning regimen was 2 Gy total body irradiation [31]. In the French study, only patients with high-risk features (β2 microglobulin >3 mg/L and 13q- deletion) were included, and the conditioning regimen comprised busulfan, Flu, and ATG [32]. The high TRM was attributed to profound immunosuppression from the previous auto-HSCT, which was exacerbated by opportunistic infections and GVHD resulting from RIC allo-HSCT. Given the lack of an unequivocal benefit, the role of RIC allo-HSCT in front-line therapy is considered experimental, and these transplantations should be performed only as part of well-designed clinical trials in the highest-risk patients [33].
Retrospective studies of RIC allo-HSCT for relapsed or refractory MM have demonstrated decreased TRM with maintenance of the GVM effect 16, 17, 34, 35, 36, 37. Most of these reports were based on a small number of patients, however, with the exception of a European Group for Blood and Marrow Transplantation (EBMT) study [16]. That study included 229 patients who underwent RIC allo-HSCT, of whom 168 were beyond first remission and 169 had undergone previous auto-HSCT. TRM was 11% at 100 days and 22% at 1 year. The response rate (CR + PR) was 73%, and 3-year OS and PFS were 41% and 21%, respectively. Ninety-three patients (41%) relapsed or progressed; 80 of these patients went on to receive DLI, with 63% obtaining CR or PR after DLI [16]. Other studies conducted with much smaller sample sizes (19-45 patients) have yielded similar TRM and response outcomes. Poor prognostic factors for outcome included chemoresistant disease, disease beyond first remission, more than one previous auto-HSCT, and a ≥1-year interval between diagnosis and HSCT 16, 34.
In our study, the 100-day TRM was 12% and the 1-year TRM was 25%, comparable to the percentages found in the EMBT series [16]. The response rate was 74% (CR, 23%; PR, 51%), similar to what was seen in previous studies 16, 17, 34. The incidence of GVHD was not adversely affected by the use of unrelated donors or PBSCs. This might be attributed to the use of high-resolution molecular HLA typing and the use of ATG for GVHD prophylaxis [19]. The 2-year OS was 32%, comparable to that found in previous series, although our patients generally had more advanced disease.
We emphasize that compared with the EBMT study, the patients in our series were more heavily pretreated and had a longer median time from diagnosis to allo-HSCT (34 months vs 18 months). Age, immunoglobulin subtype, disease status, serum LDH, serum albumin, stem cell source, donor type, use of DLI, interval between diagnosis and allo-HSCT, or interval between auto-HSCT and allo-SCT did not emerge as statistically significant predictors of outcome. We recognize that some of these analyses suffer from the known limitations of a retrospective analysis, including small sample size, heterogeneous patient population, and missing data. The ongoing multicenter Bone Marrow Transplant-Clinical Trial Network (BMT-CTN) BMT-CTN trial comparing tandem auto-HSCT with and without maintenance therapy versus single auto-HSCT followed by RIC allo-HSCT in patients with newly diagnosed MM will help define the role of RIC allo-HSCT in this patient population.
In conclusion, our data indicate that allo-HSCT after RIC regimens in selected patients with advanced MM is associated with durable PFS and OS and a lower TRM compared with allo-HSCT after MA regimens. RIC regimens in patients with advanced MM do not increase the risk of relapse or the incidence of aGVHD and cGVHD. The application of RIC allo-HSCT earlier in the course of the disease may be of greater benefit in selected patients.
Acknowledgments
Financial disclosure: The authors have nothing to disclose.
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Financial disclosure: See Acknowledgments on page 1128.
PII: S1083-8791(10)00086-8
doi:10.1016/j.bbmt.2010.02.015
© 2010 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.
Volume 16, Issue 8 , Pages 1122-1129, August 2010
