Abstract
Background
Allogeneic stem cell transplantation (allo‐SCT) has curative potential and was previously considered by several experts superior to autologous stem cell transplantation (auto‐SCT) for patients with multiple myeloma relapsing after first‐line auto‐SCT.
Methods
The authors conducted a comprehensive literature review of English‐language studies published from 1995 to October 2024. Five studies comparing allo‐SCT with second auto‐SCT following first line auto‐SCT in multiple myeloma were included. Two additional studies comparing patients with or without a suitable allo‐SCT donor after relapse were analyzed separately. Individual data from 815 patients were obtained from two large databases: the Japan Society for Hematopoietic Stem Cell Transplantation and the Center for International Blood & Marrow Transplant Research (CIBMTR). Data from five smaller studies (three comparing allo‐vs. auto‐SCT and two comparing donor vs. no‐donor groups) presented via Kaplan–Meier curves were digitized using the Shiny app. Meta‐analyses were performed using R 4.3.3. Kaplan–Meier and log‐rank tests for overall survival (OS) and progression‐free survival (PFS) were conducted in SPSS.
Results
Individual patient data analysis showed significantly longer OS in the auto‐SCT group. This benefit was consistent in the three smaller studies. PFS was also superior for auto‐SCT in the CIBMTR data set and the pooled smaller studies. In the two‐donor vs. no‐donor studies, the donor group showed better PFS, with OS also improved when data were combined.
Conclusions
Allo‐SCT after relapse from first line auto‐SCT resulted in inferior OS and PFS compared to a second auto‐SCT. These findings indicate that allo‐SCT should no longer be recommended in patients with multiple myeloma relapsing after first line auto‐SCT.
Keywords: allogeneic stem cell transplantation, autologous stem cell transplantation, multiple myeloma, relapsed/refractory myeloma, second‐line therapy
The authors compared allogeneic (allo‐SCT) with autologous stem cell transplantation (auto‐SCT) in patients who relapsed after first‐line auto‐SCT. The results showed significantly better progression‐free and overall survival with auto‐SCT.
INTRODUCTION
The majority of patients who receive an autologous stem cell transplant (auto‐SCT) as part of their initial therapy eventually relapse at some point. Today, there are many effective treatments for relapse, but only a fraction of the more than 110,000 myeloma patients diagnosed worldwide each year have access to new drugs or cellular immunotherapies. At first relapse, a second autologous transplant is an effective treatment for patients with long progression‐free survival (PFS), with response rates increasing as the interval between the two procedures increases. 1 Allogeneic transplantation (allo‐SCT) is the precursor to the recently introduced cellular immunotherapies, is associated with response rates comparable to auto‐SCT, and results in long‐term disease control in a small number of patients. 2 , 3 The main limitations of allo‐SCT are treatment‐related mortality and acute and chronic graft‐versus‐host disease (GVHD). 4 Although the use of allo‐SCT as a salvage therapy has declined significantly with introduction of novel treatments, 5 a group of American and European bone marrow transplantation experts published a consensus statement in 2015 recommending consideration of allo‐SCT as an option after the first relapse following auto‐SCT 6 because of the possibility of benefit from the graft‐versus‐myeloma effect with the hope of curing patents. 7 Recently, a prospective trial was initiated in Germany, randomizing 280 patients to an allo‐SCT or to conventional therapy in patients who have relapsed after first‐line auto‐SCT. 8 Because results will not be available before several years, we aimed to clarify the benefit of both treatment approaches. We reviewed and pooled the results of trials comparing auto‐SCT and allo‐SCT in terms of PFS and overall survival (OS). We considered individual patient data from two large study groups 9 , 10 and data obtained by digitizing survival curves from three smaller studies. 11 , 12 , 13 In addition, we analyzed two studies with biological randomization to a donor for allo‐SCT or no donor. The latter group received different, conventional, or no therapies after relapse to first‐line auto‐SCT. 14 , 15
MATERIALS AND METHODS
We searched the electronic databases of PubMed, Embase, the Cochrane Library, and Up to Date. Searches were restricted to publications in English language from 1995 until October 2024. The following search terms were used: “allogeneic,” “transplantation,” “autologous,” “myeloma,” “plasma cell disease,” and “relapsed/refractory” (Figure S1). Searches were conducted independently by two reviewers, who then convened to reach consensus on the relevance of the retrieved articles for this review. The retrieved manuscripts were tabulated (Tables 1 and 2), including inclusion/exclusion criteria and other relevant study details. Only five studies were retrieved that fulfilled the requirements of comparisons between allogeneic and autologous transplantation for relapsed disease after initial autologous transplantation. 9 , 10 , 11 , 12 , 13 Two studies compared the outcome of patients with a suitable donor for an allo‐SCT with patients without a donor. 15 , 17 Because treatment was not given or only partly specified in the no‐donor group, those studies are reported separately. One study 16 was excluded from this analysis because patients had at least two prior therapies before transplantation for relapse after first line auto‐SCT. 16 Individual patient data were available from 526 patients included in the registry of the Japan Society for Hematopoietic Cell Transplantation 10 , 16 and from 289 patients of the Center for International Blood and Marrow Transplant Research registry, 9 whereas data from the other three studies were extracted from figures in the original publications, 11 , 12 , 13 which included 170 patients. The online application Shiny was used for extraction of individual patient data. 18 To minimize bias and to provide an overview of steps taken, a Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) checklist was completed (Table S1). The risk of bias in the included studies was studied by Funnel plots (Figures S2A,D).
TABLE 1.
Studies comparing allo‐SCT with auto‐SCT in patients after relapsing from initial auto‐SCT.
| Authors and reference | Type of SCT | No. of patients | Age (years) | NRM (%) a | ≥VGPR after transplant | ORR after transplant | PFS | OS | Comments |
|---|---|---|---|---|---|---|---|---|---|
| Freytes 2014 9 | Auto | 137 | 56 (28–65) | 4 | NA | NA | 4% at 5 years | 29% at 5 years | Nonmyeloablative or RIC b conditioning, data from the CIBMTR registry |
| Allo | 152 | 53 (32–65) | 15 | NA | NA | 2% at 5 years | 9% at 5 years | ||
| Mehta 1998 11 | Auto | 42 | 56 (36–71) | 10 | 33% | 81% | NA | 54% at 3 years | Ablative conditioning |
| Allo | 42 | 45 (29–59) | 43 | 41% | 62% | NA | 29% at 3 years | Case‐matched series | |
| Qazilbash 2006 12 | Auto | 14 | 52 (37–69) | 7 | 21% | 64% | 6.8 months | 29.5 months | RIC conditioning, retrospective, not case controlled |
| Allo | 26 | 51 (32–65) | 11 | 31% | 69% | 7.3 months | 13.0 months | ||
| Wirk 2013 13 | Auto | 27 | 62 (32–69) | 3.7 | 56% | 81% | 19 months | 23 months | Several conditioning regimens, retrospective, only first relapse |
| Allo | 19 | 54 (43–63) | 5.3 | 37% | 58% | 6 months | 19 months | ||
| Ikeda 2019 10 | Auto | 334 | 18.9% <50 years old | 12 | NA | NA | NA | 33.7% at 5 years | Registry data of the Japan Society for Hematopoietic Cell Transplantation (2001–2015) |
| Allo | 192 | 34.9% <50 years old | 32 | NA | NA | NA | 23.8% at 5 years | ||
| Steiner 2022 16 | Auto | 41 | 56 (35–70) | 5 | NA | NA | 21% at 5 years | 54% at 5 years | Two or more therapies before transplantation for relapse after first line auto‐SCT (exclusion from analysis) |
| Allo | 34 | 49 (36–59) | 45 | NA | NA | 14% at 5 years | 17% at 5 years |
Abbreviations: allo‐SCT, allogeneic stem cell transplantation; auto‐SCT, autologous stem cell transplantation; CIBMTR, Center for International Blood & Marrow Transplant Research; NA, not available; NRM, nonrelapse mortality; ORR, objective response rate; OS, overall survival; PFS, progression‐free survival; RIC, reduced‐intensity conditioning; SCT, stem cell transplantation; VGPR, very good partial response.
Non‐relapse mortality.
Reduced intensity.
TABLE 2.
Trials comparing allo‐SCT in patients with donors versus those without a donor and no or various rescue treatments.
| Authors and reference | Type of SCT | No. of patients | Age (years) | NRM (%) a | ≥VGPR after transplant | ORR after transplant | PFS | OS | Comments |
|---|---|---|---|---|---|---|---|---|---|
| De Lavallade 2008 15 | No donor | 13 | 54 (46–65) | 0 | NA | NA | 8% at 3 years | 50% at 3 years | Donor vs. no donor comparison; RIC conditioning; multiple lines of therapy |
| Allo | 19 | 54 (37–63) | 33 | 28% | 83% | 46% at 3 years | 49% at 3 years | ||
| Patriarca 2018, 2012 14 , 17 | No donor | 90 | 59 (31–73) | NA | NA | NA | 0% at 7 years | 9% at 7 years | Donor vs. no donor comparison on consecutive patients at first relapse after auto‐SCT who had HLA typing |
| Allo | 79 | 55 (34–69) | 27 | NA | NA | 18% at 7 years | 31% at 7 years |
Abbreviations: allo‐SCT, allogeneic stem cell transplantation; auto‐SCT, autologous stem cell transplantation; NA, not available; NRM, nonrelapse mortality; ORR, objective response rate; OS, overall survival; PFS, progression‐free survival; RIC, reduced‐intensity conditioning; SCT, stem cell transplantation; VGPR, very good partial response.
Nonrelapse mortality.
Meta‐analyses were performed in R 4.3.3 (R Core Team, package 7.3.0 and 7.0.0) based on a restricted maximum‐likelihood model (common effects) including 95% confidence intervals. The pooled log hazard ratios (HRs) were tested for significant divergence from 0 using z tests (two‐sided). Heterogeneity was tested using Q tests and quantified as I2 percentage. Additionally, a Kaplan–Meier and log‐rank test analysis of the pooled OS and PFS data was conducted in SPSS Statistics for Windows (version 17.0; SPSS Inc, Chicago, Illinois).
RESULTS
PFS and OS in patients with individual data available
The included studies are summarized in Tables 1 and 2, with individual patient data available from two large data sets. 9 , 10 The most recent study retrospectively compared 335 patients who underwent auto‐SCT with 192 patients who received allo‐SCT after first relapse. 10 , 19 Significant imbalances were observed: the allo‐SCT group was younger (p < .01) but had fewer standard‐risk chromosomal abnormalities (64.1% vs. 75.7%, p < .01), a lower response rate to re‐induction before transplantation (50% vs. 67.4%, p < .01), and a shorter interval between the first and second SCT (p < .01). Although response and PFS data were not reported, OS was significantly shorter in the allo‐SCT group (14.5 vs. 36.9 months, p < .001) (Figure 1A). Patients were stratified into three risk groups based on response to re‐induction therapy, performance status, and interval between transplants. In the intermediate‐risk group, auto‐SCT showed a significant OS benefit (p < .0001), whereas no difference was observed in the low‐ and high‐risk groups. Among low‐risk allo‐SCT patients, 16 of 21 appeared to reach a survival plateau.
FIGURE 1.
(A) Overall survival of patients receiving allo‐SCT or auto‐SCT using individual patient data from the JSHCT registry. (B) Progression‐free survival and (C) overall survival of patients receiving allo‐SCT or auto‐SCT using individual patient data from the CBMTR registry. (D) Combined results from both registries. allo‐SCT indicates allogeneic stem cell transplantation; auto‐SCT, autologous stem cell transplantation; CIBMTR, Center for International Blood & Marrow Transplant Research; JSHCT, Japan Society for Hematopoietic Cell Transplantation.
Another study using Center for International Blood & Marrow Transplant Research (CIBMTR) data 9 included 289 patients, revealing relevant imbalances before transplantation. The nonmyeloablative/reduced‐intensity conditioning (RIC) allo‐SCT group (n = 152) was younger (median 53 vs. 56 years, p < .001), had a lower complete remission rate at transplantation (1% vs. 39%, p < .001), shorter time to first relapse (12 vs. 17 months, p = .009), and a shorter interval between transplants (23 vs. 30 months, p = .014), all favoring auto‐SCT. Nonrelapse mortality (NRM) was significantly higher with RIC allo‐SCT (14% vs. 4%, p = .001), whereas auto‐SCT resulted in superior PFS (10.5 vs. 3.2 months, p < .001) (Figure 1B) and OS (29.8 vs. 12.2 months; p < .001) (Figure 1C). Figure 1D shows survival of data from both studies combined favoring the auto‐SCT group (35.1 vs.13.4 months, p < .001).
PFS and OS of studies with digitized data
Several studies reported results via Kaplan–Meier curves. 11 , 12 , 13 One compared 42 patients who underwent allo‐SCT after failing to achieve at least a partial remission following first‐line auto‐SCT with 42 pair‐matched patients receiving a second auto‐SCT. 11 Auto‐SCT patients were older (median 56 vs. 45 years, p < .0001), had higher β2‐microglobulin levels (2.4 vs. 1.8 mg/L, p < .005), and a shorter interval between transplants (7 vs. 6 months, p = .02). The auto‐SCT group showed a significantly higher response rate (81% vs. 62%, p = .054), and a tendency for improved PFS (median 18.7 vs. 10.5 months, p = .48) (Figure 2A). TRM within the first year was significantly higher for allo‐SCT (43.3% vs. 10%, p = .0001), contributing to shorter OS (median 14.2 vs. 47.2 months, p = .003) (Figure 2E).
FIGURE 2.
Progression‐free survival (A–D) and overall survival (E–H) of patients receiving allo‐SCT or auto‐SCT in the studies with digitized data (A and E: Mehta; 11 B and F: Qazilbash; 12 C and G: Wirk; 13 D and H: three studies combined). allo‐SCT indicates allogeneic stem cell transplantation; auto‐SCT, autologous stem cell transplantation.
Another study 12 compared 26 patients receiving RIC allo‐SCT with 14 matched auto‐SCT patients after first‐line failure. Response rates were 64% and 69%, respectively, with early nonrelapse mortality of 7% for auto‐SCT and 11% for allo‐SCT. With longer follow‐up, 27% of RIC allo‐SCT patients died from nonrelapse causes. Grade 2–4 acute GVHD occurred in 31%, and chronic GVHD in 42%. Median PFS and OS were 8.1 and 29.5 months for auto‐SCT, and 6.7 and 13.3 months for RIC allo‐SCT (Figure 2B,F); OS was significantly longer in the auto‐SCT group (p = .02).
A separate retrospective study 13 of 19 allo‐SCT (16 RIC) and 27 auto‐SCT patients after first‐line relapse found significant differences: allo‐SCT patients were younger (median 54 vs. 62 years, p = .002) and had better Karnofsky peformance status (≥70%, p = .031), although the interval between SCTs was shorter (21 vs. 30 months). Response rates were 82% (≥very good partial response [VGPR] 56%) in allo‐SCT and 58% (≥VGPR 37%) in auto‐SCT. However, median PFS (6.2 vs. 19 months) and OS (19 vs. 23.1 months) did not differ significantly (Figure 2C,G). NRM at 3 years was also similar (3.7% auto‐SCT vs. 5.3% RIC allo‐SCT). When all three studies were analyzed together, both PFS (17.2 vs. 7.2 months, p = .002) and OS (30.1 vs. 15.6 months, p < .001) significantly favored auto‐SCT over allo‐SCT (Figure 2D,H).
PFS and OS of studies with patient data reconstructed from Kaplan–Meier curves combined with studies with individual patient data
Combining the individual patient data from 289 patients with data reconstructed from Kaplan–Meier curves from 170 patients revealed some heterogeneity in PFS across studies, although not statistically significant (Figure 4A). Median PFS was 11.2 vs. 3.9 months (p < .001) in patients treated by auto‐SCT or allo‐SCT, respectively. OS analysis with a total of 986 patients with individual patient or reconstructed data confirmed the survival advantage (median 35.1 vs 14.1 months, p < .001) (Figure 3C,D).
FIGURE 4.
Meta‐analysis of trials comparing allo‐SCT with auto‐SCT after relapsing from first line ASCT: (A) progression‐free survival and (B) overall survival. allo‐SCT indicates allogeneic stem cell transplantation; auto‐SCT, autologous stem cell transplantation; SCT, stem cell transplantation.
FIGURE 3.
Progression‐free survival (A) and overall survival (B) of patients receiving allo‐SCT or auto‐SCT in studies with available individual patient data combined (red and green) and with the digitized studies combined (yellow and blue). Progression‐free survival (C) and overall survival (D) of patients receiving allo‐SCT or auto‐SCT across all studies included in this analysis. allo‐SCT indicates allogeneic stem cell transplantation; auto‐SCT, autologous stem cell transplantation.
A meta‐analysis using the common effect model including four studies shows an HR of 0.55 for PFS (Figure 4A), and by including five studies, an HR of 0.50 for overall survival (Figure 4B) favoring auto‐SCT over allo‐SCT.
RIC allogeneic transplantation versus no‐donor
The largest study included 169 patients with a biological randomization to either a RIC allo‐SCT, conventional, or no therapy. The 2‐year PFS was 42% in the donor group versus 18% for the no‐donor group (HR, 2.02, p = .0018), although OS remained comparable. 17 Extended follow‐up at 110 months showed higher post‐relapse response rates (≥VGPR 81% vs. 59%, p = .039) and improved 7‐year PFS (18% vs. 0%, HR, 2.50, p < .0001) and OS (31% vs. 9%, HR, 1.84, p < .0001) in allo‐SCT recipients. 14 Overall, patients who underwent allo‐SCT had a significantly longer PFS (median 21.1 vs. 1.1 months, p < .001), whereas OS did not differ significantly between the groups (median 35.1 vs. 26.1 months, p = .08) (Figure 5A,D).
FIGURE 5.
Progression‐free survival (A and B) and overall survival (D and E) of patients receiving allo‐SCT or no stem cell transplantation (A and D: Patriarca; 14 B and E: De Lavallade; 15 C and F: combined analysis of both studies). allo‐SCT indicates allogeneic stem cell transplantation.
A study comparing 18 patients undergoing RIC allo‐SCT with 14 lacking a donor found significantly longer PFS for allo‐SCT (median 27.0 vs. 13.1 months, p = .015), although OS remained similar (median not reached vs. 27 months, p = .279) 15 (Figure 5B,E).
Combined analysis stratified by study
A combined analysis of 97 allo‐SCT patients versus 104 patients without a donor confirmed the PFS benefit (median 22.9 vs. 11.1, p < .001). OS was also significantly longer in allo‐SCT recipients (median 35.1 vs. 27 months, p = .04) (Figure 5C,F).
A meta‐analysis using the common effect model including the two studies mentioned above shows an HR of 0.5 for PFS (Figure 6A) and a HR of 0.70 for OS (Figure 6B) favoring the patient cohorts with a suitable donor for allo‐SCT compared to patients without a donor receiving either conventional chemotherapy or no therapy.
FIGURE 6.
Meta‐analysis of trials comparing patients with a donor for allo‐SCT with patients without a donor: (A) progression‐free survival and (B) overall survival. allo‐SCT indicates allogeneic stem cell transplantation.
DISCUSSION
Our analysis showed a statistically significant benefit of second auto‐SCT over allo‐SCT both regarding PFS and OS in patients who relapsed after first line auto‐SCT. This is contrary to “popular thought” that a more intensive intervention is inherently more effective than less aggressive strategies. 20 In contrast to our findings in patients who relapsed after first line auto‐SCT, a recent comparison including 1388 newly diagnosed myeloma patients who underwent either a first line auto‐auto or auto‐allo‐SCT approach showed no differences between both treatments during the first 4 years after SCT, but with longer follow‐up, the auto‐allo‐SCT strategy proved superior both regarding PFS and OS, particularly for those patients who developed chronic GVHD. 21 However, there is a relevant bias in this analysis because two trials, one showing clearly contrary results, and the other a tendency for superiority of double auto‐SCT, 22 , 23 have not been included in this analysis. Consequently, we do not find strong arguments for the use of an allo‐SCT even in newly diagnosed high‐risk patients such as those with plasma cell leukemia, a statement, which is supported by a recent consensus report on plasma cell leukemia. 24 There is no longer mention of allo‐SCT as a valuable treatment option, neither in newly diagnosed nor in relapsed/refractory patients in the recent European Myeloma Network‐European Hematology Association guidelines on the management of patients with multiple myeloma. 25 Nevertheless, the potential of a graft‐versus‐myeloma effect of allo‐SCT demonstrated by Tricot et al. 26 after the infusion of donor lymphocytes in a patient who relapsed after allo‐SCT seem to benefit a certain proportion of patients, and this effect may also account for the positive long‐term results for the auto‐allo‐SCT strategy of the study mentioned above. 7 , 21 However, this effect might be less relevant in patients relapsing after first line auto‐SCT. The disadvantages of allo‐SCT are the acute and chronic GVHD and infectious complications that affect the outcome in a much larger proportion of patients, resulting in a poorer prognosis in relapsing patients receiving an allo‐SCT. It should also be noted that no information from the studies included is available on treatment after relapse to a second auto‐ or allo‐SCT and on maintenance therapy after first‐line auto‐SCT or second line auto‐SCT. Most of the studies included in this analysis were conducted when only a few or no effective salvage treatments were available, which may partly explain the unexpectedly short PFS (median 3.9 vs. 11.2 months, p < .001) and OS (median 14.1 vs. 35.1 months, p = <.001) in patients who received an allo‐SCT or auto‐SCT. Another limitation is the lack of any maintenance therapy, which became standard of care around 2017. 27 In addition, it should be emphasized that, even today, there is still no established standard for maintenance therapy after second line SCT. 3
Another important aspect concerns differences between patients allocated to auto‐ or allo‐SCT (e.g., different patient characteristics, including differences in patient age, cytogenetic risk factors, clinical risk factors, such as presence of extramedullary disease, time between first SCT and salvage SCT) and different preparative regimens. In several, but not all, studies, patients undergoing allo‐SCT were younger than patients who received auto‐SCT, which is associated with a disadvantage for the auto‐SCT group, but the time from first‐line treatment to salvage SCT was shorter in the allo‐SCT group in several studies, which is generally associated with a worse outcome.
The results of the two studies comparing the outcome of patients with a suitable donor for allo‐SCT versus no donor 14 , 15 favoring allo‐SCT are no surprise, because many patients in the no‐donor group received treatment with conventional drugs available at the time of the study, or no treatment at all. These data indicate a moderate efficacy of allo‐SCT but must be considered historical, because novel treatments are now the new standard of care. 28
Limitations of this study include its reliance on retrospective data from several studies, small sample sizes in some studies, and a lack of information on relapse treatment following SCT progression. A key strength is that most comparisons are based on individual patient data. Most of these studies have been conducted in the era before the introduction of modern immune therapies, which have replaced allo‐SCT in countries with access to CAR‐T cells and bispecific antibodies. Nevertheless, more than 200 allo‐SCTs have been reported to the European Society for Blood and Marrow Transplantation registry in 2022 5 and as mentioned before, a prospective randomized study comparing allo‐SCT with conventional chemotherapy has recently been activated. 8 Despite these developments, we consider the results of our analysis to be relevant for decision‐making because they clearly show that allo‐SCT achieves worse results in the relapsed setting after first line auto‐SCT compared to auto‐SCT. The latter procedure appears to be a valid option for treatment after relapse especially in countries with limited access to novel treatments 1 , 29 whereas in countries with optimal access to novel immunotherapies usage of a rescue auto‐SCT will decrease in favor of antibody–drug conjugates, bispecific antibodies, and CAR‐T cells. Taken together, allo‐SCT as a salvage therapy after failure of first‐line treatment can no longer be recommended, particularly given the success of new treatment approaches that have revolutionized the management of multiple myeloma.
AUTHOR CONTRIBUTIONS
Heinz Ludwig: Writing—original draft; writing—review and editing; project administration; conceptualization; supervision; data curation; resources; investigation; and funding acquisition. Sarah Bernhard: Visualization; formal analysis; data curation; writing—review and editing; and methodology. Takashi Ikeda: Validation and writing—review and editing. Cesar O. Freytes: Validation and writing—review and editing. Martin Schreder: Validation and writing—review and editing. Koji Kawamura: Validation and writing—review and editing. Yoshiko Atsuta: Validation and writing—review and editing. Hiroyuki Takamatsu: Validation and writing—review and editing. David H. Vesole: Validation and writing—review and editing. Parameswaran Hari: Validation and writing—review and editing. Julie Krainer: Formal analysis and visualization. Axel Hinke: Formal analysis; validation; writing—review and editing; and methodology.
CONFLICT OF INTEREST STATEMENT
Yoshiko Atsuta reports fees for professional activities from Chugai Pharmaceutical Co, Ltd, Janssen Pharmaceuticals, JCR Pharmaceuticals Co, Ltd, Meiji Seika Pharma, Novartis Pharma, and Otsuka Pharmaceutical Co, Ltd. Hiroyuki Takamatsu reports consulting fees from SRL; fees as an expert witness from Johnson and Johnson; and fees for other professional activities from Bristol‐Myers Squibb, Ono Pharmaceuticals, and Sanofi. David H. Vesole reports fees for professional activities from AbbVie, Amgen, Biogen Idec, Bristol‐Myers Squibb, Eli Lilly, Gilead Sciences (Gilead Foundation, GlaxoSmithKline, Janssen Biotech, Johnson & Johnson Health Care Systems Inc, Karyopharm Therapeutics, Sanofi Pasteur Biologics LLC, and Takeda Oncology. The other authors declare no conflicts of interest.
Supporting information
Supplementary Material
Figure S1
Figure S2
Table S1
ACKNOWLEDGMENTS
This study was supported by the Austrian Forum Against Cancer.
Ludwig H, Bernhard S, Ikeda T, et al. Allogeneic versus autologous stem cell transplantation after relapsing following first line autologous transplantation for multiple myeloma: a systematic review. Cancer. 2025;e35896. doi: 10.1002/cncr.35896
DATA AVAILABILITY STATEMENT
The individual patient data used for this analysis are not publicly available, but requests for data sharing may be addressed to the respective scientific study groups (Japanese Society for Transplantation and Cellular Therapy and Center for International Blood & Marrow Transplant Research). Data obtained by digitizing survival curves can be obtained from the corresponding author on reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Supplementary Material
Figure S1
Figure S2
Table S1
Data Availability Statement
The individual patient data used for this analysis are not publicly available, but requests for data sharing may be addressed to the respective scientific study groups (Japanese Society for Transplantation and Cellular Therapy and Center for International Blood & Marrow Transplant Research). Data obtained by digitizing survival curves can be obtained from the corresponding author on reasonable request.