Unrelated stem cell transplantation after reduced intensity conditioning for patients with multiple myeloma relapsing after autologous transplantation

Allogeneic stem cell transplantation in multiple myeloma: is there still a place?

The introduction of novel agents dramatically improved response and outcomes of multiple myeloma (MM) and led to a sharp decline in the use of allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Thus, recent guidelines do not recommend anymore allo-HSCT as consolidation in the first-line treatment of newly diagnosed MM, even in high-risk patients. In a relapsed/refractory setting, allo-HSCT is not routinely recommended but should only be performed within clinical trials in young and high-risk patients. Nonetheless, allo-HSCT still represents a potential curative approach that has been used for decades in the treatment of MM and plasma cell neoplasms with favorable results and may still represent a treatment option for carefully selected patients. Despite that promising results were obtained with CAR T-cell therapies and bispecific antibodies in triple- and penta-exposed/refractory MM, these patients will inevitably relapse. To date, less is known about outcomes of allo-HSCT in patients exposed to novel immunotherapeutic drugs. Therefore, allo-HSCT could represent a reasonable treatment choice for younger and high-risk patients who have relapsed after CAR T-cell therapies and bispecific antibodies as well as an alternative for patients not eligible to these treatments and in those countries where immunotherapies are not yet available. In the choice of conditioning, reduced intensity conditioning regimens are currently recommended for the lower toxicity and mortality. Moreover, the use of alternative donors, particularly haploidentical, has progressively increased in last years with results comparable to full matched donors. Finally, post-transplantation maintenance strategies are encouraged whenever feasible.

Analysis of risk factors for fatal renal complications after allogeneic hematopoietic cell transplantation

Various complications can influence hematopoietic cell transplantation (HCT) outcomes. Renal complications can occur during the early to late phases of HCT along with various factors. However, studies focusing on fatal renal complications (FRCs) are scarce. Herein, we analyzed 36,596 first allogeneic HCT recipients retrospectively. Overall, 782 patients died of FRCs at a median of 108 (range, 0-3,440) days after HCT. The cumulative incidence of FRCs was 1.7% and 2.2% at one and five years, respectively. FRCs were associated with older age, male sex, non-complete remission (non-CR), lower performance status (PS), and HCT comorbidity index (HCT-CI) associated with renal comorbidity in multivariate analysis. The risk factors within 100 days included older age, multiple myeloma, PS, and HCT-CI comorbidities (psychiatric disturbance, hepatic disease, obesity, and renal disease). Older age and male sex were risk factors between 100 days and one year. After one year, HCT-CI was associated with the presence of diabetes and prior solid tumor; total body irradiation was identified as a risk factor. Non-CR was a common risk factor in all three phases. Furthermore, acute and chronic graft-versus-host disease, reactivation of cytomegalovirus, and relapse of underlying disease also affected FRCs. Systematic follow-up may be necessary based on the patients' risk factors and post-HCT events.

Long-term outcomes of allogeneic stem cell transplant in multiple myeloma

Allogeneic stem cell transplant (allo SCT) for multiple myeloma (MM) is potentially curative in some, while toxic in many others. We retrospectively analyzed 85 patients diagnosed with MM who underwent allo SCT as frontline or salvage therapy between 2000 and 2022 at Mayo Clinic Rochester and examined patient outcomes and prognostic markers. Overall survival (OS), progression free survival (PFS), treatment related mortality (TRM), and relapse rates (RR) were estimated using the Kaplan Meier method and competing risk models. Median follow-up was 11.5 years. Median OS and PFS were 1.7 and 0.71 years, respectively. Five-year OS and PFS were 22.2% and 15.1%, respectively. One-year TRM was 23.5%. Twelve patients demonstrated durable overall survival, living 10+ years beyond their allo SCT. This subgroup was more likely to have no or one prior auto SCT (p = 0.03) and to have been transplanted between 2000 and 2010 (p = 0.03). Outcomes were poor in this cohort with long follow-up, with few patients surviving 5 years or more, and most relapsing or dying within 2 years. We would expect better outcomes and tolerability with an expanded array of novel therapeutics and would prefer them to allo SCT.

Allogeneic Stem Cell Transplantation in Patients with High-Risk Multiple Myeloma: Utopia or Continuous Challenge in Aiming for Cure?

OPINION STATEMENT

Nowadays, several novel agents have been introduced in the treatment of multiple myeloma, not only resulting in high response rates and prolonged survival but also offering good quality of life. However, the potential of cure, especially for patients with advanced or unfavorable disease features, remains elusive. Allogeneic hematopoietic stem cell transplantation, based mainly on the graft vs. myeloma effect, can offer prolonged disease control and probability of cure but unfortunately at the cost of considerable transplant-related toxicity rates. Therefore, the role of allogeneic hematopoietic stem cell transplantation in the treatment of multiple myeloma has been called into question. Recently, several studies, particularly those with long-term follow-up, demonstrated a trend of survival superiority for allografted patients with high-risk disease. These data fuel again the interest in allogeneic stem cell transplantation for selected patients with high-risk multiple myeloma, especially if the high remission rates which can be achieved with the currently used treatment protocols could be long-life sustained through the additional exploitation of the long-lasting anti-multiple myeloma effect, originating from the allograft.

Allogeneic Hematopoietic Transplantation for Multiple Myeloma in the New Drugs Era: A Platform to Cure

Allogeneic hematopoietic cell transplantation (alloHCT) represents a treatment option for multiple myeloma (MM) patients. As shown in several studies, alloHCT is highly effective, but it is hampered by a high toxicity, mainly related to the graft-versus-host disease (GVHD), a complex immunological reaction ascribable to the donor’s immune system. The morbidity and mortality associated with GVHD can weaken the benefits of this procedure. On the other side, the high therapeutic potential of alloHCT is also related to the donor’s immune system, through immunological activity known as the graft-versus-myeloma effect. Clinical research over the past two decades has sought to enhance the favorable part of this balance, along with the reduction in treatment-related toxicity. Frontline alloHCT showed promising results and a potential for a cure in the past. Currently, thanks to the improved results of first-line therapies and the availability of effective second- or third-line salvage therapies, alloHCT is reserved for selected high-risk patients and is considered a clinical option. For donor lymphocyte infusion, bortezomib or lenalidomide have been used as consolidation or maintenance therapies post-transplant—none has become standard of care. For those patients who relapse, the best treatment should be evaluated considering the patient’s clinical status and the previous lines of therapy. The use of newer drugs, such as monoclonal antibodies or other immunotherapies in the post-transplant setting, deserves further investigation. However, acceptable toxicity and a synergic effect with the newer immune system could be hopefully expected.

Allogeneic Transplantation in Multiple Myeloma-Does It Still Have a Place?

Novel drugs have improved survival for patients with multiple myeloma in recent years. However, the disease is still fatal. Allogeneic stem cell transplantation (Allo) has proven to cure some patients with the disease, but its role is controversial due to relatively high transplant-related toxicity and mortality (nonrelapse mortality, NRM). Using nonmyeloablative reduced-intensity conditioning (RIC), both toxicity and NRM can be reduced, and RICAllo is, therefore, an option for subgroups of patients. Upfront tandem autologous/RICAllo (Auto/RICAllo) was shown to be superior to single Auto or tandem Auto/Auto in both progression-free (PFS) and overall survival (OS) in two prospective studies with long-term follow-up, while three similarly designed studies did not detect a difference. A recent update of pooled patient data from four of these studies showed significantly superior PFS and OS with Auto/RICAllo. Importantly, none of these studies showed inferior results with Auto/RICAllo in patients less than 70 years of age. Auto/RICAllo appears to overcome some poor risk cytogenetic markers. Encouraging results have also been seen in treatment of relapsed patients. Combining Allo with new proteasome inhibitors and immunomodulatory drugs may further improve results. Other encouraging new cell therapies such as with CAR T-cells, NK- and CAR NK-cells may well have a place in combination with RICAllo. Such studies are warranted.

Long-term survival and polyclonal immunoglobulin reconstitution after allogeneic stem cell transplantation in multiple myeloma

Despite significant progress made in the treatment of patients with multiple myeloma (MM) in the last decade, for patients with early relapse or rapidly progressing high-risk disease, allogeneic hematopoietic stem cell transplantation (SCT) might be an option leading to long-term survival. Here, we retrospectively analyzed the outcomes of 90 MM patients who received allogeneic SCT in our center between 1999 and 2017. We specifically assessed the association of impaired humoral immune reconstitution, referred to as immunoparesis, and post-transplant survival. Sixty-four patients received allogeneic SCT in relapse following 2–7 lines of therapy; 26 patients received upfront tandem autologous-allogeneic SCT. With a median follow-up of 76 months, OS and PFS were 52.6% (95% CI 42.9–64.3) and 36.4% (95% CI 27.6–47.9) at 2 years and 38.6% (95% CI 29.2–51.1) and 25.3% (95% CI 17.5–36.4) at 5 years, respectively. Receiving more than two therapy lines prior to transplantation was an independent risk factor for OS (HR 3.68, 95% CI 2.02–6.70) and PFS (HR 3.69, 95% CI 2.09–6.50). In a landmark analysis at day 200, prolonged immunoparesis was associated with reduced OS (HR 3.22, 95% CI 1.14–9.11). Allogeneic stem cell transplantation offers an additional treatment element that may lead to long-term remission in selected patients with poor prognosis, probably exploiting graft-versus-myeloma effects. Immunoparesis could potentially serve as an indicator for impaired survival following allogeneic transplantation, an observation to be further studied prospectively.

Outcomes of Haploidentical Transplantation in Patients with Relapsed Multiple Myeloma: An EBMT/CIBMTR Report

Allogeneic hematopoietic cell transplantation (allo-HCT) using siblings and matched donors has the potential for long-term disease control in a subset of high-risk patients with multiple myeloma (MM); however, the data on using haploidentical donors in this disease are limited. We conducted a retrospective analysis to examine the outcomes of patients with MM who underwent haploidentical allo-HCT within European Society for Blood and Marrow Transplantation/Center for International Blood and Marrow Transplant Research centers. A total of 96 patients underwent haploidentical allo-HCT between 2008 and 2016. With a median follow-up of 24.0 months (range, 13.2 to 24.9 months), 97% (95% confidence interval [CI], 93% to 100%) of patients had neutrophil engraftment by day 28, and 75% (95% CI, 66% to 84%) achieved platelet recovery by day 60. Two-year progression-free survival (PFS) was 17% (95% CI, 8% to 26%), and overall survival (OS) was 48% (95% CI, 36% to 59%). At 2 years, the cumulative risk of relapse/progression was 56% (95% CI, 45% to 67%), and 1-year nonrelapse mortality (NRM) was 21% (95% CI, 13% to 29%). The incidences of acute graft-versus-host-disease (GVHD) grades II-IV by 100 days and chronic GVHD at 2 years were 39% (95% CI, 28% to 49%) and 46% (95% CI, 34% to 59%), respectively. On univariate analysis, use of post-transplantation cyclophosphamide (PT-Cy) (54% [95% CI, 41% to 68%] versus 25% [95% CI, 1% to 48%]; P =.009) and use of bone marrow as source of stem cells (72% [95% CI, 55% to 89%] versus 31% [95% CI, 17% to 46%]; P = .001) were associated with improved OS at 2 years. Disease status, patient sex, intensity of conditioning regimen, recipient/donor sex mismatch, and cytomegalovirus serostatus had no impact on OS, PFS, or NRM. Haploidentical transplantation is feasible for patients with multiply relapsed or high-risk MM, with an encouraging 2-year OS of 48% and an NRM of 21% at 1 year, supporting further investigation of haploidentical allo-HCT in suitable candidates with MM.

Prevention and treatment of relapse after stem cell transplantation in lymphoid malignancies

Relapse is now the major cause of treatment failure after allogeneic HSCT (alloHSCT). Many novel strategies to address this critical issue are now being developed and tested. At the 3rd International Workshop on Biology, Prevention, and Treatment of Relapse held in Hamburg, Germany in November 2016, international experts presented and discussed recent developments in the field. Some approaches may be applicable to a wide range of patients after transplant, whereas some may be very disease-specific. We present a report from the session dedicated to issues related to prevention and treatment of relapse of lymphoid malignancies after alloHSCT. This session included detailed reviews as well as forward-looking commentaries that focused on Hodgkin lymphoma, chronic lymphocytic leukemia and mantle cell lymphoma, diffuse large cell and follicular lymphoma, and multiple myeloma.

A look at treatment strategies for relapsed multiple myeloma

INTRODUCTION

Multiple myeloma treatment considerably improved during the past decade, thanks to novel effective drugs, a better understanding of myeloma biology and clonal heterogeneity, and an improved management of toxicities. The choice of regimen at relapse is usually based on prior response, toxicities, age and comorbidities of relapsed patients. Areas covered: A review was performed of the most recent and effective therapeutic strategies for the relapsed myeloma setting, by documenting the latest clinical evidence from phase II and III clinical trials. Of note, new drugs, such as carfilzomib, ixazomib, pomalidomide, daratumumab and elotuzumab, alone or in combinations in doublet or triplet regimens, have greatly increased the treatment armamentarium against myeloma. Expert commentary: Impressive results have been obtained with new drugs in relapsed patients. Besides number of prior therapies and previous response, other factors play a crucial role in the selection of therapy. Re-challenge with previous drugs can be adopted if previous responses lasted at least 6 months and therapy had induced low toxicity. Patients' risk status can further help to appropriately select therapy at relapse, and clinical trials will allow physicians to use newer targeted therapies and immune-therapies, thus delaying palliative approaches to later relapse stages.

Allogeneic stem-cell transplantation for multiple myeloma: a systematic review and meta-analysis from 2007 to 2017

Background

Despite recent advances, multiple myeloma (MM) remains incurable. However, the appearance of allogeneic stem cell transplantation (allo-SCT) through graft-versus-myeloma effect provides a potential way to cure MM to some degree. This systematic review aimed to evaluate the outcome of patients receiving allo-SCT and identified a series of prognostic factors that may affect the outcome of allo-SCT.

Patients/methods

We systematically searched PubMed, Embase, and the Cochrane Library from 2007.01.01 to 2017.05.03 using the keywords ‘allogeneic’ and ‘myeloma’.

Results

A total of 61 clinical trials involving 8698 adult patients were included. The pooled estimates (95% CI) for overall survival (OS) at 1, 2, 3 and 5 years were 70 (95% CI 56–84%), 62 (95% CI 53–71%), 52 (95% CI 44–61%), and 46 (95% CI 40–52%), respectively; for progression-free survival were 51 (95% CI 38–64%), 40 (95% CI 32–48%), 34 (95% CI 27–41%), and 27 (95% CI 23–31%), respectively; and for treatment-related mortality (TRM) were 18 (95% CI 14–21%), 21 (95% CI 17–25%), 20 (95% CI 13–26%), and 27 (95% CI 21–33%), respectively. Additionally, the pooled 100-day TRM was 12 (95% CI 5–18%). The incidences of grades II–IV acute graft-versus-host disease (GVHD) and chronic GVHD were 34 (95% CI 30–37%) and 51 (95% CI 46–56%), respectively. The incidences of relapse rate (RR) and death rate were 50 (95% CI 45–55%) and 51 (95% CI 45–57%), respectively. Importantly, disease progression was the most major cause of death (48%), followed by TRM (44%). The results failed to show an apparent benefit of allo-SCT for standard risk patients, compared with tandem auto-SCT. In contrast, all 14 trials in our study showed that patients with high cytogenetic risk after allo-SCT had similar OS and PFS compared to those with standard risk, suggesting that allo-SCT may overcome the adverse prognosis of high cytogenetic risk.

Conclusion

Due to the lack of consistent survival benefit, allo-SCT should not be considered as a standard of care for newly diagnosed and relapsed standard-risk MM patients. However, for patients with high-risk MM who have a poor long-term prognosis, allo-SCT may be a strong consideration in their initial course of therapy or in first relapse after chemotherapy, when the risk of disease progression may outweigh the transplant-related risks. A large number of prospective randomized controlled trials were needed to prove the benefits of these therapeutic options.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0553-8) contains supplementary material, which is available to authorized users.

From transplant to novel cellular therapies in multiple myeloma: European Myeloma Network guidelines and future perspectives

Survival of myeloma patients has greatly improved with the use of autologous stem cell transplantation and novel agents, such as proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies. Compared to bortezomib- and lenalidomide-based regimens alone, the addition of high-dose melphalan followed by autologous transplantation significantly improves progression-free survival, although an overall survival benefit was not observed in all trials. Moreover, follow up of recent trials is still too short to show any difference in survival. In the light of these findings, novel agent-based induction followed by autologous transplantation is considered the standard upfront treatment for eligible patients (level of evidence: 1A). Post-transplant consolidation and maintenance treatment can further improve patient outcome (1A). The availability of several novel agents has led to the development of multiple combination regimens such as salvage treatment options. In this context, the role of salvage autologous transplantation and allotransplant has not been extensively evaluated. In the case of prolonged remission after upfront autologous transplantation, another autologous transplantation at relapse can be considered (2B). Patients who experience early relapse and/or have high-risk features have a poor prognosis and may be considered as candidates for clinical trials that, in young and fit patients, may also include an allograft in combination with novel agents (2B). Ongoing studies are evaluating the role of novel cellular therapies, such as inclusion of antibody-based triplets and quadruplets, and chimeric antigen receptor-T cells. Despite encouraging preliminary results, longer follow up and larger patient numbers are needed before the clinical use of these novel therapies can be widely recommended.

Allograft for Myeloma: Examining Pieces of the Jigsaw Puzzle

Multiple myeloma (MM) cure remains elusive despite the availability of newer anti-myeloma agents. Patients with high-risk disease often suffer from early relapse and short survival. Allogeneic hematopoietic cell transplantation (allo-HCT) is an “immune-based” therapy that has the potential to offer long-term remission in a subgroup of patients, at the expense of high rates of transplant-related morbidity and mortality. Donor lymphocyte infusion (DLI) upon disease relapse after allo-HCT is able to generate an anti-myeloma response suggestive of a graft-versus-myeloma effect. Allo-HCT provides a robust platform for additional immune-based therapy upon relapse including DLI and, maintenance with immunomodulatory drugs and immunosuppressive therapy. There have been conflicting findings from randomized prospective trials questioning the role of allo-HCT. However, to this date, allo-HCT remains the only potential curable treatment for MM and its therapeutic role needs to be better defined especially for patients with high-risk disease. This review examines different aspects of this treatment and summarizes ongoing attempts at improving its therapeutic index.

Allogeneic stem cell transplantation and subsequent treatments as a comprehensive strategy for long-term survival of multiple myeloma patients

We evaluated 71 patients treated with allogeneic hematopoietic cell transplantation (allo-HCT) for multiple myeloma (MM). Forty-three patients (61%) received allo-HCT after the first line of therapy. Fifty-eight patients (82%) had chemosensitive disease at the time of allo-HCT. A HLA-matched related or unrelated donor was available for 68 patients (96%). Non-myeloablative or reduced-intensity conditioning regimen and peripheral blood hematopoietic cells as a graft source were used in most patients. The cumulative incidence of grade II-IV acute GVHD at day +100 and chronic GVHD at 5 years was 13% (95% CI 7-23%) and 35% (95% CI 24-46), respectively. Non-relapse mortality and relapse/progression incidence at 5 years were 12% (95% CI 5-23) and 65% (95% CI 49-76), respectively. With a median follow-up in survivors of 100 months (range 16-186), the 5-year PFS and OS were 39% (95% CI 27-52) and 60% (95% CI 55-77), respectively. On multivariate analysis: age >55 years was associated with both a reduced PFS (RR 2.11, 95% CI 1.15-3.87) and OS (RR 5.53, 95% CI 2.22-13.76); chemorefractory disease at allo-HCT was associated with both reduced PFS (RR 3.09, 95% CI 1.37-7.00) and OS (RR 3.19, 95% CI 1.23-8.22). At relapse, 24 patients (56%) received bortezomib, 28 (65%) lenalidomide, 11 (26%) pomalidomide, 16 (37%) donor lymphocytes infusion as part of salvage therapy after allo-HCT relapse. Median PFS from time of salvage treatment was 7 months (range 0-113 months) for bortezomib-based therapy, 14 months (range 0-79 months) for lenalidomide and 10 months (range 1-28) for pomalidomide. Allo-HCT is a feasible and effective strategy in selected patients with MM and could be an effective platform for subsequent therapies.

In search of the optimal platform for Post-Allogeneic SCT immunotherapy in relapsed multiple myeloma: a systematic review

Allogeneic stem cell transplantation (allo-SCT) has the potential to induce sustained remissions in patients with multiple myeloma (MM). Currently, allo-SCT is primarily performed in high-risk MM patients, most often in the setting of early relapse after first-line therapy with autologous SCT. However, the implementation of allo-SCT for MM is jeopardized by high treatment-related mortality (TRM) rates as well as high relapse rates. In this systematic review, we aimed to identify a safe allo-SCT strategy that has optimal 1-year results regarding mortality, relapse and severe GvHD, creating opportunities for post-transplantation strategies to maintain remissions in the high-risk group of relapsed MM patients. Eleven studies were included. Median PFS ranged from 5.2 to 36.8 months and OS was 13.0 to 63.0 months. The relapse related mortality at 1 year varied between 0 and 50% and TRM between 8 and 40%. Lowest GvHD incidences were reported for conditioning regimens with T-cell depletion using ATG or graft CD34+ selection. Similar strategies could lay the foundation for a post-transplant immune platform, this should be further evaluated in prospective clinical trials.

Reduced-intensity conditioning allogeneic transplantation after salvage treatment with DT-PACE in myeloma patients relapsing early after autologous transplant

OBJECTIVE

In this retrospective single-centre study, we have looked into the transplant outcomes(overall survival OS, progression-free survival PFS, GvHD) and the role of chimerism, DLI and pretransplant characteristics in patients who had a suboptimal response (<12 months) to an autologous stem cell transplant for myeloma and underwent an alemtuzumab T-cell depleted reduced-intensity allograft(RIC).

METHODS

Twenty-four patients were salvaged with two cycles of DT-PACE and received a RIC transplant with fludarabine, melphalan and alemtuzumab. All the patients received PBSC grafts, eight patients had a sibling donor, and 16 had a graft from a fully matched unrelated donor. The median follow-up was 65.3 months (6-132 months).

RESULTS

The median overall survival was 55.4 months. DLI administration was associated with a trend towards better overall survival (P=.05). Disease status at allo-HCT, PR or VGPR, ISS score and CMV serostatus was not significant predictors of OS and PFS. Full donor whole blood chimerism (≥98%) at 3 months post-transplant was associated with PFS (P=.04) but did not have a significant impact on OS(P=.45).

CONCLUSION

Reduced-intensity alemtuzumab-conditioned allograft for myeloma after DT-PACE salvage chemotherapy is an efficient and low toxicity treatment for those who had a suboptimal response postautologous stem cell transplant for myeloma.

Practical Considerations in Managing Relapsed Multiple Myeloma

Considerable advances have been made in the treatment of relapsed and relapsed/refractory multiple myeloma, with numerous novel agents and combination strategies receiving regulatory approval worldwide during the past several years. An increasing body of phase III data has clearly demonstrated increased overall response rates, improved depths of response, and more durable responses when a third novel agent is incorporated into lenalidomide-dexamethasone and bortezomib-dexamethasone platforms, in most cases with acceptable toxicity. The carfilzomib-dexamethasone doublet has also demonstrated promising activity. With this rapid progress has come many new questions. We review the data supporting the use of these novel treatment paradigms for relapsed/refractory multiple myeloma, discuss the place of autologous and allogeneic hematopoietic stem cell transplantation in this rapidly evolving treatment space, and propose strategies to best use these regimens, considering the disease, host, and previous treatment factors.

Outcomes of unrelated cord blood transplantation in patients with multiple myeloma: a survey on behalf of Eurocord, the Cord Blood Committee of Cellular Therapy and Immunobiology Working Party, and the Chronic Leukemia Working Party of the EBMT

Although allogeneic stem cell transplantation is not a standard therapy for multiple myeloma, some patients can benefit from this intense therapy. There are few reports on outcomes after umbilical cord blood transplantation in multiple myeloma, and investigation of this procedure is warranted. We retrospectively analyzed 95 patients, 85 with multiple myeloma and 10 with plasma cell leukemia, receiving single or double umbilical cord blood transplantation from 2001 to 2013. Median follow up was 41 months. The majority of patients received a reduced intensity conditioning. The cumulative incidence of neutrophil engraftment was 97%±3% at 60 days, and that of 100-day acute graft-versus-host disease grade II-IV was 41%±5%. Chronic graft-versus-host disease at two years was 22%±4%. Relapse and non-relapse mortality was 47%±5% and 29%±5% at three years, respectively. Three-year progression-free survival and overall survival were 24%±5% and 40%±5%, respectively. Anti-thymocyte globulin was associated with decreased incidence of acute graft-versus-host disease, higher non-relapse mortality, decreased overall and progression-free survival. Patients with high cytogenetic risk had higher relapse, and worse overall and progression-free survival. In conclusion, umbilical cord blood transplantation is feasible for multiple myeloma patients.

Stem cell transplantation in multiple myeloma and other plasma cell disorders (report from an EBMT preceptorship meeting)

The European Society for Blood and Marrow Transplantation Chronic Malignancies Working Party held a preceptorship meeting in Turin, Italy on 25-26 September 2014, to discuss the role of stem cell transplantation (SCT) in the treatment of multiple myeloma and other plasma cell disorders. Scientists and clinicians working in the field gathered to discuss a variety of topics including the results of recent clinical trials, basic research, the concept of minimal residual disease, and immune modulation. As individual presentations revealed, important advances have occurred in our understanding of the pathophysiology of myeloma and the role that SCT, along with other forms of immunotherapy, plays in treating it. Each presentation stimulated discussion and exchange of ideas among the attendants. We decided to summarize and, importantly, to update the meeting proceedings in this review to share stimulating discussions and ideas on potentially novel treatment strategies among clinicians.

American Society of Blood and Marrow Transplantation, European Society of Blood and Marrow Transplantation, Blood and Marrow Transplant Clinical Trials Network, and International Myeloma Working Group Consensus Conference on Salvage Hematopoietic Cell Transplantation in Patients with Relapsed Multiple Myeloma

In contrast to the upfront setting in which the role of high-dose therapy with autologous hematopoietic cell transplantation (HCT) as consolidation of a first remission in patients with multiple myeloma (MM) is well established, the role of high-dose therapy with autologous or allogeneic HCT has not been extensively studied in MM patients relapsing after primary therapy. The International Myeloma Working Group together with the Blood and Marrow Transplant Clinical Trials Network, the American Society of Blood and Marrow Transplantation, and the European Society of Blood and Marrow Transplantation convened a meeting of MM experts to: (1) summarize current knowledge regarding the role of autologous or allogeneic HCT in MM patients progressing after primary therapy, (2) propose guidelines for the use of salvage HCT in MM, (3) identify knowledge gaps, (4) propose a research agenda, and (5) develop a collaborative initiative to move the research agenda forward. After reviewing the available data, the expert committee came to the following consensus statement for salvage autologous HCT: (1) In transplantation-eligible patients relapsing after primary therapy that did NOT include an autologous HCT, high-dose therapy with HCT as part of salvage therapy should be considered standard; (2) High-dose therapy and autologous HCT should be considered appropriate therapy for any patients relapsing after primary therapy that includes an autologous HCT with initial remission duration of more than 18 months; (3) High-dose therapy and autologous HCT can be used as a bridging strategy to allogeneic HCT; (4) The role of postsalvage HCT maintenance needs to be explored in the context of well-designed prospective trials that should include new agents, such as monoclonal antibodies, immune-modulating agents, and oral proteasome inhibitors; (5) Autologous HCT consolidation should be explored as a strategy to develop novel conditioning regimens or post-HCT strategies in patients with short (less than 18 months remissions) after primary therapy; and (6) Prospective randomized trials need to be performed to define the role of salvage autologous HCT in patients with MM relapsing after primary therapy comparing it to "best non-HCT" therapy. The expert committee also underscored the importance of collecting enough hematopoietic stem cells to perform 2 transplantations early in the course of the disease. Regarding allogeneic HCT, the expert committee agreed on the following consensus statements: (1) Allogeneic HCT should be considered appropriate therapy for any eligible patient with early relapse (less than 24 months) after primary therapy that included an autologous HCT and/or high-risk features (ie, cytogenetics, extramedullary disease, plasma cell leukemia, or high lactate dehydrogenase); (2) Allogeneic HCT should be performed in the context of a clinical trial if possible; (3) The role of postallogeneic HCT maintenance therapy needs to be explored in the context of well-designed prospective trials; and (4) Prospective randomized trials need to be performed to define the role salvage allogeneic HCT in patients with MM relapsing after primary therapy.

Allogeneic stem cell transplantation in multiple myeloma: immunotherapy and new drugs

INTRODUCTION

Autologous (auto) stem cell transplantation (SCT) and the development of new drugs have improved the survival of multiple myeloma (MM) patients. By contrast, though potentially curative, the use of allogeneic (allo)-SCT is controversial.

AREAS COVERED

A review has been conducted to examine the current evidence for the use of allo-SCT in MM. We have examined novel cell therapies that may be exploited to induce myeloma-specific immune responses including the new promising frontier of chimeric antigen receptor (CAR)-T and -natural killer (NK) cells.

EXPERT OPINION

One of the major controversies facing researchers in exploring the allo approach is the remarkable recent treatment improvement observed with second- and third-generation proteasome inhibitors and immunomodulatory drugs, monoclonal antibodies and deacetylase inhibitors. Despite these great advances, the disease remains to be incurable and allo-SCT may still play a role in the cure of MM. We think that allo-SCT conserves a role in MM and its curative potential in high-risk patients should be explored in the setting of control clinical trials. Novel cell therapies such as CAR technologies may open new avenues of research toward a potential cure. Data from currently ongoing prospective studies will be helpful to clarify pending clinical questions.

A randomized phase II trial of fludarabine/melphalan 100 versus fludarabine/melphalan 140 followed by allogeneic hematopoietic stem cell transplantation for patients with multiple myeloma

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is a potentially curative treatment for multiple myeloma (MM); however, because of high treatment-related mortality (TRM), its role is not well defined. Patients with newly diagnosed, relapsed, or primary refractory myeloma were enrolled in a randomized phase II trial of 2 reduced-intensity conditioning regimens: fludarabine 120 mg/m(2) + melphalan 100 mg/m(2) (FM100) versus fludarabine 120 mg/m(2) + melphalan 140 mg/m(2) (FM140) before allo-HCT from related or unrelated donors. Fifty patients underwent allo-HCT using FM100 (n = 23) or FM140 (n = 27) conditioning between April 2002 and 2011. There were no significant differences between FM100 and FM140 in time to neutrophil engraftment (P = .21), acute grade II to IV graft-versus-host disease (GVHD) (P = 1.0), chronic GVHD (P = .24), response rate (P = 1.0), TRM (13% versus 15%, P = 1.0), median progression-free survival (PFS), 11.7 versus 8.4 months, P = .12, and median overall survival (OS), 35.1 versus 19.7 months, P = .38. Cumulative incidence of disease progression in FM100 and FM140 was 43% and 70%, respectively (P = .08). Recurrent disease was the most common cause of death for both FM100 (26%) and FM140 (44%), P = .24. On multivariate analysis, disease status at allo-HCT, complete response or very good partial response (VGPR) was significantly associated with longer PFS (15.6 versus 9.6 months in patients with <VGPR, P = .05). OS was similar across all variables. We conclude that FM100 and FM140 may result in similar patient outcomes after allo-HCT for MM.

Reduced intensity-conditioned allogeneic stem cell transplantation for multiple myeloma relapsing or progressing after autologous transplantation: a study by the European Group for Blood and Marrow Transplantation

Outcomes and prognostic factors of reduced intensity-conditioned allo-SCT (RIC allo-SCT) for multiple myeloma (MM) relapsing or progressing after prior autologous (auto)-SCT are not well defined. We performed an analysis of 413 MM patients who received a related or unrelated RIC allo-SCT for the treatment of relapse/progression after prior auto-SCT. Median age at RIC allo-SCT was 54.1 years, and 44.6% of patients had undergone two or more prior auto-SCTs. Median OS and PFS from the time of RIC allo-SCT for the entire population were 24.7 and 9.6 months, respectively. Cumulative non-relapse mortality (NRM) at 1 year was 21.5%. In multivariate analysis, CMV seronegativity of both patient and donor was associated with significantly better PFS, OS and NRM. Patient-donor gender mismatch was associated with better PFS, fewer than two prior auto-SCT was associated with better OS, and shorter time from the first auto-SCT to the RIC allo-SCT was associated with lower NRM. The results of this study identify patient and donor CMV seronegativity as the key prognostic factor for outcome after RIC allo-SCT for MM relapsing or progressing after prior auto-SCT.

Long-term outcome after allogeneic stem-cell transplantation with reduced-intensity conditioning in patients with multiple myeloma

This study examines the long-term outcomes of a cohort of patients with myeloma who were treated with reduced-intensity conditioning (RIC) regimens after a minimum follow-up of 5 years at our centre. A total of 53 patients with multiple myeloma (MM) who received allogeneic hematopoietic stem-cell transplantation (Allo-SCT) between January 2000 and January 2007 were identified. The median follow-up of living patients was 84 months (51-141). The median age of the MM patients was 50 (28-70) years. Fifty-one patients (96%) received a transplant from a sibling donor. The median time between diagnosis and Allo-SCT was 34 months (6-161), and the median time between auto-SCT and Allo-SCT was 10 months (1-89). Fifty-one patients (96%) received at least one auto-SCT; 24 patients (45%) received a tandem auto-Allo-SCT. At last follow-up, 21 patients (40%) are alive > 5 years post RIC Allo-SCT. At last follow-up, 14 (26%) are in first complete remission (CR), and four patients (8%) in second CR after donor lymphocyte infusion or re-induction with one of the new anti-myeloma drugs (bortezomib or lenalidomide) after Allo-SCT. Eight patients (38%) among these long survivors received one of these new drugs as induction or relapse treatment before Allo-SCT. Disease status and occurrence of cGvHD were significantly associated with progression-free survival (PFS); hazard ratio (HR) = 0.62 (0.30-1.29, P = 0.20). Acute GvHD was correlated with higher transplant-related mortality; HR = 4.19 (1.05-16.77, P = 0.04). No variables were associated with overall survival (OS). In conclusion, we observe that long-term disease control can be expected in a subset of MM patients undergoing RIC Allo-SCT. After 10 years, the OS and PFS were 32% and 24%, respectively. The PFS curve after Allo-SCT stabilizes in time with a plateau after 6 years post Allo-SCT.

Allogeneic hematopoietic cell transplantation from unrelated donors in multiple myeloma: study from the Italian Bone Marrow Donor Registry

To evaluate trends in allografting from unrelated donors, we conducted a study on 196 consecutive myeloma patients transplanted between 2000 and 2009 in Italy. Twenty-eight percent, 37%, and 35%, respectively, received myeloablative, reduced-intensity, and nonmyeloablative conditioning. In these 3 cohorts, 1-year and 5-year transplantation-related mortalities were 28.8% and 37.0%, 20.3% and 31.3%, and 25.0% and 30.3%, respectively (P = .745). Median overall survival (OS) and event-free survival from transplantation for the 3 cohorts were 29 and 10 months, 11 and 6 months, and 32 and 13 months, respectively (P = .039 and P = .049). Overall cumulative incidences of acute and chronic graft-versus-host-disease (GVHD) were 46.1% and 51.1%. By Cox multivariate analyses, chronic GVHD was significantly associated with longer OS (hazard ratio [HR], .51; P = .009), whereas the use of peripheral blood stem cells was borderline significant (HR, .55; P = .051). Better response posttransplantation was associated with longer event-free survival (HR, 2.13 to 4.25; P < .001). Acute GVHD was associated with poorer OS (HR, 2.53; P = .001). This analysis showed a strong association of acute and chronic GVHD and depth of response posttransplantation with clinical outcomes. Long-term disease control remains challenging regardless of the conditioning. In the light of these results, prospective trials may be designed to better define the role of allografting from unrelated donors in myeloma.

Predictors of prolonged survival after allogeneic hematopoietic stem cell transplantation for multiple myeloma

A total of 149 patients with multiple myeloma (MM) who received allogeneic hematopoietic stem cell transplantation (allo-HCT) with myeloablative (MAC; n = 38) or reduced-intensity conditioning (RIC; n = 110) regimens at MD Anderson Cancer Center were evaluated. Of the total, 120 (81%) patients had relapsed or had refractory disease. Median age of MM patients was 50 (28-70) years with a followup time of 28.5 (3-164) months. The 100-day and 5-year treatment related mortality (TRM) rates were 17% and 47%, respectively. TRM was significantly lower with RIC regimens (13%) vs. 29% for MAC at 100 days (P = 0.012). The cumulative incidence of Grade II-IV acute graft-versus-host disease (GVHD) was 35% and chronic GVHD was 46%. PFS and OS at 5 years were 15% and 21%, respectively. In multivariate analysis, allo-HCT for primary remission consolidation was associated with longer PFS (HR 0.35; 95% CI, 0.18-0.67) and OS (HR 0.29; 95% CI 0.15-0.55), while absence of high-risk cytogenetics was associated with longer PFS only (HR 0.59; 95% CI 0.37-0.95). We observe that TRM has decreased with the use of RIC regimens, and long-term disease control can be expected in a subset of MM patients undergoing allo-HCT. Further studies should be conducted in carefully designed clinical trials in this patient population.

Advances in the autologous and allogeneic transplantation strategies for multiple myeloma

BACKGROUND

Multiple myeloma is largely an incurable malignant plasma cell neoplasm; however, the landscape of its treatment is rapidly changing.

METHODS

The recent literature on both autologous and allogeneic transplant approaches for multiple myeloma was reviewed.

RESULTS

High-dose chemotherapy followed by autologous hematopoietic cell transplantation (HCT) remains an integral component of upfront treatment strategy, and the incorporation of novel immunomodulators and proteasome inhibitor to induction regimens improves response rates and increases overall survivals. Bortezomib and lenalidomide-based combination chemotherapy regimens have become the standard induction myeloma therapy. When myeloma patients proceed to transplant after novel combination regimens, their response rates are further improved. Despite these recent major improvements, myeloma remains incurable and long-term survival appears elusive. Due in part to a potential graft-vs-myeloma effect, allogeneic HCT is a potentially curative transplant option. However, initial attempts have been hampered by the high transplant-related mortality. With a reduction of toxicity, allogeneic transplant approaches with reduced-intensity conditioning have been utilized, although they are subject to continued disease progression and relapse following transplantation. Recent research efforts have shifted to the use of a tandem autologous-allogeneic HCT approach. The long-term follow-up of this new strategy is awaited.

CONCLUSIONS

Recent advances in HCT have improved outcomes of patients with multiple myeloma. Ongoing research activity focuses on the strategies to improve outcomes of HCT by incorporation of tandem autologous-allogeneic transplantation schema, novel conditioning regimens, and the use of consolidation and maintenance therapy.

Allogeneic hematopoietic cell transplant for multiple myeloma using reduced intensity conditioning therapy, 1998-2006: factors associated with improved survival outcome

This study reports on the outcome of 95 allogeneic hematopoietic cell transplants (HCTs) using reduced intensity conditioning (RIC) performed for patients with multiple myeloma (MM) in Australia and New Zealand between 1998 and 2006. The median age at HCT was 52 years. Of the 32 patients for whom the allograft was performed as a first transplant, 15 (47%) had their allograft less than 1 year from diagnosis, while for the 63 patients who had an allograft following an autograft, nine (14%) were allografted within 1 year post-diagnosis (p < 0.001). The cumulative incidence of transplant-related mortality (TRM) was 19% at 1 year post-transplant. At 5 years post-transplant the overall survival (OS) was 40% and progression-free survival (PFS) was 23%, with no apparent survival plateau. Three factors were independently favorable predictors of OS in a Cox regression model: immunoglobulin G (IgG) myeloma (hazard ratio [HR] = 0.42, 95% confidence interval [CI] 0.24-0.75, p = 0.004), a human leukocyte antigen (HLA)-identical sibling donor (HR = 0.37, 95% CI 0.18-0.74, p = 0.005), and less than 1 year between MM diagnosis and RIC HCT (HR = 0.27, 95% CI 0.12-0.59, p = 0.001). Patterns of outcome indicate that RIC HCT may offer the potential for cure for only a small group of patients with MM.

Allogeneic stem cell transplantation in multiple myeloma relapsed after autograft: a multicenter retrospective study based on donor availability

Allogeneic stem cell transplantation (allo-SCT) using reduced-intensity conditioning (RIC) is a feasible procedure in selected patients with relapsed multiple myeloma (MM), but its efficacy remains a matter of debate. The mortality and morbidity related to the procedure and the rather high relapse risk make the use of allo-SCT controversial. In addition, the availability of novel antimyeloma treatments, such as bortezomib and immunomodulatory agents, have made allo-SCT less appealing to clinicians. We investigated the role of RIC allo-SCT in patients with MM who relapsed after autologous stem cell transplantation and were then treated with a salvage therapy based on novel agents. This study was structured similarly to an intention-to-treat analysis and included only those patients who underwent HLA typing immediately after the relapse. Patients with a donor (donor group) and those without a suitable donor (no-donor group) were compared. A total of 169 consecutive patients were evaluated retrospectively in a multicenter study. Of these, 75 patients found a donor and 68 (91%) underwent RIC allo-SCT, including 24 from an HLA-identical sibling (35%) and 44 from an unrelated donor (65%). Seven patients with a donor did not undergo allo-SCT for progressive disease or concomitant severe comorbidities. The 2-year cumulative incidence of nonrelapse mortality was 22% in the donor group and 1% in the no-donor group (P < .0001). The 2-year progression-free survival (PFS) was 42% in the donor group and 18% in the no-donor group (P < .0001). The 2-year overall survival (OS) was 54% in the donor group and 53% in the no-donor group (P = .329). In multivariate analysis, lack of a donor was a significant unfavorable factor for PFS, but not for OS. Lack of chemosensitivity after salvage treatment and high-risk karyotype at diagnosis significantly shortened OS. In patients who underwent allo-SCT, the development of chronic graft-versus-host disease had a significant protective effect on OS. This study provides evidence for a significant PFS benefit of salvage treatment with novel drugs followed by RIC allo-SCT in patients with relapsed MM who have a suitable donor.

Tandem autologous/reduced-intensity conditioning allogeneic stem-cell transplantation versus autologous transplantation in myeloma: long-term follow-up

PURPOSE

Results of allogeneic stem-cell transplantation (allo) in myeloma are controversial. In this trial autologous stem-cell transplantation (auto) followed by reduced-intensity conditioning matched sibling donor allo (auto-allo) was compared with auto only in previously untreated multiple myeloma.

PATIENTS AND METHODS

In all, 357 patients with myeloma up to age 69 years were enrolled from 2001 to 2005. Patients with an HLA-identical sibling donor were allocated to the auto-allo arm (n = 108) and patients without a matched sibling donor were allocated to the auto arm (n = 249). Single (n = 145) or tandem (n = 104) auto was optional. Conditioning for the auto arm was melphalan 200 mg/m(2); conditioning for the allo arm was total-body irradiation 2 Gy plus fludarabine 30 mg/m(2)/d for 3 days. Median follow-up time was 61 months. Primary end point was progression-free survival.

RESULTS

Progression-free survival at 60 months was significantly better with auto-allo than with auto [corrected] alone (35% v 18%; P = .001), as was the risk of death and of relapse in the long term (P = .047 and P = .003, respectively). Overall survival at 60 months was 65% versus 58%, and relapse incidence was 49% versus 78%. Complete remission rates were 51% and 41%, respectively (P = .020). Nonrelapse mortality at 24 months was 12% after auto-allo compared with 3% in the auto group (P < .001). The incidence of grade 2 to 4 acute graft-versus-host disease (GvHD) was 20%, and the incidence of limited and extensive chronic GvHD was 31% and 23%.

CONCLUSION

In patients with previously untreated multiple myeloma, long-term outcome with respect to progression-free survival, overall survival, and relapse rate is superior after auto-allo compared with auto only. Nonrelapse mortality is at a reasonable level in both groups.

Reduced-intensity allogeneic hematopoietic stem cell transplantation for multiple myeloma: a concise review

Reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (HSCT) can result in reliable donor engraftment, relatively low treatment-related mortality, and sustained remissions in the treatment of multiple myeloma. However, substantial cytoreduction pre-allografting is often necessary because of a variable graft-versus-myeloma effect. The use of RIC allogeneic HSCT immediately after autologous HSCT provides a temporal separation between tumor reduction by high-dose chemotherapy and the graft-versus-myeloma effect. There are currently a number of prospective trials attempting to address the issue of whether this strategy leads to decreases in relapse and/or improvement in overall survival as compared with double autologous transplants. Unfortunately, similar to autografting, relapse remains the major cause of treatment failure after RIC allogeneic HSCT. To improve treatment results with allografting, consideration should be given to incorporating immunomodulatory drugs and targeted treatments to enhance pretransplantation remission status, as posttransplantation maintenance therapy, or in combination with donor lymphocyte infusions for refractory or relapsed disease. Studies exploring these strategies are ongoing.

Unrelated stem cell transplantation for patients with multiple myeloma

PURPOSE OF REVIEW

The role of allogeneic stem cell transplantation (SCT) in treatment of myeloma patients is still controversial. Meanwhile, the numbers of unrelated SCT for hematological diseases in Europe are higher than for human leukocyte antigen (HLA)-identical sibling transplantations, but in multiple myeloma only 39% of the allogeneic transplantations are performed from unrelated donors and only a minority were done within prospective clinical trials.

RECENT FINDINGS

The few published data of unrelated SCT in multiple myeloma reported a higher treatment-related mortality for standard myeloablative conditioning in comparison to reduced-intensity conditioning. Despite the heterogeneous patient selection in the trial, lower nonrelapse mortality and improved survival can be achieved by careful donor selection (10/10 HLA-alleles, male donor). Natural killer-alloreactivity might play a role, but conclusive data are lacking. Transplantation in more advanced or refractory patients is associated with an inferior outcome. The results of an unrelated SCT seem to be comparable to those of HLA-identical siblings, but a direct comparison is lacking so far.

SUMMARY

Unrelated SCT in multiple myeloma is feasible, but prospective clinical trials using unrelated stem cell donors are urgently needed to define the role of an unrelated SCT in multiple myeloma in the era of novel agents.

International Myeloma Working Group Consensus Statement Regarding the Current Status of Allogeneic Stem-Cell Transplantation for Multiple Myeloma

Purpose

To define consensus statement regarding allogeneic stem-cell transplantation (Allo-SCT) as a treatment option for multiple myeloma (MM) on behalf of International Myeloma Working Group.

Patients and Methods

In this review, results from prospective and retrospective studies of Allo-SCT in MM are summarized.

Results

Although the introduction of reduced-intensity conditioning (RIC) has lowered the high treatment-related mortality associated with myeloablative conditioning, convincing evidence is lacking that Allo-RIC improves the survival compared with autologous stem-cell transplantation.

Conclusion

New strategies are necessary to make Allo-SCT safer and more effective for patients with MM. Until this is achieved, Allo-RIC in myeloma should only be recommended in the context of clinical trials.