Haploidentical Allogeneic Hematopoietic Cell Transplantation for Multiple Myeloma Using Post-Transplantation Cyclophosphamide Graft-versus-Host Disease Prophylaxis

Efficacy and survival outcome of allogeneic stem-cell transplantation in multiple myeloma: meta-analysis in the recent 10 years

Introduction

Allogeneic hematopoietic cell transplantation (alloHCT) possessed direct cytotoxicity and graft-versus-multiple myeloma effect (GvMM). Growing trials have shown survival benefits of performing alloHCT in both newly diagnosed and relapsed MM.

Methods

We aimed to provide a comprehensive analysis in the recent 10 years to verify the efficacy and survival outcome of alloHCT in MM patients. A total of 61 studies which provide data between 14/04/2013 and 14/04/2023 and a total of 15,294 data from MM patients who had undergone alloSCT were included in our study. The best response rates (CR, VGPR, PR) and survival outcomes (1-, 2-, 3-,5-, and 10-year OS, PFS, NRM) were assessed. We further conducted meta-analysis in the NDMM/frontline setting and RRMM/salvage setting independently.

Results

The pooled estimate CR, VGPR, and PR rates were 0.45, 0.21, and 0.24, respectively. The pooled estimates of 1-, 2-, 3-, 5-, and 10-year OS were 0.69, 0.57, 0.45, 0.45, and 0.36, respectively; the pooled estimates of 1-, 2-, 3-, 5-, and 10-year PFS were 0.47, 0.35, 0.24, 0.25, and 0.28, respectively; and the pooled estimates of 1-, 2-, 3-, 5-, and 10-year NRM were 0.16, 0.21, 0.16, 0.20, and 0.15, respectively. In the NDMM/upfront setting, the pooled estimate CR rate was 0.54, and those for 5-year OS, PFS, and NRM were 0.69, 0.40, and 0.11, respectively. In a relapsed setting, the pooled estimate CR rate was 0.31, and those for 5-year OS, PFS, and NRM were 0.24, 0.10, and 0.15, respectively.

Discussion

Our results showed constant OS, PFS, and NRM from the third year onwards till the 10th year, suggesting that alloSCT has sustained survival benefits. Good response rate and promising survival outcome were observed in the NDMM/ frontline setting.

Conclusion

Although comparing with other treatments, alloSCT had a lower response rate and poorer short-term survival outcome, long-term follow-up could reveal survival benefits of alloSCT in MM patients.

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.

[Clinical analysis of 14 patients aged ≤ 50 years with high-risk multiple myeloma treated with allogeneic hematopoietic stem cell transplantation]

Objective: To evaluate the efficacy of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in young patients with high-risk multiple myeloma (HRMM) and analyzed the factors affecting patient prognosis. Methods: In this retrospective study, we analyzed the clinical data of 14 patients with HRMM with cytogenetic abnormalities or high-risk biological factors who underwent allo-HSCT at the Hematopoietic Stem Cell Transplantation Center of the Institute of Hematology & Blood Diseases Hospital between November 2016 and November 2022. Results: There were seven males and seven females included in the study, with a median age of 39.5 (31-50) years at the time of allo-HSCT. The median number of treatment lines before transplantation was 2 (1-6) . Before allo-HSCT, 42.9% (6/14) of the patients did not achieve complete remission, while 35.7% (5/14) of the patients achieved measurable residual disease positivity. After transplantation, all patients were evaluated for their treatment response, and the overall response rate was 100% (14/14) . All 14 patients successfully underwent allo-HSCT, with median engraftment times for neutrophils and platelets of 11 (10-14) days and 13 (9-103) days, respectively. Acute grade Ⅱ-Ⅳ graft-versus-host disease (GVHD) occurred in five patients (35.7%) , and two patients (14.3%) developed moderate-to-severe chronic GVHD. The median follow-up time after allo-HSCT was 18.93 (4.10-72.53) months, with an expected 2-year transplant-related mortality rate of 7.1% (95% CI 0%-21.1%) and an expected 2-year overall survival rate of 92.9% (95% CI 80.3%-100.0%) . Moreover, the expected 1-year and 2-year progression-free survival rates were 92.9% (95% CI 80.3%-100.0%) and 66.0% (95% CI 39.4%-100.0%) , respectively, and the 2-year cumulative incidence of relapse was 28.9% (95% CI 0%-56.7%) . Upfront allo-HSCT following complete remission after induced therapy and the presence of chronic GVHD might be favorable prognostic factors. Conclusion: allo-HSCT is an effective treatment for improving the prognosis of young patients with HRMM.

Current Role of Allogeneic Stem Cell Transplantation in Multiple Myeloma

Major progress in the treatment of multiple myeloma has been made in the last several years. However, myeloma remains incurable and patients with high-risk cytogenetics or advanced stage disease have an even worsen survival. Only allogeneic transplantation may have curative potential in some patients. However, the high non-relapse mortality and incidence of chronic graft-versus-host disease have raised controversy regarding this procedure. In this review, we will address the role of upfront and delayed allogeneic transplant.

Allogeneic Stem Cell Transplantation in Multiple Myeloma

The development of new inhibitory and immunological agents and combination therapies significantly improved response rates and survival of patients diagnosed with multiple myeloma (MM) in the last decade, but the disease is still considered to be incurable by current standards and the prognosis is dismal especially in high-risk groups and in relapsed and/or refractory patients. Allogeneic hematopoietic stem cell transplantation (allo-SCT) may enable long-term survival and even cure for individual patients via an immune-mediated graft-versus-myeloma (GvM) effect, but remains controversial due to relevant transplant-related risks, particularly immunosuppression and graft-versus-host disease, and a substantial non-relapse mortality. The decreased risk of disease progression may outweigh this treatment-related toxicity for young, fit patients in high-risk constellations with otherwise often poor long-term prognosis. Here, allo-SCT should be considered within clinical trials in first-line as part of a tandem approach to separate myeloablation achieved by high-dose chemotherapy with autologous SCT, and following allo-SCT with a reduced-intensity conditioning to minimize treatment-related organ toxicities but allow GvM effect. Our review aims to better define the role of allo-SCT in myeloma treatment particularly in the context of new immunomodulatory approaches.

Post-Transplantation Cyclophosphamide for Graft-versus- Host Disease Prophylaxis in Multiple Myeloma Patients Who Underwent Allogeneic Hematopoietic Cell Transplantation: First Comparison by Donor Type. A Study from the Chronic Malignancies Working Party of the European Society for Blood and Marrow Transplantation

Graft-versus-host disease (GVHD) remains among the major causes of treatment failure in patients with multiple myeloma (MM) undergoing allogeneic hematopoietic cell transplantation (allo-HCT). The use of post-transplantation cyclophosphamide (PT-Cy) is now a well-established and widely used method for GVHD prophylaxis after HLA haploidentical HCT. However, the rationale for using PT-Cy in the setting of matched donor transplantation is less apparent, given the lesser degree of bidirectional alloreactivity. In this retrospective study, we investigated the role of PT-Cy as GVHD prophylaxis in patients with multiple myeloma underoing allo-HCT, among different donor types, to determine cumulative incidence of acute and chronic GVHD and impact on engraftment, progression-free survival (PFS), GVHD-free/relapse- free survival (GRFS), overall survival (OS), and NRM A total of 295 patients with MM underwent allo-HCT using grafts from a matched related donor (MRD; n = 67), matched unrelated donor (MUD; n = 72), mismatched related or unrelated donor (MMRD/MMUD, 1 antigen; n = 27), or haploidentical donor (haplo; n = 129) using PT-Cy between 2012 and 2018. In addition to PT-Cy, agents used in GVHD prophylaxis included calcineurin inhibitors in 239 patients (81%), with mycophenolate mofetil in 184 of those 239 (77%). For grade II-IV acute GVHD, the cumulative incidence at day +100 was 30% (95% confidence interval [CI], 25% to 36%), 9% (95% CI, 5% to 12%) for grade III-IV acute GVHD, and 27% (95% CI, 21% to 32%) for chronic GVHD (limited, 21%; extensive, 6%), with no differences by donor type. The median time to neutrophil engraftment was 19d (95% CI, 18-19), with no significant difference by donor type. The median time to platelet engraftment was delayed in haploidentical donor graft recipients (27 days versus 21 days; P < .001). Two-year OS, PFS, GRFS, and NRM were 51% (95% CI, 45% to 58%), 26% (95% CI, 20% to 32%), 24% (95% CI, 18% to 30%), and 19% (95% CI, 14% to 24%), respectively, with no significant difference between different donor types. In multivariable analyses, compared with the haplo donors, the use of MRDs was associated with significantly better OS (hazard ratio [HR], 0.6; 95% CI, 0.38 to 0.95; P = .029), and the use of MUDs was associated with a significantly higher GRFS (HR, 0.63; 95% CI, 0.42 to 0.97; P = .034). There was a trend toward improved PFS with use of MUDs (HR, 0.69; 95% CI, 0.46 to 1.04; P = .08). Our data show that PT-Cy in MM patients undergoing allo-HCT resulted in low rates of acute and chronic GVHD and led to favorable survival, especially in the matched related donor setting. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

The Role of Allogeneic Stem Cell Transplantation in Multiple Myeloma: A Systematic Review of the Literature

Multiple myeloma (MM) is an indolent B-cell malignancy, where treatment is aimed at preventing organ dysfunction from light chain accumulation (slowing disease progression) and inducing remission. Allogeneic stem cell transplant (allo-SCT), through graft versus myeloma (GVM) effects, has the potential to induce remission to a potentially curative-like state. In this systematic review, we aimed to understand this relationship to the risks and severity of disease in categorized patients and gain an updated comprehension of the future of allo-SCT in MM treatment. We conducted this review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and searched the PubMed database to obtain the specified literature with both the use of keywords and Medical Subject Headings (MeSH). A total of 16 relevant articles were included for discussion after the quality appraisal was completed, as appropriate, by either the Cochrane tool or Newcastle-Ottawa checklist. Our review concludes that while allo-SCT may benefit high-risk patients, successful procedures may incorporate a tandem autologous hematopoietic stem cell transplant approach in combination with novel pharmacologic contributions for which there is an observed synergy in the modulation of the immunologic microenvironment. Furthermore, tailored patient selection by evaluating pre-transplant factors including high-risk cytogenetics, age, and pre-salvage International Staging System (ISS) can predict post-transplantation success including non-relapse mortality. Successive research should continue to revise and update treatment options as the evolving therapeutic drug regimens may change over the course of indolent disease.

Current Use of Total Body Irradiation in Haploidentical Allogeneic Hematopoietic Stem Cell Transplantation

Total body irradiation (TBI) is included in the conditioning regimen for allogeneic hematopoietic stem cell transplantation (HSCT), with unique advantages such as uniform distribution over the whole body and decreased exposure to cytotoxic chemotherapeutic agents. For individuals who lack matched sibling or matched unrelated donors, the use of haploidentical donors has been increasing despite challenges such as graft rejection and graft-versus-host disease (GVHD). Although a limited number of studies have been performed to assess the clinical role of TBI in haploidentical HSCT, TBI-based conditioning showed comparable results in terms of survival outcomes, rate of relapse, and GVHD in diverse hematologic malignancies such as leukemia, lymphoma, and multiple myeloma. Advances in supportive care, along with recent technical improvements such as restriction of maximum tolerated dose, appropriate fractionation, and organ shielding, help to overcome diverse adverse events related to TBI. Post-transplantation cyclophosphamide was used in most studies to reduce the risk of GVHD. Additionally, it was found that post-transplantation rituximab may improve outcomes in TBI-based haploidentical HSCT, especially in patients with B-cell lymphoma. Along with the advances of techniques and strategies, the expansion of age restriction would be another important issue for TBI-based haploidentical HSCT considering the current tendency toward increasing age limitation and lack of matched donors. This review article summarizes the current use and future perspectives of TBI in haploidentical HSCT.

Role of Stem Cell Transplantation in Multiple Myeloma

Autologous stem cell transplantation (auto-SCT) has been the standard of care in eligible newly diagnosed multiple myeloma (MM) patients. Outcomes of patients with MM have improved significantly due to the advent of several novel drugs. Upfront use of these drugs in induction therapy has significantly increased the rate and depth of responses that have translated into longer remission and survival. This has now raised a debate regarding the role and relevance of auto-SCT in the management of myeloma. However, clinical trials have confirmed the utility of auto-SCT even in the era of novel drugs. Tandem auto-SCT followed by maintenance has shown a progression-free survival (PFS) benefit in high-risk MM, and hence can be considered in young and fit patients with high-risk disease. Auto-SCT has the advantages of resetting the bone marrow microenvironment, short-lived toxicity compared to the long-term physical and financial toxicities of continued chemotherapy in the absence of SCT, very low transplant-related mortality (TRM) in high volume centers, and providing longer disease-free survival when followed by maintenance therapy. Allogeneic SCT is one potentially curative option for MM, albeit with an increased risk of death due to high TRM. Strategies to modulate the graft-versus-host disease (GVHD) while maintaining or improving the graft-versus-myeloma (GVM) effect could place allogeneic SCT back in the treatment armamentarium of MM.

Haploidentical transplantation in patients with multiple myeloma making use of natural killer cell alloreactive donors

Disease relapse is an important problem after allogeneic stem cell transplantations in multiple myeloma (MM). To test the hypothesis that natural killer (NK) cell alloreactivity in the setting of a haploidentical stem cell transplantation (haploSCT) can reduce the risk of myeloma relapse, we performed a small prospective phase 2 study in which we transplanted poor-risk MM patients using a killer cell immunoglobulin-like receptor (KIR)-ligand mismatched haploidentical donor. Patients received bone marrow grafts after reduced-intensity conditioning, with post-transplantation cyclophosphamide (PTCY) graft-versus-host-disease (GVHD) prophylaxis. The primary endpoint was 1.5-year progression-free survival (PFS); stopping rules were installed in case interim results made a benefit of 50% PFS at 1.5 years unlikely. After inclusion of 12 patients, of which 9 were evaluable for the primary endpoint, all patients relapsed within a median time of 90 days. All except 1 patient showed engraftment, with a median time to neutrophil recovery of 18 (12–30) days. The study was prematurely terminated based on the predefined stopping rules after the inclusion of 12 patients. With this small study, we show that in chemo-resistant myeloma patients, NK cell KIR-mismatch is not superior to conventional alloSCT. This strategy, however, can serve as a platform for new treatment concepts.

Clinical Trial Registry: NCT02519114

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.

Prognostic Factors for Postrelapse Survival after ex Vivo CD34+-Selected (T Cell-Depleted) Allogeneic Hematopoietic Cell Transplantation in Multiple Myeloma

Allogeneic hematopoietic cell transplantation (alloHCT) for multiple myeloma (MM), with its underlying graft-versus-tumor capacity, is a potentially curative approach for high-risk patients. Relapse is the main cause of treatment failure, but predictors for postrelapse survival are not well characterized. We conducted a retrospective analysis to evaluate predictors for postrelapse overall survival (OS) in 60 MM patients who progressed after myeloablative T cell-depleted alloHCT. The median patient age was 56 years, and 82% had high-risk cytogenetics. Patients received a median of 4 lines of therapy pre-HCT, and 88% achieved at least a partial response (PR) before alloHCT. Of the 38% who received preemptive post-HCT therapy, 13 received donor lymphocyte infusions (DLIs) and 10 received other interventions. Relapse was defined as very early (<6 months; 28%), early (6 to 24 months; 50%), or late (>24 months; 22%). At relapse, 27% presented with extramedullary disease (EMD). The median postrelapse overall survival (OS) by time to relapse was 4 months for the very early relapse group, 17 months for the early relapse group, and 72 months for the late relapse group (P = .002). Older age, relapse with EMD, <PR before alloHCT, <PR by day +100, and no maintenance were prognostic for inferior postrelapse OS on univariate analysis. On multivariate analysis adjusted for age and sex, very early relapse (hazard ratio [HR], 4.37; 95% confidence interval [CI], 1.42 to 13.5), relapse with EMD (HR, 5.20; 95% CI, 2.10 to 12.9), and DLI for relapse prevention (HR, .11; 95% CI, 2.10 to 12.9) were significant predictors for postrelapse survival. Despite their shared inherent high-risk status, patients with MM have significantly disparate post-HCT relapse courses, with some demonstrating long-term survival despite relapse.

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.

Relapse after Allogeneic Hematopoietic Cell Transplantation for Multiple Myeloma: Survival Outcomes and Factors Influencing Them

Many patients with multiple myeloma (MM) eventually relapse even after allogeneic hematopoietic cell transplantation (alloHCT) for curative intent. Over the past decade, outcomes for patients with MM have improved significantly with the availability of new therapies, including next-generation proteasome inhibitors, immunomodulatory agents, and, more recently, monoclonal antibodies. Although several published studies have evaluated the outcomes of alloHCT for MM, the data on survival outcomes in patients with MM experiencing disease relapse following alloHCT are limited. In addition, the predictors for postrelapse survival in these patients are not known. In this study, we examined the outcomes of a single-center cohort of 60 patients with MM who experienced relapse or progression after alloHCT. In addition, we evaluated the use of salvage regimens for treatment of relapsed MM and analyzed the predictors for improved postrelapse survival. After a median follow-up of 2.2 years from the time of relapse, the median duration of postrelapse survival was 1.8 years (95% confidence interval [CI], 1.2 to 5.0 years). Patients received a median of 3 lines of therapy (range, 0 to 10) for treatment of MM beyond the post-alloHCT relapse/progression. Multivariate analysis identified cytogenetic risk (standard risk versus high risk; hazard ratio [HR], .34; P = .01), time to relapse after alloHCT (>12 months versus ≤12 months: HR, .41; P = .04), and occurrence of acute graft-versus-host disease (GVHD) before relapse (GVHD versus no GVHD: HR, 2.89; P = .01) significantly affected postrelapse survival. These data illustrate that long-term myeloma control and survival is attainable in those relapsing/progressing after alloHCT and suggest that the synergism between novel therapies and the allogeneic immune platform is the key to improved survival in this high-risk patient population.

Comparison of outcomes after human leukocyte antigen-matched and haploidentical hematopoietic stem-cell transplantation for multiple myeloma

Background:

Allogeneic stem-cell transplantation (SCT) is a well-established immunotherapeutic strategy for multiple myeloma (MM) with a potent and often sustained graft-vs.-myeloma effect. This multicenter investigation aimed to analyze the complications and survival of haploidentical SCT in patients with MM, and compare the main outcomes with matched-related donors (MRDs).

Methods:

Haploidentical and MRD SCT was identified from a cohort of 97 patients with MM who received a myeloablative transplantation in 13 hospitals from May 2001 to December 2017. A matched-pair analysis was designed. For each haplo recipient, the recipients were randomly selected from the MRD group and were matched according to the following criteria: year of the hematopoietic SCT (±2 years), disease status at transplantation, and the length of follow-up.

Results:

Seventy cases received MRD and 27 received haploidentical transplantation. The two groups showed no significant differences regarding age, gender, cytogenetic risk, and diagnostic stage. The cumulative incidences of non-relapse mortality (NRM) at 1 and 3 years based on donor type were 20.5% (95% confidence interval [CI], 10.90–30.10%) and 24.2% (95% CI, 13.81–34.59%) for the MRD group and 16.80% (95% CI, 1.71–31.89%) and 28.70% (95% CI, 8.71–48.69%) for the haplo group, respectively. Cumulative incidence of NRM did not differ significantly between the two groups (χ² = 0.031, P = 0.861). The cumulative incidences of progression-free survival (PFS) and 1 year and 3 years by type of donors were 59.8% (95% CI, 48.24–71.36%) and 45.4% (95% CI, 33.44–57.36%), and 65.6% (95% CI, 47.18–84.02%) and 26.8% (95% CI, 7.59–46. 01%) for MRD and haploidentical donor, respectively. Cumulative incidence of PFS did not differ significantly between the two groups (χ² = 0.182, P = 0.670). In multivariate analyses, no statistically significant differences were observed between haploidentical and MRD for relapse, NRM, PFS, and overall survival. There were no statistically differences on main outcomes after haploidentical and MRD.

Conclusion:

Haploidentical SCT could be performed safely and feasibly for patients with MM in need.

Tandem Autologous-Autologous versus Autologous-Allogeneic Hematopoietic Stem Cell Transplant for Patients with Multiple Myeloma: Long-Term Follow-Up Results from the Blood and Marrow Transplant Clinical Trials Network 0102 Trial

Allogeneic hematopoietic cell transplant (HCT) may improve long-term multiple myeloma (MM) control through the graft-versus-myeloma effect. The Blood and Marrow Transplant Clinical Trials Network 0102 trial was a biologic assignment trial comparing tandem autologous transplant (auto-auto) versus autologous followed by reduced-intensity allogeneic (auto-allo) transplant in patients with newly diagnosed MM with standard-risk (n = 625) or high-risk (n = 85; β₂-microglobulin at diagnosis ≥ 4 mg/dL or deletion of chromosome 13 by conventional karyotyping) disease. Although the initial 3-year analysis showed no difference in progression-free survival (PFS) between arms in either risk group, we hypothesized that long-term follow-up may better capture the impact of the graft-versus-myeloma effect. Median follow-up of survivors was over 10 years. Among standard-risk patients there was no difference in PFS (hazard ratio [HR], 1.11; 95% confidence interval [CI], .93 to 1.35; P = .25) or OS (HR, 1.03; 95% CI, .82 to 1.28; P = .82). The 6-year PFS was 25% in the auto-auto arm versus 22% in the auto-allo arm (P = .32), and 6-year overall survival (OS) was 60% and 59%, respectively (P = .85). In the high-risk group, although there was no statistically significant difference in PFS (HR, .66; 95% CI, .41 to 1.07; P = .07) and OS (HR, 1.01; 95% CI, .60 to 1.71; P = .96), a reduction in 6-year risk of relapse of 77% versus 47% (P = .005) was reflected in better PFS of 13% versus 31% (P = .05) but similar OS, at 47% versus 51% (P = .69). Allogeneic HCT can lead to long-term disease control in patients with high-risk MM and needs to be explored in the context of modern therapy.

Efficacy of bortezomib to intensify the conditioning regimen and the graft-versus-host disease prophylaxis for high-risk myeloma patients undergoing transplantation

This multicenter phase I trial was designed to evaluate the safety and efficacy of bortezomib (Bz) as part of both the conditioning regimen and the graft-versus-host disease (GvHD) prophylaxis. Patients received fludarabine, melphalan and Bz (days -9 and -2). GVHD prophylaxis consisted of Bz (days +1, +4, and +7), sirolimus (Siro) from day -5 and tacrolimus (Tk) from -3 (except the first five patients that did not receive Tk). Twenty-five patients with poor prognostic multiple myeloma were included. Eleven out of the 19 patients had high-risk features. Out of the 21 patients evaluable at day +100, 14 were in CR (67%) and 7 (33%) in PR. Cumulative incidence (CI) of nonrelapse mortality at 1 year was 24%. CI of grades 2-4 and 3-4 acute GvHD was 35% and 10%, respectively; CI of chronic GvHD was 35% and 55% at 1 and 2 years, respectively. Overall and event free survival at 2 years were 64% and 31%, respectively. Bz as part of the conditioning regimen and in the combination with Siro/tacrolimus for GvHD prophylaxis is safe and effective allowing an optimal disease control early after transplant and reducing the risk of GvHD.

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.

Haploidentical versus matched donor stem cell transplantation for patients with hematological malignancies: a systemic review and meta-analysis

We compared the safety and efficacy of haploidentical stem cell transplantation (haplo-SCT) to matched donor SCT (matched-SCT) in treating hematological malignancies. The Medline, Cochrane, EMBASE, and Google Scholar databases were searched through 21 June 2017 using the search term "(hematological disease) AND matched AND (haploidentical OR haplo-identical OR haplo identical OR haplo transplantation OR haplo transplant OR haplo-SCT OR haplo-HSCT OR haplo-HCT)." Twenty-five studies enrolling 11,359 patients (haplo-SCT: 2677; matched-SCT: 8682) were included. The primary outcomes were acute and chronic graft-versus-host disease (GVHD), non-relapse mortality, and 1-year cumulative incidence of relapse. Haplo-SCT was associated with similar risks as matched-SCT for all primary endpoints. Subgroup analysis of patients who received a matched-SCT from a related donor revealed that patients who received haplo-SCT had a lower risk of acute GVHD. Among patients who received reduced-intensity conditioning (RIC), those who received haplo-SCT had a higher risk of acute grade II-IV GVHD and non-relapse mortality than did patients who received a matched-SCT from a related or unrelated donor. Haplo-SCT should continue to be considered as a safe and effective transplant option when a matched donor is unavailable, but it may not be suitable for patients who receive RIC.

Proceedings From the Fourth Haploidentical Stem Cell Transplantation Symposium (HAPLO2016), San Diego, California, December 1, 2016

The resurgence of haploidentical stem cell transplantation (HaploSCT) over the last decade is one of the most important advances in the field of hematopoietic stem cell transplantation (HSCT). The modified platforms of T cell depletion either ex vivo (CD34+ cell selection, "megadoses" of purified CD34+ cells, or selective depletion of T cells) or newer platforms of in vivo depletion of T cells, with either post-transplantation high-dose cyclophosphamide or intensified immune suppression, have contributed to better outcomes, with survival similar to that in HLA-matched donor transplantation. Further efforts are underway to control viral reactivation using modified T cells, improve immunologic reconstitution, and decrease the relapse rate post-transplantation using donor-derived cellular therapy products, such as genetically modified donor lymphocytes and natural killer cells. Improvements in treatment-related mortality have allowed the extension of haploidentical donor transplants to patients with hemoglobinopathies, such as thalassemia and sickle cell disease, and the possible development of platforms for immunotherapy in solid tumors. Moreover, combining HSCT from a related donor with solid organ transplantation could allow early tapering of immunosuppression in recipients of solid organ transplants and hopefully prevent organ rejection in this setting. This symposium summarizes some of the most important recent advances in HaploSCT and provides a glimpse in the future of fast growing field.

Update on current research into haploidentical hematopoietic stem cell transplantation

INTRODUCTION

Haploidentical stem cell transplantation (Haplo-SCT) is currently a suitable alternative worldwide for patients with hematological diseases, who lack human leukocyte antigen (HLA)-matched siblings or unrelated donors. Areas covered: This review summarizes the advancements in Haplo-SCT in recent years, primarily focusing on the global trends of haploidentical allograft, the comparison of outcomes between Haplo-SCT and other transplantation modalities, strategies for improving clinical outcomes, including donor selection, hematopoietic reconstitution promotion, and graft-versus-host disease, and relapse prevention/management, as well as the expanded indications of Haplo-SCT, such as severe aplastic anemia, myeloma and lymphoma. Expert commentary: Haploidentical allografts, including granulocyte colony-stimulating factor-based protocol and a post-transplant cyclophosphamide-based protocol, have been the mainstream strategy for Haplo-SCT. However, there are many unanswered questions in this field.

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.