Safety and efficacy of haploidentical stem cell transplantation for multiple myeloma

[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.

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.

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

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.

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.