Treosulfan-based conditioning is feasible and effective for cord blood recipients: a phase 2 multicenter study

Relationship between donor source, pre-transplant measurable residual disease, and outcome after allografting for adults with acute myeloid leukemia

Lack of HLA-matched related/unrelated donor remains a barrier to allogeneic hematopoietic cell transplantation (HCT) for adult acute myeloid leukemia (AML), with ongoing uncertainty about optimal donor type if more than one alternative donor is available. To assess the relationship between donor type, pre-HCT measurable residual disease (MRD), and post-HCT outcomes, we retrospectively analyzed 1265 myelodysplastic neoplasm (MDS)/AML and AML patients allografted in first or second remission with an HLA-matched sibling (MSD) or unrelated donor (MUD), HLA-mismatched unrelated donor (MMD), an HLA-haploidentical donor, or umbilical cord blood (UCB) at a single institution. Relapse risk was non-significantly higher after HLA-haploidentical and lower after UCB HCT. Non-relapse mortality (NRM) was significantly higher in patients undergoing MMD HCT, HLA-haploidentical HCT, and UCB, translating into significantly lower relapse-free survival (RFS) and overall survival for MMD and HLA-haploidentical HCT. There was a significant interaction between conditioning intensity and post-HCT outcomes for UCB HCT with better RFS for UCB HCT after MAC but higher NRM after non-MAC. In patients with pre-HCT MRD receiving MAC, relapse risk was significantly lower and RFS higher in those who underwent UCB HCT in comparison to MSD/MUD. Together, UCB HCT is a valuable alternative for MAC HCT, particularly in patients with pre-HCT MRD.

Umbilical Cord Blood Hematopoietic Cells: From Biology to Hematopoietic Transplants and Cellular Therapies

Umbilical cord blood (UCB) is a rich source of hematopoietic stem and progenitor cells that are biologically superior to their adult counterparts. UCB cells can be stored for several years without compromising their numbers or function. Today, public and private UCB banks have been established in several countries around the world. After 35 years since the first UCB transplant (UCBT), more than 50,000 UCBTs have been performed worldwide. In pediatric patients, UCBT is comparable to or superior to bone marrow transplantation. In adult patients, UCB can be an alternative source of hematopoietic cells when an HLA-matched unrelated adult donor is not available and when a transplant is urgently needed. Delayed engraftment (due to reduced absolute numbers of hematopoietic cells) and higher costs have led many medical institutions not to consider UCB as a first-line cell source for hematopoietic transplants. As a result, the use of UCB as a source of hematopoietic stem and progenitor cells for transplantation has declined over the past decade. Several approaches are being investigated to make UCBTs more efficient, including improving the homing capabilities of primitive UCB cells and increasing the number of hematopoietic cells to be infused. Several of these approaches have already been applied in the clinic with promising results. UCB also contains immune effector cells, including monocytes and various lymphocyte subsets, which, together with stem and progenitor cells, are excellent candidates for the development of cellular therapies for hematological and non-hematological diseases.

Cord blood transplantation for adult mature lymphoid neoplasms in Europe and Japan

ABSTRACT

To clarify the different characteristics and prognostic factors of cord blood transplantation (CBT) in adult patients with lymphoid neoplasms in Europe and Japan, we conducted a collaborative study. Patients aged 18-75 years receiving their first CBT (Europe: single CBT, n = 192; double CBT, n = 304; Japan: single CBT, n = 1150) in 2000-2017 were analyzed. Fewer patients with Hodgkin lymphoma (Europe vs Japan, 26% vs 5%), and older patients (≥50 years) (39% vs 59%) with a higher refined disease risk index (rDRI) (high-very high: 49% vs 14%) were included in the Japanese registry. High-very high rDRI was associated with inferior overall survival (OS) (vs low rDRI, Europe: hazard ratio [HR], 1.87; P = .001; Japan: HR, 2.34; P < .001) with higher progression/relapse risks. Total body irradiation (TBI)-containing conditioning contributed to superior OS both in Europe (vs TBI-reduced-intensity conditioning [RIC], non-TBI-RIC: HR, 1.93; P < .001; non-TBI-Myeloablative conditioning [MAC]: HR, 1.90; P = .003) and Japan (non-TBI-RIC: HR, 1.71; P < .001; non-TBI-MAC: HR 1.50, P = .007). The impact of HLA mismatches (≥2) on OS differed (Europe: HR, 1.52; P = .007; Japan: HR, 1.18; P = .107). CBT for lymphoid neoplasms, especially in those with high rDRI showed poor outcomes despite all the different characteristics in both registries. TBI should be considered in conditioning regimens to improve these outcomes. The different impacts of HLA mismatches call attention to the fundamental differences among these populations.

Excellent leukemia control after second hematopoietic cell transplants with unrelated cord blood grafts for post-transplant relapse in pediatric patients

Background

Patients with leukemia relapse after allogeneic hematopoietic cell transplant (HCT) have poor survival due to toxicity and disease progression. A second HCT often offers the only curative treatment.

Methods

We retrospectively reviewed our bi-institutional experience (MSKCC-USA; Utrecht-NL) with unrelated cord blood transplantation (CBT) for treatment of post-transplant relapse. Overall survival (OS) and event-free survival (EFS) were evaluated using the Kaplan-Meier method, treatment-related mortality (TRM) and relapse were evaluated using the competing risk method by Fine-Gray.

Results

Twenty-six patients age < 21 years received a second (n=24) or third (n=2) HCT with CB grafts during the period 2009-2021. Median age at first HCT (HCT1) was 11.5 (range: 0.9-17.7) years and all patients received myeloablative cytoreduction. Median time from HCT1 to relapse was 12.8 (range 5.5-189) months. At CBT, median patient age was 13.5 (range 1.4-19.1) years. Diagnoses were AML: 13; ALL: 4, MDS: 5, JMML: 2; CML: 1; mixed phenotype acute leukemia: 1. Sixteen patients (62%) were in advanced stage, either CR>2 or with active disease. Median time from HCT1 to CBT was 22.2 (range 7-63.2) months. All patients engrafted after CBT. Thirteen patients developed acute GvHD; 7 had grade III or IV. With a median survivor follow-up of 46.6 (range 17.4-155) months, 3-year OS was 69.2% (95% CI 53.6-89.5%) and 3-year EFS was 64.9% (95% CI 48.8-86.4%). Eight patients died, 3 of AML relapse and 5 due to toxicity (respiratory failure [n=4], GvHD [n=1]) at a median time of 7.7 (range 5.9-14.4) months after CBT. Cumulative incidence of TRM at 3 years was 19.2% (95% CI 4.1-34.4%). Notably, all TRM events occurred in patients transplanted up to 2015; no toxicity-related deaths were seen in the 16 patients who received CBT after 2015. Cumulative incidence of relapse was 15.9% (95% CI 1.6-30.2%) at 3 years, remarkably low for these very high-risk patients.

Conclusions

Survival was very encouraging following CB transplants in pediatric patients with recurrent leukemia after first HCT, and TRM has been low over the last decade. CBT needs to be strongly considered as a relatively safe salvage therapy option for post-transplant relapse.

Impact of Center Experience with Donor Type on Outcomes: A Secondary Analysis, Blood and Marrow Transplant Clinical Trials Network 1101Open for Accrual June 2012Open for Accrual June 2012

We previously reported the results of Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 1101, a randomized comparison of hematopoietic cell transplantation (HCT) performed with double umbilical cord blood units (dUCB) or with haploidentical bone marrow (haplo-BMT) with post-transplantation cyclophosphamide (PTCy) in the nonmyeloablative setting. Those results showed similar progression-free survival in the 2 treatment groups but lower nonrelapse mortality and better overall survival in the haplo-BM arm. In this secondary analysis, we sought to investigate whether transplantation center's previous experience with haplo-BM and/or dUCB HCT had an impact on outcomes. All patients randomized in BMT CTN 1101 were included. Center experience was assigned based on the number of transplantations with each platform performed in the year before initiation of the study according to the Center for International Blood and Marrow Transplant Research. Centers were then classified as a dUCB center (>10 dUCB HCTs; n = 117 patients, 10 centers), a haplo-BM center (>10 haplo-BM HCTs and ≤10 dUCB HCTs; n = 110 patients, 2 centers), or other center (≤10 haplo and ≤10 dUCB HCTs; n = 140 patients, 21 centers). After adjusting for age, Karnofsky Performance Status, and Disease Risk Index, we found that haplo-BM centers had lower overall mortality with this donor type compared with dUCB centers (hazard ratio [HR], 2.56; 95% confidence interval [CI], 1.44 to 4.56). In contrast, there were no differences in overall mortality between haplo-BM and dUCB in centers that were experienced with dUCB HCT (HR, 1.02; 95% CI, .59 to 1.79) or had limited to no experience with either dUCB or haplo-BM HCT (HR, 1.36; 95% CI, .83 to 2.21). The higher risk of treatment failure and overall mortality in dUCB HCT in haplo BM-experienced centers was driven by a significantly higher risk of relapse (HR, 1.78; 95% CI, 1.07 to 2.97). With the exception of worse outcomes among dUCB HCT recipients in haplo-BM centers, transplantation center experience in the year before initiation of BMT CTN 1101 had a limited impact on the outcomes of this randomized clinical trial.

Infusion of Non-HLA-Matched Off-the-Shelf Ex Vivo Expanded Cord Blood Progenitors in Patients Undergoing Cord Blood Transplantation: Result of a Phase II Clinical Trial

Recipients of myeloablative cord blood transplants (CBT) are known to experience delayed hematopoietic recovery and an increased risk of transplant related mortality (TRM). We developed methods for ex vivo expansion and cryopreservation of CB stem and progenitor cells. 15 patients with hematologic malignancies were enrolled in this single center phase II trial between September 2010 and August 2012 to assess the safety of infusing a non-HLA-matched expanded CB product to bolster a conventional CBT. On the day of transplant, an infusion of the expanded CB product followed the primary graft (1 or 2 unmanipulated CB units). All patients engrafted. Median time to neutrophil and platelet recovery was 19 and 35 days, respectively. Early myelomonocytic recovery was almost entirely due to cells arising from the non-HLA-matched expansion product and were no longer detected at day 14 in all but 2 patients. The probability of 3-years disease free survival was 86%. No TRM was observed throughout the study period, and only 2 patients relapsed. All patients presented with grade II acute graft-versus-host disease (aGVHD) at a median time of 32 days, with no grade III-IV aGVHD observed. At 2 years only 2 patients remain on immunosuppressive therapy for mild chronic GVHD. This phase II safety study demonstrate that infusion of an off-the-shelf non-HLA-matched expanded CB product in addition to a conventional CB graft was safe and led to sustained myeloid recovery. Based on these encouraging results, a prospective multicenter randomized trial utilizing this product has been conducted and results will be soon released. ClinicalTrials.gov Identifier: NCT01175785.

The impact of GVHD on outcomes after adult single cord blood transplantation in European and Japanese populations

The impact of GVHD and graft-versus-leukemia effect in unrelated cord blood transplantation (UCBT) is controversial. In the Eurocord/ALWP EBMT and JSTCT/JDCHCT collaborative study, we evaluated the impact of GVHD on UCBT outcomes in Japanese and European registries. A total of 3,690 adult patients with acute leukemia who received their first single UCBT were included. A multivariate analysis of overall survival (OS) revealed a positive impact of grade II acute GVHD compared with grade 0-I GVHD, in the Japanese cohort (hazard ratio (HR), 0.81; P = 0.001), and an adverse impact in the European cohort (HR, 1.37; P = 0.007). A negative impact of grade III-IV acute GVHD on OS was observed regardless of registries. In the analysis of relapse, a positive impact of grade II acutes GVHD compared with grade 0-I GVHD was observed only in the Japanese cohort, regardless of disease risk. The positive impact of limited chronic GVHD on OS was observed only in the Japanese cohort. In conclusion, a positive impact of mild GVHD after a single UCBT was observed only in the Japanese cohort. This could explain the ethnic difference in UCBT outcomes and might contribute to the preference usage of UCBT in Japan.

Engraftment of Double Cord Blood Transplantation after Nonmyeloablative Conditioning with Escalated Total Body Irradiation Dosing to Facilitate Engraftment in Immunocompetent Patients

To improve accrual to a randomized clinical trial of double unrelated cord blood (dUCB) versus HLA-haploidentical bone marrow (haplo-BM) transplantation, patients with less previous therapy and potentially greater immunocompetence were enrolled. To reduce the risk of graft rejection, patients randomized to receive dUCB received a higher dose of total body irradiation (TBI) (300 cGy versus 200 cGy). In this study, we investigated whether the inclusion of recipients of 300 cGy TBI influenced the trial outcomes. This was a secondary analysis of dUCB recipients, 161 who received TBI 200 cGy and 18 who received TBI 300 cGy. Fine and Gray regression was used to evaluate the effect of TBI dose on relapse and nonrelapse mortality (NRM). Cox regression was used for evaluation of neutrophil engraftment and overall survival. Patient characteristics were similar in the 2 TBI dose subgroups. The probability of neutrophil engraftment was 100% for patients who received TBI 300 cGy versus 91% (95% confidence interval, 86% to 95%) for those who received TBI 200 cGy (P = .64), which was similar after regression analysis adjusting for age, total infused nucleated cell dose, HLA matching to the patient, and comorbidity score. We also investigated whether the lower survival probability and higher cumulative incidence of NRM observed in the dUCB arm of BMT CTN 1101 could be influenced by the TBI 300 cGy patient subset. There was no significant difference in the 1-year incidences of NRM and relapse or in 1-year survival, even after adjustment in multivariate analysis. Patients in BMT CTN 1101 who received TBI 300 cGy and 200 cGy had similar engraftment and early mortality. We conclude that inclusion of a modified regimen for dUCB transplantation had no demonstrable influence on this large randomized trial.

Guidelines for Adult Patient Selection and Conditioning Regimens in Cord Blood Transplant Recipients with Hematologic Malignancies and Aplastic Anemia

For cord blood transplantation (CBT), appropriate patient and conditioning regimen selection is necessary to achieve long-term disease-free survival. This review aims to provide comprehensive guidelines on these issues using evidence from the literature and experience at dedicated CBT centers. Topics include patient and disease characteristics that make CBT a good or poor choice and a review of outcomes in commonly used conditioning regimens in CBT. This is accompanied with recommendations on regimen intensity based on disease, organ function, and patient performance status and age. In addition, the use of antithymocyte globulin in CBT is discussed, as is the choice of conditioning in aplastic anemia patients who have access to acceptable CB units.

The wider perspective: cord blood banks and their future prospects

Over the past three decades, cord blood transplantation (CBT) has established its role as an alternative allograft stem cell source. But the future of stored CB units should be to extend their use in updated transplant approaches and develop new CB applications. Thus, CBT will require a coordinated, multicentric, review of transplantation methods and an upgrade and realignment of banking resources and operations. Significant improvements have already been proposed to support the clinical perspective including definition of the cellular threshold for engraftment, development of transplantation methods for adult patients, engraftment acceleration with single cell expansion and homing technologies, personalised protocols to improve efficacy, use of adoptive cell therapy to mitigate delayed immune reconstitution, and further enhancement of the graft-versus-leukaemia effect using advanced therapies. The role of CB banks in improving transplantation results are also critical by optimizing the collection, processing, storage and characterization of CB units, and improving reproducibility, efficiency and cost of banking. But future developments beyond transplantation are needed. This implies the extension from transplantation banks to banks that support cell therapy, regenerative medicine and specialized transfusion medicine. This new "CB banking 2.0" concept will require promotion of international scientific and technical collaborations between bank specialists, clinical investigators and transplant physicians.