56. Jahrestagung der Deutschen Gesellschaft für Transfusionsmedizin und Immunhämatologie

Prof. Dr.

Vorsitz

PD Dr.

Outcomes of haploidentical stem cell transplantation with post-tx-cyclophosphamide in comparison with 10/10 MUD in Germany - An observational analysis of German registry data

Background Allogeneic stem cell transplantation (alloHSCT) is the best curative treatment modality for many benign or malignant haematological disorders. In the absence of a matched related donor (MRD), matched unrelated donors (MUD) and haploidentical donors (Haplo-SCT) are the most important sources of stem cells. Despite the increasing number of Haplo-SCT in recent years, multicentre real-life data to compare 10/10 MUD transplantations with Haplo-SCT is still limited.Methods In this registry based study, we compared the outcomes of alloHSCTs from 10/10 MUD with conventional graft versus host disease (GvHD) prophylaxis (n=10740) versus haploidentical donors using post-transplant cyclophosphamide as a component of the immunosuppressive regimen (n=515) in adult patients with haematological malignancies. These transplantations were performed between 2010 and 2020. Outcomes for overall survival (OS), disease free survival (DFS), acute GvHD/relapse free survival (GRFS), non-relapse mortality (NRM), relapse, as well as acute GvHD (aGvHD) and chronic GvHD (cGvHD) incidences were analysed. Cox proportional hazard models and competing risks regression models were built to compare the outcomes of the groups. Results The stem cell source was more often PBSC in the 10/10 MUD group (96% vs. 75.5%) and 81.2% of the patients in 10/10 MUD group had received ATG. 5-year OS and DFS was seen slightly lower in PT-CY Haplo patients compared to 10/10 MUD (42.8% vs. 45.9%, p=0.032; 34.3% vs. 38.4%, p=0.043, retrospectively). 5-year GRFS was significantly worse in PT-CY Haplo patients (22.6% vs. 32.0%, p&lt;0.001). Multivariate analysis was consistent. Additionally, aGvHD grade II-IV and NRM was found to be increased in the PT-CY Haplo group, whereas cGvHD was higher in the 10/10 MUD group. Interestingly when analyzed for severe aGvHD (grades III-IV) no differences were present between both groups. Also, no difference was observed for relapse incidence.Conclusion Our findings suggest that 10/10 MUD transplantation in the lack of MRD remains a better alternative than haploidentical transplantations in terms of better OS, DFS, GRFS and lower incidence of NRM and aGVHD.Offenlegung Interessenkonflikt: No conflicts of interest are presentInvited talks abstract/summary

Stem Cells

Freier Vortrag

Predictive factors for successful hematopoietic stem cell collection in healthy allogeneic donors

Background Collection of peripheral blood stem cells (PBSC) from healthy donors after mobilization with G-CSF is performed routinely. We aimed to identify factors predictive of successful CD34+ PBSC collection and established a formula capable of predicting the CD34+ cell yield.Methods We retrospectively evaluated 588 healthy adult donors (median age 29 years, range 18–69 years) at our institution from 2017 to 2022. The predicted minimal number of CD34+ cells was calculated as follows: [(peripheral CD34+ cells/µL × adjusted collection efficiency of 30%] × total liters processed. This formula was further modified taking the donor and recipient body weight (BW) into account.Results Total CD34+ collection was in median 8.0 × 106 CD34+ cells/kg of recipient BW (range 1.0–47.1 × 106 cells/kg BW) with 522 donors (89%) collecting ≥5.0 × 106 cells/kg of recipient BW. A second leukapheresis (LP) session the following day was required in 49 donors (8%). Female donors (p&lt;0.001), donors with higher age (p=0.003), donors with WBC count &lt;30 × 109/L after 5 days of G-CSF stimulation (p=0.004), and a donor/recipient weight ratio &lt;1 (p&lt;0.001) had a higher risk for a second LP session. Predictive factors for optimal LP were peripheral blood CD34+ cell count &gt;50/µL (p&lt;0.001), male donor (p=0.04), and a donor/recipient weight ratio &gt;1 (p=0.001). Conclusion Of the routinely monitored indicators in PBSC donors, CD34+ cell count in peripheral blood is the most important factor in predicting G-CSF-induced PBSC yields. Risk factors for suboptimal mobilizers were higher age, female sex, WBC &lt;30 × 109/L, and a donor/recipient weight ratio &lt;1. We applied a formula that has shown successful and consistent performance in the prediction of key outcome measures.Offenlegung Interessenkonflikt: All authors declare no competing conflicts of interest.

Plerixafor vs placebo for stem cell mobilization in patients with multiple myeloma optimize collection results in moderate mobilizers (Optimize)

Background This study evaluates the safety and efficacy of plerixafor (PLER), a CXCR4 antagonist, in mobilizing hematopoietic progenitor cells for autologous hematopoietic cell transplantation (HCT) in multiple myeloma (MM) patients.Methods This is a phase IV, multicenter, randomized (1:1), double-blind, placebo-controlled study. Patients with MM scheduled for 2 autologous HCTs mobilized with granulocyte colony-stimulating factor (G-CSF; 2x5 µg/kg) s.c. daily for up to 5 days were eligible. On day 4 of G-CSF, peripheral blood (PB) CD34+ count was analyzed and patients were enrolled if they had 15-40 CD34+ cells/µL. They received either PLER at a dose of 240 µg/kg or placebo 4-12 hours before start of apheresis. The primary endpoint was to collect 6 x106 CD34+ cells/kg in one apheresis, thus enabling 2 autologous HCTs. In addition, CD34+ and lymphocyte subsets, colony forming units (CFU) and engraftment kinetics were analyzed.Results The study was designed for 90 patients but was stopped after 21 patients due to approval of daratumumab also for first line therapy in MM, which led to insufficient mobilization (i.e. &lt;15 CD34+ cells/µl in the PB) in the predefined patient cohort. With PLER pre-apheresis CD34+ cell counts were significantly higher than with placebo (median 93,3/µL vs. 29,34; p-Value 1.71E-08). Ten of 21 (48%) patients received PLER and 11 (52%) placebo. All patients in the PLER group met the primary endpoint with a median of 7.6 x106 (range 7.03 to 13.18) CD34+ cells/kg compared to none in the placebo group (median 2.52 x106 CD34+ cells/kg, range 1.40 to 5.27 x106 CD34+ cells/kg). PLER was tolerated well with only rare cases of gastrointestinal disorders.Conclusion In contrast to G-CSF alone, PLER + G-CSF allowed to collect &gt;6x106 CD34+ cells/kg for 2 autologous HCTs in only one apheresis session in moderately mobilizing MM patients (i.e. 15-40 CD34+ cells/µl). This not only reduces apheresis procedures and workload for operators and technicians but also facilitates planning of apheresis and increases patient"s comfort. Therefore, PLER should be considered not only in cases of imminent mobilization failure but also in patients with moderate mobilization.Offenlegung Interessenkonflikt: keiner

PD Dr. Dr.

BluStar - A project to recruit non-Caucasian hematopoietic stem cell donors resulting in more than 9,100 donors and 12 PBSC, one bone marrow and three donor lymphocyte aphereses so far

Background 19 million non-Caucasians live in Germany. These people have genetically different HLA antigens compared to the most common HLA frequencies in Central Europe. In severe hematological diseases, allogeneic stem cell transplantation offers the only curative therapy. However, finding HLA-compatible hematopoietic stem cells (HSC) donors in case a related donor is lacking, is a major challenge as there are only few unrelated donors with a similar genetic background registered in HSC donor registries.Methods The "BluStar" project was initiated to recruit non-Caucasian donors of HSC. The non-Caucasian donors were registered and typed by the Westdeutsche SpenderZentrale (WSZE), Ratingen, Germany. Several dedicated recruiting events, multi-lingual flyers, and intensive interactions with relevant social stakeholders have been employed to attract potential non-Caucasian HSC donors. We analysed the gender and age distribution of donors recruited in the BluStar project. Besides, we documented the "work-ups" (i.e. requests for a potential HSC donation) resulting out of the BluStar cohort per country and compared the apheresis probability and cancellation rate of work-ups in the BluStar cohort with that in the non-BluStar WSZE donor cohort.Results More than 9,100 non-Caucasian HSC donors have been recruited. Gender distribution is equal: 4,583 (50%) donors are male (m) and 4,550 (50%) donors are female (f). The age distribution is as follows: &lt; 30 years: 2,937/3,168 (32%/35%, m/f); &lt;40 years: 962/627 (11%/7%, m/f); &lt;50 years: 551/589 (6%/6%, m/f); &gt;50 years: 133/166 (1%/2%, m/f). 29 work-ups were initiated. 13 work-ups were cancelled; however, 12 PBSC, one BM and three DLI were collected so far. The PBSC/BM/DLI were delivered to Germany, USA, France, Spain, UK, Poland and Australia. Apheresis probability is twofold higher in the BluStar donor cohort (0.18% vs. 0.07%). In contrast, the cancellation rate of work-ups in the BluStar cohort is almost twice as high (45% vs. 25%).Conclusion Within the BluStar project more than 9,100 non-Caucasian donors were registered as unrelated HSC donors. The twice-fold apheresis probability in the non-Caucasian donor cohort pinpoints the lack of non-Caucasian HSC donors. However, the high cancellation rate might indicate higher logistic hurdles in this cohort. Obviously, there is serious medical need to increase the number of non-Caucasian HSC donors to enable more allogeneic stem cell transplantations in the non-Caucasian patient population.Offenlegung Interessenkonflikt: There is no conflict of interest to declare. The European Development Fund 2014-2020 (ERDF) and the European Union funded this project.Invited talks abstract/summary

Prof. Dr. Dr.

Prof.

Automatic generation of alloreactivity-reduced donor lymphocytes and hematopoietic stem cells from the same mobilized apheresis product

Background In vitro or in vivo depletion of alloreactive T-cells can facilitate haplo-identical hematopoietic stem cell transplantation (HSCT). We established and validated a TCRαß/CD19 depletion module for automatic cell-processing on CliniMACS Prodigy, and investigated quality attributes of the HSPC products. The process was combined with aCD45RA depletion module as such a product could serve as allo-reactivity attenuated donor lymphocyte infusion (DLI) after transplantation.Methods We evaluated 6 apheresis products from G-CSF-mobilized volunteer donors which were split, one portion each depleted of CD45RA+ or of TCRα/ß+ and CD19+ cells. Products were assessed for recovery of HSPCs and certain mature subsets, as well as depletion of targeted cells using flow cytometry. Effects of apheresis and product age post 48 h storage at 4 °C as well as freeze-thawing on product viability and recovery of WBC and CD34+ cells were assessed by flow cytomerty.Results Ten sequential depletions were technically uneventful, proceeding automatically with minimal hands-on time. Depletion of CD45RA+ resp. TCRα/ß+ and CD19+ cells was nearly complete, at least equally to previous reports, achieving mean depletions of 4 log of targeted cells for both products. HSPC products retained TCRγ/δ+ and NK cells and even were passively enriched. 48 h storage of apheresis product was associated with the expected modest loss of HSPCs, but depletions proceeded efficiently. Depleted products were stable until at least 72 h after apheresis with stem cell viabilities &gt; 90 %. Freeze-thawing resulted in loss of NK cells; post-thaw recovery of viable CD45+ and HSPCs was &gt; 70 % and in line with expectation.Conclusion A closed, GMP-compatible process on CliniMACS Prodigy generates two separate medicinal products from the same mobilized apheresis product. The CD45RA-depleted products contained functional memory T cells, whereas the TCRαβ/CD19-depleted products included stem cells, TCRγ/δ+ and NK cells. CD45RA-depleted DLI and/or TCRαß/CD19-depleted HSPC products are predicted to be effectively depleted of GvH-reactivity while providing immunological surveillance, in support of haplo-identical HSCT.Offenlegung Interessenkonflikt: VO and JD are employees of Miltenyi Biotec, manufacturers of the technology described here. HB has received research funding and has served on the speaker"s bureau of Miltenyi Biotec. Studies were supported by in-kind contributions of Miltenyi Biotec. None of the other authors have conflicts to declare. Funding: Miltenyi Biotec contributed all Miltenyi Biotec reagents and consumables used for these studies.

Freier Vortrag (Reinhold-Eckstein-Investigator-Award)

Hematopoietic stem cell transplantation and its influence on the bone structure and marrow cells

Background In most malignant hematological diseases the preferential treatment is a hematopoietic stem cell transplantation (HSCT). Initially, lymphopenia and diminished immunity is associated with HSCT. Several studies proved a higher risk of fractures and osteoporosis after HSCT. However it is rarely studied what happens on the cellular level within the bone directly after transplantation. This project aims to investigate the underlying proceedings responsible for changes in the bone after HSCT.Methods Within our group, a mouse model for HSCT has been developed to investigate bone and changes within during graft versus host disease (GVHD). Two groups were investigated a) syn = control without GVHD after HSCT and b) allo = a group that developed acute GVHD. 20, 40 and 60 days after cell transfer animals were sacrificed and bones were harvested. Bones underwent radiological and histological analyses. Consecutively, primary human mesenchymal stromal cells and osteoblasts were stimulated to differentiate and analyzed with metabolic assays and specific stainings in a GVHD simulating in vitro setting. During this stimulation, media immunized with immune cells were added to examine their potential to influence bone homeostasis.Results Femora of mice developing a strong GVHD after allogeneic transplantation showed a larger medullary area and thinner cortical bone in the diaphyseal as well as an increase in bone volume and trabecular number in the epiphyseal region revealing differences in the whole bone structure. Also, no osteoblastic lining cells were detectable and osteoid formation was absent, indicating an impaired bone formation capacity due to the GVHD. Furthermore, deviating B cell numbers and distributions were seen. The in vitro analyses demonstrated the involvement of immune cell signaling seen in impaired – T cells or improved – B cells osteogenesis.Conclusion Impaired recovery of the immune system after allogeneic HSCT not only leads to an increased risk of severe infections. By examining bone structure and stroma cells we could prove that the imbalance of immune cells of the adaptive immune system impedes the bone structure. This is caused by a decreased capacity of osteogenic differentiation due to the lack of B cells. This discovery may be significant for the prognosis and treatment of long-term effects on the musculoskeletal tissue after HSCT.Offenlegung Interessenkonflikt: No conflict of interest is present in this project.

Hematopoetic Stem Cells

Appointment

Vorsitz

Programme