Numbers of Hematopoietic cell transplantation (HCT) in Europe and collaborating countries continues to rise with 48,512 HCT in 43,581 patients, comprising of 19,798 (41%) allogeneic and 28,714 (59%) autologous, reported by 700 centers in 51 countries during 2019. Main indications were myeloid malignancies 10,764 (25%), lymphoid malignancies 27,895 (64%), and nonmalignant disorders 3173 (7%). A marked growth in CAR-T cellular therapies from 151 in 2017 to 1134 patients in 2019 is observed. This year’s analyses focus on changes over 30 years. Since the first survey in 1990 where 143 centers reported 4234 HCT, the number has increased to 700 centers and 48,512 HCT. Transplants were reported in 20 countries in 1990, and 51, 30 years later. More than 800,000 HCT in 715,000 patients were reported overall. Next to the massive expansion of HCT technology, most notable developments include the success of unrelated donor and haploidentical HCT, an increase followed by decrease in the number of cord blood transplants, use of reduced intensity HCT in older patients, and the phenomenal rise in cellular therapy. This annual report of the European Society for Blood and Marrow Transplantation (EBMT) reflects current activity and highlights important trends vital for health care planning.

Hematological toxicity is the most common adverse event after chimeric antigen receptor (CAR) T-cell therapy. Cytopenias can be profound and long-lasting and can predispose for severe infectious complications. In a recent worldwide survey, we demonstrated that there remains considerable heterogeneity in regard to current practice patterns. Here, we sought to build consensus on the grading and management of immune effector cell–associated hematotoxicity (ICAHT) after CAR T-cell therapy. For this purpose, a joint effort between the European Society for Blood and Marrow Transplantation (EBMT) and the European Hematology Association (EHA) involved an international panel of 36 CAR T-cell experts who met in a series of virtual conferences, culminating in a 2-day meeting in Lille, France. On the basis of these deliberations, best practice recommendations were developed. For the grading of ICAHT, a classification system based on depth and duration of neutropenia was developed for early (day 0-30) and late (after day +30) cytopenia. Detailed recommendations on risk factors, available preinfusion scoring systems (eg, CAR-HEMATOTOX score), and diagnostic workup are provided. A further section focuses on identifying hemophagocytosis in the context of severe hematotoxicity. Finally, we review current evidence and provide consensus recommendations for the management of ICAHT, including growth factor support, anti-infectious prophylaxis, transfusions, autologous hematopoietic stem cell boost, and allogeneic hematopoietic cell transplantation. In conclusion, we propose ICAHT as a novel toxicity category after immune effector cell therapy, provide a framework for its grading, review literature on risk factors, and outline expert recommendations for the diagnostic workup and short- and long-term management.

For over two decades, the EBMT has updated recommendations on indications for haematopoietic cell transplantation (HCT) practice based on clinical and scientific developments in the field. This is the eighth special EBMT report on the indications for HCT for haematological diseases, solid tumours and immune disorders. Our aim is to provide general guidance on HCT indications according to prevailing clinical practice in EBMT countries and centres. In order to inform patient decisions, these recommendations must be considered in conjunction with the risk of the disease, risk of HCT procedure and non-transplant strategies, including evolving cellular therapies. HCT techniques are constantly evolving and we make no specific recommendations, but encourage harmonisation of practice, where possible, to ensure experience across indications can be meaningfully aggregated via registry outputs. We also recommend working according to JACIE accreditation standards to maintain quality in clinical and laboratory components of practice, including benchmarking of survival outcomes. Since the last edition, the COVID-19 pandemic has affected clinical decision making and activity across indications. Although the full impact of the pandemic is yet to be determined, we recommend that decision making across indications is delivered with ongoing reference to EBMT and national COVID-19 guidance, in accordance with current local conditions.

T-cell therapy after hematopoietic stem cell transplantation (HSCT) has been used alone or in combination with immunosuppression to cure hematologic malignancies and to prevent recurrence. Here, we describe the outcome of patients with high-risk/advanced stage hematologic malignancies, who received T-cell depleted (TCD) haploidentical-HSC transplantation (haplo-HSCT) combined with donor T lymphocytes pretreated with IL-10 (ALT-TEN trial). IL-10 anergized donor T cells (IL-10 DLI) contained T regulatory type 1 (Tr1) cell specific for the, host alloantigens, limiting donor-vs-host reactivity, and memory T cells able to respond to pathogens. IL-10 DLI were infused in 12 patients with the goal of improving immune-reconstitution after haplo-HSCT without increasing the risk of GvHD. IL-10 DLI led to fast immune-reconstitution in five patients. In four out of the five patients, total T-cell counts, TCR-Vβ repertoire and T-cell functions progressively normalized after IL-10 DLI. These four patients are alive, in complete disease remission and immune suppression-free at 7.2 years (median follow-up) after haplo-HSCT. Transient GvHD was observed in the immune reconstituted patients, despite persistent host-specific hypo-responsiveness of donor T cells in vitro and enrichment of cells with Tr1- specific biomarkers in vivo. Gene expression profiles of immune-reconstituted patients showed a common signature of tolerance. This study provides the first indication of the feasibility of Tr1 cell-based therapy and paves the way for the use of these Tr1 cells as adjuvant treatment for malignancies and immune-mediated disorders.

Haploidentical hematopoietic stem cell transplantation (HSCT) performed using bone marrow (BM) grafts and post-transplantation cyclophosphamide (PTCy) has gained much interest for the excellent toxicity profile after both reduced-intensity and myeloablative conditioning. We investigated, in a cohort of 40 high-risk hematological patients, the feasibility of peripheral blood stem cells grafts after a treosulfan-melphalan myeloablative conditioning, followed by a PTCy and sirolimus-based graft-versus-host disease (GVHD) prophylaxis (Sir-PTCy). Donor engraftment occurred in all patients, with full donor chimerism achieved by day 30. Post-HSCT recovery of lymphocyte subsets was broad and fast, with a median time to CD4 > 200/μL of 41 days. Cumulative incidences of grade II to IV and III-IV acute GVHD were 15% and 7.5%, respectively, and were associated with a significant early increase in circulating regulatory T cells at day 15 after HSCT, with values < 5% being predictive of subsequent GVHD occurrence. The 1-year cumulative incidence of chronic GVHD was 20%. Nonrelapse mortality (NRM) at 100 days and 1 year were 12% and 17%, respectively. With a median follow-up for living patients of 15 months, the estimated 1-year overall and disease-free survival (DFS) was 56% and 48%, respectively. Outcomes were more favorable in patients who underwent transplantation in complete remission (1-year DFS 71%) versus patients who underwent transplantation with active disease (DFS, 34%; P = .01). Overall, myeloablative haploidentical HSCT with peripheral blood stem cells (PBSC) and Sir-PTCy is a feasible treatment option: the low rates of GVHD and NRM as well as the favorable immune reconstitution profile pave the way for a prospective comparative trial comparing BM and PBSC in this specific transplantation setting.

Systemic Lupus Erythematosus (SLE) is a progressive disease leading to immune-mediated tissue damage, associated with an alteration of lymphoid organs. Therapeutic strategies involving regulatory T (Treg) lymphocytes, which physiologically quench autoimmunity and support long-term immune tolerance, are considered, as conventional treatment often fails. We describe here a therapeutic strategy based on Tregs overexpressing FoxP3 and harboring anti-CD19 CAR (Fox19CAR-Tregs). Fox19CAR-Tregs efficiently suppress proliferation and activity of B cells in vitro, which are relevant for SLE pathogenesis. In an humanized mouse model of SLE, a single infusion of Fox19CAR-Tregs restricts autoantibody generation, delay lymphopenia (a key feature of SLE) and restore the human immune system composition in lymphoid organs, without detectable toxicity. Although a short survival, SLE target organs appear to be protected. In summary, Fox19CAR-Tregs can break the vicious cycle leading to autoimmunity and persistent tissue damage, representing an efficacious and safe strategy allowing restoration of homeostasis in SLE.