External validation of models for KIR2DS1/KIR3DL1-informed selection of hematopoietic cell donors fails.

Several studies suggest that harnessing natural killer (NK) cell reactivity mediated through killer cell immunoglobulin-like receptors (KIRs) could reduce the risk of relapse after allogeneic hematopoietic cell transplantation. Based on one promising model, information on KIR2DS1 and KIR3DL1 and their cognate ligands can be used to classify donors as KIR-advantageous or KIR-disadvantageous. This study was aimed at externally validating this model in unrelated donor hematopoietic cell transplantation. The impact of the predictor on overall survival (OS) and relapse incidence was tested in a Cox regression model adjusted for patient age, a modified disease risk index, Karnofsky performance status, donor age, HLA match, sex match, cytomegalovirus match, conditioning intensity, type of T-cell depletion, and graft type. Data from 2222 patients with acute myeloid leukemia or myelodysplastic syndrome were analyzed. KIR genes were typed by using high-resolution amplicon-based next-generation sequencing. In univariable analyses and subgroup analyses, OS and the cumulative incidence of relapse of patients with a KIR-advantageous donor were comparable to patients with a KIR-disadvantageous donor. The adjusted hazard ratio from the multivariable Cox regression model was 0.99 (Wald test, P = .93) for OS and 1.04 (Wald test, P = .78) for relapse incidence. We also tested the impact of activating donor KIR2DS1 and inhibition by KIR3DL1 separately but found no significant impact on OS and the risk of relapse. Thus, our study shows that the proposed model does not universally predict NK-mediated disease control. Deeper knowledge of NK-mediated alloreactivity is necessary to predict its contribution to graft-versus-leukemia reactions and to eventually use KIR genotype information for donor selection.

CD19 CAR T cells are an effective therapy for posttransplant relapse in patients with B-lineage ALL: real-world data from Germany.

Patients with precursor B-cell acute lymphoblastic leukemia (pB-ALL) who have relapsed after allogeneic hematopoietic stem cell transplantation (allo-HSCT), have relapsed more than once, or are resistant upfront have a dismal prognosis. CD19-targeted chimeric antigen receptor (CAR) T cells have evolved as potent immune therapies. Tisagenlecleucel (Tisa-cel) is a commercially available autologous CD19-directed CAR T-cell product. We performed a retrospective study inviting all CAR T-cell centers in Germany to participate. Eighty-one patients with pB-ALL were included. Twenty-eight days after CAR T-cell infusion, 71 patients (87.7%) were in complete response, and 8 (9.9%) were in nonremission. At 2 years, the probabilities of event-free survival (pEFS), relapse-free survival (pRFS), and overall survival (pOS) were 45.3%, 51.7%, and 53.2%, respectively. pEFS was not different in patients without (n = 16, 55.0%) vs with prior allo-HSCT (n = 65, 43.4%). In patients treated after allo-HSCT, the time to relapse after allo-HSCT was a strong predictor of outcome. Patients relapsing within 6 months of allo-HSCT had a disappointing pEFS of 18.4% (pOS = 16.0%); the pEFS for those relapsing later was 55.5% (pOS = 74.8%). Our study provides real-world experience in pediatric, adolescent, and young adult patients with ALL treated with Tisa-cel, where most patients were treated after having relapsed after allo-HSCT. A total of 45.3% were rescued with a single dose of Tisa-cel. Our novel finding that patients with ALL after allo-HSCT had by far a better pEFS if relapse occurred beyond 6 months might be helpful in clinical decision-making and motivates studies to uncover the reasons.

Benchmarking of survival outcomes following Haematopoietic Stem Cell Transplantation (HSCT): an update of the ongoing project of the European Society for Blood and Marrow Transplantation (EBMT) and Joint Accreditation Committee of ISCT and EBMT (JACIE).

From 2016 EBMT and JACIE developed an international risk-adapted benchmarking program of haematopoietic stem cell transplant (HSCT) outcome to provide individual EBMT Centers with a means of quality-assuring the HSCT process and meeting FACT-JACIE accreditation requirements relating to 1-year survival outcomes. Informed by previous experience from Europe, North America and Australasia, the Clinical Outcomes Group (COG) established criteria for patient and Center selection, and a set of key clinical variables within a dedicated statistical model adapted to the capabilities of the EBMT Registry. The first phase of the project was launched in 2019 to test the acceptability of the benchmarking model through assessment of Centers' performance for 1-year data completeness and survival outcomes of autologous and allogeneic HSCT covering 2013-2016. A second phase was delivered in July 2021 covering 2015-2019 and including survival outcomes. Reports of individual Center performance were shared directly with local principal investigators and their responses were assimilated. The experience thus far has supported the feasibility, acceptability and reliability of the system as well as identifying its limitations. We provide a summary of experience and learning so far in this 'work in progress', as well as highlighting future challenges of delivering a modern, robust, data-complete, risk-adapted benchmarking program across new EBMT Registry systems.

Immune Monitoring Assay for Extracorporeal Photopheresis Treatment Optimization After Heart Transplantation.

Background: Extracorporeal photopheresis (ECP) induces immunological changes that lead to a reduced risk of transplant rejection. The aim of the present study was to determine optimum conditions for ECP treatment by analyzing a variety of tolerance-inducing immune cells to optimize the treatment. Methods: Ten ECP treatments were applied to each of 17 heart-transplant patients from month 3 to month 9 post-HTx. Blood samples were taken at baseline, three times during treatment, and four months after the last ECP treatment. The abundance of subsets of tolerance-inducing regulatory T cells (Tregs) and dendritic cells (DCs) in the samples was determined by flow cytometry. A multivariate statistical model describing the immunological status of rejection-free heart transplanted patients was used to visualize the patient-specific immunological improvement induced by ECP. Results: All BDCA+ DC subsets (BDCA1+ DCs: p < 0.01, BDCA2+ DCs: p < 0.01, BDCA3+ DCs: p < 0.01, BDCA4+ DCs: p < 0.01) as well as total Tregs(p < 0.01) and CD39+ Tregs(p < 0.01) increased during ECP treatment, while CD62L+ Tregs decreased (p < 0.01). The cell surface expression level of BDCA1 (p < 0.01) and BDCA4 (p < 0.01) on DCs as well as of CD120b (p < 0.01) on Tregs increased during the study period, while CD62L expression on Tregs decreased significantly (p = 0.04). The cell surface expression level of BDCA2 (p = 0.47) and BDCA3 (p = 0.22) on DCs as well as of CD39 (p = 0.14) and CD147 (p = 0.08) on Tregs remained constant during the study period. A cluster analysis showed that ECP treatment led to a sustained immunological improvement. Conclusions: We developed an immune monitoring assay for ECP treatment after heart transplantation by analyzing changes in tolerance-inducing immune cells. This assay allowed differentiation of patients who did and did not show immunological improvement. Based on these results, we propose classification criteria that may allow optimization of the duration of ECP treatment.

Randomized controlled study of ECP with methoxsalen as first-line treatment of patients with moderate to severe cGVHD.

The investigation of extracorporeal photopheresis (ECP) plus standard of care (SoC) (SoC+ECP) in chronic graft-versus-host disease (cGVHD) within prospective, randomized clinical studies is limited, despite its frequent clinical use. This phase 1/pilot study was the first randomized, prospective study to investigate ECP use as first-line therapy in cGVHD, based on the 2015 National Institutes of Health (NIH) consensus criteria for diagnosis and response assessment. Adult patients with new-onset (≤3 years of hematopoietic stem cell transplantation) moderate or severe cGVHD were randomized 1:1 to 26 weeks of SoC+ECP vs SoC (corticosteroids and cyclosporine A/tacrolimus) between 2011 and 2015. The primary endpoint was overall response rate (ORR), defined as complete or partial response, at week 28 in the intention-to-treat population (ITT). Other outcomes included quality of life (QoL) measures and safety. Sixty patients were randomized; ITT included 53 patients (SoC+ECP: 29; SoC: 24). Week 28 ORR was 74.1% (SoC+ECP) and 60.9% (SoC). Investigator-assessed ORR was 56.0% (SoC+ECP) and 66.7% (SoC). Patients treated with SoC experienced a decline in QoL over the 28-week study period; QoL remained unchanged in SoC+ECP patients. Most frequent treatment-emergent adverse events (TEAEs) in SoC+ECP patients were hypertension (31.0%), cough (20.7%), dyspnea (17.2%), and fatigue (17.2%). Seventeen patients (SoC+ECP: 8; SoC: 9) experienced 35 serious adverse events (SAEs). No TEAEs or SAEs were considered related to the ECP instrument or methoxsalen. The encouraging short-term results of this study could inform the design of subsequent studies. This trial was registered at www.clinicaltrials.gov as #NCT01380535.

Dose-reduced conditioning regimen followed by allogeneic stem cell transplantation in patients with myelofibrosis with myeloid metaplasia.

Three patients with myelofibrosis received allogeneic stem cell transplantation after a dose-reduced conditioning regimen of busulphan (8 mg/kg), fludarabine (180 mg/m2) and antithymocyte globulin (4 x 10 mg/kg). The median age at transplantation was 51 years (range 44-58). All patients engrafted with a leucocyte count > 1.0 x 10(9)/l after a median of 18 d (range 16-20). Grade II acute skin graft-versus-host disease (GvHD) occurred in one patient. One limited and one extensive chronic GvHD was observed. All patients achieved complete haematological remission. In one patient the fibrosis resolved completely 180 d post transplant. All patients are alive 126, 466 and 764 d after transplantation.