Characterization of engraftment dynamics in myelofibrosis after allogeneic hematopoietic cell transplantation including novel conditioning schemes.

INTRODUCTION Myelofibrosis (MF) is a rare hematopoietic stem cell disorder progressing to bone marrow (BM) failure or blast phase. Allogeneic hematopoietic cell transplantation (HCT) represents a potentially curative therapy for a limited subset of patients with advanced MF, who are eligible, but engraftment in MF vs. AML is delayed which promotes complications. As determinants of engraftment in MF are incompletely characterized, we studied engraftment dynamics at our center. METHODS A longitudinal cohort of 71 allogeneic HCT performed 2000-2019 with >50% after 2015 was evaluated. RESULTS Median time to neutrophil engraftment ≥0.5x109/l was +20 days post-transplant and associated with BM fibrosis, splenomegaly and infused CD34+ cell number. Engraftment dynamics were similar in primary vs. secondary MF and were independent of MF driver mutations in JAK2, CALR and MPL. Neutrophil engraftment occurred later upon haploidentical HCT with thiotepa-busulfan-fludarabine conditioning, post-transplant cyclophosphamide and G-CSF (TBF-PTCy/G-CSF) administered to 9.9% and 15.6% of patients in 2000-2019 and after 2015, respectively. Engraftment of platelets was similarly delayed, while reconstitution of reticulocytes was not affected. CONCLUSIONS Since MF is a rare hematologic malignancy, this data from a large number of HCT for MF is essential to substantiate that later neutrophil and platelet engraftment in MF relates both to host and treatment-related factors. Observations from this longitudinal cohort support that novel conditioning schemes administered also to rare entities such as MF, require detailed evaluation in larger, multi-center cohorts to assess also indicators of long-term graft function and overall outcome in patients with this infrequent hematopoietic neoplasm undergoing allogeneic transplantation

Long-term observation reveals high-frequency engraftment of human acute myeloid leukemia in immunodeficient mice

Repopulation of immunodeficient mice remains the primary method for functional assessment of human acute myeloid leukemia. Published data report engraftment in ~40-66% of cases, mostly of intermediate- or poor-risk subtypes. Here we report that extending follow-up beyond the standard analysis endpoints of 10 to 16 weeks after transplantation permitted leukemic engraftment from nearly every case of xenotransplanted acute myeloid leukemia (18/19, ~95%). Xenogeneic leukemic cells showed conserved immune pheno-types and genetic signatures when compared to corresponding pre-transplant cells and, furthermore, were able to induce leukemia in re-transplantation assays. Importantly, bone marrow biopsies taken at standardized time points failed to detect leukemic cells in 11/18 of cases that later showed robust engraftment (61%, termed "long-latency engrafters"), indicating that leukemic cells can persist over months at undetectable levels without losing disease-initiating properties. Cells from favorable-risk leukemia subtypes required longer to become detectable in NOD/SCID/IL2Rγ; null; mice (27.5±9.4 weeks) than did cells from intermediate-risk (21.9±9.4 weeks,; P; <0.01) or adverse-risk (17±7.6 weeks;; P; <0.0001) subtypes, explaining why the engraftment of the first was missed with previous protocols. Mechanistically, leukemic cells engrafting after a prolonged latency showed inferior homing to the bone marrow. Finally, we applied our model to favorable-risk acute myeloid leukemia with inv(16); here, we showed that CD34; +; (but not CD34; -; ) blasts induced robust, long-latency engraftment and expressed enhanced levels of stem cell genes. In conclusion, we provide a model that allows; in vivo; mouse studies with a wide range of molecular subtypes of acute myeloid leukemia subtypes which were previously considered not able to engraft, thus enabling novel insights into leukemogenesis

External Validation of the Revised Pretransplant Assessment of Mortality Score in Allogeneic Hematopoietic Cell Transplantation: A Cohort Study

Pretransplant risk scores such as the revised Pretransplant Assessment of Mortality (rPAM) score help to predict outcome of patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Since the rPAM has not been validated externally in a heterogeneous patient population with different diseases, we aimed to validate the rPAM score in a real-world cohort of allo-HCT patients. A total of 429 patients were included receiving their first allo-HCT from 2008 to 2015. The predictive capacity of the rPAM score for 4-year overall survival (OS), nonrelapse mortality (NRM), and cumulative incidence of relapse (CIR) after allo-HCT was evaluated. Moreover, we evaluated the impact of the rPAM score for OS and used uni- and multivariable analyses to identify patient- and transplant-related predictors for OS. In rPAM score categories of 30, the OS probability at 4 years differed significantly with 61%, 36%, 26%, and 10%, respectively (P < 0.0001). In contrast to CIR, the NRM increased significantly in patients with higher rPAM scores (P < 0.001). Regarding the OS, the rPAM score had an area under the receiver operating characteristics curve of 0.676 (95% confidence interval [CI], 0.625-0.727) at 4 years. In the multivariable analysis, the rPAM score was associated with OS-independently of conditioning regimens (adjusted hazard ratio per 1-unit increase, 1.10; 95% CI, 1.06-1.10; P < 0.001). Additionally, forced expiratory volume in 1 second and the disease risk index were the components of the rPAM significantly associated with outcome. In our large real-world cohort with extended follow-up, the rPAM score was validated as an independent predictor of OS in patients with hematologic disorders undergoing allo-HCT

Feasibility of electronic patient-reported outcome monitoring and self-management program in aplastic anemia and paroxysmal nocturnal hemoglobinuria-a pilot study (ePRO-AA-PNH).

INTRODUCTION Electronic patient-reported outcomes (ePRO) are increasingly recognized in health care, as they have been demonstrated to improve patient outcomes in cancer, but have been less studied in rare hematological diseases. The aim of this study was to develop and test the feasibility of an ePRO system specifically customized for aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH). METHODS After performing a user-centered design evaluation an ePRO system for AA and PNH patients could be customized and the application was tested by patients and their medical teams for 6 months. Symptom-reporting triggered self-management advice for patients and prompts them to contact clinicians in case of severe symptoms, while the medical team received alerts of severe symptoms for patient care. RESULTS All nine included patients showed a high adherence rate to the weekly symptom-reporting (72%) and reported high satisfaction. The system was rated high for usage, comprehensibility, and integration into daily life. Most patients (78%) would continue and all would recommend the application to other AA/PNH patients. Technical performance was rarely a barrier and healthcare providers saw ePRO-AA-PNH as a useful supplement, but the lacking integration into the hospital information system was identified as a major barrier to usage. CONCLUSION An ePRO system customized for AA and PNH was feasible in terms of adherence, satisfaction, and performance, showing a high potential for these rare conditions in terms of data collection and patient guidance. However, the integration into clinical workflows is crucial for further routine use. TRIAL REGISTRATION ClinicalTrials.gov NCT04128943

Association of Nutritional Parameters with Clinical Outcomes in Patients with Acute Myeloid Leukemia Undergoing Haematopoietic Stem Cell Transplantation.

INTRODUCTION In acute myeloid leukemia (AML) patients undergoing allogeneic haematopoietic stem cell transplantation (HSCT), there is uncertainty about the extent of influence nutritional parameters have on clinical outcomes. In this study, we investigated the association between initial body mass index (BMI) and weight loss during HSCT on clinical outcomes in a well-characterised cohort of AML patients. METHODS We analysed data of the Basel stem-cell transplantation registry ('KMT Kohorte') including all patients with AML undergoing first allogeneic HSCT from January 2003 to January 2014. We used multivariable regression models adjusted for prognostic indicators (European Group for Blood and Marrow Transplantation risk score and cytogenetics). RESULTS Mortality in the 156 AML patients (46% female, mean age 46 years) over the 10 years of follow-up was 57%. Compared to patients with a baseline BMI (kg/m2) of 20-25, a low BMI 7 vs. <2%) was associated with higher risk for bacterial infections (52 vs. 28%, OR 2.8, 95% CI 0.96-8.18, p = 0.059) and fungal infections (48 vs. 23%, OR 3.37, 95% CI 1.11-10.19, p = 0.032), and longer hospital stays (64 vs. 38 days, adjusted mean difference 25.6 days (15.7-35.5), p < 0.001). CONCLUSION In patients with AML, low initial BMI and more pronounced weight loss during HSCT are strong prognostic indicators associated with lower survival and worse disease outcomes. Intervention research is needed to investigate whether nutritional therapy can reverse these associations

IL-2 Stimulated but Not Unstimulated NK Cells Induce Selective Disappearance of Peripheral Blood Cells: Concomitant Results to a Phase I/II Study

In an ongoing clinical phase I/II study, 16 pediatric patients suffering from high risk leukemia/tumors received highly purified donor natural killer (NK) cell immunotherapy (NK-DLI) at day (+3) +40 and +100 post haploidentical stem cell transplantation. However, literature about the influence of NK-DLI on recipient's immune system is scarce. Here we present concomitant results of a noninvasive in vivo monitoring approach of recipient's peripheral blood (PB) cells after transfer of either unstimulated (NK-DLI(unstim)) or IL-2 (1000 U/ml, 9–14 days) activated NK cells (NK-DLI(IL-2 stim)) along with their ex vivo secreted cytokine/chemokines. We performed phenotypical and functional characterizations of the NK-DLIs, detailed flow cytometric analyses of various PB cells and comprehensive cytokine/chemokine arrays before and after NK-DLI. Patients of both groups were comparable with regard to remission status, immune reconstitution, donor chimerism, KIR mismatching, stem cell and NK-DLI dose. Only after NK-DLI(IL-2 stim) was a rapid, almost complete loss of CD56(bright)CD16(dim/−) immune regulatory and CD56(dim)CD16(+) cytotoxic NK cells, monocytes, dendritic cells and eosinophils from PB circulation seen 10 min after infusion, while neutrophils significantly increased. The reduction of NK cells was due to both, a decrease in patients' own CD69(−) NCR(low)CD62L(+) NK cells as well as to a diminishing of the transferred cells from the NK-DLI(IL-2 stim) with the CD56(bright)CD16(+/−)CD69(+)NCR(high)CD62L(−) phenotype. All cell counts recovered within the next 24 h. Transfer of NK-DLI(IL-2 stim) translated into significantly increased levels of various cytokines/chemokines (i.e. IFN-γ, IL-6, MIP-1β) in patients' PB. Those remained stable for at least 1 h, presumably leading to endothelial activation, leukocyte adhesion and/or extravasation. In contrast, NK-DLI(unstim) did not cause any of the observed effects. In conclusion, we assume that the adoptive transfer of NK-DLI(IL-2 stim) under the influence of ex vivo and in vivo secreted cytokines/chemokines may promote NK cell trafficking and therefore might enhance efficacy of immunotherapy

The sympathomimetic agonist mirabegron did not lower JAK2-V617F allele burden, but restored nestin-positive cells and reduced reticulin fibrosis in patients with myeloproliferative neoplasms: results of phase II study SAKK 33/14

The β-3 sympathomimetic agonist BRL37344 restored nestin-positive cells within the stem cell niche, and thereby normalized blood counts and improved myelofibrosis in a mouse model of JAK2-V617F positive myeloproliferative neoplasms. We therefore tested the effectiveness of mirabegron, a β-3 sympathomimetic agonist, in a phase II trial including 39 JAK2-V617F positive MPN with a mutant allele burden >20%. Treatment consisted of mirabegron 50 mg daily for 24 weeks. The primary endpoint, reduction of the JAK2-V617F allele burden ≥50%, was not reached in any of the patients. One patient achieved a 25% reduction in JAK2-V617F allele burden by 24 weeks. A small subgroup of patients showed hematological improvement. As a side study, bone marrow biopsies were evaluated in 20 patients.We found an increase in the nestin+ cells from a median of 1.09 (interquartile range 0.38-3.27)/mm2 to 3.95 (interquartile range 1.98-8.79)/mm2 (p<0.0001) and a slight decrease of reticulin fibrosis from a median grade of 1.0 (interquartile range 0-3) to 0.5 (interquartile range 0-2) (p=0.01) between start and end of mirabegron treatment. Despite the fact that the primary endpoint of reducing JAK2-V617F allele burden was not reached, the observed effects on nestin+ MSCs and reticulin fibrosis is encouraging and shows that mirabegron can modify the microenvironment where the JAK2-mutant stem cells are maintained