Treosulfan-Versus Melphalan-Based Reduced Intensity Conditioning in HLA-Haploidentical Transplantation for Patients ≥ 50 Years with Advanced MDS/AML.

Relapse and regimen-related toxicities remain major challenges in achieving long-term survival, particularly among older patients with high-risk myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Previous studies have demonstrated the feasibility of treosulfan-based conditioning, noting stable engraftment and low non-relapse mortality (NRM) in patients undergoing HLA-matched allo-HSCT. However, data on treosulfan-based conditioning in the HLA-haploidentical transplantation (HaploT) setting are limited. We retrospectively compared conditioning with fludarabine-cyclophosphamide (FC)-melphalan (110 mg/m2) and FC-treosulfan (30 g/m2) prior to HaploT using post-transplantation cyclophosphamide (PTCy) in patients with high-risk MDS/AML patients ≥ 50 years, transplanted from 2009-2021 at our institution (n = 80). After balancing patient characteristics by a matched-pair analysis, we identified twenty-one matched pairs. Two-year OS and LFS were similar among the groups (OS 66% and LFS 66%, p = 0.8 and p = 0.57). However, FC-melphalan was associated with a significantly lower probability of relapse compared to FC-treosulfan (0% vs. 24%, p = 0.006), counterbalanced by a higher NRM (33% vs. 10%, p = 0.05). Time to engraftment and incidences of acute and chronic graft-versus-host disease (GvHD) did not differ significantly. In conclusion, HaploT using FC-treosulfan in combination with PTCy in patients aged ≥50 years with MDS/AML appears safe and effective, particularly in advanced disease stages. We confirm the favorable extramedullary toxicity profile, allowing for potential dose intensification to enhance antileukemic activity.

PTCY-Based Haploidentical Donor Transplantation versus HLA-Matched Related and Unrelated Donor Transplantations in Patients with Refractory or Relapsed Lymphoma-A Matched-Pair Analysis.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has demonstrated its potential as a curative option for patients with r/r lymphoma. With the introduction of post-transplant cyclophosphamide-based (PTCY) graft-versus-host disease (GvHD) prophylaxis, allo-HCT using haploidentical related donors (Haplo-HSCT) has emerged as a valuable alternative for patients without an available HLA-matched donor. In this study, we compared intermediate and long-term outcomes between Haplo-HSCT and HLA-matched related donor (MRD) and unrelated donor (URD) transplantations in 16 matched pairs using age, disease status, lymphoma classification and performance status as matching criteria. Of note, 88% of patients in each group presented with active disease at the time of conditioning. After a median follow-up of >10 years, 10-year overall and progression-free survival and non-relapse mortality incidence after Haplo-HSCT were 31%, 25% and 38%, respectively, and did not differ compared to the values observed in MRD-HSCT and URD-HSCT. A remarkable lower incidence of acute GvHD ≥ II and moderate and severe chronic GvHD was observed after Haplo-HSCT compared to MRD-HSCT (50%/50%, p = 0.03/0.03) and URD-HSCT (44%/38%, p = 0.04/0.08), resulting in slightly higher 10-year GvHD-free and relapse-free survival (25%) and chronic GvHD-free and relapse-free survival (25%) in the Haplo-HSCT group. In conclusion, Haplo-HSCT is an effective treatment in patients with non-remission NHL. Given its advantage of immediate availability, haploidentical donors should be preferably used in patients with progressive disease lacking an HLA-matched related donor.

The feasibility of electromagnetic sensing aided post pyloric feeding tube placement (CORTRAK) in patients with thrombocytopenia with or without anticoagulation on the intensive care unit.

BACKGROUND: The successful initiation of enteral nutrition is frequently hampered by various complications occurring in patients treated in the intensive care unit (ICU). Successful placement of a nasojejunal tube by CORTRAK enteral access system (CEAS) has been reported to be a simple bedside tool for placing the postpyloric (PP) feeding tube. METHODS: We evaluated the efficacy and side effects using CEAS to establish EN in patients with critical illness, thrombocytopenia, and/or anticoagulation. RESULTS: Fifty-six mechanically ventilated patients were analyzed. Twenty-four of them underwent prior hematopoietic stem cell transplantation (SCT). Sixteen patients received extracorporeal membrane oxygenation treatment because of acute respiratory distress syndrome. The median platelet count at PP placement was 26 g/L (range, 4-106 g/L); 16 patients received therapeutic anticoagulation (activated partial thromboplastin time, 50-70 s). CEAS-assisted placement of a PP nasojejunal tube was performed successfully in all patients. The most frequent adverse event was epistaxis in 27 patients (48.2%), which was mostly mild (Common Terminology Criteria for Adverse Events grade 1, n = 21 [77.8%], and grade 2, n = 6). A significant association between a low platelet count and bleeding complications was observed (P < 0.001). CONCLUSION: Performed by an experienced operator, CEAS is a simple, rapidly available, and effective bedside tool for safely placing PP feeding tubes for EN in patients with thrombocytopenia, even when showing an otherwise-caused coagulopathy in the ICU. Higher-grade bleeding complications were not observed despite their obvious correlation to thrombocytopenia. A prospective study is in preparation.

IL-8 as mediator in the microenvironment-leukaemia network in acute myeloid leukaemia.

The bone marrow microenvironment is physiologically hypoxic with areas being as low as 1% O2, e.g. the stem cell niche. Acute myeloid leukaemia (AML) blasts misuse these bone marrow niches for protection by the local microenvironment, but also might create their own microenvironment. Here we identify IL-8 as a hypoxia-regulated cytokine in both AML cell lines and primary AML samples that is induced within 48 hours of severe hypoxia (1% O2). IL-8 lacked effects on AML cells but induced migration in mesenchymal stromal cells (MSC), an integral part of the bone marrow. Accordingly, MSC were significantly increased in AML bone marrow as compared to healthy bone marrow. Interestingly, mononuclear cells obtained from healthy bone marrow displayed both significantly lower endogenous and hypoxia-induced production of IL-8. IL-8 mRNA expression in AML blasts from 533 patients differed between genetic subgroups with significantly lower expression of IL-8 in acute promyelocytic leukaemia (APL), while in non APL-AML patients with FLT ITD had the highest IL-8 expression. In this subgroup, high IL-8 expression was also prognostically unfavourable. In conclusion, hypoxia as encountered in the bone marrow specifically increases IL-8 expression of AML, which in turn impacts niche formation. High IL-8 expression might be correlated with poor prognosis in certain AML subsets.

Microenvironmental hypoxia regulates FLT3 expression and biology in AML.

Fms-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase constitutively expressed by acute myeloid leukaemia (AML) blasts. In addition, 25% of AML patients harbour a FLT3-ITD mutation, associated with inferior outcome due to increased relapse rate. Relapse might be propagated by interactions between AML blasts and the bone marrow microenvironment. Besides cellular elements of the microenvironment (e.g. mesenchymal stromal cells), bone marrow hypoxia has emerged as an additional crucial component. Hence, effects of hypoxia on FLT3 expression and biology could provide novel insight into AML biology. Here we show that 25% of AML patients down-regulate FLT3 expression on blasts in response to in vitro hypoxia (1% O2), which was independent of its mutational state. While virtually no AML cell lines regulate FLT3 in response to hypoxia, the down-regulation could be observed in Ba/F3 cells stably transfected with different FLT3 mutants. Hypoxia-mediated down-regulation was specific for FLT3, reversible and proteasome-dependent; with FLT3 half-life being significantly shorter at hypoxia. Also, PI-3K inhibition could partially abrogate down-regulation of FLT3. Hypoxia-mediated down-regulation of FLT3 conferred resistance against cytarabine in vitro. In conclusion, FLT3 expression in AML is dependent on the oxygen partial pressure, but response to hypoxia differs.

Hypoxia regulates proliferation of acute myeloid leukemia and sensitivity against chemotherapy.

Reduced oxygen partial pressure (pO2, hypoxia) is an important component of the bone marrow microenvironment and the hematopoietic stem cell niche. It is unclear whether this applies to the leukemic stem cell as well and if differences in pO2 between the normal hematopoetic and the leukemic stem cell niche exits. Here, we demonstrate that while there is no detectable difference in the hypoxic level of bone marrow infiltrated by acute myeloid leukemia (AML) and healthy bone marrow, physiological hypoxia of 1% O2 itself leads to cell cycle arrest of AML blasts (both cell lines and primary AML samples) in the G0/G1 phase with upregulation of p27 and consecutive decrease of cells in the S phase. Hence, susceptibility of AML blasts toward cytarabine as S phase dependent drug is significantly decreased as shown by decreased cytotoxicity in vitro. In addition, cells exposed to hypoxia activate PI3K/Akt and increase expression of anti-apoptotic XIAP. Inhibition of PI3K can restore cytarabine sensitivity of AML blasts at hypoxic conditions. In conclusion, hypoxia mediated effects encountered in the bone marrow might contribute to chemoresistance of AML blasts.

The bone marrow microenvironment is a critical player in the NK cell response against acute myeloid leukaemia in vitro.

Immune therapy for acute myeloid leukaemia (AML) has been largely disappointing. One possible explanation might lie in the microenvironment of the bone marrow, comprising cellular (e.g. mesenchymal stromal cells, MSC) and non-cellular components (e.g. hypoxia). The purpose of this study was to investigate the effects of these components in the immune response against AML in vitro. In vitro exposure of lymphocytes to hypoxia resulted in an increased expression of CD69 as an activation marker in NK cells only, with subsequently enhanced cell lysis of K-562 cell line by NK cells but not in lysis of primary blast. However, co-culture of AML cells with MSC significantly protected leukemic blasts from NK cell mediated lysis, mainly in a specific manner requiring cell-to-cell contact with supportive MSC. These data imply a relevant but unequivocal role of hypoxia and MSC the immune response against AML blasts.

Physiological hypoxia prevents bile salt-induced apoptosis in human and rat hepatocytes.

BACKGROUND & AIMS: Hydrophobic bile salts such as glycochenodeoxycholate (GCDC) accumulate in cholestatic liver disease and induce hepatocellular apoptosis, promoting profibrotic signalling. The tissue microenvironment is an integral player in cellular pathophysiology, but it is not routinely incorporated into laboratory studies. Tissue oxygen partial pressure (pO2) may be an underestimated component of the microenvironment: in the liver, a pO2 of 30-45 mmHg (approximately 6% O2) is physiological, because of predominant portal blood supply. It was the aim of this project to investigate the impact of physiological hypoxia (i.e. 6% O2) on hepatocellular function, namely, bile salt-induced apoptosis. METHODS: Human hepatoma cells (HepG2-Ntcp) and primary rat hepatocytes were cultured at standard laboratory (hyperoxic) conditions (21% O2) and at physiological hypoxia (6% O2) in parallel for 1-8 days to study hepatocellular apoptosis and activation of signalling pathways. Standard laboratory analyses were applied for bile salt uptake, caspase-3/-7 activity, western blotting and gene-array analysis. RESULTS: Culturing at physiological hypoxia protected both human and rat hepatocytes against GCDC-induced apoptosis: caspase-3/-7 activation was diminished by 3.1 ± 0.5-fold in human HepG2-Ntcp and completely abolished in primary rat hepatocytes. Bile salt uptake was unaffected. Induction of hypoxia-inducible factor-1α indicated adaption to physiological hypoxia. The MEK/ERK cascade was activated and anti-apoptotic mediators were induced: N-Myc down-regulated gene, gelsolin and carbonic anhydrase IX were upregulated 12.4-, 6.5- and 5.2-fold respectively. CONCLUSIONS: We conclude from these data that (i) physiological hypoxia protects hepatocytes from bile salt-induced apoptosis, (ii) tissue pO2 is a crucial, underestimated component of the microenvironment and should (iii) be considered when studying hepatocellular physiology in vitro.