Fludarabine induces apoptosis, activation, and allogenicity in human endothelial and epithelial cells: protective effect of defibrotide

Abstract

Fludarabine is a nonmyeloablative immunosuppressant increasingly used as a component of alternative conditioning regimens before allogeneic bone marrow transplantation. It is expected to reduce conditioning-related toxicity and proinflammatory activation of the host tissues. However, in our in vitro study, we provide evidence that 2-fluoroadenine 9-␤-D-arabinofuranoside (F-Ara) as the active metabolized form of fludarabine damages human microvascular endothelial cells (HMECs) and dermal and alveolar epithelial cell lines after 48 hours of culture when it is used in pharmacologically relevant concentrations (range, 10 g/mL-1 g/mL). In addition, flow cytometric analyses revealed a significant up-regulation of intercellular adhesion molecule 1 and major histocompatibility complex (MHC) class I molecules by F-Ara, suggesting a proinflammatory activation of HMECs. Cytotoxicity assays demonstrated that target HMECs pretreated with F-Ara (10 g/ mL) showed increased lysis by allogeneic MHC class I-restricted cytotoxic T lymphocytes from healthy human donors. We conclude that, beside its immunosuppressive activities, F-Ara can be harmful for target tissues of transplantation-related complications and can even stimulate allogeneic immune responses. We identified the pharmaceutical compound defibrotide as protective against F-Arainduced apoptosis and alloactivation, importantly, without affecting the antileukemic effect of F-Ara. This observation argues for a potential clinical usage of defibrotide in pretransplantation conditioning. (Blood. 2002;100:334-340)

Fludarabine as a risk factor for poor stem cell harvest, treatment-related MDS and AML in follicular lymphoma patients after autologous hematopoietic cell transplantation

“…However, in addition to hematopoietic cells, fludarabine also damages non-hematopoietic cells. Eissner et al 24 first reported fludarabine's adverse effects on human microvascular endothelial cells, dermal and alveolar epithelial cell lines, as well as hematopoietic cells. In cell cultures, Berger et al 25 demonstrated a dose-dependent decrease in clonogenic progenitor Table 2 Univariable risk factors for treatment-associated myelodysplastic syndrome or AML in patients with follicular lymphoma treated with auto-HCT Our small study is retrospective and data were incomplete for some patients, as indicated in Table 1.…”

The role of the endothelium in the short-term complications of hematopoietic SCT

“…9 Using microvascular ECs, they further demonstrated that ECs incubated with fludarabine show an increased lysis by allogeneic MHC-restricted cytotoxic T-lymphocytes. 37 Finally, they evaluated microvascular endothelial damage in vitro after allo-HSCT. They observed an increase in the apoptotic activity of the sera from patients at the time of engraftment and preceding episodes of acute and chronic GVHD and TAM.…”

“…Many publications describe the beneficial effects of defibrotide as a pro-fibrinolytic, antithrombotic and thrombolytic, anti-ischemic, anti-shock, anti-atherosclerotic, and anti-rejection drug. 45 Eissner et al 37 demonstrated in vitro that defibrotide protected ECs from fludarabine toxicity.…”

Preferential sensitivity of hematopoietic (HPs) and mesenchymal (MPs) progenitors to fludarabine suggests impaired bone marrow niche and HP mobilization

“…In conclusion, whereas clinical data argue for an hematopoietic and immune cell specificity of FDR, the scope of its action is larger than expected and involves endothelial, epithelial and nurse-like cells, 8 as well as MC as demonstrated here. Possible impairment of hematopoietic and stromal components might contribute to a certain extent to the myelosuppression observed in vivo, but also to the antileukemic effect of FDR in B-chronic lymphocytic leukemia, by modifying the environment of the B-cell clone.…”