Etanercept treatment in Fanconi anaemia; combined US and Italian experience

Chromosome fragility in the buccal epithelium in patients with Fanconi anemia

Fanconi anemia (FA) is a rare genome instability syndrome characterized by progressive bone marrow failure and predisposition to cancer, especially head and neck squamous cell carcinoma. Surgical resection is the standard of care for solid tumors, as patients with FA do not tolerate genotoxic chemotherapies or radiation, leading to poor prognosis. It is therefore imperative to develop chemoprevention strategies such as the identification of novel biomarkers to detect the formation of the tumor before its emergence and to use them in clinical trials aimed to counteract genome instability of patients with FA in tissues at risk. Micronuclei (MN) are chromosome fragments that are left behind in anaphase and appear in daughter cells as small additional nuclei. In this work, we analyzed MN frequencies in exfoliated buccal cells from 40 patients with FA and 24 controls. We found that MN frequency was significantly increased in the FA cohort indicating that we can detect chromosome fragility in patients with FA in basal conditions and in a tissue that is divided in vivo. Consequently, the MN assay in exfoliated buccal cells of patients with FA could be used in cancer risk studies and clinical trials aimed to identify cancer chemopreventive drugs.

Natural Killer Cell Degranulation Defect: A Cause for Impaired NK-Cell Cytotoxicity and Hyperinflammation in Fanconi Anemia Patients

Fanconi anemia (FA) is a rare inherited syndrome characterized by progressive bone marrow failure (BMF), abnormal skin pigmentation, short stature, and increased cancer risk. BMF in FA is multifactorial and largely results from the death of hematopoietic stem cells due to genomic instability. Also, inflammatory pathology in FA has been previously reported, however the mechanism is still not clear. In literature, decreased NK-cell count and/or impaired NK-cell activity, along with other immunological abnormalities have been described in FA-patients (1). However, to the best of our knowledge, this is the first report showing a defective degranulation mechanism leading to abnormal NK-cell cytotoxicity in FA-patients, which may explain the development of a hyperinflammatory response in these patients. This may predispose some patients to develop Hemophagocytic lymphohistiocytosis (HLH) which manifests with prolonged fever, progressive cytopenias and organomegaly. Early diagnosis and initiation of immunosuppressive therapy in these patients will help to better manage these patients. We also propose FA genes to be listed as a cause of familial HLH.

How I manage patients with Fanconi anaemia

Fanconi Anaemia is a rare, genetic heterogeneous multisystem disease that is the most common congenital syndrome of marrow failure. Twenty genes have been reported to cause the disease. Remarkable progress has been made over the last 20 years in the understanding of the genetic and pathophysiological mechanisms. Unfortunately, these advances have not been completely paralleled by advances in medical treatment, where the most important component remains stem cell transplantation. This therapy, although contributing to long-term negative effects, such as increased occurrence of late malignancies, is the only current option capable of prolonging the survival of patients. In spite of relevant recent progress in matched unrelated donor transplants, the largest studies with longer follow-up still show a superiority of matched sibling donor transplants with a success rate, in selected cohorts, of over 90%. This article reviews different aspects of the disease, including genetics, diagnosis and treatment options, with special focus on stem cell transplantation, comprehensive post-diagnosis management, decision-making processes and long-term follow-up.

Hematopoietic cell transplantation in Fanconi anemia: current evidence, challenges and recommendations

INTRODUCTION

Hematopoietic cell transplantation for Fanconi Anemia (FA) has improved dramatically over the past 40 years. With an enhanced understanding of the intrinsic DNA-repair defect and pathophysiology of hematopoietic failure and leukemogenesis, sequential changes to conditioning and graft engineering have significantly improved the expectation of survival after allogeneic hematopoietic cell transplantation (alloHCT) with incidence of graft failure decreased from 35% to <10% and acute graft-versus-host disease (GVHD) from >40% to <10%. Today, five-year overall survival exceeds 90% in younger FA patients with bone marrow failure but remains about 50% in those with hematologic malignancy. Areas covered: We review the evolution of alloHCT contributing to decreased rates of transplant related complications; highlight current challenges including poorer outcomes in cases of clonal hematologic disorders, alloHCT impact on endocrine function and intrinsic FA risk of epithelial malignancies; and describe investigational therapies for prevention and treatment of the hematologic manifestations of FA. Expert commentary: Current methods allow for excellent survival following alloHCT for FA associated BMF irrespective of donor hematopoietic cell source. Alternative curative approaches, such as gene therapy, are being explored to eliminate the risks of GVHD and minimize therapy-related adverse effects.

Upregulated LINE-1 Activity in the Fanconi Anemia Cancer Susceptibility Syndrome Leads to Spontaneous Pro-inflammatory Cytokine Production

Fanconi Anemia (FA) is a genetic disorder characterized by elevated cancer susceptibility and pro-inflammatory cytokine production. Using SLX4^FANCP deficiency as a working model, we questioned the trigger for chronic inflammation in FA. We found that absence of SLX4 caused cytoplasmic DNA accumulation, including sequences deriving from active Long INterspersed Element-1 (LINE-1), triggering the cGAS-STING pathway to elicit interferon (IFN) expression. In agreement, absence of SLX4 leads to upregulated LINE-1 retrotransposition. Importantly, similar results were obtained with the FANCD2 upstream activator of SLX4. Furthermore, treatment of FA cells with the Tenofovir reverse transcriptase inhibitor (RTi), that prevents endogenous retrotransposition, decreased both accumulation of cytoplasmic DNA and pro-inflammatory signaling. Collectively, our data suggest a contribution of endogenous RT activities to the generation of immunogenic cytoplasmic nucleic acids responsible for inflammation in FA. The additional observation that RTi decreased pro-inflammatory cytokine production induced by DNA replication stress-inducing drugs further demonstrates the contribution of endogenous RTs to sustaining chronic inflammation. Altogether, our data open perspectives in the prevention of adverse effects of chronic inflammation in tumorigenesis.

•

Cytoplasmic DNA, comprising LINE-1-derived sequences, elicits IFN expression via the cGAS-STING pathway in SLX4-deficiency.

•

Members of the Fanconi Anemia DNA repair pathway negatively regulate LINE-1 retrotransposition.

•

Endogenous reverse transcriptase activities contribute to spontaneous and chemotherapy-induced inflammation.

Chronic inflammation favors tumorigenesis, negatively influencing patient prognosis. Yet, the underlying molecular mechanisms are poorly understood. Here, we show that increased endogenous retroelement-associated reverse transcriptase activity contributes to generate immunogenic cytoplasmic nucleic acids susceptible of triggering a pro-inflammatory response in the Fanconi Anemia (FA) cancer susceptibility syndrome. In addition, treatment of FA cells or of cells exposed to replication stress inducing drugs, with a reverse transcriptase inhibitor, decreases pro-inflammatory signals. Altogether our data suggest the involvement of endogenous reverse transcriptase activities in sustaining pervasive chronic inflammation, opening therapeutic perspectives for preventing its impact on tumorigenesis.

Fanconi Anemia: Overview of the Disease and the Role of Hematopoietic Transplantation

Fanconi anemia (FA) is an inherited bone marrow failure syndrome characterized by congenital abnormalities and chromosomal breakages with the occurrence of hematological and solid malignancies. FA is the most common type of inherited bone marrow failure and poses tremendous challenges. FA patients are uniquely hypersensitive to hematopoietic stem cell transplantation (HSCT) conditioning agents due to the underling chromosomal instability. HSCT has shown important progress in the last years, especially after the introduction of fludarabine and the reduction of cyclophosphamide in the preparative regimen. For patients with HLA-identical-related donors HSCT should be performed as first-line therapy, for patients with alternative donors HSCT remains a therapy with increased morbidity and mortality.

p38 Mitogen-activated protein kinase inhibition enhances in vitro erythropoiesis of Fanconi anemia, complementation group A-deficient bone marrow cells

Bone marrow failure in Fanconi anemia (FA) has been linked in part to overproduction of inflammatory cytokines, to which FA stem and progenitor cells are hypersensitive. In cell lines and murine models p38 mitogen-activated protein kinase (MAPK)-dependent tumor necrosis factor α (TNF-α) overexpression can be induced by the Toll-like receptors (TLRs) 4 and 7/8 ligands Lipopolysaccharide (LPS) and R848. Ex vivo exposure of FA stem cells to TNF-α suppresses their replication and selects preleukemic clones. Here we show that inhibition of p38 MAPK also reduces TLR4 and 7/8-mediated TNF-α production in primary human FA complementation group A (FANCA)-deficient monocytes from nine patients and demonstrate that, while p38 MAPK inhibition also enhances clonal growth of FANCA-deficient erythroid progenitors, the effect was mediated indirectly by the influence of the inhibitor on auxiliary cells, not erythroid colony-forming units themselves. Taken together, these results support the view that inhibition of the p38 MAPK pathway in monocytes may improve hematopoiesis in FANCA patients.

TNF-α, a good or bad factor in hematological diseases?

Tumor necrosis factor-alpha (TNF-α) is a highly pleiotropic cytokine involved in a spectrum of physiological processes that control inflammation, anti-tumor responses and homeostasis through two receptors, TNF-R1 and TNF-R2. In general, TNF-R1 mediates cytotoxicity, resistance to infection and stimulation of NF-κB. By contrast, TNF-R2 has been implicated in proliferation of T-cell line, thymocytes and human mononuclear cells. Hematological malignancies are the types of cancer that affect normal hematopoiesis, have a speedy development, high lethal rate and until now still have no effective treatment. Several studies have shown that inflammatory cytokines play an important role in the onset and progress of these diseases. In this review, we summarize the recent studies and evaluate the positive or negative role of TNF-α in some hematological malignancies or diseases with a malignant tendency.

Remission of severe aphthous stomatitis of celiac disease with etanercept

Celiac disease is a common autoimmune disease triggered by gluten-containing foods (wheat, barley and rye) in genetically predisposed individuals. We present a patient with celiac disease complicated by severe aphthous stomatitis resulting in impairing swallowing, chewing and speaking. This led to weight loss, psychosocial problems as well as inability to perform her work. A variety of topical and systemic medications used resulted in either no improvement or only partial alleviation of the patient’s symptoms. After informed consent, etanercept was initiated and resulted in complete remission of aphthous stomatitis, decrease in arthralgia and fatigue and considerable improvement in her quality of life. The use of newer biological agents for selected and severe manifestations of celiac disease may lead to improved morbidity in these patients, but more studies are needed to determine long-term efficacy as well as safety of these drugs in the mucosal and/or systemic complications of this disease.

FANCA and FANCC modulate TLR and p38 MAPK-dependent expression of IL-1β in macrophages

Hematopoietic stem and progenitor cells with inactivated Fanconi anemia (FA) genes, FANCA and FANCC, are hypersensitive to inflammatory cytokines. One of these, tumor necrosis factor α (TNF-α), is also overproduced by FA mononuclear phagocytes in response to certain Toll-like receptor (TLR) agonists, creating an autoinhibitory loop that may contribute to the pathogenesis of progressive bone marrow (BM) failure and selection of TNF-α-resistant leukemic stem cell clones. In macrophages, the TNF-α overproduction phenotype depends on p38 mitogen-activated protein kinase (MAPK), an enzyme also known to induce expression of other inflammatory cytokines, including interleukin 1β (IL-1β). Reasoning that IL-1β might be involved in a like autoinhibitory loop, we determined that (1) TLR activation of FANCA- and FANCC-deficient macrophages induced overproduction of both TNF-α and IL-1β in a p38-dependent manner; (2) exposure of Fancc-deficient BM progenitors to IL-1β potently suppressed the expansion of multipotent progenitor cells in vitro; and (3) although TNF-α overexpression in FA cells is controlled posttranscriptionally by the p38 substrate MAPKAPK-2, p38-dependent overproduction of IL-1β is controlled transcriptionally. We suggest that multiple inflammatory cytokines overproduced by FANCA- and FANCC-deficient mononuclear phagocytes may contribute to the progressive BM failure that characterizes FA, and that to achieve suppression of this proinflammatory state, p38 is a more promising molecular therapeutic target than either IL-1β or TNF-α alone.

Cytokine production by bone marrow mononuclear cells in inherited bone marrow failure syndromes

Fanconi anaemia (FA), dyskeratosis congenita (DC), Diamond-Blackfan anaemia (DBA), and Shwachman-Diamond syndrome (SDS) are characterized by the progressive development of bone marrow failure. Overproduction of tumour necrosis factor-α (TNF-α) from activated bone marrow T-cells has been proposed as a mechanism of FA-related aplasia. Whether such overproduction occurs in the other syndromes is unknown. We conducted a comparative study on bone marrow mononuclear cells to examine the cellular subset composition and cytokine production. We found lower proportions of haematopoietic stem cells in FA, DC, and SDS, and a lower proportion of monocytes in FA, DC, and DBA compared with controls. The T- and B-lymphocyte proportions were similar to controls, except for low B-cells in DC. We did not observe overproduction of TNF-α or IFN-γ by T-cells in any patients. Induction levels of TNF-α, interleukin (IL)-6, IL-1β, IL-10, granulocyte colony-stimulating factor, and granulocyte-macrophage colony-stimulating factor in monocytes stimulated with high-dose lipopolysaccharide (LPS) were similar at 4 h but lower at 24 h when compared to controls. Unexpectedly, patient samples showed a trend toward higher cytokine level in response to low-dose (0·001 μg/ml) LPS. Increased sensitivity to LPS may have clinical implications and could contribute to the development of pancytopenia by creating a chronic subclinical inflammatory micro-environment in the bone marrow.

TNF-α signaling in Fanconi anemia

Tumor necrosis factor-alpha (TNF-α) is a major pro-inflammatory cytokine involved in systemic inflammation and the acute phase reaction. Dysregulation of TNF production has been implicated in a variety of human diseases including Fanconi anemia (FA). FA is a genomic instability syndrome characterized by progressive bone marrow failure and cancer susceptibility. The patients with FA are often found overproducing TNF-α, which may directly affect hematopoietic stem cell (HSC) function by impairing HSC survival, homing and proliferation, or indirectly change the bone marrow microenvironment critical for HSC homeostasis and function, therefore contributing to disease progression in FA. In this brief review, we discuss the link between TNF-α signaling and FA pathway with emphasis on the implication of inflammation in the pathophysiology and abnormal hematopoiesis in FA.