Severe Aplastic Anemia
Severe aplastic anemia (SAA) is a rare acquired hematological disorder characterized by hypocellular bone marrow and pancytopenia in the peripheral blood. The differential diagnosis of hypocellular bone marrow disorders is challenging and includes inherited bone marrow failure syndromes as well as myelodysplastic syndromes. In SAA, T-cell mediated destruction of hematopoietic stem cells has been shown to be the main pathophysiological mechanism and about 50% of patients respond to immunosuppressive therapy. Allogeneic stem cell transplantation is a curative treatment approach that has traditionally been applied in patients with a matched sibling donor or non-responders to immunosuppressive therapy. We aim to improve patient outcomes with a) a better diagnostic work-up to exclude patients with inherited bone marrow failure syndromes (i.e. dyskeratosis congenita) b) the definition of prognostic markers for response to immune suppressive therapy and c) improved transplant strategies. The network of the European Working Group for Severe Aplastic Anemia (EWOG-SAA) offers a unique chance to address these questions.
Hematopoietic Stem Cell Transplantation (HSCT) for myelodysplastic syndromes and bone marrow failure syndromes
Myelodysplastic Syndromes (MDS) are a heterogeneous group of disorders characterized by bone marrow dysplasia, cytopenias in peripheral blood and the risk to develop myeloid malignancies. Hematopoietic stem cell transplantation is a curative treatment for patients with MDS, and EWOG-MDS has developed stem cell transplantation guidelines for patients with MDS (https://ewog-mds.de/studies.html). In the current guidelines the indication for HSCT and more specifically the choice of the conditioning regimen depends on the hematological presentation, MDS subtype and karyotype. Our aim is to assess the impact of new diagnostic insights on HSCT outcomes and optimize the HSCT procedure.
Telomere length in Severe Aplastic Anemia
The differential diagnosis of acquired aplastic anemia encompasses inherited bone marrow failure syndromes such as dyskeratosis congenital (DC). Premature telomere shortening caused by mutations in genes involved in telomere elongation or maintenance is the cause of the clinical manifestation of DC. However, there are other pathophysiological mechanisms such as regenerative stress or DNA damage that possibly contribute to telomere shortening. With the EWOG-SAA registry (EWOG-SAA 2010) we perform telomere length analysis in patients diagnosed with SAA with the aim a) to identify patients with unrecognized DC and b) analyze the association of telomere length with response to immunosuppressive therapy.
Impact of GATA2 germline mutations on HSCT outcome in MDS
Genetic research has resulted in the identification of new predisposition syndromes caused by germline mutation in GATA2 or SAMD9/L. In our cohort of children and adolescents with MDS, germline GATA2 mutations have been identified in 7% of patients with MDS and 15% of patients with advanced MDS. In these patients, HSCT procedures have been applied in accordance with the current recommendation of EWOG-MDS using the hematological manifestation, the karyotype and the MDS subtype, but not the underlying germline mutation for stratification. The impact of the underlying GATA2 germline mutation on HSCT outcomes will be analyzed.
HSCT with a reduced toxicity conditioning regimen in MDS-RCC
We have previously shown that patients with refractory cytopenia of childhood (RCC) have a low risk of relapse following HSCT and can successfully be transplanted with a reduced intensity regimen. However, the procedure was associated with a considerable risk of relapse. We now investigate whether a low toxicity conditioning regimen offers reliable engraftment combined with the expected low toxicity for patient with RCC.
HSCT in bone marrow failure syndromes
HSCT offers the potential to cure the hematological manifestations in patients with an inherited bone marrow failure syndrome (IBMFS). However, the procedure is generally associated with a considerable risk of early and late morbidity which maybe even more pronounced in IBMF patients. IBMFS are rare and there are virtually no controlled clinical trials for HSCT in patients with IBMFS. Data collection in and detailed analysis of clinical registries therefore offers a unique chance to provide a scientific basis for treatment decisions. Analyzing the data of the French and the German registry for Diamond Blackfan Anemia we were able to demonstrate a favorable outcome for DBA patients being transplanted from a matched sibling or a matched unrelated donor. These results will be incorporated in future clinical guidelines.
BMBF consortium „MyPred“ (Information in German)