e18552 Background: Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis resulting in peripheral cytopenia. In low risk MDS, a pro-apoptotic milieu was found with increased levels of apoptosis-promoting factors (e.g. CD95L) resulting in increased apoptosis of erythroid progenitors and peripheral cytopenia. APG101 is a fusion protein consisting of the extracellular domain of human CD95 and the Fc part of human IgG1. By binding to CD95L, it inhibits the activation of CD95. Here, we report interim results of a phase I study in transfusion-dependent low or intermediate risk MDS patients treated with APG101. Methods: Results are based on data from 14 of 20 patients which gave written informed consent. The study was performed according to ICH-GCP and approved by IRB and Authorities. Patients were treated for 12 weeks with weekly i.v. infusions of 100 mg (6 patients) or 400 mg APG101 (8 patients). Thereafter, they were followed for 6 months. Bone marrow (BM) biopsies were taken predose, at end of treatment, week 25 and week 37 (follow up) and were subject to cytologic, cytogenetic, molecular and immunophenotypic analyses. Methylcellulose assays on isolated CD34+ cells from BM aspirates were performed as well as amplicon deep sequencing to detect gene mutations. Results: WPSS was low (2 patients) and intermediate (12 patients); medullary blast count was ‹5%. Evaluation of BM smears as well as immune phenotypic analysis showed no increase in blasts. Quantification of the allele burden of pre-existing mutations showed no expansion of mutated clones. Ex vivodifferentiation analyses revealed an increase in CFU-E/BFU-E forming capacity as well as granulocytic colony forming. 5 of 14 patients showed a significant decrease in transfusion frequency, 1 patient became transfusion-free. Conclusions: APG101 was tolerated very well. No patient discontinued treatment. Deep amplicon sequencing did not show any signs of expansion of preexisting clones during therapy. Major and minor hematologic improvement was seen in 4 (major) and 1 (minor) of the patients, one patient became transfusion-free. Therefore, APG101 is an interesting target for further investigation. Clinical trial information: NCT01736436.

Expression of ERG is of prognostic significance in acute myeloid leukemia (AML) and T-lymphoblastic leukemia (T-ALL) pointing to its role in leukemogenesis. To unravel its transcriptional regulation we analyzed the expression of ERG specific isoforms. Expression of the two main isoforms ERG2 and ERG3 was found in AML and normal CD34+ cells, whereas T-ALL blasts only expressed ERG isoforms harboring exon 5 (ERG3) lacking expression of ERG2. Bisulfite sequencing revealed hypermethylation of a CpG island within the ERG2 promoter region in T-ALL. Treatment of the T-lymphoblastic cell line BE13 with decitabine led to re-expression of ERG2 and pyrosequencing showed concordant DNA hypomethylation, thus confirming a methylation regulated expression of ERG2. Moreover, the identification of a new ERG isoform (ERG3Deltaex12) suggests the association with different interaction partners and adds to the complexity of downstream pathways mediated by the expression of specific ERG transcripts in acute leukemia.

BackgroundNOTCH1 mutations have been associated with a favorable outcome in pediatric acute T-lymphoblastic leukemia However, the results of studies on the prognostic significance of NOTCH1 mutations in adult T-lymphoblastic leukemia remain controversial.Design and MethodsHere we have investigated the prognostic impact of mutations in the NOTCH1 pathway, in particular, the NOTCH1 and FBXW7 genes, in a large cohort of adult patients with T-lymphoblastic leukemia (n=126). We determined the occurrence Of Mutations In NOTCH1 and FBXW7 by DNA amplification and direct sequencing of polymerase chain reaction productsResultsMutations were identified in 57% and 12% of the NOTCH1 and FBXW7 genes, respectively. The characteristics of patients carrying NOTCH1 and/or FBXW7 (NOTCH1-FBXW7) mutations were similar to those with wild-type genes Patients with NOTCH1-FBXW7 mutations more often showed a thymic immunophenotype (p=0.001) In the over-all cohort; no significant differences were seen in the complete remission or event-free survival rates between patients with mutated or wild-type NOTCH1-FBXW7 (p=0.39)ConclusionsNOTCH1 and FBXW7 mutations were not predictive of outcome in the overall cohort of adult patients with T-lymphoblastic leukemia. but there was a trend towards a favorable prognostic impact of NOTCH1-FBXW7 mutations in the small subgroup of patients with low-risk ERG/BAALC expression status. Our findings further confirm the high frequency of NOTCH1 mutations in adult T-lymphoblastic leukemia