First-hit SETBP1 mutations cause a myeloproliferative disorder with bone marrow fibrosis.

ABSTRACT: SETBP1 mutations are found in various clonal myeloid disorders. However, it is unclear whether they can initiate leukemia, because SETBP1 mutations typically appear as later events during oncogenesis. To answer this question, we generated a mouse model expressing mutated SETBP1 in hematopoietic tissue: this model showed profound alterations in the differentiation program of hematopoietic progenitors and developed a myeloid neoplasm with megakaryocytic dysplasia, splenomegaly, and bone marrow fibrosis, prompting us to investigate SETBP1 mutations in a cohort of 36 triple-negative primary myelofibrosis (TN-PMF) cases. We identified 2 distinct subgroups, one carrying SETBP1 mutations and the other completely devoid of somatic variants. Clinically, a striking difference in disease aggressiveness was noted, with patients with SETBP1 mutation showing a much worse clinical course. In contrast to myelodysplastic/myeloproliferative neoplasms, in which SETBP1 mutations are mostly found as a late clonal event, single-cell clonal hierarchy reconstruction in 3 patients with TN-PMF from our cohort revealed SETBP1 to be a very early event, suggesting that the phenotype of the different SETBP1+ disorders may be shaped by the opposite hierarchy of the same clonal SETBP1 variants.

Biosimilar erythropoiesis-stimulating agents are an effective and safe option for the management of myelofibrosis-related anemia.

OBJECTIVES: Erythropoiesis-stimulating agents (ESA) have an established role in treating anemia in hematological malignancies. However, their role, particularly biosimilar ESA (B-ESA), in myelofibrosis (MF) is not well established. METHODS: This study retrospectively collected data on 96 MF patients treated with B-ESA (alpha/zeta) for the management of anemia to assess safety, efficacy (anemia response [AR]), and survival. RESULTS: Seventy-seven patients (80%) obtained AR. The median time to AR was 2.5 months. In multivariate analysis, significant predictive factors of AR were transfusion independency (p = .006) and ferritin levels <200 ng/ml (p = .009) at baseline. After a median follow-up of 43.8 months from diagnosis, 38 patients (39%) died, 11 (28.9%) from leukemic evolution. Only two patients (2.5%) stopped B-ESA for toxicity. The 24-month survival was significantly affected by response to B-ESA (70.8% in AR vs. 55.3% in non-responder patients, p = .016). In multivariate analysis, age ≤ 70 years (p = .029) and Hb > 8.5 g/dl (p = .047) at baseline were significantly associated with improved survival, with a trend for longer survival in AR patients (p = .06). CONCLUSIONS: B-ESA seems to be an effective and well-tolerated option for anemia treatment in the MF setting. This strategy deserves further clinical investigation.

Tyrosine Kinase Inhibitor discontinuation in Chronic Myeloid Leukemia: eligibility criteria and predictors of success.

TKI discontinuation proved to be safe and feasible in patients with CML with deep and durable molecular responses, introducing an additional treatment goal for these patients beyond overall survival. However, treatment interruption is a safe procedure only with appropriate patient selection and monitoring. Clinical and biological factors associated with better outcomes do not yet offer a precise stratification of patients according to their risk of relapse. This article aims at reviewing the leading studies present in the field in order to define eligibility criteria for discontinuation and predictors of success.