Myelodysplastic syndromes and chronic myelomonocytic leukemia are blood disorders characterized by ineffective hematopoiesis and progressive marrow failure that can transform into acute leukemia. The DNA methyltransferase inhibitor 5-azacytidine (AZA) is the most effective pharmacological option, but only ∼50% of patients respond. A response only manifests after many months of treatment and is transient. The reasons underlying AZA resistance are unknown, and few alternatives exist for non-responders. Here, we show that AZA responders have more hematopoietic progenitor cells (HPCs) in the cell cycle. Non-responder HPC quiescence is mediated by integrin α5 (ITGA5) signaling and their hematopoietic potential improved by combining AZA with an ITGA5 inhibitor. AZA response is associated with the induction of an inflammatory response in HPCs in vivo. By molecular bar coding and tracking individual clones, we found that, although AZA alters the sub-clonal contribution to different lineages, founder clones are not eliminated and continue to drive hematopoiesis even in complete responders.

Key Points• Triple therapy is well tolerated and effective in patients with chronic ITP.• Relapse free survival was 92%for responders after 12 months and 76% after 24 months.Promising reports of combination immunosuppression with high-dose dexamethasone and rituximab for the treatment of primary immune thrombocytopenia (ITP) have recently emerged. They suggest a potential to further optimize the efficacy of therapy. We investigate the use of a novel combination of conventional therapies in ITP given over 4 weeks. From 2011 to 2014, 20 patients were prospectively enrolled onto a single-arm phase 2b study to describe the safety, efficacy, and tolerability of oral dexamethasone 40 mg for days 1 to 4, oral cyclosporine 2.5 to 3 mg/kg daily for day 1 to 28, and intravenous low-dose rituximab 100 mg for days 7, 14, 21, and 28. There were no therapy-related serious adverse side effects, 6-month response rate was 60%, and treatment was well tolerated. Responders enjoyed relapse-free survivals of 92% and 76%, respectively, at 12 and 24 months. This study highlights the possibility of achieving an enduring remission from 4 weeks of therapy. This study is registered at www.anzctr.org.au (#ANZCTRN12611000015943). (Blood. 2015;126(4):500-503)

The authors revise the concept of anaplastic large cell lymphoma (ALCL) in the light of the recently updated WHO classification of Tumors of Hematopoietic and Lymphoid Tissues both on biological and clinical grounds. The main histological findings are illustrated with special reference to the cytological spectrum that is indeed characteristic of the tumor. The phenotype is reported in detail: the expression of the ALK protein as well as the chromosomal abnormalities is discussed with their potential pathogenetic implications. The clinical features of ALCL are presented by underlining the difference in terms of response to therapy and survival between the ALK-positive and ALK-negative forms. Finally, the biological rationale for potential innovative targeted therapies is presented.