Interferon and PV stem cells

Non ABL-directed inhibitors as alternative treatment strategies for chronic myeloid leukemia

The introduction of ABL Tyrosine Kinase Inhibitors (TKIs) has significantly improved the outcome of Chronic Myeloid Leukemia (CML) patients that, in large part, achieve satisfactory hematological, cytogenetic and molecular remissions. However, approximately 15-20% fail to obtain optimal responses according to the current European Leukemia Network recommendation because of drug intolerance or resistance.Moreover, a plethora of evidence suggests that Leukemic Stem Cells (LSCs) show BCR-ABL1-independent survival. Hence, they are unresponsive to TKIs, leading to disease relapse if pharmacological treatment is discontinued.All together, these biological events generate a subpopulation of CML patients in need of alternative therapeutic strategies to overcome TKI resistance or to eradicate LSCs in order to allow cure of the disease.In this review we update the role of "non ABL-directed inhibitors" targeting signaling pathways downstream of the BCR-ABL1 oncoprotein and describe immunological approaches activating specific T cell responses against CML cells.

Ruxolitinib in the treatment of polycythemia vera: patient selection and special considerations

The discovery of JAK2 V617F mutation in the mid-2000s started to fill the gap between clinical presentation of polycythemia vera (PV), first described by Vaquez at the end of the 19th century, and spontaneous erythroid colony formation, reported by Prchal and Axelrad in the mid-1970s. The knowledge on this mutation brought an important insight to our understanding of PV pathogenesis and led to a revision of the World Health Organization diagnostic criteria in 2008. JAK-STAT is a major signaling pathway implicated in survival and proliferation of hematopoietic precursors. High prevalence of JAK2 V617F mutation among myeloproliferative neoplasms (>95% in PV and ~50% in primary myelofibrosis and essential thrombocythemia) together with its role in constitutively activating JAK-STAT made JAK2 a privileged therapeutic target. Ruxolitinib, a JAK 1 and 2 inhibitor, has already proven to be efficient in relieving symptoms in primary myelofibrosis and PV. In the latter, it also appears to improve microvascular involvement. However, evidence regarding its potential role in altering the natural course of PV and its use as an adjunct to current standard therapies is sparse. Therapeutic advances are needed in PV as phlebotomy, low-dose aspirin, cytoreductive agents, and interferon alpha are the only therapeutic tools available at the moment to influence outcome. Even though several questions are still unanswered, this review aims to serve as an overview article of the potential role of ruxolitinib in PV according to current literature and expert opinion. It should help hematologists to visualize the place of this tyrosine kinase inhibitor in the field of current practice and offer criteria for a careful patient selection.