Form Of Myeloproliferative Disorder Research Articles

The current status and the future of JAK2 inhibitors for the treatment of myeloproliferative diseases

Janus kinases (JAKs) are critical components of cytokine signaling pathways which regulate immunity, inflammation, hematopoiesis, growth, and development. The recent discovery of JAK2-activating mutations as a causal event in the majority of patients with Philadelphia chromosome negative (Ph-) myeloproliferative disorders (MPDs) prompted many pharmaceutical companies to develop JAK2-selective inhibitors for the treatment of MPDs. JAK2 inhibitors effectively reduce JAK2-driven phosphorylation of signal transducer and activator of transcription 5, and cell proliferation and cell survival in JAK2-activated cells in vitro and in vivo. Most inhibitors are currently being evaluated in patients with one form of MPD, myelofibrosis. Patients treated with these inhibitors experienced a rapid reduction of splenomegaly, significant improvement of constitutional symptoms, and increased daily activity with few adverse events. A partial reduction of JAK2V617F disease burden during the treatment with JAK2 inhibitors was also observed. The inhibitors appear to have a therapeutic benefit in the treatment of these disorders. The results of ongoing clinical trials will allow further evaluation of clinical benefits and safety of these compounds. In this review, the authors summarize the status of JAK2 inhibitors in development and discuss their benefits and challenges.

Detection of the JAK2V617F mutation in patients with slightly elevated platelets or hemoglobin without a secondary cause

Recently, an activating somatic mutation of Janus kinase 2 (JAK2V617F) was identified in the myeloproliferative disorders (MPDs). In this study, we investigated the occurrence of JAK2V617F in patients with slightly elevated platelets or hemoglobin without a secondary cause, who did not meet the criteria of polycythemia vera or essential thrombocythemia. Six out of 18 patients (33%) were positive for the JAK2 mutation, and five of these six patients had a history of thrombosis. These findings suggest that apart from thrombocytosis/erythrocytosis, other mechanisms exist that cause thrombosis, and more patients with a latent form of MPD are likely to exist. Future studies will have to elucidate how to treat these patients.

Neutrophils with ring-shaped nuclei in chronic neutrophilic leukemia.

A significant incidence of neutrophils with ring-shaped nuclei was observed in all of four patients with chronic neutrophilic leukemia. The present data may give further support for the view that chronic neutrophilic leukemia is not a reactive disorder but a rare form of myeloproliferative disorder. It seems possible that this phenomenon can be used as a marker for abnormal granulopoiesis in human diseases.

AGNOGENIC MYELOFIBROSIS IN CHILDREN

The case presented here is an 18‐month‐old female infant with agnogenic myelofibrosis. Clinically, this case was characterized by pancytopenia, bepatosplenomegaly, and rapidly fatal course, without response to steroids or other chemotherapy. Bone marrow biopsy and postmortem examination, revealed myeloid metaplasia of the liver, spleen, and lymph nodes, and conspicuous proliferation of immature cells, presumably of reticulum cells or precursors of hematopoietic cell lines, associated with prominent proliferation of reticular fibrous tissue. These morphologic features corresponded with those of agnogenic myelofibrosis, classified as a form of myeloproliferative disorder. A review of 15 cases of myelofibrosis in children collected from the literature showed a mean age of 2 years and 9 months with most cases being less than 2 years of age. There was a distinct female preponderance, while male infants with myelofibrosis were associated with Down's syndrome or C monosomy. The mean survival waa 6.7 months. Approximately 25 cases of myeloflbrosis have been reported in the English literature, while only 5 cases have been described in Japan.