Medical Biology - Research Publications

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Author: Ng, Ashley × Author: Seymour, John × Start date: 2000 ×

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    JAK2 is dispensable for maintenance of JAK2 mutant B-cell acute lymphoblastic leukemias
    Kim, S-K ; Knight, DA ; Jones, LR ; Vervoort, S ; Ng, AP ; Seymour, JF ; Bradner, JE ; Waibel, M ; Kats, L ; Johnstone, RW (COLD SPRING HARBOR LAB PRESS, PUBLICATIONS DEPT, 2018-06-01)
    Activating JAK2 point mutations are implicated in the pathogenesis of myeloid and lymphoid malignancies, including high-risk B-cell acute lymphoblastic leukemia (B-ALL). In preclinical studies, treatment of JAK2 mutant leukemias with type I JAK2 inhibitors (e.g., Food and Drug Administration [FDA]-approved ruxolitinib) provided limited single-agent responses, possibly due to paradoxical JAK2Y1007/1008 hyperphosphorylation induced by these agents. To determine the importance of mutant JAK2 in B-ALL initiation and maintenance, we developed unique genetically engineered mouse models of B-ALL driven by overexpressed Crlf2 and mutant Jak2, recapitulating the genetic aberrations found in human B-ALL. While expression of mutant Jak2 was necessary for leukemia induction, neither its continued expression nor enzymatic activity was required to maintain leukemia survival and rapid proliferation. CRLF2/JAK2 mutant B-ALLs with sustained depletion or pharmacological inhibition of JAK2 exhibited enhanced expression of c-Myc and prominent up-regulation of c-Myc target genes. Combined indirect targeting of c-Myc using the BET bromodomain inhibitor JQ1 and direct targeting of JAK2 with ruxolitinib potently killed JAK2 mutant B-ALLs.
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    Cytomegalovirus DNAemia and disease: natural history and management in settings other than allogeneic stem cell transplantation
    Ng, Ashley P. ; WORTH, LEON ; Chen, Luke ; Seymour, John F. ; Prince, H. Miles ; SLAVIN, MONICA ; Thursky, Karin (Ferrata Storti Foundation, 2005-12)
    Background and Objectives. Despite increasing intensity and profound immunosuppressionassociated with newer therapies for hematologic malignancies, little information exists regarding cytomegalovirus (CMV) reactivation in settings other than allogeneic stem cell transplantation (SCT).Design and Methods. We reviewed the epidemiology of CMV disease in patients who were CMV polymerase chain reaction (PCR) positive during treatment for hematologic malignancies without allogeneic SCT from June 1999 to June 2004.Results. Thirty-six patients with CMV reactivation were identified. Of these, 92% were undergoing investigation for fever. Fifteen patients with CMV DNAemia were treatedwith ganciclovir without CMV disease developing. Notably, 20 patients with untreated CMV DNAemia did not develop CMV disease during a median follow-up of 3.5 (1-19)months. The highest rates of reactivation were observed with HyperCVAD (7.8%) and alemtuzumab (50%).Interpretation and Conclusions. We recommend that screening for CMV DNAemia be instituted and pre-emptive therapy contemplated for asymptomatic CMV reactivationonly in patients receiving alemtuzumab therapy, but not routinely for other patients outside the allogeneic SCT setting. Indeed for such patients, detection of isolated CMV DNAemia does not imply the need for immediate therapy and future studies are needed to validate PCR detection of CMV DNA and CMV DNA titers as predictors for CMV disease.