Glucocorticoids and selumetinib are highly synergistic in RAS pathway-mutated childhood acute lymphoblastic leukemia through upregulation of BIM

New drugs are needed for relapsed acute lymphoblastic leukemia and preclinical evaluation of the MEK inhibitor, selumetinib, has shown excellent activity in those with RAS pathway mutations. The proapoptotic protein, BIM is pivotal in the induction of cell death by both selumetinib and glucocorticoids, suggesting the potential for synergy. Thus, combination indices for dexamethasone and selumetinib were determined in RAS pathway mutated acute lymphoblastic leukemia primagraft cells in vitro and were indicative of strong synergism (CI <0.2; n=5). Associated pharmacodynamic assays were consistent with the hypothesis that the drug combination enhanced BIM upregulation over single drug alone. Dosing of dexamethasone and selumetinib singly, and in combination in mice engrafted with primary derived RAS pathway mutated leukemia cells, resulted in a marked reduction in spleen size which was significantly greater with the drug combination. Assessment of the central nervous system leukaemia burden showed a significant reduction in drug treated mice, with no detectable leukemia in those treated with the drug combination. These data suggest that a selumetinib-dexamethasone combination may be highly effective in RAS pathway mutated acute lymphoblastic leukemia and an international phase I/II clinical trial of dexamethasone and selumetinib (Seludex trial) is underway for children with multiple relapsed/refractory disease

A randomized clinical trial on the effects of progestin contraception in the genital tract of HIV-infected and uninfected women in Lilongwe, Malawi: Addressing evolving research priorities

Hormonal contraception is central in the prevention of unintended pregnancy; however there are concerns that certain methods may increase the risk of HIV acquisition and transmission. Hormonal contraceptives may modify the genital mucosa in several ways, however the mechanisms are incompletely understood. Few studies have examined genital HIV shedding prospectively before and after initiation of hormonal contraception. The effects of hormonal contraception on genital HIV shedding in the setting of antiretroviral therapy (ART) are also unknown. We designed a pilot clinical trial in which HIV-infected and uninfected women were randomized to either depot medroxyprogesterone acetate (DMPA) injectable or levonorgestrel (LNG) implant in Lilongwe, Malawi. The objectives were to: 1) assess the effect and compare the impact of type of progestin contraception (injectable versus implant) on HIV genital shedding among HIV-infected women, 2) assess the effect and compare the impact of type of progestin contraception on inflammatory/immune markers in the genital tract of both HIV-infected and uninfected women, and 3) assess the interaction of progestin contraception and ART by examining contraceptive efficacy and ART efficacy. An additional study aim was to determine the feasibility and need for a larger study of determinants of HIV transmissibility and acquisition

Adherence to extended postpartum antiretrovirals is associated with decreased breast milk HIV-1 transmission

Estimate association between postpartum antiretroviral adherence and breastmilk HIV-1 transmissio

CREBBP knockdown enhances RAS/RAF/MEK/ERK signaling in Ras pathway mutated acute lymphoblastic leukemia but does not modulate chemotherapeutic response

Relapsed acute lymphoblastic leukemia is the most common cause of cancer-related mortality in young people and new therapeutic strategies are needed to improve outcome. Recent studies have shown that heterozygous inactivating mutations in the histone acetyl transferase, CREBBP, are particularly frequent in relapsed childhood acute lymphoblastic leukemia and associated with a hyperdiploid karyotype and KRAS mutations. To study the functional impact of CREBBP haploinsufficiency in acute lymphoblastic leukemia, RNA interference was used to knock down expression of CREBBP in acute lymphoblastic leukemia cell lines and various primagraft acute lymphoblastic leukemia cells. We demonstrate that attenuation of CREBBP results in reduced acetylation of histone 3 lysine 18, but has no significant impact on cAMP-dependent target gene expression. Impaired induction of glucocorticoid receptor targets was only seen in 1 of 4 CREBBP knockdown models, and there was no significant difference in glucocorticoid-induced apoptosis, sensitivity to other acute lymphoblastic leukemia chemotherapeutics or histone deacetylase inhibitors. Importantly, we show that CREBBP directly acetylates KRAS and that CREBBP knockdown enhances signaling of the RAS/RAF/MEK/ERK pathway in Ras pathway mutated acute lymphoblastic leukemia cells, which are still sensitive to MEK inhibitors. Thus, CREBBP mutations might assist in enhancing oncogenic RAS signaling in acute lymphoblastic leukemia but do not alter response to MEK inhibitors

MMSET deregulation affects cell cycle progression and adhesion regulons in t(4;14) myeloma plasma cells

Background: The recurrent immunoglobulin translocation, t(4;14)(p16;q32) occurs in 15% of multiple myeloma patients and is associated with poor prognosis, through an unknown mechanism. The t(4;14) up-regulates fibroblast growth factor receptor 3 (FGFR3) and multiple myeloma SET domain (MMSET) genes. The involvement of MMSET in the pathogenesis of t(4;14) multiple myeloma and the mechanism or genes deregulated by MMSET upregulation are still unclear.Design and Methods: The expression of MMSET was analyzed using a novel antibody. The involvement of MMSET in t(4;14) myelomagenesis was assessed by small interfering RNA mediated knockdown combined with several biological assays. In addition, the differential gene expression of MMSET-induced knockdown was analyzed with expression microarrays. MMSET gene targets in primary patient material was analyzed by expression microarrays.Results: We found that MMSET isoforms are expressed in multiple myeloma cell lines, being exclusively up-regulated in t(4;14)-positive cells. Suppression of MMSET expression affected cell proliferation by both decreasing cell viability and cell cycle progression of cells with the t(4;14) translocation. These findings were associated with reduced expression of genes involved in the regulation of cell cycle progression (e.g. CCND2, CCNG1, BRCA1, AURKA and CHEK1), apoptosis (CASP1, CASP4 and FOXO3A) and cell adhesion (ADAM9 and DSG2). Furthermore, we identified genes involved in the latter processes that were differentially expressed in t(4;14) multiple myeloma patient samples.Conclusions: In conclusion, dysregulation of MMSET affects the expression of several genes involved in the regulation of cell cycle progression, cell adhesion and survival

A comprehensive analysis of the CDKN2A gene in childhood acute lymphoblastic leukaemia reveals genomic deletion, copy number neutral loss of heterozygosity and association with specific cytogenetic subgroups.

Inactivation of the tumor suppressor gene, CDKN2A, can occur by deletion, methylation, or mutation. We assessed the principal mode of inactivation in childhood acute lymphoblastic leukemia (ALL) and frequency in biologically relevant subgroups. Mutation or methylation was rare, whereas genomic deletion occurred in 21% of B-cell precursor ALL and 50% of T-ALL patients. Single nucleotide polymorphism arrays revealed copy number neutral (CNN) loss of heterozygosity (LOH) in 8% of patients. Array-based comparative genomic hybridization demonstrated that the mean size of deletions was 14.8 Mb and biallelic deletions composed a large and small deletion (mean sizes, 23.3 Mb and 1.4 Mb). Among 86 patients, only 2 small deletions were below the resolution of detection by fluorescence in situ hybridization. Patients with high hyperdiploidy, ETV6-RUNX1, or 11q23/MLL rearrangements had low rates of deletion (11%, 15%, 13%), whereas patients with t(9;22), t(1;19), TLX3, or TLX1 rearrangements had higher frequencies (61%, 42%, 78%, and 89%). In conclusion, CDKN2A deletion is a significant secondary abnormality in childhood ALL strongly correlated with phenotype and genotype. The variation in the incidence of CDKN2A deletions by cytogenetic subgroup may explain its inconsistent association with outcome. CNN LOH without apparent CDKN2A inactivation suggests the presence of other relevant genes in this regio