BET Bromodomain Inhibition as a Therapeutic Strategy to Target c-Myc

SummaryMYC contributes to the pathogenesis of a majority of human cancers, yet strategies to modulate the function of the c-Myc oncoprotein do not exist. Toward this objective, we have targeted MYC transcription by interfering with chromatin-dependent signal transduction to RNA polymerase, specifically by inhibiting the acetyl-lysine recognition domains (bromodomains) of putative coactivator proteins implicated in transcriptional initiation and elongation. Using a selective small-molecule bromodomain inhibitor, JQ1, we identify BET bromodomain proteins as regulatory factors for c-Myc. BET inhibition by JQ1 downregulates MYC transcription, followed by genome-wide downregulation of Myc-dependent target genes. In experimental models of multiple myeloma, a Myc-dependent hematologic malignancy, JQ1 produces a potent antiproliferative effect associated with cell-cycle arrest and cellular senescence. Efficacy of JQ1 in three murine models of multiple myeloma establishes the therapeutic rationale for BET bromodomain inhibition in this disease and other malignancies characterized by pathologic activation of c-Myc.PaperFlic

The Society for Immunotherapy of Cancer consensus statement on immunotherapy for the treatment of hematologic malignancies: multiple myeloma, lymphoma, and acute leukemia

Increasing knowledge concerning the biology of hematologic malignancies as well as the role of the immune system in the control of these diseases has led to the development and approval of immunotherapies that are resulting in impressive clinical responses. Therefore, the Society for Immunotherapy of Cancer (SITC) convened a hematologic malignancy Cancer Immunotherapy Guidelines panel consisting of physicians, nurses, patient advocates, and patients to develop consensus recommendations for the clinical application of immunotherapy for patients with multiple myeloma, lymphoma, and acute leukemia. These recommendations were developed following the previously established process based on the Institute of Medicine’s clinical practice guidelines. In doing so, a systematic literature search was performed for high-impact studies from 2004 to 2014 and was supplemented with further literature as identified by the panel. The consensus panel met in December of 2014 with the goal to generate consensus recommendations for the clinical use of immunotherapy in patients with hematologic malignancies. During this meeting, consensus panel voting along with discussion were used to rate and review the strength of the supporting evidence from the literature search. These consensus recommendations focus on issues related to patient selection, toxicity management, clinical endpoints, and the sequencing or combination of therapies. Overall, immunotherapy is rapidly emerging as an effective therapeutic strategy for the management of hematologic malignances. Evidence-based consensus recommendations for its clinical application are provided and will be updated as the field evolves

Review of Multiple Myeloma Genetics including Effects on Prognosis, Response to Treatment, and Diagnostic Workup

Multiple myeloma is a disorder of the monoclonal plasma cells and is the second most common hematologic malignancy. Despite improvements in survival with newer treatment regimens, multiple myeloma remains an incurable disease and most patients experience multiple relapses. Multiple myeloma disease initiation and progression are highly dependent on complex genetic aberrations. This review will summarize the current knowledge of these genetic aberrations, how they affect prognosis and the response to treatment, and review sensitive molecular techniques for multiple myeloma workup, with the ultimate goal of detecting myeloma progression early, allowing for timely treatment initiation

The Mutational and Signaling Landscape of Multiple Myeloma Varies Dependent upon Translocation Cyclin D (TC) Subgroup

Abstract Introduction The spectrum and frequency of mutations in newly diagnosed and relapsed MM has been reported and exhibits a pattern which is distinct from other peripheral lymphoid disorders. A number of data sources have suggested that MM is not a single disease, but rather a collection of molecularly diverse entities which present as malignancies of plasma cells with different clinical courses and response to therapy. To test this hypothesis we examined the spectrum of common mutations and their associations with gene expression in etiological subgroups defined by a simplified TC classification based on translocation subgroup and the deregulation of a D group cyclin. Materials and methods We examined a set of gene expression data from 907 newly diagnosed MM patients and classified them according to an updated TC model. An additional set of 482 cases underwent both sequencing by the FoundationOne Heme targeted panel and gene expression profiling. Mutational data were analyzed for significant associations with gene expression data within five primary TC subgroups: D1, D2, CCND (translocated 11q13 or 6p21), MMSET, and MAF. Results Gene expression signatures of GEP70 risk status, chromosomal aberrations [1q+, 1p-, 13q-, 17p-, HRD], proliferation index, NF-kB activation, and BCL2/MCL1 ratio were not distributed evenly across the TC subgroups, consistent with distinct biological differences amongst groups. Having noted differential expression patterns between subgroups, we hypothesized that distinct patterns of mutation may also exist across TC subgroups. Mutations in RB1 and CDKN2C, seen primarily in the D2 and MMSET subgroups, were mutually exclusive yet both associated with increased proliferation and HR status. Thus two paths to extreme proliferation emerge through either ahomozygous deletion of CDKN2C (with low expression of CDKN2C) or an RB1 alteration (with high expression of CDKN2C). Mutations in KRAS, NRAS, and BRAF were not evenly distributed across subgroups and were significantly inversely associated with an NF-kB signature. RRAS2 was also significantly inversely associated with MAPK mutations in the D1 and D2 subgroups, while genes encoding sprouty-related proteins, SPRED1 and SPRED2, were positively associated with MAPK mutations in the CCND-11q13 subgroup. Overall, MAPK mutations were most significantly associated with elevated expression of DKK1, a known Wnt antagonist, and DUSP6, a known inhibitor of the pathway. These gene expression patterns were primarily localized in the D1, D2, and CCND-11q13 subgroups. In contrast, the MMSET and MAF subgroups had a unique patterns of expression not seen in the D1, D2, or CCND subgroups. A gene set enrichment analysis showed that the DNA replication and cell cycle pathways were significantly enriched in the MMSET and MAF subgroups in the presence of MAPK pathway mutations. Within the MMSET subgroup, MAPK mutations were positively associated with GEP70 HR, proliferation index, and membership of the UAMS-PR subtype, while being negatively associated with FGFR3 expression. This result indicates that the reliance on FGFR3 signaling as an oncogenic driver is lost in the presence of a MAPK activating mutation. Conclusions In MM proliferative signals are delivered via the RAS and NF-kB pathways and activation of these two pathways appears to offer mutually exclusive pathways to disease progression since the majority of cases exhibit a reciprocal relationship between these two signaling pathways. The MMSET and MAF subgroups lack a strong association between NF-kB and MAPK signaling pathways, which may indicate that their initiating translocation event and subsequent genetic patterns provide a unique background in which MAPK alterations accelerate progression. As mutational interactions are differential across TC subgroups, we propose a comprehensive approach to MM classification that includes the etiologic designation by simplified TC subgroups and the subsequent use of genetic and biological markers characteristic of acquired features associated with disease progression, such as MAPK or NF-kB activation. Distinct patterns of RNA expression are associated with DNA mutations in myeloma when contextualized by etiologic subgroups. This indicates that the cellular background in which a mutation occurs has a distinct impact on downstream expression patterns-this observation is particularly relevant to the MMSET and MAF subgroups. Disclosures Pawlyn: Celgene: Consultancy, Honoraria, Other: Travel Support; Takeda Oncology: Consultancy. Morgan:Univ of AR for Medical Sciences: Employment; Takeda: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Bristol Meyers: Consultancy, Honoraria; Janssen: Research Funding