A comprehensive case study on successful multimodal therapy in philadelphia chromosome-positive acute myeloid leukemia with NPM1 and IDH2 mutations.

A 67-year-old female came to Tampa General Hospital with Philadelphia chromosome-positive (Ph+) acute myeloid leukemia (AML) featuring an intriguing combination of mutations, including NPM1 and IDH2 mutations. Novel combination therapy with azacitidine, venetoclax and ponatinib allowed her to successfully achieve a complete response (CR) and undergo an allogeneic hematopoietic stem cell transplant (HSCT). This case report provides an overview of her clinical course, emphasizing the significance of integrated therapy and the challenges associated with balancing treatment for AML. It also underscores the importance of a multidisciplinary approach and careful monitoring of patients with complex hematologic conditions.

Long-term follow up of the combination of ofatumumab, high-dose methylprednisolone, and lenalidomide for untreated chronic lymphocytic leukemia with biomarker analysis.

BACKGROUND: Advancements in frontline therapy and chemotherapy-sparing treatments in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) have altered the treatment algorithms of this disease. We present a frontline alternative for treatment- naïve (TN) CLL/SLL patients. METHODS: This was a single-center, phase 2 study of high-dose methylprednisolone (HDMP) and ofatumumab with lenalidomide and ofatumumab consolidative therapy for all comers with TN CLL/SLL. Treatment was continued until disease progression or intolerable side effects. Patients were assessed for response per iwCLL 2008 criteria after completing cycles 3 and 12. RESULTS: Forty-five patients were enrolled (median age, 62.6 years). High-risk features included del17p (18%), Del11q (22%), and unmutated IGHV gene (76%). Median treatment duration was 32·2 (2·7-75·9) months. Thirty-six patients discontinued treatment due to disease progression (22%), adverse events (40%), allogeneic hematopoietic cell transplantation (allo-HCT) (7%), consent withdrawal (4%), and secondary malignancies (7%). The best overall and complete response rates were 96& and 29% respectively. At median follow-up of 61·7 (5·6-84·9) months, 9 patients remained on treatment. Median progression-free survival was 54·4 (2·9-77·6) months. Three patients underwent allo-HCT after a median of 3 (3-4) treatment cycles. Treatment was well tolerated, with a grade 3/4 infusion reaction in one patient. The most common grade 3/4 hematological adverse event was neutropenia (69%). Four patients had grade 3/4 infections. No grade 3/4 tumor flares, tumor lysis syndrome, or thrombosis were observed. CONCLUSION: The combination of ofatumumab, HDMP, and lenalidomide was effective and relatively well tolerated in treatment-naive CLL/SLL. Its role in the frontline setting remains unclear given the current available and effective treatment options. FUNDING: The funders had no role in the study.

Response and resistance to CDK12 inhibition in aggressive B-cell lymphomas.

Despite significant progress in the treatment of patients with diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL), the prognosis of patients with relapsed disease remains poor due to the emergence of drug resistance and subsequent disease progression. Identification of novel targets and therapeutic strategies for these diseases represents an urgent need. Here, we report that both MCL and DLBCL are exquisitely sensitive to transcription-targeting drugs, in particular THZ531, a covalent inhibitor of cyclin-dependent kinase 12 (CDK12). By implementing pharmacogenomics and a cell-based drug screen, we found that THZ531 leads to inhibition of oncogenic transcriptional programs, especially the DNA damage response pathway, MYC target genes and the mTOR-4EBP1-MCL-1 axis, contributing to dramatic lymphoma suppression in vitro. We also identified de novo and established acquired THZ531-resistant lymphoma cells conferred by over-activation of the MEK-ERK and PI3K-AKT-mTOR pathways and upregulation of multidrug resistance-1 (MDR1) protein. Of note, EZH2 inhibitors reversed resistance to THZ531 by competitive inhibition of MDR1 and, in combination with THZ531, synergistically inhibited MCL and DLBCL growth in vitro. Our study indicates that CDK12 inhibitors, alone or together with EZH2 inhibitors, offer promise as novel effective approaches for difficult-to-treat DLBCL and MCL.

Plasma cell dependence on histone/protein deacetylase 11 reveals a therapeutic target in multiple myeloma.

The clinical utility of histone/protein deacetylase (HDAC) inhibitors in combinatorial regimens with proteasome inhibitors for patients with relapsed and refractory multiple myeloma (MM) is often limited by excessive toxicity due to HDAC inhibitor promiscuity with multiple HDACs. Therefore, more selective inhibition minimizing off-target toxicity may increase the clinical effectiveness of HDAC inhibitors. We demonstrated that plasma cell development and survival are dependent upon HDAC11, suggesting this enzyme is a promising therapeutic target in MM. Mice lacking HDAC11 exhibited markedly decreased plasma cell numbers. Accordingly, in vitro plasma cell differentiation was arrested in B cells lacking functional HDAC11. Mechanistically, we showed that HDAC11 is involved in the deacetylation of IRF4 at lysine103. Further, targeting HDAC11 led to IRF4 hyperacetylation, resulting in impaired IRF4 nuclear localization and target promoter binding. Importantly, transient HDAC11 knockdown or treatment with elevenostat, an HDAC11-selective inhibitor, induced cell death in MM cell lines. Elevenostat produced similar anti-MM activity in vivo, improving survival among mice inoculated with 5TGM1 MM cells. Elevenostat demonstrated nanomolar ex vivo activity in 34 MM patient specimens and synergistic activity when combined with bortezomib. Collectively, our data indicated that HDAC11 regulates an essential pathway in plasma cell biology establishing its potential as an emerging theraputic vulnerability in MM.

HDAC11 regulates expression of C/EBPß and immunosuppressive molecules in myeloid-derived suppressor cells.

Myeloid-derived suppressor cells (MDSCs) constitute a heterogeneous population of immature myeloid cells derived from bone marrow and negatively regulate both innate and adaptive immunity in the tumor microenvironment. Previously we have demonstrated that MDSCs lacking histone deacetylase 11 (HDAC11) displayed an increased suppressive activity against CD8+ T-cells. However, the mechanisms of HDAC11 that contribute to the suppressive function of MDSCs remain unclear. Here, we show that arginase activity and NO production is significantly higher in HDAC11 knockout MDSCs when compared with wild-type (WT) controls. In the absence of HDAC11, elevated arginase level and enzymatic activity were observed preferentially in the tumor-infiltrated granulocytic MDSCs, whereas iNOS expression and NO production were increased in the tumor-infiltrated monocytic MDSCs. Of note and for the first time, we demonstrated an association between the elevated expression of immunosuppressive molecules with up-regulation of the transcription factor C/EBPß in MDSCs lacking HDAC11. Interestingly, the highest expression of C/EBPß was observed among CD11b+ Gr-1+ MDSCs isolated from tumor-bearing mice. The additional demonstration that HDAC11 is recruited to the promoter region of C/EBPß in WT MDSCs suggests a novel molecular mechanism by which HDAC11 influence the expression of immunosuppressive molecules in MDSCs through regulation of C/EBPß gene expression.

Transcriptional programming drives Ibrutinib-resistance evolution in mantle cell lymphoma.

Ibrutinib, a bruton's tyrosine kinase (BTK) inhibitor, provokes robust clinical responses in aggressive mantle cell lymphoma (MCL), yet many patients relapse with lethal Ibrutinib-resistant (IR) disease. Here, using genomic, chemical proteomic, and drug screen profiling, we report that enhancer remodeling-mediated transcriptional activation and adaptive signaling changes drive the aggressive phenotypes of IR. Accordingly, IR MCL cells are vulnerable to inhibitors of the transcriptional machinery and especially so to inhibitors of cyclin-dependent kinase 9 (CDK9), the catalytic subunit of the positive transcription elongation factor b (P-TEFb) of RNA polymerase II (RNAPII). Further, CDK9 inhibition disables reprogrammed signaling circuits and prevents the emergence of IR in MCL. Finally, and importantly, we find that a robust and facile ex vivo image-based functional drug screening platform can predict clinical therapeutic responses of IR MCL and identify vulnerabilities that can be targeted to disable the evolution of IR.

Liver prometastatic reaction: Stimulating factors and responsive cancer phenotypes.

Cancer is first a localized tissue disorder, whose soluble and exosomal molecules and invasive cells induce a host response providing the stromal components of the primary tumor microenvironment (TME). Once the TME is developed, cancer-derived molecules and cells can more efficiently spread out and a whole-body response takes place, whose pathophysiological changes may result in a paraneoplastic syndrome. Remote organ-specific prometastatic reactions may also occur at this time, facilitating metastatic activities of circulating tumor cells (CTCs) through premetastatic niche development at targeted organs. However, additional signaling factors from the inter-organ communication network involved in the pathophysiology and comorbidities of cancer patients may also regulate prometastatic reaction-stimulating effects of cancer and non-cancer tissue factors. This article provides a conceptual overview of our ongoing clinical research on the liver prometastatic reaction (LPR) of patients with colorectal cancer (CRC), their portal vein- and hepatic artery-driven LPR-Stimulating Factors (LPR-SF), and their resulting LPR-derived Metastasis-Stimulating Factors (LPR-MSF) acting on liver-invading CRC cells. In addition, we also provide new insights on the molecular subtyping of LPR-responsive cancer phenotypes in patients with CRC and melanoma; and on how to investigate and interpret the prometastatic infrastructure in the real pathophysiological context of patients with cancer undergoing surgical procedures and receiving pharmacological treatments with multiple side effects, including those affecting the LPR, its stimulating factors and responsive cancer phenotypes.

Targeting Macrophages as a Therapeutic Option in Coronavirus Disease 2019.

Immune cells of the monocyte/macrophage lineage are characterized by their diversity, plasticity, and variety of functions. Among them, macrophages play a central role in antiviral responses, tissue repair, and fibrosis. Macrophages can be reprogrammed by environmental cues, thus changing their phenotype during an antiviral immune response as the viral infection progresses. While M1-like macrophages are essential for the initial inflammatory responses, M2-like macrophages are critical for tissue repair after pathogen clearance. Numerous reports have evaluated the detrimental effects that coronaviruses, e.g., HCoV-229E, SARS-CoV, MERS-CoV, and SARS-CoV-2, have on the antiviral immune response and macrophage functions. In this review, we have addressed the breadth of macrophage phenotypes during the antiviral response and provided an overview of macrophage-coronavirus interactions. We also discussed therapeutic approaches to target macrophage-induced complications, currently under evaluation in clinical trials for coronavirus disease 2019 patients. Additionally, we have proposed alternative approaches that target macrophage recruitment, interferon signaling, cytokine storm, pulmonary fibrosis, and hypercoagulability.

HDAC6 Plays a Noncanonical Role in the Regulation of Antitumor Immune Responses, Dissemination, and Invasiveness of Breast Cancer.

Despite the outstanding clinical results of immune checkpoint blockade (ICB) in melanoma and other cancers, clinical trials in breast cancer have reported low responses to these therapies. Current efforts are now focused on improving the treatment efficacy of ICB in breast cancer using new combination designs such as molecularly targeted agents, including histone deacetylase inhibitors (HDACi). These epigenetic drugs have been widely described as potent cytotoxic agents for cancer cells. In this work, we report new noncanonical regulatory properties of ultra-selective HDAC6i over the expression and function of epithelial-mesenchymal transition pathways and the invasiveness potential of breast cancer. These unexplored roles position HDAC6i as attractive options to potentiate ongoing immunotherapeutic approaches. These new functional activities of HDAC6i involved regulation of the E-cadherin/STAT3 axis. Pretreatment of tumors with HDAC6i induced critical changes in the tumor microenvironment, resulting in improved effectiveness of ICB and preventing dissemination of cancer cells to secondary niches. Our results demonstrate for the first time that HDAC6i can both improve ICB antitumor immune responses and diminish the invasiveness of breast cancer with minimal cytotoxic effects, thus departing from the cytotoxicity-centric paradigm previously assigned to HDACi. SIGNIFICANCE: Ultraselective HDAC6 inhibitors can reduce tumor growth and invasiveness of breast cancer by noncanonical mechanisms unrelated to the previously cytotoxic properties attributed to HDAC inhibitors.

A Multi-Institutional Validation of the Prognostic Value of the Neutrophil-to-Lymphocyte Ratio in Patients With Diffuse Large B-Cell Lymphoma: A Study From The Latin American Group of Lymphoproliferative Disorders (GELL).

INTRODUCTION: We aimed at investigating the prognostic role of the neutrophil-to-lymphocyte ratio (NLR) in 2 independent cohorts of Latin American patients with diffuse large B-cell lymphoma (DLBCL) treated with chemoimmunotherapy. PATIENTS AND METHODS: The learning cohort was composed of 274 patients and the validation cohort of 323 patients, for a total of 597 patients. An optimal NLR cutoff ≥ 4 was determined using receiver operating characteristic analysis. RESULTS: In multivariate models, NLR ≥ 4 was independently associated with lower odds for complete response to chemoimmunotherapy in the learning (odds ratio, 0.46; P = .006) and the validation cohort (odds ratio, 0.49; P = .01), and independently associated with worse survival in the learning (hazard ratio, 1.55; P = .04) and the validation cohort (hazard ratio, 1.80; P = .003). CONCLUSIONS: The adverse prognostic value of NLR ≥ 4 was independent of the International Prognostic Index and the National Comprehensive Cancer Network-International Prognostic Index score. Based on the results of this multi-institutional study, NLR ≥ 4 emerges as an adverse prognostic factor in Latin American patients with DLBCL treated with chemoimmunotherapy.

HDAC11 deficiency disrupts oncogene-induced hematopoiesis in myeloproliferative neoplasms.

Protein acetylation is an important contributor to cancer initiation. Histone deacetylase 6 (HDAC6) controls JAK2 translation and protein stability and has been implicated in JAK2-driven diseases best exemplified by myeloproliferative neoplasms (MPNs). By using novel classes of highly selective HDAC inhibitors and genetically deficient mouse models, we discovered that HDAC11 rather than HDAC6 is necessary for the proliferation and survival of oncogenic JAK2-driven MPN cells and patient samples. Notably, HDAC11 is variably expressed in primitive stem cells and is expressed largely upon lineage commitment. Although Hdac11is dispensable for normal homeostatic hematopoietic stem and progenitor cell differentiation based on chimeric bone marrow reconstitution, Hdac11 deficiency significantly reduced the abnormal megakaryocyte population, improved splenic architecture, reduced fibrosis, and increased survival in the MPLW515L-MPN mouse model during primary and secondary transplantation. Therefore, inhibitors of HDAC11 are an attractive therapy for treating patients with MPN. Although JAK2 inhibitor therapy provides substantial clinical benefit in MPN patients, the identification of alternative therapeutic targets is needed to reverse MPN pathogenesis and control malignant hematopoiesis. This study establishes HDAC11 as a unique type of target molecule that has therapeutic potential in MPN.

Secretome profiling identifies neuron-derived neurotrophic factor as a tumor-suppressive factor in lung cancer.

Clinical and preclinical studies show tissue-specific differences in tumorigenesis. Tissue specificity is controlled by differential gene expression. We prioritized genes that encode secreted proteins according to their preferential expression in normal lungs to identify candidates associated with lung cancer. Indeed, most of the lung-enriched genes identified in our analysis have known or suspected roles in lung cancer. We focused on the gene encoding neuron-derived neurotrophic factor (NDNF), which had not yet been associated with lung cancer. We determined that NDNF was preferentially expressed in the normal adult lung and that its expression was decreased in human lung adenocarcinoma and a mouse model of this cancer. Higher expression of NDNF was associated with better clinical outcome of patients with lung adenocarcinoma. Purified NDNF inhibited proliferation of lung cancer cells, whereas silencing NDNF promoted tumor cell growth in culture and in xenograft models. We determined that NDNF is downregulated through DNA hypermethylation near CpG island shores in human lung adenocarcinoma. Furthermore, the lung cancer-related DNA hypermethylation sites corresponded to the methylation sites that occurred in tissues with low NDNF expression. Thus, by analyzing the tissue-specific secretome, we identified a tumor-suppressive factor, NDNF, which is associated with patient outcomes in lung adenocarcinoma.

High Red Cell Distribution Width is an Adverse Predictive and Prognostic Factor in Patients With Diffuse Large B-Cell Lymphoma Treated With Chemoimmunotherapy.

INTRODUCTION: The red blood cell distribution width (RDW) is an easy-to-obtain laboratory value that has emerged as a potential prognostic factor in solid and hematologic malignancies. PATIENTS AND METHODS: We evaluated 121 patients with de novo diffuse large B-cell lymphoma (DLBCL) treated with standard chemoimmunotherapy at our institution between 2010 and 2012. We categorized patients with high RDW (> 14.6%) and normal RDW (11.6%-14.6%). We fitted multivariate regression models for complete response (CR) and overall survival (OS). RESULTS: Patients with high RDW were less likely to achieve CR to chemoimmunotherapy than patients with normal RDW (48% vs. 83%; P < .001). The 5-year OS rate for patients with high RDW was lower than in patients with normal RDW (51% vs. 79%; P = .001). In multivariate regression models, high RDW was independently associated with lower odds of achieving CR (odds ratio, 0.32; 95% confidence interval [CI], 0.12-0.83; P = .02) and with higher risk of death from any cause (hazard ratio [HR], 2.04; 95% CI, 1.03-4.02; P = .04) than normal RDW in patients with DLBCL treated with chemoimmunotherapy. High RDW remained an independent adverse factor for OS after adjustment for the International Prognostic Index and the National Comprehensive Cancer Network-International Prognostic Index scores with HR 2.20 (95% CI, 1.12-4.31; P = .02) and HR 2.67 (95% CI 1.28-5.59; P = .009), respectively. CONCLUSION: High RDW appears to be an adverse predictive and prognostic factor in patients with de novo DLBCL treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone).

Targeting MYC activity in double-hit lymphoma with MYC and BCL2 and/or BCL6 rearrangements with epigenetic bromodomain inhibitors.

Double/triple-hit lymphomas (DHL/THL) account for 5-10% of diffuse large B cell lymphoma (DLBCL) with rearrangement of MYC and BCL2 and/or BCL6 resulting in MYC overexpression. Despite the poor prognosis of DHL, R-CHOP chemotherapy remains the treatment backbone and new targeted therapy is needed. We performed comprehensive cytogenetic studies/fluorescence in situ hybridization on DLBCL and Burkitt lymphoma cell lines (n = 11) to identify the DHL/THL DLBCL in vitro model. We identified MYC/IG in Raji and Ramos (single hit); MYC/IG-BCL2 (DHL) in DOHH2, OCI-LY1, SUDHL2, and OCI-LY10; MYC/IG-BCL2/BCL6 (THL) in VAL; and no MYC rearrangement in U2932 and HBL1 (WT-MYC). Targeting MYC in the DHL/THL DLBCLs through bromodomain extra-terminal inhibitors (BETi) (JQ1, I-BET, and OTX015) significantly (p < 0.05) reduced proliferation, similar to WT-MYC cells, accompanied by decreased MYC but not BCL2 protein. Moreover, BETi suppressed MYC transcription and decreased BRD4 binding to MYC promoter in DHL cells. CD47 and PD-L1 are immunoregulatory molecules often expressed on tumors and regulated by MYC. High levels of surface CD47 but not surface PD-L1 was observed in DHL/THL, which was reduced by JQ1 treatment. BETi in combination with Pan-HDAC inhibitor had a limited effect on survival of DHL/THL, while combination of BETi and BCL2 inhibitor (ABT-199) had a significant (p < 0.005) inhibitory effect on survival followed by BCL-XL inhibition. Overall, the data suggests that MYC-expressing DLBCLs are probably addicted to the MYC-oncogenic effect regardless of MYC rearrangements. In summary, we identified an in vitro model for DHL/THL DLBCLs and provide evidence for the therapeutic potential of BET inhibitor alone or in combination with BCL2 inhibitor.

BCL2 Amplicon Loss and Transcriptional Remodeling Drives ABT-199 Resistance in B Cell Lymphoma Models.

Drug-tolerant "persister" tumor cells underlie emergence of drug-resistant clones and contribute to relapse and disease progression. Here we report that resistance to the BCL-2 targeting drug ABT-199 in models of mantle cell lymphoma and double-hit lymphoma evolves from outgrowth of persister clones displaying loss of 18q21 amplicons that harbor BCL2. Further, persister status is generated via adaptive super-enhancer remodeling that reprograms transcription and offers opportunities for overcoming ABT-199 resistance. Notably, pharmacoproteomic and pharmacogenomic screens revealed that persisters are vulnerable to inhibition of the transcriptional machinery and especially to inhibition of cyclin-dependent kinase 7 (CDK7), which is essential for the transcriptional reprogramming that drives and sustains ABT-199 resistance. Thus, transcription-targeting agents offer new approaches to disable drug resistance in B-cell lymphomas.

Recent advances and future directions in mantle cell lymphoma research: report of the 2018 mantle cell lymphoma consortium workshop.

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma characterized by the t(11;14) chromosomal translocation. This translocation most often results in overexpression of cyclin D1. MCL is clinically heterogeneous, outcomes are generally poor, and no standard treatment has been established. The recent approvals of ibrutinib and acalabrutinib have provided an additional therapeutic option; however, resistance has emerged as a significant issue and presents the need for more detailed studies of resistance mechanisms. Recent clinical trials have provided new perspectives on the relative efficacy and safety of various approaches for both transplant-eligible and transplant-ineligible patients. Multiple novel strategies are being evaluated in the treatment of MCL, including both targeted agents and cellular immunotherapies. At the Lymphoma Research Foundation's 13th MCL Workshop, researchers gathered to discuss research findings, clinical trial results, and future directions related to MCL, its biology, and its treatment. This report, which includes a summary of each presentation, aims to review recent findings in MCL research and highlight potential areas for future study.

Silencing of HDAC6 as a therapeutic target in chronic lymphocytic leukemia.

Although the treatment paradigm for chronic lymphocytic leukemia (CLL) is rapidly changing, the disease remains incurable, except with allogeneic bone marrow transplantation, and resistance, relapsed disease, and partial responses persist as significant challenges. Recent studies have uncovered roles for epigenetic modification in the regulation of mechanisms contributing to malignant progression of CLL B cells. However, the extent to which epigenetic modifiers can be targeted for therapeutic benefit in CLL patients remains poorly explored. We report for the first time that expression of epigenetic modifier histone deacetylase 6 (HDAC6) is upregulated in CLL patient samples, cell lines, and euTCL1 transgenic mouse models compared with HDAC6 in normal controls. Genetic silencing of HDAC6 conferred survival benefit in euTCL1 mice. Administration of isoform-specific HDAC6 inhibitor ACY738 in the euTCL1 aging and adoptive transfer models deterred proliferation of CLL B cells, delayed disease onset via disruption of B-cell receptor signaling, and sensitized CLL B cells to apoptosis. Furthermore, coadministration of ACY738 and ibrutinib displayed synergistic cell kill against CLL cell lines and improved overall survival compared with either single agent in vivo. These results demonstrate for the first time the therapeutic efficacy of selective HDAC6 inhibition in preclinical CLL models and suggest a rationale for the clinical development of HDAC6 inhibitors for CLL treatment, either alone or in combination with Bruton tyrosine kinase inhibition.

Loss of HDAC11 ameliorates clinical symptoms in a multiple sclerosis mouse model.

Multiple sclerosis (MS) is a chronic, immune-mediated, demyelinating disease of the central nervous system (CNS). There is no known cure for MS, and currently available drugs for managing this disease are only effective early on and have many adverse side effects. Results from recent studies suggest that histone deacetylase (HDAC) inhibitors may be useful for the treatment of autoimmune and inflammatory diseases such as MS. However, the underlying mechanisms by which HDACs influence immune-mediated diseases such as MS are unclear. More importantly, the question of which specific HDAC(s) are suitable drug targets for the potential treatment of MS remains unanswered. Here, we investigate the functional role of HDAC11 in experimental autoimmune encephalomyelitis, a mouse model for MS. Our results indicate that the loss of HDAC11 in KO mice significantly reduces clinical severity and demyelination of the spinal cord in the post-acute phase of experimental autoimmune encephalomyelitis. The absence of HDAC11 leads to reduced immune cell infiltration into the CNS and decreased monocytes and myeloid DCs in the chronic progressive phase of the disease. Mechanistically, HDAC11 controls the expression of the pro-inflammatory chemokine C-C motif ligand 2 (CCL2) gene by enabling the binding of PU.1 transcription factor to the CCL2 promoter. Our results reveal a novel pathophysiological function for HDAC11 in CNS demyelinating diseases, and warrant further investigations into the potential use of HDAC11-specific inhibitors for the treatment of chronic progressive MS.

PLK1 stabilizes a MYC-dependent kinase network in aggressive B cell lymphomas.

Concordant activation of MYC and BCL-2 oncoproteins in double-hit lymphoma (DHL) results in aggressive disease that is refractory to treatment. By integrating activity-based proteomic profiling and drug screens, polo-like kinase-1 (PLK1) was identified as an essential regulator of the MYC-dependent kinome in DHL. Notably, PLK1 was expressed at high levels in DHL, correlated with MYC expression, and connoted poor outcome. Further, PLK1 signaling augmented MYC protein stability, and in turn, MYC directly induced PLK1 transcription, establishing a feed-forward MYC-PLK1 circuit in DHL. Finally, inhibition of PLK1 triggered degradation of MYC and of the antiapoptotic protein MCL-1, and PLK1 inhibitors showed synergy with BCL-2 antagonists in blocking DHL cell growth, survival, and tumorigenicity, supporting clinical targeting of PLK1 in DHL.