abt-199 and Disease-Models--Animal

BCL-2 is an antiapoptotic protein that plays a critical role acute and chronic leukemias. Venetoclax is an orally selective BCL-2 inhibitor and BH3 mimetic approved in chronic lymphocytic leukemia and in combination with low dose cytarabine or hypomethylating agent in acute myeloid leukemia for the treatment of patients unfit for intensive chemotherapy. This article reviews the biology of BCL-2, focusing on its relationship to the myeloid microenvironment, and discusses the rationale for BCL-2 inhibition in myelodysplastic syndrome (MDS). Clinical trials testing venetoclax in MDS patients are under way. Potential biomarkers for clinical response to BCL-2 inhibition are discussed. Therapeutic opportunities for venetoclax in the therapeutic landscape of MDS are explored.

Topics: Animals; Antineoplastic Agents; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Clinical Studies as Topic; Disease Management; Disease Models, Animal; Disease Susceptibility; Drug Evaluation, Preclinical; Humans; Leukemia, Myeloid, Acute; Mitochondria; Myelodysplastic Syndromes; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Treatment Outcome

Treatment for myelodysplastic syndromes (MDS) remains insufficient due to clonal heterogeneity and lack of effective clinical therapies. Dysregulation of apoptosis is observed across MDS subtypes regardless of mutations and represents an attractive therapeutic opportunity. Venetoclax (VEN), a selective inhibitor of anti-apoptotic protein B-cell lymphoma- 2 (BCL2), has yielded impressive responses in older patients with acute myeloid leukemia (AML) and high risk MDS. BCL2 family anti-apoptotic proteins BCL-XL and induced myeloid cell leukemia 1 (MCL1) are implicated in leukemia survival, and upregulation of MCL1 is seen in VEN-resistant AML and MDS. We determined in vitro sensitivity of MDS patient samples to selective inhibitors of BCL2, BCL-XL and MCL1. While VEN response positively correlated with MDS with excess blasts, all MDS subtypes responded to MCL1 inhibition. Treatment with combined VEN + MCL1 inhibtion was synergistic in all MDS subtypes without significant injury to normal hematopoiesis and reduced MDS engraftment in MISTRG6 mice, supporting the pursuit of clinical trials with combined BCL2 + MCL1 inhibition in MDS.

Topics: Animals; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; Leukemia, Myeloid, Acute; Mice; Myelodysplastic Syndromes; Myeloid Cell Leukemia Sequence 1 Protein; Proto-Oncogene Proteins c-bcl-2

Topics: Animals; Disease Models, Animal; Humans; Mice; Phosphatidylinositol 3-Kinases; PPAR alpha; Stem Cells

HIV-1 persists indefinitely in people living with HIV (PLWH) on antiretroviral therapy (ART). If ART is stopped, the virus rapidly rebounds from long-lived latently infected cells. Using a humanized mouse model of HIV-1 infection and CD4

Topics: Animals; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; HIV Seropositivity; HIV-1; Humans; Mice

The deregulation of BCL2 family proteins plays a crucial role in leukemia development. Therefore, pharmacological inhibition of this family of proteins is becoming a prevalent treatment method. However, due to the emergence of primary and acquired resistance, efficacy is compromised in clinical or preclinical settings. We developed a drug sensitivity prediction model utilizing a deep tabular learning algorithm for the assessment of venetoclax sensitivity in T-cell acute lymphoblastic leukemia (T-ALL) patient samples. Through analysis of predicted venetoclax-sensitive and resistant samples, PLK1 was identified as a cooperating partner for the BCL2-mediated antiapoptotic program. This finding was substantiated by additional data obtained through phosphoproteomics and high-throughput kinase screening. Concurrent treatment using venetoclax with PLK1-specific inhibitors and PLK1 knockdown demonstrated a greater therapeutic effect on T-ALL cell lines, patient-derived xenografts, and engrafted mice compared with using each treatment separately. Mechanistically, the attenuation of PLK1 enhanced BCL2 inhibitor sensitivity through upregulation of BCL2L13 and PMAIP1 expression. Collectively, these findings underscore the dependency of T-ALL on PLK1 and postulate a plausible regulatory mechanism.

Topics: Algorithms; Animals; Disease Models, Animal; Humans; Mice; Polo-Like Kinase 1; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2

The covalent inhibitor of Bruton's tyrosine kinase ibrutinib and the specific Bcl-2 inhibitor venetoclax are both highly efficacious single-agent drugs in the treatment of chronic lymphocytic leukemia (CLL). Based on their complementary modes of action, ibrutinib and venetoclax are hypothesized to act in a synergistic fashion. Currently, it is unclear whether combined treatment is indeed superior to continuous single-agent treatment and what mechanisms underlie the resistance to combination treatment. In addition, the effects of such treatment on the skewed T-cell compartment characteristic of CLL are as yet unknown. In the murine Eµ-TCL1 adoptive transfer model resembling aggressive CLL, we found that combined treatment resulted in the deepest responses, with the longest duration related to a combination of decreased proliferation and increased induction of apoptosis. In addition, alterations in T-cell subsets were most prominent after combination treatment, with increased naive cells and reduced effector memory cells. Remarkably, effects of single agents but also combination treatment were eventually interrupted by relapse, and we found downregulation of BIM expression as a plausible cause of acquired drug resistance. Nevertheless, in this murine model, the combination of venetoclax and ibrutinib has increased efficacy over single agents, accompanied by a restoration of the T-cell compartment.

Topics: Adenine; Animals; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; Leukemia, Lymphocytic, Chronic, B-Cell; Mice; Piperidines; Proto-Oncogene Proteins; Pyrazoles; Pyrimidines; Sulfonamides

Death receptor 5 (DR5) is an attractive target for cancer therapy due to its broad upregulated expression in multiple cancers and ability to directly induce apoptosis. Though anti-DR5 IgG antibodies have been evaluated in clinical trials, limited efficacy has been attributed to insufficient receptor crosslinking. IGM-8444 is an engineered, multivalent agonistic IgM antibody with 10 binding sites to DR5 that induces cancer cell apoptosis through efficient DR5 multimerization. IGM-8444 bound to DR5 with high avidity and was substantially more potent than an IgG with the same binding domains. IGM-8444 induced cytotoxicity in a broad panel of solid and hematologic cancer cell lines but did not kill primary human hepatocytes

Topics: Animals; Antineoplastic Agents; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; Female; Genes, bcl-2; Humans; Immunoglobulin M; Mice; Mice, Nude; Receptors, TNF-Related Apoptosis-Inducing Ligand; Sulfonamides

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Patients with acute myeloid leukemia (AML) frequently do not respond to conventional therapies. Leukemic cell survival and treatment resistance have been attributed to the overexpression of B-cell lymphoma 2 (BCL-2) and aberrant DNA hypermethylation. In a phase Ib study in elderly patients with AML, combining the BCL-2 selective inhibitor venetoclax with hypomethylating agents 5-azacitidine (5-Aza) or decitabine resulted in 67% overall response rate; however, the underlying mechanism for this activity is unknown.. In this study, we demonstrate that venetoclax and 5-Aza act synergistically to kill AML cells. These data provide a novel nonepigenetic mechanism of action for 5-Aza and its combinatorial activity with venetoclax through the ISR-mediated induction of

Topics: Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Azacitidine; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; DNA Methylation; Dose-Response Relationship, Drug; Drug Synergism; Gene Expression Regulation, Leukemic; Gene Knockdown Techniques; Humans; Leukemia, Myeloid, Acute; Mice; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

Recurrent high-risk neuroblastoma is a childhood cancer that often fails to respond to therapy. Fenretinide (4-HPR) is a cytotoxic retinoid with clinical activity in recurrent neuroblastoma and venetoclax (ABT-199) is a selective inhibitor of the antiapoptotic protein B-cell lymphoma-2 (BCL-2). We evaluated activity of 4-HPR + ABT-199 in preclinical models of neuroblastoma. Patient-derived cell lines and xenografts from progressive neuroblastoma were tested. Cytotoxicity was evaluated by DIMSCAN, apoptosis by flow cytometry, and gene expression by RNA sequencing, quantitative RT-PCR, and immunoblotting. 4-HPR + ABT-199 was highly synergistic against high BCL-2-expressing neuroblastoma cell lines and significantly improved event-free survival of mice carrying high BCL-2-expressing patient-derived xenografts (PDX). In 10 matched-pair cell lines [established at diagnosis (DX) and progressive disease (PD) from the same patients], BCL-2 expression in the DX and PD lines was comparable, suggesting that BCL-2 expression at diagnosis may provide a biomarker for neuroblastomas likely to respond to 4-HPR + ABT-199. In a pair of DX (COG-N-603x) and PD (COG-N-623x) PDXs established from the same patient, COG-N-623x was less responsive to cyclophosphamide + topotecan than COG-N-603x, but both DX and PD PDXs were responsive to 4-HPR + ABT-199. Synergy of 4-HPR + ABT-199 was mediated by induction of NOXA via 4-HPR stimulation of reactive oxygen species that induced expression of ATF4 and ATF3, transcription factors for NOXA. Thus, fenretinide + venetoclax is a synergistic combination that warrants clinical testing in high BCL-2-expressing neuroblastoma.

Topics: Animals; Antineoplastic Agents; Bridged Bicyclo Compounds, Heterocyclic; Cell Culture Techniques; Cell Line, Tumor; Disease Models, Animal; Female; Fenretinide; Humans; Mice; Neuroblastoma; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

Our present study has shown a potential role for VEGF-A-mediated autocrine signalling to promote survival and proliferation of SU-DHL-6 cells, but the cells could not undergo apoptosis but rather decrease proliferation after bevacizumab treatment. Therefore, we would like to further study the antitumour efficacy of venetoclax (BCL2 inhibitor) in combination with bevacizumab in B-cell NHL.. The human cytokine antibody array, RT-qPCR, Western blot, ELISA, apoptosis assay and xenografted mouse model et al were used.. We described a unique phenomenon that SU-DHL-6 cells showed cell density-dependent survival and growth. Then, we suggested the expression of VEGF-A was positively correlated with the cell density using a human cytokine antibody array and indicated an important role of VEGF-A in the survival and proliferation of SU-DHL-6 cells. Additionally, xenografted SU-DHL-6 cells formed tumours in mice that grew in response to VEGF stimulation. GEO data set also suggested that high VEGF-A expression reflected poor prognosis. The combination therapy with bevacizumab and navitoclax could significantly induce of cell death in vitro and reduce the tumour size and weight with well tolerated in vivo.. Our findings propose a novel combined strategy in which bevacizumab synergises with the BCL2 inhibitor venetoclax that is effective against B-cell NHL.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Bevacizumab; Biomarkers; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cytokines; Disease Models, Animal; Drug Synergism; Female; Humans; Lymphoma, B-Cell; Mice; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; Sulfonamides; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-2; Xenograft Model Antitumor Assays

To investigate the efficacy of the combination of the FLT3 inhibitors midostaurin or gilteritinib with the Bcl-2 inhibitor venetoclax in FLT3-internal tandem duplication (ITD) acute myeloid leukemia (AML) and the underlying molecular mechanism.. Using both FLT3-ITD cell lines and primary patient samples, Annexin V-FITC/propidium iodide staining and flow cytometry analysis were used to quantify cell death induced by midostaurin or gilteritinib, alone or in combination with venetoclax. Western blot analysis was performed to assess changes in protein expression levels of members of the JAK/STAT, MAPK/ERK, and PI3K/AKT pathways, and members of the Bcl-2 family of proteins. The MV4-11-derived xenograft mouse model was used to assess. The combination of midostaurin or gilteritinib with venetoclax potently and synergistically induces apoptosis in FLT3-ITD AML cell lines and primary patient samples. The FLT3 inhibitors induced downregulation of Mcl-1, enhancing venetoclax activity. Phosphorylated-ERK expression is induced by venetoclax but abolished by the combination of venetoclax with midostaurin or gilteritinib. Simultaneous downregulation of Mcl-1 by midostaurin or gilteritinib and inhibition of Bcl-2 by venetoclax results in "free" Bim, leading to synergistic induction of apoptosis.. Inhibition of Bcl-2 via venetoclax synergistically enhances the efficacy of midostaurin and gilteritinib in FLT3-mutated AML.

Topics: Aniline Compounds; Animals; Apoptosis; Biomarkers, Tumor; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; Drug Synergism; Extracellular Signal-Regulated MAP Kinases; fms-Like Tyrosine Kinase 3; Gene Duplication; Gene Expression Regulation, Leukemic; Humans; Leukemia, Myeloid, Acute; Mice; Mutation; Myeloid Cell Leukemia Sequence 1 Protein; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Pyrazines; Staurosporine; Sulfonamides; Xenograft Model Antitumor Assays

Topics: Animals; Antibodies, Monoclonal, Humanized; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; Drug Therapy, Combination; Humans; Lymphoma, Non-Hodgkin; Mice; para-Aminobenzoates; Pyrrolidines; Sulfonamides; Xenograft Model Antitumor Assays

Topics: Animals; Antineoplastic Agents; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; DNA Methylation; Drug Resistance, Neoplasm; Gene Expression; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Mice; Promoter Regions, Genetic; Proto-Oncogene Proteins c-bcl-2; Small Cell Lung Carcinoma; Sulfonamides; Xenograft Model Antitumor Assays

The identification of targetable vulnerabilities in the context of therapeutic resistance is a key challenge in cancer treatment. We detected pervasive aberrant splicing as a characteristic feature of chronic lymphocytic leukemia (CLL), irrespective of splicing factor mutation status, which was associated with sensitivity to the spliceosome modulator, E7107. Splicing modulation affected CLL survival pathways, including members of the B cell lymphoma-2 (BCL2) family of proteins, remodeling antiapoptotic dependencies of human and murine CLL cells. E7107 treatment decreased myeloid cell leukemia-1 (MCL1) dependence and increased BCL2 dependence, sensitizing primary human CLL cells and venetoclax-resistant CLL-like cells from an Eμ-TCL1-based adoptive transfer murine model to treatment with the BCL2 inhibitor venetoclax. Our data provide preclinical rationale to support the combination of venetoclax with splicing modulators to reprogram apoptotic dependencies in CLL for treating venetoclax-resistant CLL cases.

Topics: Adult; Aged; Aged, 80 and over; Alternative Splicing; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Disease Models, Animal; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Epoxy Compounds; Female; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Macrolides; Male; Mice; Mice, Transgenic; Middle Aged; Mitochondria; Mutation; Myeloid Cell Leukemia Sequence 1 Protein; Phosphoproteins; Primary Cell Culture; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrimidines; RNA Splicing Factors; Spliceosomes; Sulfonamides; Thiophenes

BCL-2 family proteins dictate survival of human multiple myeloma cells, making them attractive drug targets. Indeed, multiple myeloma cells are sensitive to antagonists that selectively target prosurvival proteins such as BCL-2/BCL-XL (ABT-737 and ABT-263/navitoclax) or BCL-2 only (ABT-199/GDC-0199/venetoclax). Resistance to these three drugs is mediated by expression of MCL-1. However, given the selectivity profile of venetoclax it is unclear whether coexpression of BCL-XL also affects antitumor responses to venetoclax in multiple myeloma. In multiple myeloma cell lines (n = 21), BCL-2 is expressed but sensitivity to venetoclax correlated with high BCL-2 and low BCL-XL or MCL-1 expression. Multiple myeloma cells that coexpress BCL-2 and BCL-XL were resistant to venetoclax but sensitive to a BCL-XL-selective inhibitor (A-1155463). Multiple myeloma xenograft models that coexpressed BCL-XL or MCL-1 with BCL-2 were also resistant to venetoclax. Resistance to venetoclax was mitigated by cotreatment with bortezomib in xenografts that coexpressed BCL-2 and MCL-1 due to upregulation of NOXA, a proapoptotic factor that neutralizes MCL-1. In contrast, xenografts that expressed BCL-XL, MCL-1, and BCL-2 were more sensitive to the combination of bortezomib with a BCL-XL selective inhibitor (A-1331852) but not with venetoclax cotreatment when compared with monotherapies. IHC of multiple myeloma patient bone marrow biopsies and aspirates (n = 95) revealed high levels of BCL-2 and BCL-XL in 62% and 43% of evaluable samples, respectively, while 34% were characterized as BCL-2(High)/BCL-XL (Low) In addition to MCL-1, our data suggest that BCL-XL may also be a potential resistance factor to venetoclax monotherapy and in combination with bortezomib. Mol Cancer Ther; 15(5); 1132-44. ©2016 AACR.

Topics: Animals; Antineoplastic Agents; Bcl-2-Like Protein 11; bcl-X Protein; Bortezomib; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; Drug Resistance, Neoplasm; Drug Therapy, Combination; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Mice; Multiple Myeloma; Myeloid Cell Leukemia Sequence 1 Protein; Protein Binding; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Xenograft Model Antitumor Assays

Acute lymphoblastic leukemia (ALL) is a hematopoietic malignancy derived from immature B-lymphoid and T-lymphoid cells (T-ALL). In T-ALL, there is an early T-cell progenitor (ETP) subgroup that has a very high risk for relapse. In this study, we used mitochondrial BH3 profiling to determine antiapoptotic protein dependencies in T-ALL. We found that T-ALL cell lines and primary patient samples are dependent upon BCL-XL, except when the cancer bears an ETP phenotype, in which case it is BCL-2 dependent. These distinctions directly relate to differential sensitivity to the BH3 mimetics ABT-263 and ABT-199, both in vitro and in vivo. We thus describe for the first time a change of antiapoptotic protein dependence that is related to the differentiation stage of the leukemic clone. Our findings demonstrate that BCL-2 is a clinically relevant target for therapeutic intervention with ABT-199 in ETP-ALL.. ETP T-ALL is a treatment-resistant subtype of T-ALL for which novel targeted therapies are urgently needed. We have discovered, through BH3 profiling, that ETP-ALL is BCL-2 dependent and is very sensitive to in vitro and in vivo treatment with ABT-199, a drug well tolerated in clinical trials.

Topics: Animals; Antineoplastic Agents; bcl-X Protein; Bridged Bicyclo Compounds, Heterocyclic; Cell Line, Tumor; Disease Models, Animal; Drug Resistance, Neoplasm; Gene Expression; Humans; Models, Biological; Neoplasm Grading; Neoplastic Stem Cells; Peptide Fragments; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Xenograft Model Antitumor Assays