gx-15-070 and navitoclax

Topics: Aniline Compounds; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Bridged Bicyclo Compounds, Heterocyclic; Drug Screening Assays, Antitumor; Humans; Indoles; MAP Kinase Signaling System; Mitochondrial Dynamics; Molecular Targeted Therapy; Neoplasm Proteins; Neoplasms; Oncogene Addiction; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

The BCL-2 family of proteins integrates pro- and anti-apoptotic signals within the cell and is responsible for initiation of caspase-dependent apoptosis. Chronic lymphocytic leukemia (CLL) cells are particularly dependent on the anti-apoptotic protein BCL-2 for their survival, making this an attractive therapeutic target in CLL. Several early efforts to create inhibitors of the anti-apoptotic family members faced significant challenges, but eventually, the BCL-2 specific inhibitor venetoclax moved forward in CLL. Overall and complete response rates to venetoclax monotherapy in relapsed, refractory CLL are approximately 80 and 20%, respectively, even in patients with high-risk 17p deletion. Toxicities have been manageable and include neutropenia, diarrhea, and nausea. The risk of tumor lysis syndrome (TLS), seen in early experience with the drug, has been mitigated by the use of appropriate TLS risk assessment, prophylaxis, and management. Future studies of venetoclax will focus on combination approaches, predictive biomarker discovery, and mechanisms of resistance.

Topics: Aniline Compounds; Antineoplastic Agents; Bridged Bicyclo Compounds, Heterocyclic; Gossypol; Humans; Indoles; Leukemia, Lymphocytic, Chronic, B-Cell; Neutropenia; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides; Thionucleotides

The failure of apoptosis (programmed cell death) underpins the development of many tumors and often renders them resistant to cytotoxic therapies. In hematologic malignancies, this impairment of apoptosis is often caused by overexpression of the pro-survival protein BCL2. Because abnormally high levels of BCL2 sustain these tumors, there has been much interest in targeting BCL2 as a novel approach to treating various hematologic malignancies. One such approach is the development of BH3 mimetic compounds, small molecules that mimic the action of the BH3-only proteins, natural antagonists of BCL2 and its pro-survival relatives. These compounds act by restoring the ability of a cell to undergo apoptotic cell death. Some of them have shown very encouraging results in early-phase clinical trials that are currently underway, particularly in patients with chronic lymphocytic leukemia and some non-Hodgkin lymphomas, diseases marked by BCL2 overexpression. In this review, we discuss the rationale behind targeting BCL2, highlight the recent findings from clinical trials, and pinpoint the next steps in the clinical development of this interesting and promising class of targeted agents, particularly for the treatment of lymphoid malignancies.

Topics: Aniline Compounds; Antineoplastic Agents; Bridged Bicyclo Compounds, Heterocyclic; Gossypol; Hematologic Neoplasms; Humans; Indoles; Leukemia, Lymphocytic, Chronic, B-Cell; Peptide Fragments; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

Targeting apoptosis is an attractive approach in cancer therapy. The BH3-only proteins of the BCL-2 family (having only the BCL-2 homology domain BH3) can trigger apoptosis by binding to the prosurvival members of this family and neutralizing their functional activity (sequestration of the proapoptotic Bcl-2 family members). The "BH3 mimetic" concept has prompted the development of small molecules capable of mimicking BH3-only proteins and thus inducing apoptosis. The prototype BH3 mimetic ABT-737 selectively targets the three prosurvival proteins BCL-XL, BCL-2, and BCL-W (but not MCL-1 or A1) and its oral derivative ABT-263 has proved promising in clinical trials. Some putative BH3 mimetics are also tested clinically while others are still being characterized. This article recapitulates the various known BH3 mimetics and presents the recent developments in the field. The latter include (i) the identification of molecular determinants responsible for the specific interactions between BH3 motifs and the binding grooves of prosurvival proteins and (ii) the characterization of new compounds and particularly BH3 mimetics that antagonize either selectively MCL-1 or BCL-2 or a broad range of prosurvival proteins. These data are critical advances toward the discovery of novel anticancer agents.

Topics: Amino Acid Motifs; Aniline Compounds; Antineoplastic Agents; Apoptosis; Bridged Bicyclo Compounds, Heterocyclic; Clinical Trials as Topic; Drug Design; Drug Screening Assays, Antitumor; Gossypol; Humans; Indoles; Molecular Mimicry; Neoplasms; Peptide Fragments; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

The dysregulation of apoptosis is a key step in developing cancers, and mediates resistance to cancer therapy. Commitment to apoptosis is caused by permeabilization of the outer mitochondrial membrane, a process regulated by the interactions between different proteins of Bcl-2 family. Furthermore, Bcl-2 family proteins also bind to the endoplasmic reticulum, where they modulate autophagy, another important pathway regulating cell survival and death. Dysregulation of Bcl-2 family has been demonstrated in a wide spectrum of human cancers, including gastrointestinal cancers. Therefore, targeting the Bcl-2 family of proteins represents a promising therapeutic approach for these malignancies. Recent advances have yielded small molecules that have close structural or functional similarity to BH3-only proteins and are therefore named BH3 mimetics. Of these BH3 mimetics, obatoclax, (-)-gossypol, and ABT-263 are currently in clinical trials for multiple cancers. Growing evidence indicates that these BH3 mimetics not only induce apoptosis, but also regulate autophagy which may serve as a pro-survival or pro-death mechanism to counteract or mediate the cytotoxicity of BH3 mimetics. This review discusses the role of autophagy in cell-fate decision upon BH3 mimetics treatment. Further exploration of our understanding of the association between autophagy and cellular outcomes in response to BH3 mimetics treatment will likely offer improved therapies for patients with cancer.

Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Autophagy; Gastrointestinal Neoplasms; Humans; Indoles; Molecular Mimicry; Protein Interaction Domains and Motifs; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

The B-cell lymphoma/leukemia 2 (BCL-2) family of proteins has attracted the attention of cancer biologists since the cloning of BCL-2 more than 25 years ago. In the intervening decades, the way the BCL-2 family controls commitment to programmed cell death has been greatly elucidated. Several drugs directed at inhibiting BCL-2 and related antiapoptotic proteins have been tested clinically, with some showing considerable promise, particularly in lymphoid malignancies. A better understanding of the BCL-2 family has also provided insight into how conventional chemotherapy selectively kills cancer cells and why some cancers are more chemosensitive than others. Further exploitation of our understanding of the BCL-2 family promises to offer improved predictive biomarkers for oncologists and improved therapies for patients with cancer.

Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Drug Resistance, Neoplasm; Humans; Indoles; Molecular Targeted Therapy; Neoplasms; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides; Thionucleotides; Treatment Outcome

Blocks in apoptosis are now widely regarded as key pathophysiological maladaptations critical for tumour persistence. Importantly, it has also been recognised that they confer resistance to cytotoxic therapy, and hence often portend an adverse prognosis. The advent of BH3-mimetics represents a nascent clinical capability to directly reverse the evasion of apoptosis, and indeed exploit the very molecular abnormalities which have hitherto posed major obstacles to therapeutic success. Clinical trials with BH3-mimetics have demonstrated clear single agent anti-tumour activity in selected haematological malignancies. These drugs also offer promise as adjuncts to existing or emerging therapies in a broader range of cancers.

Topics: Aniline Compounds; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Hematologic Neoplasms; Humans; Indoles; Molecular Mimicry; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

Inhibiting apoptosis is widely accepted as a necessary step in the transition from normal to cancer cells, and most cancer therapies exert their effects by indirectly reversing this process. Commitment to apoptosis is caused by permeabilisation of the outer mitochondrial membrane--a process regulated by the binding between different members of the Bcl-2 family. Furthermore, Bcl-2 family members also bind to the endoplasmic reticulum, where they modify processes such as the unfolded-protein response and autophagy that also cause or modify different types of cell death. With the growing understanding of the importance of the Bcl-2 family as crucial regulators of the decision to initiate apoptosis, much effort has been directed at developing small molecules that modify function by directly binding to Bcl-2 proteins. Preclinical experiments have confirmed that these agents kill cancer cells and overcome chemotherapy resistance. Two of these drugs are in the initial stages of clinical development (ABT-263 and obatoclax), and early results show clinical efficacy at tolerable doses. Important questions for the future include the role of these drugs as monotherapy versus combination therapy with other anticancer drugs, and the related issue of the relative toxicity to cancerous versus normal cells.

Topics: Aniline Compounds; Antineoplastic Agents; Drug Delivery Systems; Humans; Indoles; Neoplasms; Protein Binding; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

A critical regulator of the apoptotic machinery is the Bcl-2 family proteins whose over expression confers a protective effect on malignant cells against death signals of apoptosis. Cancer cells that are resistant to various anti-cancer drugs and treatment regimen are found to over express these Bcl-2 proteins such as Bcl-2, Bcl-X(L), Mcl-1, Bcl-w, and A1/Bfl1. In recent years there has been an exponential growth in the identification as well as synthesis of non-peptidic cell permeable small-molecule inhibitors (SMIs) of protein-protein interaction. The focus of this article is on inhibitors of anti-apoptotic protein Bcl-2. This review summarizes an up to date knowledge of the available SMIs, their mode of action as well as their current status in preclinical as well as clinical development.

Topics: Aniline Compounds; Animals; Apoptosis; Benzamides; Binding Sites; Biphenyl Compounds; Gossypol; Humans; Indoles; Lymphoma; Models, Molecular; Neoplasms; Nitrophenols; Piperazines; Protein Structure, Tertiary; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides; Sulfones

Defects in apoptotic pathways can promote cancer cell survival and also confer resistance to antineoplastic drugs. One pathway being targeted for antineoplastic therapy is the anti-apoptotic B-cell lymphoma-2 (Bcl-2) family of proteins (Bcl-2, Bcl-XL, Bcl-w, Mcl-1, Bfl1/A-1, and Bcl-B) that bind to and inactivate BH3-domain pro-apoptotic proteins. Signals transmitted by cellular damage (including antineoplastic drugs) or cytokine deprivation can initiate apoptosis via the intrinsic apoptotic pathway. It is controversial whether some BH3-domain proteins (Bim or tBid) directly activate multidomain pro-apoptotic proteins (e.g., Bax and Bak) or act via inhibition of those anti-apoptotic Bcl-2 proteins (Bcl-2, Bcl-XL, Bcl-w, Mcl-1, Bfl1/A-1, and Bcl-B) that stabilize pro-apoptotic proteins. Overexpression of anti-apoptotic Bcl-2 family members has been associated with chemotherapy resistance in various human cancers, and preclinical studies have shown that agents targeting anti-apoptotic Bcl-2 family members have preclinical activity as single agents and in combination with other antineoplastic agents. Clinical trials of several investigational drugs targeting the Bcl-2 family (oblimersen sodium, AT-101, ABT-263, GX15-070) are ongoing. Here, we review the role of the Bcl-2 family in apoptotic pathways and those agents that are known and/or designed to inhibit the anti-apoptotic Bcl-2 family of proteins.

Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Gossypol; Humans; Indoles; Mitochondria; Neoplasms; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides; Thionucleotides

Cancer cells show deviant behavior that induces apoptotic signaling. To survive, cancer cells typically acquire changes enabling evasion of death signals. One way they do this is by increasing the expression of anti-apoptotic BCL-2 proteins. Anti-apoptotic BCL-2 family proteins antagonize death signaling by forming heterodimers with pro-death proteins. Heterodimer formation occurs through binding of the pro-apoptotic protein's BH3 domain into the hydrophobic cleft of anti-apoptotic proteins. The BH3 mimetics are small molecule antagonists of the anti-apoptotic BCL-2 members that function as competitive inhibitors by binding to the hydrophobic cleft. Under certain conditions, antagonism of anti-apoptotic BCL-2 family proteins can unleash pro-death molecules in cancer cells. Thus, the BH3 mimetics are a new class of cancer drugs that specifically target a mechanism of cancer cell survival to selectively kill cancer cells.

Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Benzamides; Binding, Competitive; Biphenyl Compounds; Clinical Trials as Topic; Dimerization; Drug Delivery Systems; Drug Design; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Humans; Indoles; Mice; Mitochondria; Multigene Family; Neoplasm Proteins; Neoplasms; Nitrophenols; Piperazines; Protein Structure, Tertiary; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Structure-Activity Relationship; Sulfonamides; Sulfones; Thionucleotides

Rational therapeutic approaches based on synthetic lethality may improve cancer management. On the basis of a high-throughput drug screen, we provide preclinical proof of concept that targeting the mitochondrial Hsp90 chaperone network (mtHsp90) and inhibition of Bcl-2, Bcl-xL, and Mcl-1 is sufficient to elicit synthetic lethality in tumors recalcitrant to therapy. Our analyses focused on BH3 mimetics that are broad acting (ABT263 and obatoclax) or selective (ABT199, WEHI-539, and A1210477), along with the established mitochondrial matrix chaperone inhibitor gamitrinib-TPP. Drug combinations were tested in various therapy-resistant tumors

Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Biomimetic Materials; Cell Line, Tumor; Cell Proliferation; Female; HSP90 Heat-Shock Proteins; Humans; Indoles; Male; Mice; Mice, SCID; Mitochondria; Peptide Fragments; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides; Xenograft Model Antitumor Assays

The B cell lymphoma-2 (BCL-2) family is the key mediator of cellular sensitivity to apoptosis during pharmacological interventions for numerous human pathologies, including cancer. There is tremendous interest to understand how the proapoptotic BCL-2 effector members (e.g. BCL-2-associated X protein, BAX) cooperate with the BCL-2 homology domain only (BH3-only) subclass (e.g. BCL-2 interacting mediator of death, BIM; BCL-2 interacting-domain death agonist, BID) to induce mitochondrial outer membrane permeabilization (MOMP) and apoptosis and whether these mechanisms may be pharmacologically exploited to enhance the killing of cancer cells. Indeed, small molecule inhibitors of the anti-apoptotic BCL-2 family members have been designed rationally. However, the success of these "BH3 mimetics" in the clinic has been limited, likely due to an incomplete understanding of how these drugs function in the presence of multiple BCL-2 family members. To increase our mechanistic understanding of how BH3 mimetics cooperate with multiple BCL-2 family members in vitro, we directly compared the activity of several BH3-mimetic compounds (i.e. ABT-263, ABT-737, GX15-070, HA14.1, TW-37) in biochemically defined large unilamellar vesicle model systems that faithfully recapitulate BAX-dependent mitochondrial outer membrane permeabilization. Our investigations revealed that the presence of BAX, BID, and BIM differentially regulated the ability of BH3 mimetics to derepress proapoptotic molecules from anti-apoptotic proteins. Using mitochondria loaded with fluorescent BH3 peptides and cells treated with inducers of cell death, these differences were supported. Together, these data suggest that although the presence of anti-apoptotic BCL-2 proteins primarily dictates cellular sensitivity to BH3 mimetics, additional specificity is conferred by proapoptotic BCL-2 proteins.

Topics: Aniline Compounds; Animals; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Bcl-2-Like Protein 11; bcl-X Protein; Benzamides; Benzopyrans; BH3 Interacting Domain Death Agonist Protein; Biphenyl Compounds; HeLa Cells; Humans; Indoles; Membrane Proteins; Mice; Mitochondria, Liver; Mitochondrial Membranes; Molecular Mimicry; Myeloid Cell Leukemia Sequence 1 Protein; Nitriles; Nitrophenols; Permeability; Piperazines; Protein Interaction Domains and Motifs; Proto-Oncogene Proteins; Pyrroles; Sulfonamides; Sulfones; Unilamellar Liposomes

Despite real advances made in chemoimmunotherapy, chronic lymphocytic leukemia (CLL) is still an incurable disease. New therapeutic strategies based on the restoration of the cell death program seemed relevant. Some members of the Bcl-2 family are critical players in the defective apoptotic program in CLL cells and/or targets of apoptosis inducers in vitro. The concept of BH3 mimetics has led to the characterization of small molecules mimicking proapoptotic BH3-only members of the Bcl-2 family by their ability to bind and antagonize the prosurvival members. Some putative or actual BH3 mimetics are already being tested in clinical trials with somewhat promising results. However, none of them has a high enough interaction affinity with Mcl-1, a crucial antiapoptotic factor in CLL. It has been suggested that resistance to BH3 mimetics can be overcome by using inhibitors of Mcl-1 expression. An alternative and more direct strategy is to design mimetics of the Noxa BH3 domain, which is a specific antagonistic Mcl-1 ligand. The development of such Noxa-like BH3 mimetics, capable of directly interacting with Mcl-1 and efficiently neutralizing its antiapoptotic activity, is extremely important to evaluate their impact on the clinical outcome of patients with CLL.

Topics: Aniline Compounds; Apoptosis; Biomimetic Materials; Gossypol; Humans; Indoles; Leukemia, Lymphocytic, Chronic, B-Cell; Myeloid Cell Leukemia Sequence 1 Protein; Peptide Fragments; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Sulfonamides

The molecular pathology of thymic epithelial tumors (TETs) is largely unknown. Using array comparative genomic hybridization (CGH), we evaluated 59 TETs and identified recurrent patterns of copy number (CN) aberrations in different histotypes. GISTIC algorithm revealed the presence of 126 significant peaks of CN aberration, which included 13 cancer-related genes. Among these peaks, CN gain of BCL2 and CN loss of CDKN2A/B were the only genes in the respective regions of CN aberration and were associated with poor outcome. TET cell lines were sensitive to siRNA knockdown of the anti-apoptotic molecules BCL2 and MCL1. Gx15-070, a pan-BCL2 inhibitor, induced autophagy-dependent necroptosis in TET cells via a mechanism involving mTOR pathways, and inhibited TET xenograft growth. ABT263, an inhibitor of BCL2/BCL-XL/BCL-W, reduced proliferation in TET cells when administered in combination with sorafenib, a tyrosine kinase inhibitor able to downregulate MCL1. Immunohistochemistry on 132 TETs demonstrated that CN loss of CDKN2A correlated with lack of expression of its related protein p16(INK4) and identified tumors with poor prognosis. The molecular markers BCL2 and CDKN2A may be of potential value in diagnosis and prognosis of TETs. Our study provides the first preclinical evidence that deregulated anti-apoptotic BCL2 family proteins may represent suitable targets for TET treatment.

Topics: Adult; Aged; Aged, 80 and over; Algorithms; Aniline Compounds; Animals; Apoptosis Regulatory Proteins; Autophagy; bcl-X Protein; Benzenesulfonates; Cell Line, Tumor; Cell Proliferation; Comparative Genomic Hybridization; Cyclin-Dependent Kinase Inhibitor p15; Cyclin-Dependent Kinase Inhibitor p16; DNA Copy Number Variations; Female; Humans; Indoles; Male; Mice; Mice, Nude; Middle Aged; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasms, Glandular and Epithelial; Niacinamide; Phenylurea Compounds; Prognosis; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Pyridines; Pyrroles; RNA Interference; RNA, Small Interfering; Sorafenib; Sulfonamides; Thymus Neoplasms; TOR Serine-Threonine Kinases; Transplantation, Heterologous