ABSTRACT
Uveal melanoma (UM) is the most common primary intraocular malignancy in the adult eye. Despite the aggressive local management of primary UM, the development of metastases is common with no effective treatment options for metastatic disease. Genetic analysis of UM samples reveals the presence of mutually exclusive activating mutations in the Gq alpha subunits GNAQ and GNA11. One of the key downstream targets of the constitutively active Gq alpha subunits is the protein kinase C (PKC) signaling pathway. Herein, we describe the discovery of darovasertib (NVP-LXS196), a potent pan-PKC inhibitor with high whole kinome selectivity. The lead series was optimized for kinase and off target selectivity to afford a compound that is rapidly absorbed and well tolerated in preclinical species. LXS196 is being investigated in the clinic as a monotherapy and in combination with other agents for the treatment of uveal melanoma (UM), including primary UM and metastatic uveal melanoma (MUM).
Subject(s)
Melanoma , Uveal Neoplasms , Adult , Humans , GTP-Binding Protein alpha Subunits/genetics , GTP-Binding Protein alpha Subunits/metabolism , GTP-Binding Protein alpha Subunits, Gq-G11/metabolism , Melanoma/drug therapy , Melanoma/pathology , Uveal Neoplasms/drug therapy , Uveal Neoplasms/metabolism , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , MutationABSTRACT
Uveal melanoma is a rare and aggressive cancer that originates in the eye. Currently, there are no approved targeted therapies and very few effective treatments for this cancer. Although activating mutations in the G protein alpha subunits, GNAQ and GNA11, are key genetic drivers of the disease, few additional drug targets have been identified. Recently, studies have identified context-specific roles for the mammalian SWI/SNF chromatin remodeling complexes (also known as BAF/PBAF) in various cancer lineages. Here, we find evidence that the SWI/SNF complex is essential through analysis of functional genomics screens and further validation in a panel of uveal melanoma cell lines using both genetic tools and small-molecule inhibitors of SWI/SNF. In addition, we describe a functional relationship between the SWI/SNF complex and the melanocyte lineage-specific transcription factor Microphthalmia-associated Transcription Factor, suggesting that these two factors cooperate to drive a transcriptional program essential for uveal melanoma cell survival. These studies highlight a critical role for SWI/SNF in uveal melanoma, and demonstrate a novel path toward the treatment of this cancer.
Subject(s)
Chromatin/metabolism , Melanoma/genetics , Uveal Neoplasms/genetics , Animals , Cell Line, Tumor , Chromosomal Proteins, Non-Histone , Humans , Mice , Transcription FactorsABSTRACT
SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin subfamily A member 2 (SMARCA2), also known as Brahma homologue (BRM), is a Snf2-family DNA-dependent ATPase. BRM and its close homologue Brahma-related gene 1 (BRG1), also known as SMARCA4, are mutually exclusive ATPases of the large ATP-dependent SWI/SNF chromatin-remodeling complexes involved in transcriptional regulation of gene expression. No small molecules have been reported that modulate SWI/SNF chromatin-remodeling activity via inhibition of its ATPase activity, an important goal given the well-established dependence of BRG1-deficient cancers on BRM. Here, we describe allosteric dual BRM and BRG1 inhibitors that downregulate BRM-dependent gene expression and show antiproliferative activity in a BRG1-mutant-lung-tumor xenograft model upon oral administration. These compounds represent useful tools for understanding the functions of BRM in BRG1-loss-of-function settings and should enable probing the role of SWI/SNF functions more broadly in different cancer contexts and those of other diseases.
Subject(s)
Antineoplastic Agents/administration & dosage , Antineoplastic Agents/pharmacology , DNA Helicases/genetics , Drug Design , Mutation , Nuclear Proteins/genetics , Transcription Factors/antagonists & inhibitors , Transcription Factors/genetics , Administration, Oral , Animals , Antineoplastic Agents/chemistry , Cell Line, Tumor , Dose-Response Relationship, Drug , Humans , Mice , Models, Molecular , Protein Conformation , Structure-Activity Relationship , Transcription Factors/chemistry , Xenograft Model Antitumor AssaysSubject(s)
Pyrazines/chemistry , Pyridazines/chemistry , Receptors, G-Protein-Coupled/antagonists & inhibitors , Animals , Cell Line , Disease Models, Animal , Dogs , Drug Evaluation, Preclinical , ERG1 Potassium Channel , Ether-A-Go-Go Potassium Channels/metabolism , Half-Life , Humans , Mice , Pyrazines/chemical synthesis , Pyrazines/pharmacokinetics , Pyridazines/chemical synthesis , Pyridazines/pharmacokinetics , Rats , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism , Smoothened Receptor , Solubility , Structure-Activity RelationshipABSTRACT
The malignant brain cancer medulloblastoma is characterized by mutations in Hedgehog (Hh) signaling pathway genes, which lead to constitutive activation of the G protein (heterotrimeric guanosine triphosphate-binding protein)-coupled receptor Smoothened (Smo). The Smo antagonist NVP-LDE225 inhibits Hh signaling and induces tumor regression in animal models of medulloblastoma. However, evidence of resistance was observed during the course of treatment. Molecular analysis of resistant tumors revealed several resistance mechanisms. We noted chromosomal amplification of Gli2, a downstream effector of Hh signaling, and, more rarely, point mutations in Smo that led to reactivated Hh signaling and restored tumor growth. Analysis of pathway gene expression signatures also, unexpectedly, identified up-regulation of phosphatidylinositol 3-kinase (PI3K) signaling in resistant tumors as another potential mechanism of resistance. Probing the relevance of increased PI3K signaling, we demonstrated that addition of the PI3K inhibitor NVP-BKM120 or the dual PI3K-mTOR (mammalian target of rapamycin) inhibitor NVP-BEZ235 to the initial treatment with the Smo antagonist markedly delayed the development of resistance. Our findings may be useful in informing treatment strategies for medulloblastoma.
Subject(s)
Aminopyridines/pharmacology , Drug Resistance, Neoplasm/drug effects , Medulloblastoma/enzymology , Morpholines/pharmacology , Phosphoinositide-3 Kinase Inhibitors , Protein Kinase Inhibitors/pharmacology , Receptors, G-Protein-Coupled/antagonists & inhibitors , Signal Transduction/drug effects , Aminopyridines/therapeutic use , Animals , Cell Proliferation/drug effects , Gene Amplification/drug effects , Hedgehog Proteins/metabolism , Insulin-Like Growth Factor I/metabolism , Kruppel-Like Transcription Factors/metabolism , Medulloblastoma/drug therapy , Medulloblastoma/genetics , Medulloblastoma/pathology , Mice , Morpholines/therapeutic use , Mutation/genetics , Phosphatidylinositol 3-Kinases/metabolism , Protein Kinase Inhibitors/therapeutic use , Receptors, G-Protein-Coupled/metabolism , Smoothened Receptor , Tumor Suppressor Protein p53/metabolism , Up-Regulation/drug effects , Zinc Finger Protein Gli2ABSTRACT
The blockade of aberrant hedgehog (Hh) signaling has shown promise for therapeutic intervention in cancer. A cell-based phenotypic high-throughput screen was performed, and the lead structure (1) was identified as an inhibitor of the Hh pathway via antagonism of the Smoothened receptor (Smo). Structure-activity relationship studies led to the discovery of a potent and specific Smoothened antagonist N-(6-((2S,6R)-2,6-dimethylmorpholino)pyridin-3-yl)-2-methyl-4'-(trifluoromethoxy)biphenyl-3-carboxamide (5m, NVP-LDE225), which is currently in clinical development.
ABSTRACT
Abnormal activation of the Hedgehog (Hh) signaling pathway has been linked to several types of human cancers, and the development of small-molecule inhibitors of this pathway represents a promising route toward novel anticancer therapeutics. A cell-based screen performed in our laboratories identified a new class of Hh pathway inhibitors, 1-amino-4-benzylphthalazines, that act via antagonism of the Smoothened receptor. A variety of analogues were synthesized and their structure-activity relationships determined. This optimization resulted in the discovery of high affinity Smoothened antagonists, one of which was further profiled in vivo. This compound displayed a good pharmacokinetic profile and also afforded tumor regression in a genetic mouse model of medulloblastoma.
