The enzyme glutaminase (GLS1) is currently in clinical trials for oncology, yet there are no clear diagnostic criteria to identify responders. The evaluation of 25 basal breast lines expressing GLS1, ...predominantly through its splice isoform GAC, demonstrated that only GLS1-dependent basal B lines required it for maintaining de novo glutathione synthesis in addition to mitochondrial bioenergetics. Drug sensitivity profiling of 407 tumor lines with GLS1 and gamma-glutamylcysteine synthetase (GCS) inhibitors revealed a high degree of co-dependency on both enzymes across indications, suggesting that redox balance is a key function of GLS1 in tumors. To leverage these findings, we derived a pan-cancer metabolic signature predictive of GLS1/GCS co-dependency and validated it in vivo using four lung patient-derived xenograft models, revealing the additional requirement for expression of GAC above a threshold (log2RPKM + 1 ≥ 4.5, where RPKM is reads per kilobase per million mapped reads). Analysis of the pan-TCGA dataset with our signature identified multiple indications, including mesenchymal tumors, as putative responders to GLS1 inhibitors.
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•Dual role in energy and glutathione synthesis drives tumor GLS1 dependency•Cell line-derived diagnostic signature is predictive of GLS1 dependency in vivo•Glutamate and citrate are key predictive biomarkers of response to GLS1 inhibition•Signature predicts response in mesenchymal breast and lung tumors and across TCGA
Daemen et al. address the current unmet need for diagnosing responders to glutaminase (GLS1) cancer therapy. They identify co-dependency of GLS1 and gamma-glutamylcysteine synthetase (GCS) inhibitors, suggesting that redox balance is a key function of GLS1 in tumors, and validate a predictive pan-cancer metabolic signature for GLS1/GCS co-dependency in vivo.
Inhibition of the bromodomain of the transcriptional regulator CBP/P300 is an especially interesting new therapeutic approach in oncology. We recently disclosed in vivo chemical tool 1 (GNE-272) for ...the bromodomain of CBP that was moderately potent and selective over BRD4(1). In pursuit of a more potent and selective CBP inhibitor, we used structure-based design. Constraining the aniline of 1 into a tetrahydroquinoline motif maintained potency and increased selectivity 2-fold. Structure–activity relationship studies coupled with further structure-based design targeting the LPF shelf, BC loop, and KAc regions allowed us to significantly increase potency and selectivity, resulting in the identification of non-CNS penetrant 19 (GNE-781, TR-FRET IC50 = 0.94 nM, BRET IC50 = 6.2 nM; BRD4(1) IC50 = 5100 nΜ) that maintained good in vivo PK properties in multiple species. Compound 19 displays antitumor activity in an AML tumor model and was also shown to decrease Foxp3 transcript levels in a dose dependent manner.
Breast cancer has been redefined into three clinically relevant subclasses: (i) estrogen/progesterone receptor positive (ER+/PR+), (ii) HER2/ERRB2 positive, and (iii) those lacking expression of all ...three markers (triple negative or basal-like). While targeted therapies for ER+/PR+ and HER2+ tumors have revolutionized patient treatment and increased lifespan, an urgent need exists for identifying novel targets for triple-negative breast cancers. Here, we used integrative genomic analysis to identify candidate oncogenes in triple-negative breast tumors and assess their function through loss of function screening. Using this approach, we identify lactate dehydrogenase B (LDHB), a component of glycolytic metabolism, as an essential gene in triple-negative breast cancer. Loss of LDHB abrogated cell proliferation in vitro and arrested tumor growth in fully formed tumors in vivo. We find that LDHB and other related glycolysis genes are specifically upregulated in basal-like/triple-negative breast cancers as compared with other subtypes, suggesting that these tumors are distinctly glycolytic. Consistent with this, triple-negative breast cancer cell lines were more dependent on glycolysis for growth than luminal cell lines. Finally, we find that patients with breast cancer and high LDHB expression in their tumors had a poor clinical outcome. While previous studies have focused on the ubiquitous role of LDHA in tumor metabolism and growth, our data reveal that LDHB is upregulated and required only in certain cancer genotypes. These findings suggest that targeting LDHB or other components of lactate metabolism would be of clinical benefit in triple-negative breast cancer.
Mitogen-activated protein kinase (MAPK) pathway dysregulation is implicated in >30% of all cancers, rationalizing the development of RAF, MEK and ERK inhibitors. While BRAF and MEK inhibitors improve ...BRAF mutant melanoma patient outcomes, these inhibitors had limited success in other MAPK dysregulated tumors, with insufficient pathway suppression and likely pathway reactivation. In this study we show that inhibition of either MEK or ERK alone only transiently inhibits the MAPK pathway due to feedback reactivation. Simultaneous targeting of both MEK and ERK nodes results in deeper and more durable suppression of MAPK signaling that is not achievable with any dose of single agent, in tumors where feedback reactivation occurs. Strikingly, combined MEK and ERK inhibition is synergistic in RAS mutant models but only additive in BRAF mutant models where the RAF complex is dissociated from RAS and thus feedback productivity is disabled. We discovered that pathway reactivation in RAS mutant models occurs at the level of CRAF with combination treatment resulting in a markedly more active pool of CRAF. However, distinct from single node targeting, combining MEK and ERK inhibitor treatment effectively blocks the downstream signaling as assessed by transcriptional signatures and phospho-p90RSK. Importantly, these data reveal that MAPK pathway inhibitors whose activity is attenuated due to feedback reactivation can be rescued with sufficient inhibition by using a combination of MEK and ERK inhibitors. The MEK and ERK combination significantly suppresses MAPK pathway output and tumor growth in vivo to a greater extent than the maximum tolerated doses of single agents, and results in improved anti-tumor activity in multiple xenografts as well as in two Kras mutant genetically engineered mouse (GEM) models. Collectively, these data demonstrate that combined MEK and ERK inhibition is functionally unique, yielding greater than additive anti-tumor effects and elucidates a highly effective combination strategy in MAPK-dependent cancer, such as KRAS mutant tumors.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Protein tyrosine phosphatase SHP2 mediates RAS-driven MAPK signaling and has emerged in recent years as a target of interest in oncology, both for treating with a single agent and in combination with ...a KRAS inhibitor. We were drawn to the pharmacological potential of SHP2 inhibition, especially following the initial observation that drug-like compounds could bind an allosteric site and enforce a closed, inactive state of the enzyme. Here, we describe the identification and characterization of GDC-1971 (formerly RLY-1971), a SHP2 inhibitor currently in clinical trials in combination with KRAS G12C inhibitor divarasib (GDC-6036) for the treatment of solid tumors driven by a KRAS G12C mutation.
Optimization of a series of aryl urea RAF inhibitors led to the identification of type II pan-RAF inhibitor GNE-0749 (7), which features a fluoroquinazolinone hinge-binding motif. By minimizing ...reliance on common polar hinge contacts, this hinge binder allows for a greater contribution of RAF-specific residue interactions, resulting in exquisite kinase selectivity. Strategic substitution of fluorine at the C5 position efficiently masked the adjacent polar NH functionality and increased solubility by impeding a solid-state conformation associated with stronger crystal packing of the molecule. The resulting improvements in permeability and solubility enabled oral dosing of 7. In vivo evaluation of 7 in combination with the MEK inhibitor cobimetinib demonstrated synergistic pathway inhibition and significant tumor growth inhibition in a KRAS mutant xenograft mouse model.
Distinct classes of neurons are generated from progenitor cells distributed in characteristic dorsoventral patterns in the developing spinal neural tube. We define restricted neural progenitor ...populations by the discrete, nonoverlapping expression of Ngn1, Math1, and Mash1. Crossinhibition between these bHLH factors is demonstrated and provides a mechanism for the generation of discrete bHLH expression domains. This precise control of bHLH factor expression is essential for proper neural development since as demonstrated in both loss- and gain-of-function experiments, expression of Math1 or Ngn1 in dorsal progenitor cells determines whether LH2A/B- or dorsal Lim1/2-expressing interneurons will develop. Together, the data suggest that although Math1 and Ngn1 appear to be redundant with respect to neurogenesis, they have distinct functions in specifying neuronal subtype in the dorsal neural tube.
A novel 2-thio-6-oxo-1,6-dihydropyrimidine-containing inhibitor of human lactate dehydrogenase (LDH) was identified by high-throughput screening (IC50=8.1μM). Biochemical, surface plasmon resonance, ...and saturation transfer difference NMR experiments indicated that the compound specifically associated with human LDHA in a manner that required simultaneous binding of the NADH co-factor. Structural variation of the screening hit resulted in significant improvements in LDHA biochemical inhibition activity (best IC50=0.48μM). A crystal structure of an optimized compound bound to human LDHA was obtained and explained many of the observed structure–activity relationships.
A 2-amino-5-aryl-pyrazine was identified as an inhibitor of human lactate dehydrogenase A (LDHA) via a biochemical screening campaign. Biochemical and biophysical experiments demonstrated that the ...compound specifically interacted with human LDHA. Structural variation of the screening hit resulted in improvements in LDHA biochemical inhibition and pharmacokinetic properties. A crystal structure of an improved compound bound to human LDHA was also obtained and it explained many of the observed structure–activity relationships.
The single bromodomain of the closely related transcriptional regulators CBP/EP300 is a target of much recent interest in cancer and immune system regulation. A co-crystal structure of a ...ligand-efficient screening hit and the CBP bromodomain guided initial design targeting the LPF shelf, ZA loop, and acetylated lysine binding regions. Structure–activity relationship studies allowed us to identify a more potent analogue. Optimization of permeability and microsomal stability and subsequent improvement of mouse hepatocyte stability afforded 59 (GNE-272, TR-FRET IC50 = 0.02 μM, BRET IC50 = 0.41 μM, BRD4(1) IC50 = 13 μM) that retained the best balance of cell potency, selectivity, and in vivo PK. Compound 59 showed a marked antiproliferative effect in hematologic cancer cell lines and modulates MYC expression in vivo that corresponds with antitumor activity in an AML tumor model.
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