BT8009; A Nectin-4 Targeting Bicycle Toxin Conjugate for Treatment of Solid Tumors.

Multiple tumor types overexpress Nectin-4 and the antibody-drug conjugate (ADC), enfortumab vedotin (EV) shows striking efficacy in clinical trials for metastatic urothelial cancer, which expresses high levels of Nectin-4, validating Nectin-4 as a clinical target for toxin delivery in this indication. Despite excellent data in urothelial cancer, little efficacy data are reported for EV in other Nectin-4 expressing tumors and EV therapy can produce significant toxicities in many patients, frequently leading to discontinuation of treatment. Thus, additional approaches to this target with the potential to extend utility and reduce toxicity are warranted.

Discovery and Optimization of a Synthetic Class of Nectin-4-Targeted CD137 Agonists for Immuno-oncology.

CD137 (4-1BB) is a co-stimulatory receptor on immune cells and Nectin-4 is a cell adhesion molecule that is overexpressed in multiple tumor types. Using a series of poly(ethylene glycol) (PEG)-based linkers, synthetic bicyclic peptides targeting CD137 were conjugated to targeting Nectin-4. The resulting bispecific molecules were potent CD137 agonists that require the presence of both Nectin-4-expressing tumor cells and CD137-expressing immune cells for activity.

BT7480, a novel fully synthetic tumor-targeted immune cell agonist™ ( TICA™) induces tumor localized CD137 agonism.

Background: CD137 (4-1BB) is an immune costimulatory receptor with high therapeutic potential in cancer. We are creating tumor target-dependent CD137 agonists using a novel chemical approach based on fully synthetic constrained bicyclic peptide () technology. Nectin-4 is overexpressed in multiple human cancers that may benefit from CD137 agonism.

Anticancer immunity induced by a synthetic tumor-targeted CD137 agonist.

Background: In contrast to immune checkpoint inhibitors, the use of antibodies as agonists of immune costimulatory receptors as cancer therapeutics has largely failed. We sought to address this problem using a new class of modular synthetic drugs, termed tumor-targeted immune cell agonists (TICAs), based on constrained bicyclic peptides ().

Methods: Phage libraries displaying were panned for binders against tumor necrosis factor (TNF) superfamily receptors CD137 and OX40, and tumor antigens EphA2, Nectin-4 and programmed death ligand 1.

MMAE Delivery Using the Toxin Conjugate BT5528.

The EphA2 receptor is found at high levels in tumors and low levels in normal tissue and high EphA2 expression in biopsies is a predictor of poor outcome in patients. Drug discovery groups have therefore sought to develop EphA2-based therapies using small molecule, peptide, and nanoparticle-based approaches (1-3). However, until now only EphA2-targeting antibody-drug conjugates (ADC) have entered clinical development.

TRPS1 Is a Lineage-Specific Transcriptional Dependency in Breast Cancer.

Perturbed epigenomic programs play key roles in tumorigenesis, and chromatin modulators are candidate therapeutic targets in various human cancer types. To define singular and shared dependencies on DNA and histone modifiers and transcription factors in poorly differentiated adult and pediatric cancers, we conducted a targeted shRNA screen across 59 cell lines of 6 cancer types. Here, we describe the TRPS1 transcription factor as a strong breast cancer-specific hit, owing largely to lineage-restricted expression.

Antitumor Properties of RAF709, a Highly Selective and Potent Inhibitor of RAF Kinase Dimers, in Tumors Driven by Mutant RAS or BRAF.

Resistance to the RAF inhibitor vemurafenib arises commonly in melanomas driven by the activated BRAF oncogene. Here, we report antitumor properties of RAF709, a novel ATP-competitive kinase inhibitor with high potency and selectivity against RAF kinases. RAF709 exhibited a mode of RAF inhibition distinct from RAF monomer inhibitors such as vemurafenib, showing equal activity against both RAF monomers and dimers.

Project DRIVE: A Compendium of Cancer Dependencies and Synthetic Lethal Relationships Uncovered by Large-Scale, Deep RNAi Screening.

Elucidation of the mutational landscape of human cancer has progressed rapidly and been accompanied by the development of therapeutics targeting mutant oncogenes. However, a comprehensive mapping of cancer dependencies has lagged behind and the discovery of therapeutic targets for counteracting tumor suppressor gene loss is needed. To identify vulnerabilities relevant to specific cancer subtypes, we conducted a large-scale RNAi screen in which viability effects of mRNA knockdown were assessed for 7,837 genes using an average of 20 shRNAs per gene in 398 cancer cell lines.

The allosteric inhibitor ABL001 enables dual targeting of BCR-ABL1.

Chronic myeloid leukaemia (CML) is driven by the activity of the BCR-ABL1 fusion oncoprotein. ABL1 kinase inhibitors have improved the clinical outcomes for patients with CML, with over 80% of patients treated with imatinib surviving for more than 10 years. Second-generation ABL1 kinase inhibitors induce more potent molecular responses in both previously untreated and imatinib-resistant patients with CML.

Design, Synthesis, and Biological Activity of Substrate Competitive SMYD2 Inhibitors.

Protein lysine methyltransferases (KMTs) have emerged as important regulators of epigenetic signaling. These enzymes catalyze the transfer of donor methyl groups from the cofactor S-adenosylmethionine to specific acceptor lysine residues on histones, leading to changes in chromatin structure and transcriptional regulation. These enzymes also methylate an array of nonhistone proteins, suggesting additional mechanisms by which they influence cellular physiology.

Allosteric inhibition of SHP2 phosphatase inhibits cancers driven by receptor tyrosine kinases.

The non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, has an important role in signal transduction downstream of growth factor receptor signalling and was the first reported oncogenic tyrosine phosphatase. Activating mutations of SHP2 have been associated with developmental pathologies such as Noonan syndrome and are found in multiple cancer types, including leukaemia, lung and breast cancer and neuroblastoma. SHP2 is ubiquitously expressed and regulates cell survival and proliferation primarily through activation of the RAS–ERK signalling pathway.

CRISPR Screens Provide a Comprehensive Assessment of Cancer Vulnerabilities but Generate False-Positive Hits for Highly Amplified Genomic Regions.

Unlabelled: CRISPR/Cas9 has emerged as a powerful new tool to systematically probe gene function. We compared the performance of CRISPR to RNAi-based loss-of-function screens for the identification of cancer dependencies across multiple cancer cell lines. CRISPR dropout screens consistently identified more lethal genes than RNAi, implying that the identification of many cellular dependencies may require full gene inactivation.

ERG signaling in prostate cancer is driven through PRMT5-dependent methylation of the Androgen Receptor.

The TMPRSS2:ERG gene fusion is common in androgen receptor (AR) positive prostate cancers, yet its function remains poorly understood. From a screen for functionally relevant ERG interactors, we identify the arginine methyltransferase PRMT5. ERG recruits PRMT5 to AR-target genes, where PRMT5 methylates AR on arginine 761.

Disordered methionine metabolism in MTAP/CDKN2A-deleted cancers leads to dependence on PRMT5.

5-Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine salvage pathway. The MTAP gene is frequently deleted in human cancers because of its chromosomal proximity to the tumor suppressor gene CDKN2A. By interrogating data from a large-scale short hairpin RNA-mediated screen across 390 cancer cell line models, we found that the viability of MTAP-deficient cancer cells is impaired by depletion of the protein arginine methyltransferase PRMT5.

High-throughput screening using patient-derived tumor xenografts to predict clinical trial drug response.

Profiling candidate therapeutics with limited cancer models during preclinical development hinders predictions of clinical efficacy and identifying factors that underlie heterogeneous patient responses for patient-selection strategies. We established ∼1,000 patient-derived tumor xenograft models (PDXs) with a diverse set of driver mutations. With these PDXs, we performed in vivo compound screens using a 1 × 1 × 1 experimental design (PDX clinical trial or PCT) to assess the population responses to 62 treatments across six indications.

Studying clonal dynamics in response to cancer therapy using high-complexity barcoding.

Resistance to cancer therapies presents a significant clinical challenge. Recent studies have revealed intratumoral heterogeneity as a source of therapeutic resistance. However, it is unclear whether resistance is driven predominantly by pre-existing or de novo alterations, in part because of the resolution limits of next-generation sequencing.

Functional epigenetics approach identifies BRM/SMARCA2 as a critical synthetic lethal target in BRG1-deficient cancers.

Defects in epigenetic regulation play a fundamental role in the development of cancer, and epigenetic regulators have recently emerged as promising therapeutic candidates. We therefore set out to systematically interrogate epigenetic cancer dependencies by screening an epigenome-focused deep-coverage design shRNA (DECODER) library across 58 cancer cell lines. This screen identified BRM/SMARCA2, a DNA-dependent ATPase of the mammalian SWI/SNF (mSWI/SNF) chromatin remodeling complex, as being essential for the growth of tumor cells that harbor loss of function mutations in BRG1/SMARCA4.

Global chromatin profiling reveals NSD2 mutations in pediatric acute lymphoblastic leukemia.

Epigenetic dysregulation is an emerging hallmark of cancers. We developed a high-information-content mass spectrometry approach to profile global histone modifications in human cancers. When applied to 115 lines from the Cancer Cell Line Encyclopedia, this approach identified distinct molecular chromatin signatures.

Discovery and mechanistic study of a small molecule inhibitor for motor protein KIFC1.

Centrosome amplification is observed in many human cancers and has been proposed to be a driver of both genetic instability and tumorigenesis. Cancer cells have evolved mechanisms to bundle multiple centrosomes into two spindle poles to avoid multipolar mitosis that can lead to chromosomal segregation defects and eventually cell death. KIFC1, a kinesin-14 family protein, plays an essential role in centrosomal bundling in cancer cells, but its function is not required for normal diploid cell division, suggesting that KIFC1 is an attractive therapeutic target for human cancers.

Structural basis of substrate methylation and inhibition of SMYD2.

Protein lysine methyltransferases are important regulators of epigenetic signaling. These enzymes catalyze the transfer of donor methyl groups from S-adenosylmethionine to specific acceptor lysines on histones, leading to changes in chromatin structure and transcriptional regulation. These enzymes also methylate nonhistone protein substrates, revealing an additional mechanism to regulate cellular physiology.

Aurora B kinase regulates the postmitotic endoreduplication checkpoint via phosphorylation of the retinoblastoma protein at serine 780.

The phenotypic change characteristic of Aurora B inhibition is the induction of polyploidy. Utilizing specific siRNA duplexes and a selective small molecule inhibitor (AZD1152) to inhibit Aurora B activity in tumor cells, we sought to elucidate the mechanism by which Aurora B inhibition results in polyploidy. Cells treated with AZD1152 progressed through mitosis with misaligned chromosomes and exited without cytokinesis and subsequently underwent endoreduplication of DNA despite activation of a p53-dependent pseudo G1 checkpoint.

Mitotic drivers--inhibitors of the Aurora B Kinase.

In this article we review the basis for current anti-mitotic, anti-cancer, therapy and the potential for Aurora B kinase inhibitors as a new differentiated class of agents--"mitotic drivers". We review the current understanding of Aurora B inhibition from basic cell biology to inhibitors currently undergoing clinical trials.

Synthesis and SAR of 1-acetanilide-4-aminopyrazole-substituted quinazolines: selective inhibitors of Aurora B kinase with potent anti-tumor activity.

A new class of 1-acetanilide-4-aminopyrazole-substituted quinazoline Aurora kinase inhibitors has been discovered possessing highly potent cellular activity. Continuous infusion into athymic mice bearing SW620 tumors of the soluble phosphate derivative 2 led to dose-proportional exposure of the des-phosphate compound 8 with a high-unbound fraction. The combination of potent cell activity and high free-drug exposure led to pharmacodynamic changes in the tumor at low doses, indicative of Aurora B-kinase inhibition and a reduction in tumor volume.

AZD1152, a selective inhibitor of Aurora B kinase, inhibits human tumor xenograft growth by inducing apoptosis.

Purpose: In the current study, we examined the in vivo effects of AZD1152, a novel and specific inhibitor of Aurora kinase activity (with selectivity for Aurora B).

Experimental Design: The pharmacodynamic effects and efficacy of AZD1152 were determined in a panel of human tumor xenograft models. AZD1152 was dosed via several parenteral (s.

Discovery, synthesis, and in vivo activity of a new class of pyrazoloquinazolines as selective inhibitors of aurora B kinase.

The Aurora kinases have been the subject of considerable interest as targets for the development of new anticancer agents. While evidence suggests inhibition of Aurora B kinase gives rise to the more pronounced antiproliferative phenotype, the most clinically advanced agents reported to date typically inhibit both Aurora A and B. We have discovered a series of pyrazoloquinazolines, some of which show greater than 1000-fold selectivity for Aurora B over Aurora A kinase activity, in recombinant enzyme assays.