Preclinical development of tuspetinib for the treatment of acute myeloid leukemia.

Tuspetinib (TUS) is a well-tolerated, once daily, oral kinase inhibitor in clinical development for treatment of AML. Nonclinical studies show that TUS targets key pro-survival kinases with IC50 values in the low nM range, including SYK, wildtype and mutant forms of FLT3, mutant but not wildtype forms of KIT, RSK2 and TAK1-TAB1 kinases, and indirectly suppresses expression of MCL1. Oral TUS markedly extended survival in subcutaneously and orthotopically inoculated xenograft models of FLT3 mutant human AML, was well tolerated, and delivered enhanced activity when combined with venetoclax or 5-azacytidine.

Luxeptinib interferes with LYN-mediated activation of SYK and modulates BCR signaling in lymphoma.

Luxeptinib (LUX) is a novel oral kinase inhibitor that inhibits FLT3 and also interferes with signaling from the BCR and cell surface TLRs, as well as activation of the NLRP3 inflammasome. Ongoing clinical trials are testing its activity in patients with lymphoma and AML. This study sought to refine understanding of how LUX modulates the earliest steps downstream of the BCR following its activation by anti-IgM in lymphoma cells in comparison to ibrutinib (IB).

Exploiting the Receptor-Binding Domains of R-Spondin 1 to Target Leucine-Rich Repeat-Containin G-Coupled Protein Receptor 5-Expressing Stem Cells in Ovarian Cancer.

Leucine-rich repeat-containing G-protein-coupled receptor (LGR5) and LGR6 mark epithelial stem cells in normal tissues and tumors. They are expressed by stem cells in the ovarian surface and fallopian tube epithelia from which ovarian cancer arises. High-grade serous ovarian cancer is unique in expressing unusually high levels of LGR5 and LGR6 mRNA.

Single-cell characterization of step-wise acquisition of carboplatin resistance in ovarian cancer.

The molecular underpinnings of acquired resistance to carboplatin are poorly understood and often inconsistent between in vitro modeling studies. After sequential treatment cycles, multiple isogenic clones reached similar levels of resistance, but significant transcriptional heterogeneity. Gene-expression based virtual synchronization of 26,772 single cells from 2 treatment steps and 4 resistant clones was used to evaluate the activity of Hallmark gene sets in proliferative (P) and quiescent (Q) phases.

Luxeptinib (CG-806) Targets FLT3 and Clusters of Kinases Operative in Acute Myeloid Leukemia.

Luxeptinib (CG-806) simultaneously targets FLT3 and select other kinase pathways operative in myeloid malignancies. We investigated the range of kinases it inhibits, its cytotoxicity landscape ex vivo with acute myeloid leukemia (AML) patient samples, and its efficacy in xenograft models. Luxeptinib inhibits wild-type (WT) and many of the clinically relevant mutant forms of FLT3 at low nanomolar concentrations.

Luxeptinib disables NLRP3 inflammasome-mediated IL-1β release and pathways required for secretion of inflammatory cytokines IL-6 and TNFα.

Luxeptinib (CG-806) is an orally bioavailable multikinase inhibitor with nanomolar potency against select clusters of kinases including the BTK, FLT3, TRK, STE/MAPK and aurora kinase clusters. It is cytotoxic to primary malignant cells obtained from patients with AML, ALL, and CLL at lower concentrations than other BTK and FLT3 inhibitors, and has activity in AML and lymphoma xenografts at concentrations attainable in patients. Exposure of macrophages and monocytes to endotoxin triggers the release of IL-1β through activation of the NLRP3 inflammasome and IL-6 and TNFα through transcriptional up-regulation.

Therapeutic Targeting of Tumor Cells Rich in LGR Stem Cell Receptors.

LGR5 and LGR6 mark epithelial stem cells in many niches including the ovarian surface and fallopian tube epithelia from which ovarian cancer arises. Human ovarian cancers express these receptors at high levels and express one of their ligands, RSPO1, at levels uniquely higher than all other tumor types except mesothelioma. Reasoning that these receptors are also important to tumor stem cells, arming the LGR binding domain of RSPO1 with a cytotoxin may permit depletion of the tumor stem cells.

WNT Signaling Driven by R-spondin 1 and LGR6 in High-grade Serous Ovarian Cancer.

Background/aim: R-spondins control WNT signaling and RSPO1 and LGR6, two of its receptors, are uniquely expressed at high levels in high-grade serous ovarian cancer (HGSOC). The aim of this study was to assess the interrelations between the expression of the RSPOs and LGRs in HGSOC and in the ovarian surface (OSE) and fallopian tube surface epithelium (FTSE) from which HGSOC arises.

Materials And Methods: Analysis of TCGA (HGSOC), CCLE (ovary), and other publicly accessed RNA-Seq data using UC San Diego Computational Cancer Analysis Library (CCAL) to perform differential expression analysis, association studies, and gene set inspection using the single-sample GSEA method.

Securing the Payload, Finding the Cell, and Avoiding the Endosome: Peptide-Targeted, Fusogenic Porous Silicon Nanoparticles for Delivery of siRNA.

Despite the promise of ribonucleic acid interference therapeutics, the delivery of oligonucleotides selectively to diseased tissues in the body, and specifically to the cellular location in the tissues needed to provide optimal therapeutic outcome, remains a significant challenge. Here, key material properties and biological mechanisms for delivery of short interfering RNAs (siRNAs) to effectively silence target-specific cells in vivo are identified. Using porous silicon nanoparticles as the siRNA host, tumor-targeting peptides for selective tissue homing, and fusogenic lipid coatings to induce fusion with the plasma membrane, it is shown that the uptake mechanism can be engineered to be independent of common receptor-mediated endocytosis pathways.

Tumor-Targeting, MicroRNA-Silencing Porous Silicon Nanoparticles for Ovarian Cancer Therapy.

Silencing of aberrantly expressed microRNAs (miRNAs or miRs) has emerged as one of the strategies for molecular targeted cancer therapeutics. In particular, miR-21 is an oncogenic miRNA overexpressed in many tumors, including ovarian cancer. To achieve efficient administration of anti-miR therapeutics, delivery systems are needed that can ensure local accumulation in the tumor environment, low systemic toxicity, and reduced adverse side effects.

Tumor Retention of Enzyme-Responsive Pt(II) Drug-Loaded Nanoparticles Imaged by Nanoscale Secondary Ion Mass Spectrometry and Fluorescence Microscopy.

In nanomedicine, determining the spatial distribution of particles and drugs, together and apart, at high resolution within tissues, remains a major challenge because each must have a different label or detectable feature that can be observed with high sensitivity and resolution. We prepared nanoparticles capable of enzyme-directed assembly of particle therapeutics (EDAPT), containing an analogue of the Pt(II)-containing drug oxaliplatin, an N-labeled monomer in the hydrophobic block of the backbone of the polymer, the near-infrared dye Cy5.5, and a peptide that is a substrate for tumor metalloproteinases in the hydrophilic block.

APTO-253 Stabilizes G-quadruplex DNA, Inhibits MYC Expression, and Induces DNA Damage in Acute Myeloid Leukemia Cells.

APTO-253 is a phase I clinical stage small molecule that selectively induces CDKN1A (p21), promotes G-G cell-cycle arrest, and triggers apoptosis in acute myeloid leukemia (AML) cells without producing myelosuppression in various animal species and humans. Differential gene expression analysis identified a pharmacodynamic effect on MYC expression, as well as induction of DNA repair and stress response pathways. APTO-253 was found to elicit a concentration- and time-dependent reduction in MYC mRNA expression and protein levels.

APTO-253 Is a New Addition to the Repertoire of Drugs that Can Exploit DNA BRCA1/2 Deficiency.

APTO-253 is a small molecule with antiproliferative activity against cell lines derived from a wide range of human malignancies. We sought to determine the mechanisms of action and basis for resistance to APTO-253 so as to identify synthetic lethal interactions that can guide combination studies. The cellular pharmacology of APTO-253 was analyzed in Raji lymphoma cells and a subline selected for resistance (Raji/253R).

LGR5 and LGR6 in stem cell biology and ovarian cancer.

Wnt signaling plays a fundamental role in patterning of the embryo and maintenance of stem cells in numerous epithelia. Epithelial stem cells are closeted in niches created by surrounding differentiated cells that express secreted Wnt and R-spondin proteins that influence proliferation rate and fate determination of stem cell daughters. R-spondins act through the LGR receptors to enhance Wnt signaling.

A phase I pharmacokinetic study of intraperitoneal bortezomib and carboplatin in patients with persistent or recurrent ovarian cancer: An NRG Oncology/Gynecologic Oncology Group study.

Purpose: Intraperitoneal (IP) therapy improves survival compared to intravenous (IV) treatment for women with newly diagnosed, optimally cytoreduced, ovarian cancer. However, the role of IP therapy in recurrent disease is unknown. Preclinical data demonstrated IP administration of the proteasome inhibitor, bortezomib prior to IP carboplatin increased tumor platinum accumulation resulting in synergistic cytotoxicity.

Copper transporters and chaperones CTR1, CTR2, ATOX1, and CCS as determinants of cisplatin sensitivity.

The development of resistance to cisplatin (cDDP) is commonly accompanied by reduced drug uptake or increased efflux. Previous studies in yeast and murine embryonic fibroblasts have reported that the copper (Cu) transporters and chaperones participate in the uptake, efflux, and intracellular distribution of cDDP. However, there is conflicting data from studies in human cells.

Cellular Delivery of Nanoparticles Revealed with Combined Optical and Isotopic Nanoscopy.

Direct polymerization of an oxaliplatin analogue was used to reproducibly generate amphiphiles in one pot, which consistently and spontaneously self-assemble into well-defined nanoparticles (NPs). Despite inefficient drug leakage in cell-free assays, the NPs were observed to be as cytotoxic as free oxaliplatin in cell culture experiments. We investigated this phenomenon by super-resolution fluorescence structured illumination microscopy (SIM) and nanoscale secondary ion mass spectrometry (NanoSIMS).

The copper transporter 1 (CTR1) is required to maintain the stability of copper transporter 2 (CTR2).

Mammalian cells have two influx Cu transporters that form trimers in membranes. CTR1 is the high affinity transporter that resides largely in the plasma membrane, and CTR2 is the low affinity transporter that is primarily associated with vesicular structures inside the cell. The major differences between CTR1 and CTR2 are that CTR1 contains a HIS/MET-rich domain N-terminal of the METS that participate in the first two stacked rings that form the pore, and a longer C-terminal tail that includes a Cu binding HIS-CYS-HIS (HCH) motif right at the end.

Cisplatin inhibits MEK1/2.

Cisplatin (cDDP) is known to bind to the CXXC motif of proteins containing a ferrodoxin-like fold but little is known about its ability to interact with other Cu-binding proteins. MEK1/2 has recently been identified as a Cu-dependent enzyme that does not contain a CXXC motif. We found that cDDP bound to and inhibited the activity of recombinant MEK1 with an IC50 of 0.

A tumor-penetrating peptide enhances circulation-independent targeting of peritoneal carcinomatosis.

Peritoneal carcinomatosis is a major source of morbidity and mortality in patients with advanced abdominal neoplasms. Intraperitoneal chemotherapy (IPC) is an area of intense interest given its efficacy in ovarian cancer. However, IPC suffers from poor drug penetration into peritoneal tumors.

Integrin αV modulates the cellular pharmacology of copper and cisplatin by regulating expression of the influx transporter CTR1.

The αV integrin is expressed in most cancer cells where it regulates a diverse array of cellular functions essential to the initiation, progression and metastasis of solid tumors. However, little is known about how αV integrin modulates cellular sensitivity to chemotherapeutic agents, particularly the platinum drugs. In this study, we found that down-regulation of αV sensitized human M21 cells to cisplatin (cDDP) through up-regulation of the copper influx transporter CTR1.

Claudin-4 controls the receptor tyrosine kinase EphA2 pro-oncogenic switch through β-catenin.

Background: The EphA2 receptor, which is expressed in many types of cancer, is activated by two different mechanisms. Activation by engagement with one of its ephrin ligands is anti-oncogenic whereas phosphorylation of S897 by AKT increases migration, invasion and metastasis. Down-regulation of claudin-4 (CLDN4) produces a loss of E-cadherin and increased β-catenin signaling and a phenotype similar to that produced by oncogenic activation of EphA2, suggesting that CLDN4 may serve to restrain the pro-oncogenic signaling of EphA2.