A first-in-human phase 0 clinical study of RNA interference-based spherical nucleic acids in patients with recurrent glioblastoma.

Glioblastoma (GBM) is one of the most difficult cancers to effectively treat, in part because of the lack of precision therapies and limited therapeutic access to intracranial tumor sites due to the presence of the blood-brain and blood-tumor barriers. We have developed a precision medicine approach for GBM treatment that involves the use of brain-penetrant RNA interference-based spherical nucleic acids (SNAs), which consist of gold nanoparticle cores covalently conjugated with radially oriented and densely packed small interfering RNA (siRNA) oligonucleotides. On the basis of previous preclinical evaluation, we conducted toxicology and toxicokinetic studies in nonhuman primates and a single-arm, open-label phase 0 first-in-human trial (NCT03020017) to determine safety, pharmacokinetics, intratumoral accumulation and gene-suppressive activity of systemically administered SNAs carrying siRNA specific for the GBM oncogene Bcl2Like12 (Bcl2L12). Patients with recurrent GBM were treated with intravenous administration of siBcl2L12-SNAs (drug moniker: NU-0129), at a dose corresponding to 1/50th of the no-observed-adverse-event level, followed by tumor resection. Safety assessment revealed no grade 4 or 5 treatment-related toxicities. Inductively coupled plasma mass spectrometry, x-ray fluorescence microscopy, and silver staining of resected GBM tissue demonstrated that intravenously administered SNAs reached patient tumors, with gold enrichment observed in the tumor-associated endothelium, macrophages, and tumor cells. NU-0129 uptake into glioma cells correlated with a reduction in tumor-associated Bcl2L12 protein expression, as indicated by comparison of matched primary tumor and NU-0129-treated recurrent tumor. Our results establish SNA nanoconjugates as a potential brain-penetrant precision medicine approach for the systemic treatment of GBM.

Synthesis, Physicochemical, and Biological Evaluation of Spherical Nucleic Acids for RNAi-Based Therapy in Glioblastoma.

Spherical nucleic acids (SNAs), an emerging class of gene-regulatory nanotherapeutics, typically consist of a nanoparticle core densely functionalized with a shell of radially oriented small interfering RNA (siRNA) oligonucleotides, microRNA (miRNA) mimics, or antagonists. The unique three-dimensional SNA structure regardless of core type (e.g., gold or lipids) confers heightened resistance to nuclease-mediated degradation and accounts for robust cell entry in the absence of auxiliary transfection vehicles. In murine models of glioblastoma (GBM), the most aggressive and prevalent form of malignant brain cancers, systemically administered siRNA or miRNA-conjugated SNAs penetrated blood-brain and blood-tumor barriers and robustly reduced tumor progression. Here, we describe methods for the synthesis and physicochemical and biological characterization of SNA gene silencing effects in glioma cells in vitro and in patient-derived xenograft models in vivo.

Cancer-associated mutation and beyond: The emerging biology of isocitrate dehydrogenases in human disease.

Isocitrate dehydrogenases (IDHs) are critical metabolic enzymes that catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (αKG), NAD(P)H, and CO2. IDHs epigenetically control gene expression through effects on αKG-dependent dioxygenases, maintain redox balance and promote anaplerosis by providing cells with NADPH and precursor substrates for macromolecular synthesis, and regulate respiration and energy production through generation of NADH. Cancer-associated mutations in IDH1 and IDH2 represent one of the most comprehensively studied mechanisms of IDH pathogenic effect. Mutant enzymes produce (R)-2-hydroxyglutarate, which in turn inhibits αKG-dependent dioxygenase function, resulting in a global hypermethylation phenotype, increased tumor cell multipotency, and malignancy. Recent studies identified wild-type IDHs as critical regulators of normal organ physiology and, when transcriptionally induced or down-regulated, as contributing to cancer and neurodegeneration, respectively. We describe how mutant and wild-type enzymes contribute on molecular levels to disease pathogenesis, and discuss efforts to pharmacologically target IDH-controlled metabolic rewiring.

IDH3α regulates one-carbon metabolism in glioblastoma.

Mutation or transcriptional up-regulation of isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) promotes cancer progression through metabolic reprogramming and epigenetic deregulation of gene expression. Here, we demonstrate that IDH3α, a subunit of the IDH3 heterotetramer, is elevated in glioblastoma (GBM) patient samples compared to normal brain tissue and promotes GBM progression in orthotopic glioma mouse models. IDH3α loss of function reduces tricarboxylic acid (TCA) cycle turnover and inhibits oxidative phosphorylation. In addition to its impact on mitochondrial energy metabolism, IDH3α binds to cytosolic serine hydroxymethyltransferase (cSHMT). This interaction enhances nucleotide availability during DNA replication, while the absence of IDH3α promotes methionine cycle activity, S-adenosyl methionine generation, and DNA methylation. Thus, the regulation of one-carbon metabolism via an IDH3α-cSHMT signaling axis represents a novel mechanism of metabolic adaptation in GBM.

Novel Trifluoromethylated Enobosarm Analogues with Potent Antiandrogenic Activity In Vitro and Tissue Selectivity In Vivo.

Prostate cancer often develops antiandrogen resistance, possibly via androgen receptor (AR) mutations, which change antagonists to agonists. Novel therapies with increased anticancer activity, while overcoming current drug resistance are urgently needed. Enobosarm has anabolic effects on muscle and bone while having no effect on the prostate. Here, we describe the activity of novel chemically modified enobosarm analogues. The rational addition of bis-trifluoromethyl groups into ring B of enobosarm, profoundly modified their activity, pharmacokinetic and tissue distribution profiles. These chemical structural modifications resulted in an improved AR binding affinity-by increasing the molecular occupational volume near helix 12 of AR. In vitro, the analogues SK33 and SK51 showed very potent antiandrogenic activity, monitored using LNCaP/AR-Luciferase cells where growth, PSA and luciferase activity were used as AR activity measurements. These compounds were 10-fold more potent than bicalutamide and 100-fold more potent than enobosarm within the LNCaP model. These compounds were also active in LNCaP/BicR cells with acquired bicalutamide resistance. In vivo, using the AR-Luc reporter mice, these drugs showed potent AR inhibitory activity in the prostate and other AR-expressing tissues, e.g., testes, seminal vesicles, and brain. These compounds do not inhibit AR activity in the skeletal muscle, and spleen, thus indicating a selective tissue inhibitory profile. These compounds were also active in vivo in the Pb-Pten deletion model. SK33 and SK51 have significantly different and enhanced activity profiles compared with enobosarm and are ideal candidates for further development for prostate cancer therapy with potentially fewer side effects. Mol Cancer Ther; 17(9); 1846-58. ©2018 AACR.