The Wnt/β-catenin pathway is among the most frequently altered signaling networks in human cancers. Despite decades of preclinical and clinical research, efficient therapeutic targeting of Wnt/β-catenin has been elusive. RNA interference (RNAi) technology silences genes at the mRNA level, and therefore can be applied to previously-undruggable targets. Lipid nanoparticles (LNPs) represent an elegant solution for delivery of RNAi-triggering oligonucleotides to disease-relevant tissues, but have been mostly restricted to applications in the liver. In this study, we systematically tuned the composition of a prototype LNP to enable tumor-selective delivery of a Dicer-substrate siRNA (DsiRNA) targeting CTNNB1, the gene encoding β-catenin. This formulation, termed EnCore-R, demonstrated pharmacodynamic activity in subcutaneous human tumor xenografts, orthotopic patient-derived xenograft (PDx) tumors, disseminated hematopoietic tumors, genetically induced primary liver tumors, metastatic colorectal tumors, murine metastatic melanoma. DsiRNA delivery was homogeneous in tumor sections, selective over normal liver and independent of apolipoprotein-E binding. Significant tumor growth inhibition was achieved in Wnt-dependent colorectal and hepatocellular carcinoma models, but not in Wnt-independent tumors. Finally, no evidence of accelerated blood clearance or sustained liver transaminase elevation was observed after repeated dosing in nonhuman primates. These data support further investigation to gain mechanistic insight, optimize dose regimens and identify efficacious combinations with standard-of-care therapeutics.

Cannabinoids both increase urine output and decrease urinary frequency in human subjects. However, these effects have not been systematically evaluated in intact mice, a species commonly used to evaluate the effects of novel cannabinoids. The present studies investigated whether cannabinoid agonists reliably produce diuresis in mice at doses comparable to those that produce other cannabinoid effects and, further, identified the receptors that may mediate these effects. Diuretic effects were measured in male mice over 6 h. In some studies, urine was collected and analyzed for electrolyte measurements. In other studies, agonist injections were preceded by pretreatment with cannabinoid CB1 or CB2 selective antagonists, including a peripherally constrained CB1 antagonist. Companion studies evaluated the antinociceptive effects of the cannabinoid agonists in a warm-water tail-withdrawal assay. Direct-acting cannabinoid CB1 agonists Δ9- tetrahydrocannabinol (THC), WIN 55,212, AM7418 and AM4054, had biphasic effects on diuresis, with peak diuretic effects occurring at lower doses than peak antinociceptive effects. Cannabinoid diuresis was similar to κ-opioid agonist–induced diuresis in terms of maximum effects with only moderate loss of Na+. Antagonism studies indicate that the diuretic effects of cannabinoids are CB1-receptor mediated, with both central and peripheral components. These findings suggest that mice may provide a model for understanding the mixed effects of marijuana on urine output, as described in clinical studies, and aid in the development of targeted cannabinoid based therapies for bladder dysfunction.

Colorectal carcinomas (CRC) harbor well-defined genetic abnormalities including aberrant activation of Wnt/β-catenin and MAPK pathways, often simultaneously. While the MAPK pathway can be targeted using potent small molecule drugs, including BRAF and MEK inhibitors, β-catenin inhibition has been historically challenging. RNA interference (RNAi) approaches have advanced to the stage of clinical viability, and are especially well-suited for transcriptional modulators such as β-catenin. In this study, we report therapeutic effects of combined targeting of these pathways with pharmacological agents. Using a recently-described tumor-selective nanoparticle containing a β-catenin-targeting RNAi trigger, in combination with the FDA-approved MEK inhibitor (MEKi) trametinib, we demonstrate synergistic tumor growth inhibition in in vivo models of CRC, melanoma and hepatocellular carcinoma. At dose levels which were insufficient to significantly impact tumor growth as monotherapies, combination regimens resulted in synergistic efficacy and complete tumor growth inhibition. Importantly, dual MEKi/RNAi therapy dramatically improved survival of mice bearing CRC liver metastases. In addition, pharmacological silencing of β-catenin mRNA was effective against tumors which are inherently resistant or which acquire drug-induced resistance to trametinib. These results provide a strong rationale for clinical evaluation of this dual-targeting approach for cancers harboring Wnt/β-catenin and MAPK pathway mutations.

Daily treatment with cannabinoids results in tolerance to many, but not all, of their behavioral and physiologic effects. The present studies investigated the effects of 7-day exposure to 10 mg/kg daily of D 9-tetrahydrocannabinol (THC) on the diuretic and antinociceptive effects of THC and the synthetic cannabinoid AM4054. Comparison studies determined diuretic responses to the k-opioid agonist U50,488 and furosemide. After determination of control dose-response functions, mice received 10 mg/kg daily of THC for 7 days, and dose-response functions were re-determined 24 hours, 7 days, or 14 days later. THC and AM4054 had biphasic diuretic effects under control conditions with maximum effects of 30 and 35 ml/kg of urine, respectively. In contrast, antinociceptive effects of both drugs increased monotonically with dose to .90% of maximal possible effect. Treatment with THC produced 9-and 7-fold rightward shifts of the diuresis and antinociception doseresponse curves for THC and, respectively, 7-and 3-fold rightward shifts in the AM4054 dose-response functions. U50,488 and furosemide increased urine output to .35 ml/kg under control conditions. The effects of U50,488 were attenuated after 7-day treatment with THC, whereas the effects of furosemide were unaltered. Diuretic effects of THC and AM4054 recovered to near-baseline levels within 14 days after stopping daily THC injections, whereas tolerance to the antinociceptive effects persisted longer than 14 days. The tolerance induced by 7-day treatment with THC was accompanied by a 55% decrease in the B max value for cannabinoid receptors (CB1). These data indicate that repeated exposure to THC produces similar rightward shifts in the ascending and descending limbs of cannabinoid diuresis doseeffect curves and to antinociceptive effects while resulting in a flattening of the U50,488 diuresis dose-effect function.