Discovery of allosteric regulators with clinical potential to stabilize alpha-L-iduronidase in mucopolysaccharidosis type I.

Mucopolysaccharidosis type I (MPS I) is an inherited lysosomal disease caused by lowered activity of the enzyme alpha-L-iduronidase (IDUA). Current therapeutic options show limited efficacy and do not treat some important aspects of the disease. Therefore, it may be advantageous to identify strategies that could improve the efficacy of existing treatments. Pharmacological chaperones are small molecules that protect proteins from degradation, and their use in combination with enzyme replacement therapy (ERT) has been proposed as an alternative therapeutic strategy. Using the SEE-Tx® proprietary computational drug discovery platform, a new allosteric ligand binding cavity in IDUA was identified distal from the active site. Virtual high-throughput screening of approximately 5 million compounds using the SEE-Tx® docking platform identified a subset of small molecules that bound to the druggable cavity and functioned as novel allosteric chaperones of IDUA. Experimental validation by differential scanning fluorimetry showed an overall hit rate of 11.4%. Biophysical studies showed that one exemplary hit molecule GT-01803 bound to (Kd = 22 µM) and stabilized recombinant human IDUA (rhIDUA) in a dose-dependent manner. Co-administration of rhIDUA and GT-01803 increased IDUA activity in patient-derived fibroblasts. Preliminary in vivo studies have shown that GT-01803 improved the pharmacokinetic (PK) profile of rhIDUA, increasing plasma levels in a dose-dependent manner. Furthermore, GT-01803 also increased IDUA enzymatic activity in bone marrow tissue, which benefits least from standard ERT. Oral bioavailability of GT-01803 was found to be good (50%). Overall, the discovery and validation of a novel allosteric chaperone for rhIDUA presents a promising strategy to enhance the efficacy of existing treatments for MPS I. The compound's ability to increase rhIDUA activity in patient-derived fibroblasts and its good oral bioavailability underscore its potential as a potent adjunct to ERT, particularly for addressing aspects of the disease less responsive to standard treatment.

Inhibition of vascular calcification by inositol phosphates derivatized with ethylene glycol oligomers.

Myo-inositol hexakisphosphate (IP6) is a natural product known to inhibit vascular calcification (VC), but with limited potency and low plasma exposure following bolus administration. Here we report the design of a series of inositol phosphate analogs as crystallization inhibitors, among which 4,6-di-O-(methoxy-diethyleneglycol)-myo-inositol-1,2,3,5-tetrakis(phosphate), (OEG2)2-IP4, displays increased in vitro activity, as well as more favorable pharmacokinetic and safety profiles than IP6 after subcutaneous injection. (OEG2)2-IP4 potently stabilizes calciprotein particle (CPP) growth, consistently demonstrates low micromolar activity in different in vitro models of VC (i.e., human serum, primary cell cultures, and tissue explants), and largely abolishes the development of VC in rodent models, while not causing toxicity related to serum calcium chelation. The data suggest a mechanism of action independent of the etiology of VC, whereby (OEG2)2-IP4 disrupts the nucleation and growth of pathological calcification.

A placebo-controlled efficacy study of the intravesical immunomodulators TMX-101 and TMX-202 in an orthotopic bladder cancer rat model.

PURPOSE: TMX-101 and TMX-202 are formulations of toll-like receptor 7 (TLR-7) agonists, under investigation for the treatment of urothelial carcinoma. Our goal was to evaluate the efficacy of intravesical instillations of TMX-101 or TMX-202 in an orthotopic bladder cancer rat model. METHODS: Four groups of 14 rats received an instillation with isogenic AY-27 tumor cells on day 0, starting tumor development. On day 2 and 5, the rats were treated with an intravesical instillation of TMX-101 0.1%, TMX-202 0.38%, vehicle solution or NaCl. On day 12 the rats were sacrificed and the bladders were evaluated histopathologically. RESULTS: No signs of toxicity were seen. The number of tumor-positive rats was 11 of 14 (79%) in the vehicle control group and in the NaCl control group, versus 9 of 14 (64%) in the TMX-101-treated group, and 8 of 14 (57%) in the TMX-20-treated group. The difference between tumor-bearing rats in the treated and control groups was not significant (p = 0.12). Bladder weight was significantly lower for TMX-202-treated rats compared to vehicle (p = 0.005). CONCLUSIONS: TMX-101 and TMX-202 are TLR-7 agonists with antitumor activity. Treatment with TMX-101 and TMX-202 resulted in less tumor-bearing rats compared to vehicle or saline control groups, although not statistically significant. In this aggressive bladder cancer model, a lower number of tumor-positive rats after treatment with TLR-7 agonists indicates activity for the treatment of non-muscle invasive bladder cancer.

Pharmacokinetics and pharmacodynamics of intravesical and intravenous TMX-101 and TMX-202 in a F344 rat model.

OBJECTIVES: To evaluate and compare the pharmacokinetic and pharmacodynamic properties of 2 investigational Toll-like receptor 7 agonists, TMX-101, and TMX-202 after intravenous and intravesical administration in a rat model. TLR-7 agonists are successfully used as topical treatment for various (pre)malignant skin lesions and are now under investigation as intravesical therapy for non-muscle-invasive bladder cancer. METHODS: Rats received an intravesical instillation with TMX-101, TMX-202, or vehicle. Additionally 2 groups of rats received an intravenous injection with TMX-101 or TMX-202. Blood sampling was performed at different time points, including pre-exposure and postexposure to determine the plasma concentrations of study drugs for pharmacokinetic and pharmacodynamic analyses and to determine the plasma concentrations of cytokines (IL-2, IL-6, and TNF-α). RESULTS: We observed no signs of toxicity after intravesical or intravenous administration. There was a limited dose dependent systemic uptake of TMX-101 and TMX-202 after intravesical administration. The systemic uptake of TMX-202 after intravesical instillation was 25 times lower compared to TMX-101. CONCLUSIONS: This in vivo study confirms the safety of intravesical TMX-101 and TMX-202 administration, with TMX-202 showing lower systemic uptake. TMX-202 has a larger molecule-mass compared to TMX-101, and it may therefore have a favorable safety profile when treating patients with non-muscle-invasive bladder cancer intravesically.

Potential of PEGylated Toll-Like Receptor 7 Ligands for Controlling Inflammation and Functional Changes in Mouse Models of Asthma and Silicosis.

Prior investigations show that signaling activation through pattern recognition receptors can directly impact a number of inflammatory lung diseases. While toll-like receptor (TLR) 7 agonists have raised interest for their ability to inhibit allergen-induced pathological changes in experimental asthma conditions, the putative benefit of this treatment is limited by adverse effects. Our aim was to evaluate the therapeutic potential of two PEGylated purine-like compounds, TMX-302 and TMX-306, characterized by TLR7 partial agonistic activity; therefore, the compounds are expected to induce lower local and systemic adverse reactions. In vitro approaches and translation to murine models of obstructive and restrictive lung diseases were explored. In vitro studies with human PBMCs showed that both TMX-302 and TMX-306 marginally affects cytokine production as compared with equivalent concentrations of the TLR7 full agonist, TMX-202. The PEGylated compounds did not induce monocyte-derived DC maturation or B cell proliferation, differently from what observed after stimulation with TMX-202. Impact of PEGylated ligands on lung function and inflammatory changes was studied in animal models of acute lung injury, asthma, and silicosis following Lipopolysaccharide (LPS), allergen (ovalbumin), and silica inhalation, respectively. Subcutaneous injection of TMX-302 prevented LPS- and allergen-induced airway hyper-reactivity (AHR), leukocyte infiltration, and production of pro-inflammatory cytokines in the lung. However, intranasal instillation of TMX-302 led to neutrophil infiltration and failed to prevent allergen-induced AHR, despite inhibiting leukocyte counts in the BAL. Aerosolized TMX-306 given prophylactically, but not therapeutically, inhibited pivotal asthma features. Interventional treatment with intranasal instillation of TMX-306 significantly reduced the pulmonary fibrogranulomatous response and the number of silica particles in lung interstitial space in silicotic mice. These findings highlight the potential of TMX-306, emphasizing its value in drug development for lung diseases, and particularly silicosis.

Monocyte targeting and activation by cationic liposomes formulated with a TLR7 agonist.

OBJECTIVES: Monocytes are one of the major phagocytic cells that patrol for invading pathogens, and upon activation, differentiate into macrophages or antigen-presenting dendritic cells (DCs) capable of migrating to lymph nodes eliciting an adaptive immune response. The key role in regulating adaptive immune responses has drawn attention to modulate monocyte responses therapeutically within cancer, inflammation and infectious diseases. We present a technology for targeting of monocytes and delivery of a toll-like receptor (TLR) agonist in fresh blood using liposomes with a positively charged surface chemistry. METHODS: Liposomes were extruded at 100 nm, incubated with fresh blood, followed by leukocyte analyses by FACS. Liposomes with and without the TLR7 agonist TMX-202 were incubated with fresh blood, and monocyte activation measured by cytokine secretion by ELISA and CD14 and DC-SIGN expression. RESULTS: The liposomes target monocytes specifically over lymphocytes and granulocytes in human whole blood, and show association with 75 - 95% of the monocytes after 1 h incubation. Formulations of TMX-202 in cationic liposomes were potent in targeting and activation of monocytes, with strong induction of IL-6 and IL-12p40, and differentiation into CD14(+) and DC-SIGN+ DCs. CONCLUSION: Our present liposomes selectively target monocytes in fresh blood, enabling delivery of TLR7 agonists to the intracellular TLR7 receptor, with subsequent monocyte activation and boost in secretion of proinflammatory cytokines. We envision this technology as a promising tool in future cancer immunotherapy.

Inhibition of keratinocyte proliferation by phospholipid-conjugates of a TLR7 ligand in a Myc-induced hyperplastic actinic keratosis model in the absence of systemic side effects.

BACKGROUND: The Toll-like receptor 7 (TLR7) activator imiquimod (IMQ) is safe and effective in treating actinic keratosis; however, an intermittent treatment regimen is necessary because of excessive local reactions. OBJECTIVES: To evaluate in vitro potency, pharmacodynamics/pharmacokinetics, toxicity and efficacy in vivo of the newly developed TLR7 ligand-phospholipid conjugate, TMX-202, in a gel formulation. MATERIAL AND METHODS: The effects of TMX-202 were assessed both in vitro on a murine macrophage cell line and in primary bone marrow-derived dendritic cells and in vivo on mice (C57BL/6-wild type, Myd88(-/-) and Tlr7(-/-)). RESULTS: TMX-202 was more potent than IMQ in vitro using murine and human cells. In contrast, in vivo it showed less systemic pro-inflammatory activity and better safety than IMQ. Moreover, the TMX-202 gel formulation exhibited at least comparable efficacy to Aldara in a mouse model for skin proliferative diseases. CONCLUSION: TMX-202 is safe and efficacious without causing excessive adverse effects, suggesting that it may be an alternative to Aldara for the treatment of proliferative skin conditions.

Pharmacokinetics and toxicity of intravesical TMX-101: a preclinical study in pigs.

OBJECTIVE: • To study the pharmacokinetic and toxicity profile of intravesically administered TMX-101, with its active ingredient R-837, a synthetic Toll-like receptor (TLR)-7 agonist, in a pig model. MATERIALS AND METHODS: • TLR-7 expression was determined by immunohistochemistry in human and pig bladder tissue. • Four groups of six pigs received a 1-h intravesical instillation with R-837 of different formulations. • Pharmacokinetic analysis was performed on plasma. Toxicity evaluation included monitoring the well-being of the animals, peripheral blood cell counts, and interleukin-6 and creatinine measurements. Urine was collected for R-837 measurement and dipstick analysis. • In total, three pigs per group were sacrificed 24 h post-treatment, and the remaining animals were sacrificed after 1 week. Histopathological examination of the bladder wall was performed. RESULTS: • TLR-7 was homogeneously expressed in human and pig urothelium. • R-837 and vehicle were well tolerated without deterioration in animal well-being. • Systemic R-837 absorption was low. • Mean maximum plasma concentration of R-837 differed depending on the formulation. Post-treatment, plasma levels were negligible at 24 h. • Histopathological examination of the bladders did not show significant abnormalities, apart from the intended inflammatory reaction in the R-837 treated groups. CONCLUSION: • Intravesically administered R-837 in pigs, which showed a similar TLR-7 distribution in bladder tissue as humans, is well tolerated and causes no bladder wall toxicity, and formulations with poloxamer and hydroxypropyl-ß-cyclodextrin showed less systemic absorption.

Intravesical Toll-like receptor 7 agonist R-837: optimization of its formulation in an orthotopic mouse model of bladder cancer.

OBJECTIVE: To study the immune response caused by the intravesical administration of the immunomodulator R-837 in various formulations and to estimate its therapeutic potential for bladder cancer. METHODS: Female C57BL/6 mice were intravesically treated with different formulations of R-837, a Toll-like receptor 7 agonist used for treating genital warts and skin malignancy. The tested formulation mixtures contained different ratios of lactic acid, a thermosensitive poloxamer polymer (Lutrol F127) and 2-(hydroxypropyl)-beta-cyclodextrin (HPbetaCD). Induction of tumor necrosis factor alpha (TNFalpha) and keratinocyte-derived chemokine (KC) was analyzed by Luminex microbeads assay. The therapeutic potential of intravesical administration of R-837 was assessed in an orthotopic, syngeneic mouse model of bladder cancer using MB49 cells. RESULTS: Intravesical administration of R-837 in lactic acid alone induced systemic and bladder TNFalpha and KC in a dose-dependent manner. Formulations including poloxamer decreased systemic absorption of R-837 and significantly reduced systemic and local induction of KC. Addition of HPbetaCD in the poloxamer formulation particularly reversed levels of systemic and local levels of TNFalpha and KC. Histological examination showed that poloxamer-HPbetaCD formulation allowed infiltration of mononuclear cells into urothelium and lamina propria. In studies using orthotopic mouse bladder cancer, the tumor loads in R-837-treated mice were significantly lower than those in vehicle-treated or non-treated mice. CONCLUSION: The optimized poloxamer-HPbetaCD formulation of R-837 shows therapeutic potential for bladder cancer while avoiding adverse side-effects.

Pressor response to intravenous tyramine in healthy subjects after safinamide, a novel neuroprotectant with selective, reversible monoamine oxidase B inhibition.

Safinamide is a novel neuroprotectant combining sodium and calcium channel blocking properties with selective, reversible monoamine oxidase type B (MAO B) inhibition. Phase 1 studies have demonstrated that in healthy volunteers, the ED50 (a dose that inhibits enzyme activity by 50% in 50% of treated subjects) for MAO B inhibition is 87.5 microg/kg/day orally, and that no MAO A inhibition occurs after 10-mg/kg oral dosing. To assess the risk of inducing the "cheese effect," the effect of safinamide and placebo on the pressor response to tyramine was investigated in a group of healthy male volunteers. The study was an open, single-dose placebo-controlled trial with the 2 treatments in sequence. An increase of 30 mm Hg systolic blood pressure was obtained by intravenous tyramine administered by 0.5-mg incremental boluses injected at 15-minute intervals. The amount of tyramine necessary to achieve such a blood pressure increase was the same after the safinamide 2-mg/kg oral load compared with placebo. These results suggest that dietary restrictions for food with high tyramine content should not be required under safinamide treatment.