PLL-g-PEG Polymer Inhibits Antibody-Drug Conjugate Uptake into Human Corneal Epithelial Cells In Vitro.

Purpose: Antibody-drug conjugates (ADCs) are a relatively recent advance in the delivery of chemotherapeutics that improve targeting of cytotoxic agents. However, despite their antitumor activity, severe ocular adverse effects, including vision loss, have been reported for several ADCs. The nonspecific uptake of ADCs into human corneal epithelial cells (HCECs) and their precursors via macropinocytosis has been proposed to be the primary mechanism of ocular toxicity. In this study, we evaluated the ability of a novel polymer, poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG), to decrease the ADC rituximab-mc monomethylauristatin F (MMAF) (RIX) uptake into human corneal epithelial (HCE-T) cells. Methods: HCE-T cells were exposed to increasing concentrations of RIX to determine inhibition of cell proliferation. HCE-T cells were treated with PLL-g-PEG, the macropinocytosis inhibitor 5-(N-ethyl-N-isopropyl) amiloride (EIPA), or vehicle. After 30 min of incubation, RIX was added. ADC was detected by fluorescent anti-human immunoglobulin G and fluorescently conjugated dextran as viewed by microscopy. Results: RIX caused dose-dependent inhibition of HCE-T cell proliferation. EIPA significantly reduced RIX uptake and decreased macropinocytosis as assessed by direct quantification of RIX using a fluorescently conjugated anti-human antibody as well as quantification of macropinocytosis using fluorescently conjugated dextran. PLL-g-PEG resulted in a dose-dependent inhibition of RIX uptake with half-maximal inhibitory concentrations of 0.022%-0.023% PLL-g-PEG. Conclusion: The data show PLL-g-PEG to be a potent inhibitor of RIX uptake by corneal epithelial cells and support its use as a novel therapeutic approach for the prevention of ocular adverse events associated with ADC therapy.

The future of HIV prevention: prospects for an effective anti-HIV microbicide.

Topical microbicides are self-administered products for prevention of HIV transmission, and they present one of the most promising strategies for combating the HIV-AIDS epidemic. The development of microbicides is a long and complicated process, with many hurdles that are unique to this class of product, including challenges in product design, in the conduct and design of clinical trials, and in obtaining licensure of a new class of products intended for use almost exclusively in developing countries. Once they have been registered, there are additional challenges to the marketing and distribution of microbicides. An overview of the types of microbicide currently in development, and a summary of the issues and the approaches being taken to address them, are provided.

Early-Stage Formulation Considerations.

When a drug candidate-i.e., a new chemical entity (NCE) or new molecular entity (NME)-is discovered, there is a requirement to identify a vehicle for in vitro and/or in vivo evaluation to assess the activity and/or toxicity of the compound (here we refer to the biologically active compound as the active pharmaceutical ingredient: API). Ideally, this vehicle will not impart any biological activity or any toxicity that would mask or confound the effects of the API. At this early stage in development, and given the high attrition rates of drug candidates in discovery, it does not make sense to fully characterize the API-speed and cost are generally the driving factors. This chapter provides guidance for the development of early-stage test articles (i.e., drug products containing APIs intended to be used for the in vitro and/or in vivo evaluation) and not necessarily formulations that are intended to progress into clinical evaluation. © 2017 by John Wiley & Sons, Inc.

Novel formulation of glycerin 1% artificial tears extends tear film break-up time compared with Systane lubricant eye drops.

PURPOSE: To evaluate the effectiveness of glycerin 1% formulated with the novel and proprietary ophthalmic excipient poly(l-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) (Eyeon Particle Sciences LLC) in extending tear film break-up time (TFBUT) compared with a market-leading artificial tear formulation of propylene glycol (0.3%) and polyethylene glycol (0.4%) (Systane(®) Lubricant Eye Drops; Alcon, Fort Worth, TX). METHODS: This prospective single-center, single visit, randomized, double-masked exploratory trial compared the new formulation and Systane using TFBUT. Noninvasive break-up time (NIBUT) was measured in subjects with asymptomatic to mild (n=5), mild to moderate (n=5), and moderate to severe (n=6) dry eye disease using the TearscopePlus™ at pre-instillation and again at 15, 30, 60, and 120 min after instillation. Fluorescein break-up time (FBUT) was measured at 120 min after instillation. RESULTS: At 15 min (N=16), the new formulation extended mean NIBUT by 14.67 s (P=0.05) compared with 7.40 s (P=0.34) by Systane. The new formulation had a mean FBUT of 4.92 s longer than Systane at 120 min (P=0.12). With outliers removed (N=13), the difference between the mean NIBUT change from baseline for the new formulation and Systane at 120 min was statistically significant (P=0.03). CONCLUSIONS: This study demonstrates that PLL-g-PEG as a polymer excipient in artificial tears is effective in improving the performance of demulcents to significantly prolong NIBUT at 15 min, and that protective activity from this artificial tear product for 2 or more hours after eye drop instillation is possible.

Ethylene vinyl acetate intravaginal rings for the simultaneous delivery of the antiretroviral UC781 and contraceptive levonorgestrel.

Ethylene vinyl acetate intravaginal rings (IVRs) were prepared by hot-melt compounding and injection moulding. The IVRs contained various levels of the antiretroviral drug UC781 and the contraceptive hormone levonorgestrel. The IVRs were assayed for drug content and related substances, characterized for physical properties, in vitro drug-elution kinetics, photostress stability, and 3-month accelerated storage stability under ICH conditions. UC781 degrades on exposure to light and during thermal processing. UC22 is the major degradant of UC781. Drug release rates were proportional to drug loading, independent of the other drug in combination with IVRs, and were stable for 3 M at 40°C/75% RH despite changes in the appearance of the IVRs which is tentatively ascribed to crystallization of UC781 at or near the surface of the IVRs. The behavior of UC781 poses a substantial barrier to the commercial development of these IVRs.

Carnauba wax nanoparticles enhance strong systemic and mucosal cellular and humoral immune responses to HIV-gp140 antigen.

Induction of humoral responses to HIV at mucosal compartments without inflammation is important for vaccine design. We developed charged wax nanoparticles that efficiently adsorb protein antigens and are internalized by DC in the absence of inflammation. HIV-gp140-adsorbed nanoparticles induced stronger in vitro T-cell proliferation responses than antigen alone. Such responses were greatly enhanced when antigen was co-adsorbed with TLR ligands. Immunogenicity studies in mice showed that intradermal vaccination with HIV-gp140 antigen-adsorbed nanoparticles induced high levels of specific IgG. Importantly, intranasal immunization with HIV-gp140-adsorbed nanoparticles greatly enhanced serum and vaginal IgG and IgA responses. Our results show that HIV-gp140-carrying wax nanoparticles can induce strong cellular/humoral immune responses without inflammation and may be of potential use as effective mucosal adjuvants for HIV vaccine candidates.

Non-aqueous silicone elastomer gels as a vaginal microbicide delivery system for the HIV-1 entry inhibitor maraviroc.

Aqueous semi-solid polymeric gels, such as those based on hydroxyethylcellulose (HEC) and polyacrylic acid (e.g. Carbopol®), have a long history of use in vaginal drug delivery. However, despite their ubiquity, they often provide sub-optimal clinical performance, due to poor mucosal retention and limited solubility for poorly water-soluble actives. These issues are particularly pertinent for vaginal HIV microbicides, since many lead candidates are poorly water-soluble and where a major goal is the development of a coitally independent, once daily gel product. In this study, we report the use of a non-aqueous silicone elastomer gel for vaginal delivery of the HIV-1 entry inhibitor maraviroc. In vitro rheological, syringeability and retention studies demonstrated enhanced performance for silicone gels compared with a conventional aqueous HEC gel, while testing of the gels in the slug model confirmed a lack of mucosal irritancy. Pharmacokinetic studies following single dose vaginal administration of a maraviroc silicone gel in rhesus macaques showed higher and sustained MVC levels in vaginal fluid, vaginal tissue and plasma compared with a HEC gel containing the same maraviroc loading. The results demonstrate that non-aqueous silicone gels have potential as a formulation platform for coitally independent vaginal HIV microbicides.

Pharmacokinetic assessment of dapivirine vaginal microbicide gel in healthy, HIV-negative women.

UNLABELLED: To assess the pharmacokinetics of dapivirine in plasma and dapivirine concentrations in cervicovaginal fluids (CVF) and cervicovaginal tissues following vaginal administration of dapivirine microbicide gel in healthy, HIV-negative women for 10 days. A randomized, double-blind, phase I study was conducted at a single research center in South Africa. A total of 18 women used dapivirine gel (0.001%, 0.005%, or 0.02%) once daily on Days 1 and 10 and twice daily on Days 2-9. Pharmacokinetics of dapivirine were assessed in plasma on Days 1 and 10. Dapivirine concentrations were measured in CVF on Days 1 and 10 and in cervicovaginal tissues on Day 10. Safety was evaluated through laboratory tests (hematology, clinical chemistry, and urinalysis), physical examinations, and assessment of adverse events. Plasma concentrations of dapivirine increased over time with gel dose and were greater on Day 10 (C(max) 31 to 471 pg/ml) than Day 1 (C(max) 23 to 80 pg/ml). T(max) was 10-12 h on Day 1, and 9 h on Day 10. Concentrations in CVF generally increased with dose but were highly variable among participants. Mean peak values ranged from 4.6-8.3 × 10(6) pg/ml on Day 1 and from 2.3-20.7 × 10(6) pg/ml on Day 10 across dose groups. Dapivirine was detectable in all tissue biopsies on Day 10 at concentrations of 1.0-356 × 10(3) pg/mg. CONCLUSIONS: Dapivirine was widely distributed throughout the lower genital tract with low systemic absorption when administered in a vaginal gel formulation for 10 consecutive days. The gel was safe and well tolerated.

Concentrations of dapivirine in the rhesus macaque and rabbit following once daily intravaginal administration of a gel formulation of [14C]dapivirine for 7 days.

Dapivirine is a nonnucleoside reverse transcriptase inhibitor being developed as a topical microbicide for the prevention of human immunodeficiency virus infection. The distribution of radioactivity and drug in plasma and in vaginal, cervical, and draining lymph node tissues was investigated after daily application of a vaginal gel formulation of [14C]dapivirine to rhesus macaques. This was preceded by a preliminary study with rabbits. Following the intravaginal administration of [14C]dapivirine ( approximately 0.1 mg/ml [15 microCi/ml]) to rabbits (0.5 ml/day) and macaques (1 ml/day) for 7 days, the dapivirine levels associated with vaginal and cervical tissue samples 1 h after the final dose were high (quantities of microg/g of tissue) and remained detectable at 24 h (mean, >or=2.5 ng/g in rabbits) and 48 h (mean, >80 ng/g in macaques). Radioactivity levels were low in the plasma and very low or unquantifiable in the draining lymph nodes of the macaques. Microautoradiography identified drug-related material (DRM) on the surfaces of the vaginal and cervical tissues of the rabbits and macaques. Although DRM was primarily associated with the outermost layer of shedding cells in rabbits, two animals showed some evidence of small quantities in the mucosal epithelium of the cervix. In macaques, DRM was seen within the keratinized layer of the vaginal epithelium and and was found to extend into the superficial cellular layers, and in at least one animal it appeared to be present in the deepest (germinal) layer of the epithelium and in submucosal tissues. The persistence of biologically significant concentrations of dapivirine in vaginal and cervical tissues for >24 h supports the development of dapivirine as a microbicide for once daily application.

Identification of xanthurenic acid 8-O-beta-D-glucoside and xanthurenic acid 8-O-sulfate as human natriuretic hormones.

Hormonal regulation of salt excretion and water balance by the kidneys is well documented. Before 1961, it was widely believed that the glomerular filtration rate and the steroid hormone aldosterone controlled sodium balance in the body. In 1961, deWardener et al. [de Wardener HE, Mills IH, Clapham WF, Hayter CJ (1961) Clin Sci 21:249-258] showed that when these two variables were controlled, the kidney was still able to increase sodium excretion in response to a salt load. Several lines of evidence argued for a small-molecule signal as a definitive modulator of sodium excretion by the kidney. However, the chemical nature of the suspected natriuretic agent remained unknown. Here we report the identification and natriuretic activity of two closely related small molecules isolated from human urine, xanthurenic acid 8-O-beta-d-glucoside and xanthurenic acid 8-O-sulfate. The two compounds were partially purified by activity-guided fractionation and subsequently identified by using NMR spectroscopic analyses of enriched active fractions. Both compounds caused substantial and sustained (1- to 2-h) natriuresis in rats and no or minimal concomitant potassium excretion. We believe these compounds constitute a class of kidney hormones that also could influence sodium transport in nonkidney tissues given that these tryptophan metabolites presumably represent evolutionarily old structures.

Microbicides for the prevention of HIV infection in women: an overview of recent trials.

PURPOSE OF REVIEW: As the HIV/AIDS pandemic continues, the development of new prevention technologies is urgently needed. Microbicides, products applied to genital mucosal surfaces, are being developed to reduce the transmission of HIV during sexual intercourse. Microbicides have been designed to inhibit HIV from the time the virus enters the genital tract to any of the multiple steps in local virus replication. RECENT FINDINGS: Preclinical research and development of microbicides has led to the advancement of many candidates into human clinical trials. This research has shown that cervicovaginal irritation is an important safety concern and needs to be evaluated carefully and early. New approaches to measuring local irritation are currently under investigation. SUMMARY: Five broad-spectrum microbicides are now being tested in large-scale effectiveness trials to measure their effects on the reduction of HIV incidence. Next-generation candidates, based on highly active antiretroviral drugs, are currently undergoing safety studies. This paper reviews the findings from trials of these products and discusses several challenges that are encountered in the clinical development of microbicides. Although complex and resource intensive, the successful completion of ongoing studies and the initiation of efficacy trials of next-generation candidates are critical to the successful development of a microbicide.