FREDERICK, MD, United States
FREDERICK, MD, United States

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Ham A.S.,Imquest Biosciences | Rohan L.C.,Magee Womens Research Institute | Boczar A.,Imquest Biosciences | Yang L.,Imquest Biosciences | And 2 more authors.
Pharmaceutical Research | Year: 2012

Purpose: Polymeric quick-dissolving films were developed as a solid dosage topical microbicide formulation for the vaginal delivery of the highly potent and non-toxic, dual-acting HIV nonnucleoside reverse transcriptase inhibitor (NNRTI) pyrimidinedione, IQP-0528. Methods: Formulated from approved excipients, a polyvinyl alcohol (PVA) based film was manufactured via solvent casting methods. The film formulations were evaluated based upon quantitative physicochemical evaluations defined by a Target Product Profile (TPP) Results: Films dosed with 0.1% (w/w) of IQP-0528 disintegrated within 10 min with over 50% of drug released and near 100% total drug released after 30 min. The IQP-0528 films were found to be non-toxic in in vitro CEM-SS and PBMC cell-based assays and biologically active with sub-nanomolar efficacy against HIV-1 infection. In a 12 month stability protocol, the IQP-0528 films demonstrated no significant degradation at International Conference on Harmonization (ICH) recommended standard (25°C/65% relative humidity (R.H.)) and accelerated (40°C/75% R.H.) environmental conditions. Conclusions: Based on the above evaluations, a vaginal film formulation has been identified as a potential solid dosage form for the vaginal delivery of the topical microbicide candidate IQP-0528. © 2012 Springer Science+Business Media, LLC.


Mesquita P.M.M.,Yeshiva University | Srinivasan P.,Centers for Disease Control and Prevention | Johnson T.J.,University of Utah | Rastogi R.,University of Utah | And 7 more authors.
Retrovirology | Year: 2013

Background: The limited success of recent HIV topical pre-exposure prophylaxis clinical trials highlights the need for more predictive models of drug efficacy that better simulate what may happen during sexual exposure. To address this gap, we developed complementary in vitro models to evaluate the ability of drugs to retain anti-HIV activity if cells were washed with seminal plasma (simulating what may happen following exposure to ejaculate), and to protect drug-naive T cells (representing newly recruited immune cells) co-cultured with explants that had been pretreated with drug. We focused on tenofovir disoproxil fumarate (TDF), the non-nucleoside reverse transcriptase inhibitors dapivirine (DPV) and IQP-0528, and the entry inhibitors maraviroc (MVC) and the D-peptide chol-PIE-12 trimer (PIE12). Studies were extended to macaques and the ability of cervical biopsies obtained from animals treated with an intravaginal ring formulation of IQP-0528 to protect ex vivo co-cultured T cells was determined. The antiviral activity of cervicovaginal lavage samples against a primary Clade C isolate was also measured and correlated with drug levels.Results: Cells exposed to TDF were equally protected from HIV whether or not the drug-treated cells were washed with medium or seminal plasma prior to challenge. In contrast, several-fold higher concentrations of NNRTIs and entry inhibitors were needed to attain similar levels of HIV inhibition following a wash with seminal plasma. Conversely, the NNRTIs and PIE12, but not TDF or MVC, were effectively transferred from ex vivo treated explants and protected co-cultured T cells. Biopsies obtained from IQP-0528 ring-treated macaques also protected co-cultured T cells with viral inhibition ranging from 42-72%. Antiviral activity correlated with the concentration of drug recovered. Combinations of TDF with IQP-0528 protected in both in vitro models.Conclusions: Together, these models suggest that intracellularly retained drugs such as TDF may protect resident immune cells following coitus but sustained delivery may be required to protect immune cells subsequently recruited into the genital tract. Sustained delivery may also be critical for NNRTIs, which are rapidly transported out of cells and could be lost following sexual intercourse. An ideal approach may be a combination of drugs with complementary bioavailability profiles formulated for sustained delivery. © 2013 Mesquita et al.; licensee BioMed Central Ltd.


Ottosen S.,Santaris Pharma | Parsley T.B.,Imquest Biosciences | Yang L.,Imquest Biosciences | Zeh K.,Santaris Pharma | And 7 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2015

Miravirsen is a β-D-oxy-locked nucleic acid-modified phosphorothioate antisense oligonucleotide targeting the liver-specific microRNA-122 (miR-122). Miravirsen demonstrated antiviral activity against hepatitis C virus (HCV) genotype 1b replicons with a mean 50% effective concentration (EC50) of 0.67 μM. No cytotoxicity was observed up to the highest concentration tested (>320 μM) in different cell culture models, yielding a therapeutic index of >297. Combination studies of miravirsen with interferon α2b, ribavirin, and nonnucleoside (VX-222) and nucleoside (2=-methylcytidine) inhibitors of NS5B, NS5A (BMS-790052), or NS3 (telaprevir) indicated additive interactions. Miravirsen demonstrated broad antiviral activity when tested against HCV replicons resistant to NS3, NS5A, and NS5B inhibitors with less than 2-fold reductions in susceptibility. In serial passage studies, an A4C nucleotide change was observed in the HCV 5= untranslated region (UTR) from cells passaged in the presence of up to 20 μM(40-fold the miravirsen EC50 concentration) at day 72 of passage but not at earlier time points (up to 39 days of passage). Likewise, a C3U nucleotide change was observed in the HCV 5=UTR from subjects with viral rebound after the completion of therapy in a miravirsen phase 2 clinical trial. An HCV variant constructed to contain the A4C change was fully susceptible to miravirsen. A C3U HCV variant demonstrated overall reductions in susceptibility to miravirsen but was fully susceptible to all other anti-HCV agents tested. In summary, miravirsen has demonstrated broad antiviral activity and a relatively high genetic barrier to resistance. The identification of nucleotide changes associated with miravirsen resistance should help further elucidate the biology of miR-122 interactions with HCV. (The clinical trial study has been registered at ClinicalTrials.gov under registration no. NCT01200420). © 2015 American Society for Microbiology. All Rights Reserved.


Mahalingam A.,University of Utah | Simmons A.P.,University of Utah | Ugaonkar S.R.,University of Utah | Watson K.M.,Imquest Biosciences | And 4 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2011

Pyrimidinediones, a novel class of compounds, have previously been shown to possess antiviral activity at nanomolar concentrations. One member of this class of compounds, IQP-0528, was selected as the lead molecule for formulation development owing to its stability at physiologically relevant conditions, wide therapeutic window, and antiviral activity in the nanomolar range. Here, we report the development of two vaginal gels - 3.0% hydroxyethyl cellulose (HEC) formulation and a 0.65% Carbopol formulation - for the sustained delivery of IQP-0528. Stability studies under accelerated conditions confirmed the chemical stability of IQP-0528 and mechanical stability of the gel formulation for 3 months. In vitro release studies revealed that diffusion-controlled release of IQP-0528 occurred over 6 h, with an initial lag time of approximately 1 h. Based on the drug release profile, the 3.0% HEC gel was selected as the lead formulation for safety and activity evaluations. The in vitro and ex vivo safety evaluations showed no significant loss in cell viability or significant inflammatory response after treatment with a 3.0% HEC gel containing 0.25% IQP-0528. In an in vitro HIV-1 entry inhibition assay, the lead formulation showed an 50% effective concentration of 0.14 μg/ml for gel in culture media, which corresponds to ∼0.001 μM IQP-0528. The antiviral activity was further confirmed by using polarized cervical explants, in which the formulation showed complete protection against HIV infection. In summary, these results are encouraging and warrant further evaluation of IQP-0528 gel formulations in in vivo models, as well as the development of alternative formulations for the delivery of IQP-0528 as a microbicide. Copyright © 2011, American Society for Microbiology. All Rights Reserved.


Wang G.,University of Nebraska Medical Center | Watson K.M.,Imquest Biosciences | Peterkofsky A.,U.S. National Institutes of Health | Buckheit Jr. R.W.,Imquest Biosciences
Antimicrobial Agents and Chemotherapy | Year: 2010

To identify novel anti-HIV-1 peptides based on the antimicrobial peptide database (APD; http://aps.unmc.edu/AP/main.php), we have screened 30 candidates and found 11 peptides with 50% effective concentrations (EC50) of <10 μM and therapeutic indices (TI) of up to 17. Furthermore, among the eight peptides (with identical amino acid compositions but different sequences) generated by shuffling the sequence of an aurein 1.2 analog, two had a TI twice that of the original sequence. Because antiviral peptides in the database have an arginine/lysine (R/K) ratio of >1, increases in the Arg contents of amphibian maximin H5 and dermaseptin S9 peptides and the database-derived GLK-19 peptide improved the TIs. These examples demonstrate that the APD is a rich resource and a useful tool for developing novel HIV-1-inhibitory peptides. Copyright © 2010, American Society for Microbiology. All Rights Reserved.


Gao Y.,Duke University | Yuan A.,Duke University | Chuchuen O.,Duke University | Ham A.,Imquest Biosciences | And 2 more authors.
Drug Delivery and Translational Research | Year: 2015

Gels are one of the soft material platforms being evaluated to deliver topically acting anti-HIV drugs (microbicides) to the vaginal environment. For each drug, its loaded concentration, gel properties and applied volume, and frequency of dosing can be designed to optimize PK and, thence, PD. These factors also impact user sensory perceptions and acceptability. Deterministic compartmental modeling of vaginal deployment and drug delivery achieved by test gels can help delineate how multiple parameters characterizing drug, vehicle, vaginal environment, and dosing govern details of PK and PD and also gel leakage from the canal. Such microbicide delivery is a transport process combining convection, e.g., from gel spreading along the vaginal canal, with drug diffusion in multiple compartments, including gel, mucosal epithelium, and stroma. The present work builds upon prior models of gel coating flows and drug diffusion (without convection) in the vaginal environment. It combines and extends these initial approaches in several key ways, including: (1) linking convective drug transport due to gel spreading with drug diffusion and (2) accounting for natural variations in dimensions of the canal and the site of gel placement therein. Results are obtained for a leading microbicide drug, tenofovir, delivered by three prototype microbicide gels, with a range of rheological properties. The model includes phosphorylation of tenofovir to tenofovir diphosphate (which manifests reverse transcriptase activity in host cells), the stromal concentration distributions of which are related to reference prophylactic values against HIV. This yields a computed summary measure related to gel protection (“percent protected”). Analyses illustrate tradeoffs amongst gel properties, drug loading, volume and site of placement, and vaginal dimensions, in the time and space history of gel distribution and tenofovir transport to sites of its anti-HIV action and concentrations and potential prophylactic actions of tenofovir diphosphate therein. © 2015, The Author(s).


Buckheit K.W.,Imquest Biosciences | Yang L.,Imquest Biosciences | Buckheit Jr. R.W.,Imquest Biosciences
Antimicrobial Agents and Chemotherapy | Year: 2011

In the absence of an effective vaccine against the human immunodeficiency virus (HIV), topical microbicides to prevent the sexual transmission of HIV represent an important strategy to prevent the continued spread of infection. The recent trend in the development of new microbicide candidates includes the utilization of FDA-approved therapeutic drugs that target the early stages of the HIV life cycle, including entry inhibitors and reverse transcriptase inhibitors. We have investigated 12 pyrimidinedione compounds with potent HIV activities and their abilities to inhibit both virus entry and reverse transcription, in an effort to determine a lead microbicide for product development. The candidate compounds were evaluated for efficacy against subtype B, C, and E clinical virus strains in fresh human peripheral blood mononuclear cells and against CCR5-tropic virus strains in both monocyte-macrophages and dendritic cells. Microbicide-specific biological assays and toxicity evaluations were also performed in a variety of established and fresh human cells as well as against Lactobacillus strains common to the vaginal environment. These evaluations resulted in the identification of congeners with cyclopropyl and cyclobutyl substituents at the N-1 of the pyrimidinedione as the most active molecules in the structure-activity relationship series. The pyrimidinediones represent excellent microbicide candidates in light of their significantly high efficacies against HIV-1 (subnanomolar concentration range), potencies (therapeutic index, > 1 million), solubility profiles, and dual mechanism of antiviral action that includes two early steps of virus replication prior to the integration of the virus that are considered most important for microbicidal activity. Copyright © 2011, American Society for Microbiology. All Rights Reserved.


Buckheit Jr. R.W.,Imquest Biosciences | Buckheit K.W.,Imquest Biosciences
Current HIV Research | Year: 2012

Throughout the world, and especially in countries comprising the developing world, women are now bearing the brunt of the HIV pandemic, with over 50% living with HIV infection primarily contracted through sexual transmission in monogamous relationships. Thus, effective chemical or physical means of preventing HIV transmission are urgently needed and in the absence of an approved and effective vaccine, microbicides have become the strategy of choice to provide women with the ability to prevent HIV transmission from their infected partners. Topical microbicides include agents specifically developed and formulated for use in either the vaginal or rectal environment to prevent the sexual transmission of infectious organisms, including pathogenic viruses, bacteria and fungi. Although a microbicide product will have many of the same properties as other anti-infective therapeutic agents and would be similarly developed through a defined preclinical program leading to human clinical trials, microbicide development bears its own challenges related to appropriate and informative preclinical investigation, formulation and delivery, and the complex biological environment in which the product must act, as well as the requirement to develop a product that is acceptable to the user. Following years of microbicide development and a series of unsuccessful human clinical trials, a preclinical microbicide development algorithm has been continuously evolving as greater understanding of the required properties of a successful microbicide are defined through laboratory and clinical experience. Herein, we discuss currently accepted practices required for the development of a successful microbicide product which will prevent cell-free and cell-associated virus transmission in the vaginal and rectal vaults. © 2012 Bentham Science Publishers.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.78M | Year: 2010

DESCRIPTION (provided by applicant): Although IQP-0410 possesses a favorable pharmacokinetic, safety pharmacology and toxicity profile, we believe that additional enhancement of biological activity is possible through additional development activities with lead molecules defined as the most active reverse transcriptase and virus entry inhibitors defined in our Phase I SBIR studies. Structure-activity relationship data obtained with the pyrimidinediones from our Phase I SBIR project indicates that a second generation pyrimidinedione may also be expected to meet and potentially exceed these necessary properties for a next generation NNRTI. A number of initial lead compounds with greater entry and RT inhibitory potential and stability have been identified for further development. Based on the results of our Phase I proposal as well as our experience with the development of our current clinical candidate pyrimidinedione IQP-0410, we intend to employ traditional medicinal chemistry to improve the solubility and stability of a new select pyrimidinedione, which will be defined according to parameters including antiviral activity, metabolism, and preformulation characteristics. Upon selection of our second generation pyrimidinedione inhibitor, we will employ formulation science to better deliver the potent, stable and more soluble pyrimidinedione to enhance bioavailability and pharmacokinetics. It is our expectation that this Phase II SBIR effort will yield a significant improvement in the therapeutic utility and potency of our next generation clinical candidate. PUBLIC HEALTH RELEVANCE: Although the currently approved NNRTIs (nevirapine, delavirdine, efavirenz and etravirine) are highly potent, significant improvements in therapeutic utility are still required. A new generation of NNRTIs must be developed which will allow once per day dosing, exhibit significantly reduced toxicity, be amenable to dosing in women of child bearing age, and possess a significantly higher genetic barrier to resistance selection. The primary goal of this proposal is to define and begin IND-directed development of a second generation pyrimidinedione clinical therapeutic candidate from among the highly active lead compounds defined during the course of our Phase I project. These selected lead pyrimidinediones have been prioritized based on their relative potential to inhibit both reverse transcription and virus entry and all are sub-nanomolar to low nanomolar concentration inhibitors of HIV-1. Detailed biological evaluation of these molecules will be combined with efforts to optimize the formulation and delivery of a new lead molecule, as well as the use of medicinal chemistry to improve the solubility, stability, and bioavailability of the selected compound. Comparative evaluation of compound metabolism and protein binding will also be utilized to help prioritize and define the next generation pryimidinedione clinical candidate possessing highly optimized pharmacokinetic properties and the highest possible potency against wild type, NNRTI-resistant and MDR viruses.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 301.47K | Year: 2010

DESCRIPTION (provided by applicant): Highly active antiretroviral therapy (HAART) has been successfully utilized in HIV-infected individuals to significantly reduce disease progression and improve the prognosis of infected individuals. However, the side-effects, toxicity, and drug-drug interactions of HAART therapies have resulted in reduced patient adherence to the drug regimens, fueling the development of drug resistance. Thus, a continuing need for new and improved antiretroviral agents exists. Current ARVs target five steps in HIV replication, and include inhibition of virus entry (CCR5 antagonism and fusion inhibition) and inhibition of the virus-specific enzymes reverse transcriptase, integrase and protease. Although improvements in the efficacy and toxicity of new generation inhibitors in these existing classes of drugs continues to occur, it is also important to consider the development of new and novel drugs targeting additional required steps in HIV replication. These new agents would be expected to remain fully active against existing drugresistant and multi-drug resistant viruses and thus might be highly effective supplements to existing HAART regimens or constituents of salvage therapy regimens in patients failing long courses of RT and protease inhibitor therapies. It is clear that the continued development of new agents with enhanced potency, reduced toxicity, and a greater genetic barrier to resistance, as well as targeting other HIV replication steps, is a critical need for the continued effectiveness of HIV therapy ImQuest Pharmaceuticals is developing IQP-0410, a highly potent nonnucleoside pyrimidinedione (PYD) inhibitor of HIV-1 with a molecular weight of 352 g/mole. The compound exhibited a therapeutic index of approximately one to four million in replicate antiviral assays, indicating that it was several orders of magnitude more active against HIV-1 than nevirapine and the early NNRTIs and of similar potency to Sustiva. but without the significant toxicities reported for Sustiva.. Although the primary mechanism of action of IQP-0410 is inhibition of the viral reverse transcriptase (RT), acting as a typical third generation nonnucleoside RT inhibitor (NNRTI) at sub-nanomolar concentrations, this compound also inhibits viral entry at nanomolar concentrations. The dual mechanism of action confers a high genetic barrier to the selection of IQP-0410-resistant viruses and in vitro assays have shown significant activity of IQP-0410 against clinically relevant drug resistant virus strains and against multi-drug resistant virus strains with resistance to protease inhibitors. Due to low solubility and poor penetration through the mucosa to the target site of action, pyrimidinediones face significant obstacles as a therapeutic. Therefore, strategic drug delivery designs are essential for pyrimidinediones to advance as viable HAART products. Through conventional administration, such as injections or oral, PYD would be subjected to extensive first pass metabolism by the liver limiting its effectiveness. We propose transdermal films an innovative drug delivery strategy to enhance PYD therapeutic efficacy and delivery through polymeric formulations. Specifically, transdermal films delivery has many advantages over conventional administration such as improved patient compliance in long-term therapy, bypassing first-pass metabolism, sustained drug delivery, avoiding drug peak and valley dosing in plasma, minimizing inter- and intra- patient variability, and allowing treatment termination. We propose that this project will identify a transdermal film formulation that will enhance efficacy and allow long term therapeutic delivery of IQP-0410. PUBLIC HEALTH RELEVANCE: ImQuest Pharmaceuticals is developing IQP-0410, a highly potent nonnucleoside pyrimidinedione inhibitor of HIV-1, as a therapeutic drug. ImQuest Biosciences will utilize their expertise in HIV drug development and formulation to develop a novel delivery system transdermal films. This delivery vehicle will provide constant HIV therapeutics in a solid dosage form that has the advantage of improved patient compliance in long-term therapy, bypassing first-pass metabolism, sustained drug delivery, avoiding drug peak and valley dosing in plasma, minimizing inter- and intra- patient variability, and allowing treatment termination. The research to be performed will include development of the transdermal film and the evaluation of its ability to deliver a therapeutic amount of IQP-0410 over long periods of time.

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