Turning the promise of multipurpose prevention technologies into a market reality: a commentary.

The promise of multipurpose prevention technologies (MPTs) for the prevention of HIV and unintended pregnancy are on the horizon. While many are still in clinical development, others are closer to becoming a realistic, accessible option for users, like the dual prevention pill (DPP). Researchers, governments, donors, and implementers will have to collaboratively address systemic challenges to successfully introduce and scale-up MPTs. To ensure the rollout of MPTs is successful, the global community should address user and country-specific needs, coordinate with advocates and policymakers, and set a realistic plan for product introduction and scale-up that considers the needs of both family planning (FP) and HIV programs, while laying the groundwork for future new product introduction. To achieve these aims, global and regional stakeholder coordination should emphasize country-led, person-centered decision-making while addressing: (1) procurement and supply chain barriers; (2) the potential burden on health systems; and (3) the impact on current programs.

A nanoparticle-incorporated STING activator enhances antitumor immunity in PD-L1-insensitive models of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) has few therapeutic options, and alternative approaches are urgently needed. Stimulator of IFN genes (STING) is becoming an exciting target for therapeutic adjuvants. However, STING resides inside the cell, and the intracellular delivery of CDNs, such as cGAMP, is required for the optimal activation of STING. We show that liposomal nanoparticle-delivered cGAMP (cGAMP-NP) activates STING more effectively than soluble cGAMP. These particles induce innate and adaptive host immune responses to preexisting tumors in both orthotopic and genetically engineered models of basal-like TNBC. cGAMP-NPs also reduce melanoma tumor load, with limited responsivity to anti-PD-L1. Within the tumor microenvironment, cGAMP-NPs direct both mouse and human macrophages (M), reprograming from protumorigenic M2-like phenotype toward M1-like phenotype; enhance MHC and costimulatory molecule expression; reduce M2 biomarkers; increase IFN-γ-producing T cells; augment tumor apoptosis; and increase CD4+ and CD8+ T cell infiltration. Activated T cells are required for tumor suppression, as their depletion reduces antitumor activity. Importantly, cGAMP-NPs prevent the formation of secondary tumors, and a single dose is sufficient to inhibit TNBC. These data suggest that a minimal system comprised of cGAMP-NP alone is sufficient to modulate the tumor microenvironment to effectively control PD-L1-insensitive TNBC.

A strategic action framework for multipurpose prevention technologies combining contraceptive hormones and antiretroviral drugs to prevent pregnancy and HIV.

OBJECTIVE: Multipurpose prevention technologies (MPTs) are an innovative class of products that deliver varied combinations of human immunodeficiency virus (HIV) prevention, other sexually transmitted infection (STI) prevention, and contraception. Combining separate strategies for different indications into singular prevention products can reduce the stigma around HIV and STI prevention, improve acceptability of and adherence to more convenient products, and be more cost-effective by addressing overlapping risks. METHODS: This article outlines a strategic action framework developed as an outcome of a series of expert meetings held between 2014 and 2016. The meetings focused on identifying opportunities and challenges for MPTs that combine hormonal contraception (HC) with antiretroviral drugs into single products. The framework aims to present an actionable strategy, by addressing key research gaps and outlining the key areas for progress, to guide current and future HC MPT development. RESULTS: We identified eight primary action areas for the development of impactful HC MPTs, and includes aspects from epidemiology, pharmacology, clinical trial design, regulatory requirements, manufacturing and commercialisation, behavioural science, and investment needs for research and development. CONCLUSION: Overall, the challenges involved with reconciling the critical social-behavioural context that will drive MPT product use and uptake with the complexities of research and development and regulatory approval are of paramount importance. To realise the potential of MPTs given their complexity and finite resources, researchers in the MPT field must be strategic about the way forward; increased support among policy-makers, advocates, funders and the pharmaceutical industry is critical.

Microparticles formulated from a family of novel silylated polysaccharides demonstrate inherent immunostimulatory properties and tunable hydrolytic degradability.

Acid-degradable polymers are well-suited for use as drug delivery vehicles because numerous physiological sites (e.g., intracellular endocytic pathway) are acidic. Here we report the synthesis of acid-sensitive silylated polysaccharides derived from either dextran or inulin with various alkyl substitutions on the silicon center: trimethylsilyl dextran (TMS-DEX), ethyldimethylsilyl dextran (EDMS-DEX), triethylsilyl dextran (TES-DEX), and trimethylsilyl inulin (TMS-IN). The silylated dextran (Silyl-DEX) and silylated inulin (Silyl-IN) polymers were fabricated into microparticles (MPs) via emulsification followed by solvent evaporation. These MPs were relatively stable at extracellular pH 7.4 and displayed a wide range of pH 2.0 and 5.0 degradation half-lives (fifteen minutes to greater than nine days) that were dependent on the extent of silylation (40 to 98%) and steric crowding on the silicon center (trimethyl to ethyldimethyl to triethyl). Silyl-DEX and Silyl-IN MPs exhibited cytocompatibility when cultured in vitro with RAW 264.7 macrophages. TES-DEX and TMS-IN MPs, composed of highly hydrophobic moieties and the parent immunostimulatory inulin, respectively, elicited substantial in vitro production of tumor necrosis factor alpha, a cytokine associated with an innate immune response. In vivo immunization with a model ovalbumin antigen encapsulated in silylated polysaccharide MPs, without a separate adjuvant, resulted in a dual humoral and cellular response that was superior to an alum-adjuvanted formulation. Overall, we present Silyl-DEX and Silyl-IN as members of the acid-degradable polymer family for potential use in subunit vaccines and other drug delivery applications.

A Novel Sterol Isolated from a Plant Used by Mayan Traditional Healers Is Effective in Treatment of Visceral Leishmaniasis Caused by Leishmania donovani.

Visceral leishmaniasis (VL), caused by the protozoan parasite Leishmania donovani, is a global health problem affecting millions of people worldwide. Treatment of VL largely depends on therapeutic drugs such as pentavalent antimonials, amphotericin B, and others, which have major drawbacks due to drug resistance, toxicity, and high cost. In this study, for the first time, we have successfully demonstrated the synthesis and antileishmanial activity of the novel sterol pentalinonsterol (PEN), which occurs naturally in the root of a Mexican medicinal plant, Pentalinon andrieuxii. In the experimental BALB/c mouse model of VL induced by infection with L. donovani, intravenous treatment with liposome-encapsulated PEN (2.5 mg/kg) led to a significant reduction in parasite burden in the liver and spleen. Furthermore, infected mice treated with liposomal PEN showed a strong host-protective TH1 immune response characterized by IFN-γ production and formation of matured hepatic granulomas. These results indicate that PEN could be developed as a novel drug against VL.

Acetalated dextran encapsulated AR-12 as a host-directed therapy to control Salmonella infection.

AR-12 has been evaluated in clinical trials as an anti-cancer agent but also has demonstrated host-directed, broad-spectrum clearance of bacteria. We have previously shown that AR-12 has activity in vitro against Salmonella enterica serovar Typhimurium and Francisella species by inducing autophagy and other host immune pathways. AR-12 treatment of S. Typhimurium-infected mice resulted in a 10-fold reduction in bacterial load in the liver and spleen and an increased survival time. However, AR-12 treatment did not protect mice from death, likely due poor formulation. In the current study, AR-12 was encapsulated in a microparticulate carrier formulated from the novel degradable biopolymer acetalated dextran (Ace-DEX) and subsequently evaluated for its activity in human monocyte-derived macrophages (hMDMs). Our results show that hMDMs efficiently internalized Ace-DEX microparticles (MPs), and that encapsulation significantly reduced host cell cytotoxicity compared to unencapsulated AR-12. Efficient macrophage internalization of AR-12 loaded MPs (AR-12/MPs) was further demonstrated by autophagosome formation that was comparable to free AR-12 and resulted in enhanced clearance of intracellular Salmonella. Taken together, these studies provide support that Ace-DEX encapsulated AR-12 may be a promising new therapeutic agent to control intracellular bacterial pathogens of macrophages by targeting delivery and reducing drug toxicity.

Treatment of experimental autoimmune encephalomyelitis by codelivery of disease associated Peptide and dexamethasone in acetalated dextran microparticles.

Multiple sclerosis (MS) is an autoimmune, demyelinating disease of the central nervous system that can cause loss of motor function and is thought to result, in part, from chronic inflammation due to an antigen-specific T cell immune response. Current treatments suppress the immune system without antigen specificity, increasing the risks of cancer, chronic infection, and other long-term side effects. In this study, we show treatment of experimental autoimmune encephalomyelitis (EAE), a model of MS, by coencapsulating the immunodominant peptide of myelin oligodendrocyte glycoprotein (MOG) with dexamethasone (DXM) into acetalated dextran (Ac-DEX) microparticles (DXM/MOG/MPs) and administering the microparticles subcutaneously. The clinical score of the mice was reduced from 3.4 to 1.6 after 3 injections 3 days apart with the coencapsulated microparticulate formulation (MOG 17.6 µg and DXM 8 µg). This change in clinical score was significantly greater than observed with phosphate-buffered saline (PBS), empty MPs, free DXM and MOG, DXM/MPs, and MOG/MPs. Additionally, treatment with DXM/MOG/MPs significantly inhibited disease-associated cytokine (e.g., IL-17, GM-CSF) expression in splenocytes isolated in treated mice. Here we show a promising approach for the therapeutic treatment of MS using a polymer-based microparticle delivery platform.

Liposomal resiquimod for the treatment of Leishmania donovani infection.

OBJECTIVES: The imidazoquinoline family of drugs are Toll-like receptor 7/8 agonists that have previously been used in the treatment of cutaneous leishmaniasis. Because of the hydrophobic nature of imidazoquinolines, they are traditionally not administered systemically for the treatment of visceral leishmaniasis. We formulated liposomal resiquimod, an imidazoquinoline, for the systemic treatment of visceral leishmaniasis. METHODS: By using lipid film hydration with extrusion, we encapsulated resiquimod in liposomes. These liposomes were then injected intravenously to treat BALB/c mice infected with Leishmania donovani. RESULTS: Treatment with liposomal resiquimod significantly decreased the parasite load in the liver, spleen and bone marrow. In addition, resiquimod treatment increased interferon-γ and interleukin-10 production in an antigen recall assay. Resiquimod was shown to be non-toxic in histology and in vitro culture experiments. CONCLUSIONS: FDA-approved resiquimod, in a liposomal formulation, displays promising results in treating visceral leishmaniasis.

Delivery of host cell-directed therapeutics for intracellular pathogen clearance.

Intracellular pathogens present a major health risk because of their innate ability to evade clearance. Their location within host cells and ability to react to the host environment by mutation or transcriptional changes often enables survival mechanisms to resist standard therapies. Host-directed drugs do not target the pathogen, minimizing the potential development of drug resistance; however, they can be difficult to deliver efficiently to intracellular sites. Vehicle delivery of host-mediated response drugs not only improves drug distribution and toxicity profiles, but can reduce the total amount of drug necessary to clear infection. In this article, we will review some host-directed drugs and current drug delivery techniques that can be used to efficiently clear intracellular infections.

Electrospun acetalated dextran scaffolds for temporal release of therapeutics.

Electrospun acetalated dextran (Ac-DEX) scaffolds were fabricated to encapsulate resiquimod, an immunomodulatory toll-like-receptor (TLR) agonist. Ac-DEX has been used to fabricate scaffolds for sustained and temporal delivery of therapeutics because it has tunable degradation rates that are dependent on its synthesis reaction time or the molecular weight of dextran. Additionally, as opposed to commonly electrospun polyesters that shift the local pH upon degradation, the degradation products of Ac-DEX are pH-neutral: dextran, an alcohol, and the metabolic byproduct acetone. Formulations of Ac-DEX with two different degradation rates were used in this study. The effects of electrospinning conditions on the scaffold size and morphology were examined as well as fibroblast adhesion as imaged with fluorescence microcopy and scanning electron microscopy. Macrophage (MΦ) viability further indicates that the scaffolds are cytocompatible. Also, the controlled release profiles of resiquimod from loaded scaffolds and nitric oxide (NO) production by MΦ incubated with these scaffolds show the potential for Ac-DEX scaffolds to be used to temporally and efficiently deliver therapeutics. Overall, we present a novel scaffold that can have tunable and unique drug release rates for tissue engineering, drug delivery, immunomodulation, and wound healing applications.

Efficient delivery of the toll-like receptor agonists polyinosinic:polycytidylic acid and CpG to macrophages by acetalated dextran microparticles.

To enhance the immune activity of vaccine adjuvants polyinosinic:polycytidylic acid (poly I:C) and CpG acetalated dextran (Ac-DEX) microparticles can be used. Ac-DEX is a biodegradable and water-insoluble polymer that degrades significantly faster at pH 5.0 (phagosomal pH) than at pH 7.4 and has tunable degradation rates that can range from hours to months. This is an ideal characteristic for delivery of an antigen and adjuvant within the lysosomal compartment of a phagocytic cell. We evaluated poly I:C and CpG encapsulated in Ac-DEX microparticles using RAW macrophages as a model antigen-presenting cell. These cells were cultured with poly I:C or CpG in their free form, encapsulated in a fast degrading Ac-DEX, in slow degrading Ac-DEX, or in the Food and Drug Administration-approved polymer poly(lactic-co-glycolic acid) (PLGA). Ac-DEX had higher encapsulation efficiencies for both poly I:C and CpG than PLGA. Furthermore, poly I:C or CpG encapsulated in Ac-DEX also showed, in general, a significantly stronger immunostimulatory response than PLGA and unencapsulated CpG or poly I:C, which was indicated by a higher rate of nitric oxide release and increased levels of cytokines such as TNF-α, IL-6, IL-10, and IFN-γ. Overall, we have illustrated a method for enhancing the delivery of these vaccine adjuvants to further enhance the development of Ac-DEX vaccine formulations.

Rapid vaccination using an acetalated dextran microparticulate subunit vaccine confers protection against triplicate challenge by bacillus anthracis.

PURPOSE: A rapid immune response is required to prevent death from Anthrax, caused by Bacillus anthracis. METHOD: We formulated a vaccine carrier comprised of acetalated dextran microparticles encapsulating recombinant protective antigen (rPA) and resiquimod (a toll-like receptor 7/8 agonist). RESULTS: We were able to protect against triplicate lethal challenge by vaccinating twice (Days 0, 7) and then aggressively challenging on Days 14, 21, 28. A significantly higher level of antibodies was generated by day 14 with the encapsulated group compared to the conventional rPA and alum group. Antibodies produced by the co-encapsulated group were only weakly-neutralizing in toxin neutralization; however, survival was not dependent on toxin neutralization, as all vaccine formulations survived all challenges except control groups. Post-mortem culture swabs taken from the hearts of vaccinated groups that did not produce significant neutralizing titers failed to grow B. anthracis. CONCLUSIONS: Results indicate that protective antibodies are not required for rapid protection; indeed, cytokine results indicate that T cell protection may play a role in protection from anthrax. We report the first instance of use of a particulate carrier to generate a rapid protective immunity against anthrax.

Electrospray encapsulation of toll-like receptor agonist resiquimod in polymer microparticles for the treatment of visceral leishmaniasis.

Leishmaniasis is a disease caused by the intracellular protozoan, Leishmania. A current treatment for cutaneous leishmaniasis involves the delivery of imidazoquinolines via a topical cream. However, there are no parenteral formulations of imidazoquinolines for the most deadly version of the disease, visceral leishmaniasis. This work investigates the use of electrospray to encapsulate the imidazoquinoline adjuvant resiquimod in acid sensitive microparticles composed of acetalated dextran (Ac-DEX) or Ac-DEX/Tween blends. The particles were characterized and tested both in vitro and in vivo. Solutions of Ac-DEX and resiquimod in ethanol were electrosprayed to generate approximately 2 µm Ac-DEX particles containing resiquimod with an encapsulation efficiency of 85%. To prevent particle aggregation, blends of Ac-DEX with Tween 20 and Tween 80 were investigated. Tween 80 was then blended with the Ac-DEX at ∼10% (w/w) of total polymer and particles containing resiquimod were formed via electrospray with encapsulation efficiencies between 40% and 60%. In vitro release profiles of resiquimod from Ac-DEX/Tween 80 particles exhibited the acid-sensitive nature of Ac-DEX, with 100% drug release after 8 h at pH 5 (phagosomal pH) and after 48 h at pH 7.4 (physiological pH). Treatment with Ac-DEX/Tween 80 particles elicited significantly greater immune response in RAW macrophages over free drug. When injected intravenously into mice inoculated with Leishmania, parasite load reduced significantly in the bone marrow compared to blank particles and phosphate-buffered saline controls. Overall, electrospray appears to offer an elegant, scalable way to encapsulate adjuvant into an acid sensitive delivery vehicle for use in treating visceral leishmaniasis.

Physiological concentrations of genistein and 17ß-estradiol inhibit MDA-MB-231 breast cancer cell growth by increasing BAX/BCL-2 and reducing pERK1/2.

AIM: The aim of the present study was to identify the mechanism by which genistein and 17ß-estradiol inhibit proliferation of MDA-MB-231 breast cancer cells. MATERIALS AND METHODS: The expression of cell signaling proteins involved in cell apoptosis, proliferation, and survival (BCL-2 associated X protein, BAX; B-cell lymphoma 2, BCL-2; extracellular signal regulated kinase, pERK1/2; and protein kinase B, pAKT) were examined by western blotting, and tested whether these effects correlated with cell proliferation and apoptosis. RESULTS: Compared to the control, 1 µM genistein plus 1 nM 17ß-estradiol significantly increased apoptosis, and the BAX/BCL-2 ratio, with a concomitant decrease in ERK1/2 phosphorylation. High concentrations of genistein (100 µM) both in the presence and absence of 17ß-estradiol also increased apoptosis; however, these changes were not correlated with the BAX/BCL-2 ratio or with phosphorylation of ERK1/2. CONCLUSION: These results suggest that different concentrations of genistein elicit cell responses through different signaling mechanisms. These results are especially relevant in premenopausal women with breast cancer who are on a soy diet.