Modification of immunological responses and clinical disease during topical R-837 treatment of genital HSV-2 infection

Topical Treatment of Melanoma In Situ, Lentigo Maligna, and Lentigo Maligna Melanoma with Imiquimod Cream: A Systematic Review of the Literature

INTRODUCTION

The classical management of melanoma is surgery, but this can be challenging because of several factors, such as age, body area, lesion size, among others. Topical imiquimod may be a therapeutic option for the treatment of melanoma in situ and lentigo maligna melanoma due to its efficacy, tolerability, and non-invasiveness. The purpose of this systematic review is to assemble current evidence on the treatment of non-metastatic melanoma with topical imiquimod.

METHODS

The PubMed/MEDLINE and Cochrane Library databases were searched as the primary sources using the main search terms "imiquimod" combined with "lentigo maligna" and "melanoma" with the command "AND." Articles were identified, screened, and extracted for relevant data, following the PRISMA guidelines.

RESULTS

A total of 87 studies covering 1803 lesions treated with imiquimod cream were identified and included in this sytematic review. Forty-nine studies were case reports, 16 were retrospective analyses, 3 were open label trials, six were case series; one study was a controlled randomized trial, one was a randomized trial, and one was a single-arm phase III trial. Because of the high number of low-evidence studies, the overall risk of bias resulted high. In 55 studies, imiquimod 5% was used in monotherapy as the primary treatment; only in one study was imiquimod 3.75% introduced. In most cases, the topical treatment was applied once daily, with the exception of nine cases where an increased daily dosage was prescribed. The total duration of the treatment regimen was extremely variable and depended on body area and tolerability, with differences among patients of the same study. In six studies, imiquimod was used as neoadjuvant therapy before the surgical excision, and in 11 studies it was used after surgery as complementary or adjuvant therapy. In total, 1133 of the 1803 (62.8%) lesions were reported to be cleared after the treatment, taking into account that not all of the patients completed the treatment. Of these 1133 lesions, histological clearance was achieved in 645 (56.9%) lesions and clinical clearance only was achieved in 490 (43.2%) lesions; relapse occurred in 107 lesions.

CONCLUSIONS

The heterogeneity of the studies included in this systematic review precludes the drawing of any relevant conclusions regarding the application of imiquimod. Its efficacy in melanoma in situ and lentigo maligna melanoma has been demonstrated, but further evidence from controlled studies concerning the modalities is missing.

Rare Cutaneous Side Effects of Imiquimod: A Review on Its Mechanisms, Diagnosis, and Management

As an immune-response modifier, imiquimod can bind to Toll-like receptors on immune cells and enhance innate and adaptive immune responses, exerting potential antitumor and antiviral effects, which led to its approval by the US Food and Drug Administration for the treatment of actinic keratosis, superficial basal cell carcinomas, and anogenital warts, and to its off-label use in treating many other benign and malignant dermatoses. Although topical administration of imiquimod has been considered well tolerated, an increasing number of cutaneous and noncutaneous side effects are being reported as its clinical applications expand. This review primarily focuses on rare cutaneous side effects. To the best of our knowledge, this is the first article to summarize the mechanism, diagnosis, and management of rare cutaneous side effects of imiquimod, which may help to heighten awareness among physicians, especially dermatologists, about potential imiquimod-induced cutaneous side effects.

Highlights into historical and current immune interventions for cancer

Immunotherapy is an additional pillar when combined with traditional standards of care such as chemotherapy, radiotherapy, and surgery for cancer patients. It has revolutionized cancer treatment and rejuvenated the field of tumor immunology. Several types of immunotherapies, including adoptive cellular therapy (ACT) and checkpoint inhibitors (CPIs), can induce durable clinical responses. However, their efficacies vary, and only subsets of cancer patients benefit from their use. In this review, we address three goals: to provide insight into the history of these approaches, broaden our understanding of immune interventions, and discuss current and future approaches. We highlight how cancer immunotherapy has evolved and discuss how personalization of immune intervention may address present limitations. Cancer immunotherapy is considered a recent medical achievement and in 2013 was selected as the "Breakthrough of the Year" by Science. While the breadth of immunotherapeutics has been rapidly expanding, to include the use of chimeric antigen receptor (CAR) T-cell therapy and immune checkpoint inhibitor (ICI) therapy, immunotherapy dates back over 3000 years. The expansive history of immunotherapy, and related observations, have resulted in several approved immune therapeutics beyond the recent emphasis on CAR-T and ICI therapies. In addition to other classical forms of immune intervention, including human papillomavirus (HPV), hepatitis B, and the Mycobacterium bovis Bacillus Calmette-Guérin (BCG) tuberculosis vaccines, immunotherapies have had a broad and durable impact on cancer therapy and prevention. One classic example of immunotherapy was identified in 1976 with the use of intravesical administration of BCG in patients with bladder cancer; resulting in a 70 % eradication rate and is now standard of care. However, a greater impact from the use of immunotherapy is documented by the prevention of HPV infections that are responsible for 98 % of cervical cancer cases. In 2020, the World Health Organization (WHO) estimated that 341,831 women died from cervical cancer [1]. However, administration of a single dose of a bivalent HPV vaccine was shown to be 97.5 % effective in preventing HPV infections. These vaccines not only prevent cervical squamous cell carcinoma and adenocarcinoma, but also oropharyngeal, anal, vulvar, vaginal, and penile squamous cell carcinomas. The breadth, response and durability of these vaccines can be contrasted with CAR-T-cell therapies, which have significant barriers to their widespread use including logistics, manufacturing limitations, toxicity concerns, financial burden and lasting remissions observed in only 30 to 40 % of responding patients. Another, recent immunotherapy focus are ICIs. ICIs are a class of antibodies that can increase the immune responses against cancer cells in patients. However, ICIs are only effective against tumors with a high mutational burden and are associated with a broad spectrum of toxicities requiring interruption of administration and/or administration corticosteroids; both of which limit immune therapy. In summary, immune therapeutics have a broad impact worldwide, utilizing numerous mechanisms of action and when considered in their totality are more effective against a broader range of tumors than initially considered. These new cancer interventions have tremendous potential notability when multiple mechanisms of immune intervention are combined as well as with standard of care modalities.

Host-pathogen protein-nucleic acid interactions: A comprehensive review

Recognition of pathogen-derived nucleic acids by host cells is an effective host strategy to detect pathogenic invasion and trigger immune responses. In the context of pathogen-specific pharmacology, there is a growing interest in mapping the interactions between pathogen-derived nucleic acids and host proteins. Insight into the principles of the structural and immunological mechanisms underlying such interactions and their roles in host defense is necessary to guide therapeutic intervention. Here, we discuss the newest advances in studies of molecular interactions involving pathogen nucleic acids and host factors, including their drug design, molecular structure and specific patterns. We observed that two groups of nucleic acid recognizing molecules, Toll-like receptors (TLRs) and the cytoplasmic retinoic acid-inducible gene (RIG)-I-like receptors (RLRs) form the backbone of host responses to pathogen nucleic acids, with additional support provided by absent in melanoma 2 (AIM2) and DNA-dependent activator of Interferons (IFNs)-regulatory factors (DAI) like cytosolic activity. We review the structural, immunological, and other biological aspects of these representative groups of molecules, especially in terms of their target specificity and affinity and challenges in leveraging host-pathogen protein-nucleic acid interactions (HP-PNI) in drug discovery.

Engaging Pattern Recognition Receptors in Solid Tumors to Generate Systemic Antitumor Immunity

Malignant tumors frequently exploit innate immunity to evade immune surveillance. The priming, function, and polarization of antitumor immunity fundamentally depends upon context provided by the innate immune system, particularly antigen presenting cells. Such context is determined in large part by sensing of pathogen specific and damage associated features by pathogen recognition receptors (PRRs). PRR activation induces the delivery of T cell priming cues (e.g. chemokines, co-stimulatory ligands, and cytokines) from antigen presenting cells, playing a decisive role in the cancer immunity cycle. Indeed, endogenous PRR activation within the tumor microenvironment (TME) has been shown to generate spontaneous antitumor T cell immunity, e.g., cGAS-STING mediated activation of antigen presenting cells after release of DNA from dying tumor cells. Thus, instigating intratumor PRR activation, particularly with the goal of generating Th1-promoting inflammation that stokes endogenous priming of antitumor CD8⁺ T cells, is a growing area of clinical investigation. This approach is analogous to in situ vaccination, ultimately providing a personalized antitumor response against relevant tumor associated antigens. Here I discuss clinical stage intratumor modalities that function via activation of PRRs. These approaches are being tested in various solid tumor contexts including melanoma, colorectal cancer, glioblastoma, head and neck squamous cell carcinoma, bladder cancer, and pancreatic cancer. Their mechanism (s) of action relative to other immunotherapy approaches (e.g., antigen-defined cancer vaccines, CAR T cells, dendritic cell vaccines, and immune checkpoint blockade), as well as their potential to complement these approaches are also discussed. Examples to be reviewed include TLR agonists, STING agonists, RIG-I agonists, and attenuated or engineered viruses and bacterium. I also review common key requirements for effective in situ immune activation, discuss differences between various strategies inclusive of mechanisms that may ultimately limit or preclude antitumor efficacy, and provide a summary of relevant clinical data.

Current and future direction in treatment of HPV-related cervical disease

Human papillomavirus (HPV) is the most common sexually transmitted virus in the world. About 70% of cervical cancers are caused by the most oncogenic HPV genotypes of 16 and 18. Since available prophylactic vaccines do not induce immunity in those with established HPV infections, the development of therapeutic HPV vaccines using E6 and E7 oncogenes, or both as the target antigens remains essential. Also, knocking out the E6 and E7 oncogenes in host genome by genome-editing CRISPR/Cas system can result in tumor growth suppression. These methods have shown promising results in both preclinical and clinical trials and can be used for controlling the progression of HPV-related cervical diseases. This comprehensive review will detail the current treatment of HPV-related cervical precancerous and cancerous diseases. We also reviewed the future direction of treatment including different kinds of therapeutic methods and vaccines, genome-editing CRISPR/Cas system being studied in clinical trials. Although the progress in the development of therapeutic HPV vaccine has been slow, encouraging results from recent trials showed vaccine-induced regression in high-grade CIN lesions. CRISPR/Cas genome-editing system is also a promising strategy for HPV cancer therapy. However, its safety and specificity need to be optimized before it is used in clinical setting.

TLR7 Activation of Macrophages by Imiquimod Inhibits HIV Infection through Modulation of Viral Entry Cellular Factors

The Toll-like receptor (TLR) 7 is a viral sensor for detecting single-stranded ribonucleic acid (ssRNA), the activation of which can induce intracellular innate immunity against viral infections. Imiquimod, a synthetic ligand for TLR7, has been successfully used for the topical treatment of genital/perianal warts in immunocompetent individuals. We studied the effect of imiquimod on the human immunodeficiency virus (HIV) infection of primary human macrophages and demonstrated that the treatment of cells with imiquimod effectively inhibited infection with multiple strains (Bal, YU2, and Jago) of HIV. This anti-HIV activity of imiquimod was the most potent when macrophages were treated prior to infection. Infection of macrophages with pseudotyped HIV NL4-3-ΔEnv-eGFP-Bal showed that imiquimod could block the viral entry. Further mechanistic studies revealed that while imiquimod had little effect on the interferons (IFNs) expression, its treatment of macrophages resulted in the increased production of the CC chemokines (human macrophage inflammatory protein-1 alpha (MIP-1α), MIP-1β, and upon activation regulated normal T cells expressed and secreted (RANTES)), the natural ligands of HIV entry co-receptor CCR5, and decreased the expression of CD4 and CCR5. The addition of the antibodies against the CC chemokines to macrophage cultures could block imiquimod-mediated HIV inhibition. These findings provide experimental evidence to support the notion that TLR7 participates in the intracellular immunity against HIV in macrophages, suggesting the further clinical evaluation of imiquimod for its additional benefit of treating genital/perianal warts in people infected with HIV.

Trial watch: FDA-approved Toll-like receptor agonists for cancer therapy

Toll-like receptors (TLRs) have first been characterized for their capacity to detect conserved microbial components like lipopolysaccharide (LPS) and double-stranded RNA, resulting in the elicitation of potent (innate) immune responses against invading pathogens. More recently, TLRs have also been shown to promote the activation of the cognate immune system against cancer cells. Today, only three TLR agonists are approved by FDA for use in humans: the bacillus Calmette-Guérin (BCG), monophosphoryl lipid A (MPL) and imiquimod. BCG (an attenuated strain of Mycobacterium bovis) is mainly used as a vaccine against tuberculosis, but also for the immunotherapy of in situ bladder carcinoma. MPL (derived from the LPS of Salmonella minnesota) is included in the formulation of Cervarix®, a vaccine against human papillomavirus-16 and -18. Imiquimod (a synthetic imidazoquinoline) is routinely employed for actinic keratosis, superficial basal cell carcinoma, and external genital warts (condylomata acuminata). In this Trial Watch, we will summarize the results of recently completed clinical trials and discuss the progress of ongoing studies that have evaluated/are evaluating FDA-approved TLR agonists as off-label medications for cancer therapy.

Imidazo[1,2-a]quinoxalines for melanoma treatment with original mechanism of action

The malignant transformation of melanocytes causes several thousand deaths each year, making melanoma an important public health concern. Melanoma is the most aggressive skin cancer, which incidence has regularly increased over the past decades. We described here the preparation of new compounds based on the 1-(3,4-dihydroxyphenyl)imidazo[1,2-a]quinoxaline structure. Different positions of the quinoxaline moiety were screened to introduce novel substituents in order to study their influence on the biological activity. Several alkylamino or alkyloxy groups were also considered to replace the methylamine of our first generation of Imiqualines. Imidazo[1,2-a]pyrazine derivatives were also designed as potential minimal structure. The investigation on A375 melanoma cells displayed interesting in vitro low nanomolar cytotoxic activity. Among them, 9d (EAPB02303) is particularly remarkable since it is 20 times more potent than vemurafenib, the reference clinical therapy used on BRAF mutant melanoma. Contrary to the first generation, EAPB02303 does not inhibit tubulin polymerization, as confirmed by an in vitro assay and a molecular modelisation study. The mechanism of action for EAPB02303 highlighted by a transcriptomic analysis is clearly different from a panel of 12 well-known anticancer drugs. In vivoEAPB02303 treatment reduced tumor size and weight of the A375 human melanoma xenografts in a dose-dependent manner, correlated with a low mitotic index but not with necrosis.

The role of topical imiquimod in melanoma cutaneous metastases: A critical review of the literature

Despite of the emerging new systemic and local oncologic treatments (immunotherapy and checkpoint inhibitors, oncolytic viral treatments and injected immunostimulants) the management of skin melanoma metastasis can be still challenging. The main aim of this review was to assess the efficacy and the role of imiquimod in local metastatic melanoma disease. An extensive literature review was performed from September 2000 to March 2020 using PubMed, MEDLINE, Embase, and Cochrane Library databases. Selected articles regarded topical imiquimod, its mode of action as an antitumoral agent and its applications in melanoma metastases treatment. We analyzed a total of 18 published article of clinical cases and small case series and five studies: two retrospective large case series, two Phase I and II clinical trials and one cohort non randomized study. Generally, the treatment is safe and well tolerated. Imiquimod lead to an unstable locoregional control. The use of topical imiquimod for the treatment of MM cutaneous metastases should be considered in selected cases and in palliative settings.

Methotrexate-Loaded Nanostructured Lipid Carrier Gel Alleviates Imiquimod-Induced Psoriasis by Moderating Inflammation: Formulation, Optimization, Characterization, In-Vitro and In-Vivo Studies

INTRODUCTION

Methotrexate exhibits poor cutaneous bioavailability and systemic side effects on topical administration, so there is an unmet need for a novel carrier and its optimized therapy. Methotrexate-loaded nanostructured lipid carriers (MTXNLCs) were formulated and characterized to determine in vitro drug release and evaluate the role of MTXNLC gel in the topical treatment of psoriasis.

METHODS

A solvent diffusion technique was employed to prepare MTXNLCs, which was optimized using 32 full factorial designs. The mean diameter and surface morphology of MTXNLCs was evaluated. The crystallinity of lyophilized MTXNLCs was characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). MTXNLCs were integrated in 1% w/w Carbopol 934 P gel base, and in vitro skin deposition studies in human cadaver skin (HCS) were carried out.

RESULTS

The optimized MTXNLCs were rod-shaped, with an average particle size of 253 ± 8.65 nm, a zeta potential of -26.4±0.86 mV, and EE of 54.00±1.49%. DSC and XRD data confirmed the formation of NLCs. Significantly higher deposition of MTX was found in HCS from MTXNLC gel (71.52 ±1.13%) as compared to MTX plain gel (38.48±0.96%). In vivo studies demonstrated significant improvement in therapeutic response and reduction in local side effects with MTXNLCs-loaded gel in the topical treatment of psoriasis. Anti-psoriatic efficacy of MTXNLCs 100 ug/cm2 compared with plain MTX gel was evaluated using imiquimod (IMQ)-induced psoriasis in BALB/c mice. The topical application of MTXNLCs to the mouse ear resulted in a significant reduction of psoriatic area and severity index, oxidative stress, inflammatory cytokines like TNF-α, IL-1β, and IL-6 and IMQ-induced histopathological alterations in mouse ear samples.

CONCLUSION

Developed formulation of MTXNLC gel demonstrated better anti-psoriatic activity and also displayed prolonged and sustained release effect, which shows that it can be a promising alternative to existing MTX formulation for the treatment of psoriasis.

Topical Imiquimod as a Treatment Option for Nodular Basal Cell Carcinoma: A Systematic Review

BACKGROUND

Surgical excision is considered standard treatment for nodular basal cell carcinoma (nBCC). However, patients who reject or are unsuited for surgery may benefit from imiquimod (IMQ) 5% cream as an alternative treatment.

OBJECTIVES

The objective of this study was to conduct a systematic review on the efficacy and safety of IMQ for the treatment of nBCC.

MATERIALS AND METHODS

The terms basal cell carcinoma AND imiquimod OR Aldara were searched on Ovid-MEDLINE, EMBASE, and Cochrane Library databases. Articles were included if they reported the efficacy or side effects of IMQ for nBCC. Primary outcomes included clearance (clinical and histological), recurrence rates, and adverse events. Number of lesions/subjects, treatment regimens, length of treatment, and time to recurrence were secondary outcomes.

RESULTS

Thirty-nine publications, totaling 738 lesions, revealed a 77.4% (335/433 lesions) clinical and 72.9% (390/535 lesions) histological clearance rate. Regimens ranged from once daily 2 days a week to twice daily 7 days a week. Average treatment duration was 8.81 (±3.49) weeks. There was a 1.80% recurrence rate after an average follow-up period of 13.03 (±15.09) months. Common adverse effects included erythema (77.2%), crusting (50.5%), pruritus (34.1%), tenderness/irritation (27.3%), ulceration (25.4%), burning (22.1%), and erosion (21.7%). Unforeseen side effects included conjunctivitis, keratitis, depigmentation, comedone formation, and ruptured epidermoid cysts.

CONCLUSION

Imiquimod showed clinical and histological clearance rates of over 70% for nBCC, with a recurrence rate of 1.80%. Although clearance rates are lower than surgery, IMQ can be considered as a treatment option for nBCC in those who decline or are unfit for surgical intervention.

Agonist and antagonist ligands of toll-like receptors 7 and 8: Ingenious tools for therapeutic purposes

The discovery of the TLRs family and more precisely its functions opened a variety of gates to modulate immunological host responses. TLRs 7/8 are located in the endosomal compartment and activate a specific signaling pathway in a MyD88-dependant manner. According to their involvement into various autoimmune, inflammatory and malignant diseases, researchers have designed diverse TLRs 7/8 ligands able to boost or block the inherent signal transduction. These modulators are often small synthetic compounds and most act as agonists and to a much lesser extent as antagonists. Some of them have reached preclinical and clinical trials, and only one has been approved by the FDA and EMA, imiquimod. The key to the success of these modulators probably lies in their combination with other therapies as recently demonstrated. We gather in this review more than 360 scientific publications, reviews and patents, relating the extensive work carried out by researchers on the design of TLRs 7/8 modulators, which are classified firstly by their biological activities (agonist or antagonist) and then by their chemical structures, which total syntheses are not discussed here. This review also reports about 90 clinical cases, thereby showing the biological interest of these modulators in multiple pathologies.

Herpes simplex virus mucocutaneous tumoural lesions - Systematic review

The goal was to characterize the clinical-epidemiological profile of patients with mucocutaneous tumoural herpes simplex virus (MCT HSV) lesions across the world. Two researchers extracted and independently reviewed data from the literature search engine PubMed/MEDLINE through October 2018. From 110 reported patients, the following data were available: the patients' ages ranged from 7 to 76 years; the majority was male (62.73 %-69/110) and immunosuppression was found in 97.25 % (106/109, missing 1) cases, of whom 88 were HIV- related. Lesions size varied from 0.2-13 cm, settling in the anogenital region in 76.36 % (84/110) patients; 84.13 % (53/63, missing 47) complained of pain and multiple recurrences were found in 44.94 % (40/89, missing 21) cases. On clinical basis, the initial hypothesis was neoplasia in 36/53 patients. Histopathological diagnosis was achieved in 90 % (90/100, missing 10) cases and was sample size-dependent. Type 2 HSV was detected in 86.07 % (68/79, missing 31) lesions. MCT HSV lesions recurrence after treatment was reported in 33.96 % (18/53, missing 57) patients. Pathophysiology is poorly understood. Physicians should be aware of MCT HSV lesions in immunosuppressed patients to avoid inappropriate therapeutic strategies.

Pharmacological modulation of nucleic acid sensors - therapeutic potential and persisting obstacles

Nucleic acid sensors, primarily TLR and RLR family members, as well as cGAS-STING signalling, play a critical role in the preservation of cellular and organismal homeostasis. Accordingly, deregulated nucleic acid sensing contributes to the origin of a diverse range of disorders, including infectious diseases, as well as cardiovascular, autoimmune and neoplastic conditions. Accumulating evidence indicates that normalizing aberrant nucleic acid sensing can mediate robust therapeutic effects. However, targeting nucleic acid sensors with pharmacological agents, such as STING agonists, presents multiple obstacles, including drug-, target-, disease- and host-related issues. Here, we discuss preclinical and clinical data supporting the potential of this therapeutic paradigm and highlight key limitations and possible strategies to overcome them.

The 6π-azaelectrocyclization of azatrienes. Synthetic applications in natural products, bioactive heterocycles, and related fields

Covering: 2006 to 2018 The application of the 6π-azaelectrocyclization of azatrienes as a key strategy for the synthesis of natural products, their analogs and related bioactive or biomedically-relevant compounds (from 2006 to date) is comprehensively reviewed. Details about reaction optimization studies, relevant reaction mechanisms and conditions are also discussed.

Cytoplasmic Mechanisms of Recognition and Defense of Microbial Nucleic Acids

Microbial nucleic acids are major signatures of invading pathogens, and their recognition by various host pattern recognition receptors (PRRs) represents the first step toward an efficient innate immune response to clear the pathogens. The nucleic acid-sensing PRRs are localized at the plasma membrane, the cytosol, and/or various cellular organelles. Sensing of nucleic acids and signaling by PRRs involve recruitment of distinct signaling components, and PRRs are intensively regulated by cellular organelle trafficking. PRR-mediated innate immune responses are also heavily regulated by posttranslational modifications, including phosphorylation, polyubiquitination, sumoylation, and glutamylation. In this review, we focus on our current understanding of recognition of microbial nucleic acid by PRRs, particularly on their regulation by organelle trafficking and posttranslational modifications. We also discuss how sensing of self nucleic acids and dysregulation of PRR-mediated signaling lead to serious human diseases.

INFLUENCE OF THE IMIQUIMOD ON THE INTERFERON PRODUCTION AND TREATMENT OF THE EXPERIMENTAL HERPES SIMPLEX VIRUS INFECTION

BACKGROUND

Imiquimod is an imidazole derivative acting as an immunomodulator on the level of innate and adaptive immune system. Our objective was to evaluate the antiviral activity of generically reproduced imiquimod administered subcutaneously in mice and intravaginally in guinea pigs against herpes simplex virus (HSV), as well as to study the dynamics of serum interferon (IFN) synthesis under different dosing regimens.

RESULTS

When administered subcutaneously at doses of 0.5, 1.0 and 10 mg/kg imiquimod increased IFN production in mice in a dose-dependent manner with maximum serum IFN concentrations occurring 4 hours after dosing. Imiquimod protected mice from intraperitoneal HSV infection at doses of 3.2 and 32 LD50.The utmost protection (100% survival) was observed when imiquimod was administered at a dose of 100 mg/kg daily for 5 days before infection. Topical application of imiquimod 5% cream exhibited significantly more rapid and complete virus elimination in guinea pigs intravaginally infected with HSV type 2 compared to control group.

CONCLUSION

Imiquimod produced as a generic possesses the same immunomodulatory and antiviral properties as the originally synthesized substance.

Strategies for Antiviral Drug Discovery

The need for antiviral drugs is growing rapidly as more viral diseases are recognized. The methods used to discover these drugs have evolved considerably over the past 40 years and the overall process of discovery can be broken down into sub-processes which include lead generation, lead optimization and lead development. Various methods are now employed to ensure these processes are carried out efficiently. For lead generation, screening methodologies have developed to the extent where hundreds of thousands of compounds can be screened against a particular target. An alternative approach is to use the structures of enzyme substrates as a starting point for drug discovery. Much use is now made of X-ray crystallographic data of target–inhibitor complexes for the optimization of lead structures, and methods for preparing libraries of compounds to assist both generation and optimization of leads are welldeveloped. The methods used to predict and improve the pharmacokinetic properties of compounds are also changing rapidly. Finally, novel approaches to antiviral therapy using oligonucleotide-based compounds or modulating the host immune response are also being explored. This review discusses these approaches, provides examples of where their application has been successful and sets them against a historical background.

Identification of novel macrolides with antibacterial, anti-inflammatory and type I and III IFN-augmenting activity in airway epithelium

BACKGROUND

Exacerbations of asthma and COPD are triggered by rhinoviruses. Uncontrolled inflammatory pathways, pathogenic bacterial burden and impaired antiviral immunity are thought to be important factors in disease severity and duration. Macrolides including azithromycin are often used to treat the above diseases, but exhibit variable levels of efficacy. Inhaled corticosteroids are also readily used in treatment, but may lack specificity. Ideally, new treatment alternatives should suppress unwanted inflammation, but spare beneficial antiviral immunity.

METHODS

In the present study, we screened 225 novel macrolides and tested them for enhanced antiviral activity against rhinovirus, as well as anti-inflammatory activity and activity against Gram-positive and Gram-negative bacteria. Primary bronchial epithelial cells were grown from 10 asthmatic individuals and the effects of macrolides on rhinovirus replication were also examined. Another 30 structurally similar macrolides were also examined.

RESULTS

The oleandomycin derivative Mac5, compared with azithromycin, showed superior induction (up to 5-fold, EC50 = 5-11 μM) of rhinovirus-induced type I IFNβ, type III IFNλ1 and type III IFNλ2/3 mRNA and the IFN-stimulated genes viperin and MxA, yet had no effect on IL-6 and IL-8 mRNA. Mac5 also suppressed rhinovirus replication at 48 h, proving antiviral activity. Mac5 showed antibacterial activity against Gram-positive Streptococcus pneumoniae; however, it did not have any antibacterial properties compared with azithromycin when used against Gram-negative Escherichia coli (as a model organism) and also the respiratory pathogens Pseudomonas aeruginosa and non-typeable Haemophilus influenzae. Further non-toxic Mac5 derivatives were identified with various anti-inflammatory, antiviral and antibacterial activities.

CONCLUSIONS

The data support the idea that macrolides have antiviral properties through a mechanism that is yet to be ascertained. We also provide evidence that macrolides can be developed with anti-inflammatory, antibacterial and antiviral activity and show surprising versatility depending on the clinical need.

Imiquimod: A Review

Background and Objective:

Imiquimod (Aldara) is an immune response modifier used primarily to treat anogenital warts. Imiquimod induces cytokines and enhances cell-mediated cytolytic antiviral activity in vivo. It exhibits antiviral and antitumor effects; however, it does not exhibit direct antiviral effects in vitro. By inducing cytokines, such as interferon A, imiquimod stimulates both the innate immune response and the cellular arm of acquired immunity. Currently, imiquimod is approved for use in the treatment of external genital and perianal warts in adults.

Conclusion:

Beyond its established use, there are case reports and preliminary studies suggesting the effectiveness of imiquimod 5% cream in the treatment of nongenital human papillomavirus warts, molluscum contagiosum, actinic keratosis, basal cell carcinoma, squamous cell carcinoma, Bowen's disease, nongenital human papillomavirus infection, and vulvar intraepithelial neoplasia.

Toll-Like Receptor 7-Targeted Therapy in Respiratory Disease

Allergic asthma and allergic rhinitis are inflammatory diseases of the respiratory tract characterized by an excessive type-2 T helper cell (Th2) immune response. Toll-like receptor 7 (TLR7) is a single-stranded viral RNA receptor expressed in the airway that initiates a Th1 immune response and has garnered interest as a novel therapeutic target for treatment of allergic airway diseases. In animal models, synthetic TLR7 agonists reduce airway hyperreactivity, eosinophilic inflammation, and airway remodeling while decreasing Th2-associated cytokines. Furthermore, activation of TLR7 rapidly relaxes airway smooth muscle via production of nitric oxide. Thus, TLR7 has dual bronchodilator and anti-inflammatory effects. Two TLR7 ligands with promising pharmacologic profiles have entered clinical trials for the treatment of allergic rhinitis. Moreover, TLR7 agonists are potential antiviral therapies against respiratory viruses. TLR7 agonists enhance influenza vaccine efficacy and also reduce viral titers when given during an active airway infection. In this review, we examine the current data supporting TLR7 as a therapeutic target in allergic airway diseases.

Melanoma arising after imiquimod use

Imiquimod belongs to the class of 1H-imidazo-[4,5-c]quinolones—drugs originally developed as nucleoside analogues with the aim of finding new potential antiviral agents (Harrison et al., 1988). Indeed, Imiquimod was first released as treatment for genital warts before its actions against skin cancer were studied. Imiquimod is a relatively small sized molecule (Mr = 240.3) and is hydrophobic, allowing it to penetrate the skin epidermal barrier and therefore making it suitable for topical formulations (Gerster et al., 2005). Imiquimod has shown itself effective against skin cancers and precancerous lesions, especially basal cell cancers and actinic keratosis (Salasche et al., 2002, Beutner et al., 1999). There have been reports of Imiquimod being used as topical treatment against cutaneous metastases of melanoma and some authors have reported its use as first-line therapy against melanoma in situ (Smyth et al., 2011, Gagnon, 2011). We report a case of an invasive malignant melanoma arising de novo at the specific site of application of Imiquimod (Aldara cream 5%) for a biopsy-proven superficial BCC. Therefore while Imiquimod has added to our topical armamentarium against skin cancer, care must be exercised in prescribing this treatment and it is especially important to follow up patients regularly.

Topical SMIP-7.7, a toll-like receptor 7 agonist, protects against genital herpes simplex virus type-2 disease in the guinea pig model of genital herpes

BACKGROUND

Development of more effective therapies for genital herpes simplex virus type-2 (HSV-2) infections remains a priority. The toll-like receptors (TLR) are attractive targets for the immunomodulation of primary and recurrent genital herpes infection. The guinea pig model of genital HSV-2 disease was therefore used to evaluate the efficacy of a new TLR-7 agonist, SMIP-7.7.

METHODS

The effects of SMIP-7.7 at concentrations between 0.90% and 0.09% were compared to the vehicle control or Aldara(®) (3M Health Care Limited, Northridge, CA, USA) as treatment for genital HSV-2 infections. Following intravaginal inoculation of Hartley guinea pigs with 10(6) pfu HSV-2 (MS strain), animals were treated intravaginally beginning at 36 h post-infection. Animals were evaluated for acute disease, acute virus replication, recurrent disease and shedding, as well as infection of the dorsal root ganglia.

RESULTS

Treatment with SMIP-7.7 significantly decreased mean total lesion scores during primary infection (all doses, P<0.01 compared with vehicle control, and similar to Aldara(®)). Vaginal virus titres were reduced in treated animals compared with vehicle control (P<0.001 for each treatment versus vehicle control on day 4). Treatment with SMIP-7.7 also significantly decreased the number of recurrent lesion days, the number of days with recurrent virus shedding and the infection of the dorsal root ganglia compared to the vehicle control, and was similar to Aldara(®). As opposed to Aldara(®), SMIP-7.7 did not induce fever or weight loss during treatment.

CONCLUSIONS

SMIP-7.7 improves the outcome of primary and recurrent HSV-2 disease comparable to Aldara(®) but without some of the side effects associated with Aldara(®).

TLRs to cytokines: mechanistic insights from the imiquimod mouse model of psoriasis

Psoriasis is an inflammatory disease of the skin affecting 2-3% of the population, characterized by a thickening of the epidermis and immune infiltrates throughout the dermis and epidermis, causing skin lesions that can seriously affect quality of life. The study of psoriasis has historically been hampered by the lack of good animal models. Various genetically induced models exist, which have provided some information about possible mechanisms of disease, but these models rely mostly on intrinsic imbalances of homeostasis. However, a mouse model of psoriasiform dermatitis caused by the repeated topical application of Aldara™ containing 5% imiquimod was described in 2009. The mechanisms of action of Aldara™ are complex. Imiquimod is an effective ligand for TLR7 (and TLR8 in humans) and also interferes with adenosine receptor signaling. In addition, isostearic acid present in the Aldara™ vehicle has been shown to be biologically active and of importance for activating the inflammasome. Interestingly, the repetitive application of Aldara™ reveals a complex aetiology involving multiple cell types, cytokines, and inflammatory pathways. In this review, we will dissect the findings of the imiquimod model to date and ask how this model can inform us about the immunological aspects of human disease.

Long-term remission of recurrent herpes labialis following topical imiquimod application on distant healthy skin: a clinical and immunological study

BACKGROUND

Given the limitations of current antiviral therapies, safer and more effective approaches to the management of recurrent herpes labialis (RHL) are needed.

METHODS

A patient with a 23-year history of RHL and 14 healthy individuals were studied. The patient applied imiquimod to distant healthy skin for 3 weeks. Peripheral blood (PB) samples were collected from the patient during treatment and 21 months after its discontinuation; samples were collected from the controls once. The distribution of lymphocyte populations in PB were analysed by flow cytometry and PB cytokine levels were measured using cytometric bead arrays.

RESULTS

The patient showed long-term remission of the disorder subsequent to a 3-week imiquimod application to distant healthy skin. Imiquimod treatment induced the activation and proliferation of T-helper and cytotoxic T-cells, B-cells and T-regulatory cells. In addition, there was a very strong transient increase of T-helper 1 cells (resulting in interferon-γ secretion) and type 1 (pro-inflammatory) polarization of the immune response accompanied by a sustainable interferon-α production. At follow-up 21 months after treatment cessation, with the patient remaining relapse-free, the patient had control levels of all cytokines, increased levels of activated cytotoxic T-cells, continuous production of new T-helper cells and B-cells and near-to-normal levels of T-regulatory cells.

CONCLUSIONS

Our results indicate that topical application of imiquimod to healthy skin is capable of causing systemic immunomodulation. This treatment might represent a new and effective alternative to established therapeutic and prophylactic regimens for RHL.

Innate immunity and cancer therapy

Classical cancer immunotherapy utilizes the immune response against microbial components, and a sequence of immune responses produce antitumor effects. The identification of mammalian Toll-like receptors (TLRs), receptors for microbial components, has shed light on antigen recognition by the innate immune system and provided a molecular basis for our understanding of the relationship between innate immunity and antitumor activity. However, accumulating evidence has revealed another important role of TLRs in maintaining tissue homeostasis and has also shown that tumor cells utilize this function to create favorable conditions for growth and survival, suggesting that TLR signaling acts as a double-edged sword in cancer therapy. In this review, innate immunity-based cancer therapy will be discussed with special reference to TLR-targeting drugs.

Plasmacytoid dendritic cell-derived type I interferon is crucial for the adjuvant activity of Toll-like receptor 7 agonists

There is a high demand for the development of adjuvants that induce cytotoxic T lymphocytes, which are crucial for the elimination of intracellular pathogens and tumor cells. Toll-like receptor (TLR) agonists are prime candidates to fulfill this role because they induce innate immune activation and promote adaptive immune responses. The successful application of the TLR7 agonist R837 for treatment of basal cell carcinoma shows the potential for exploiting this pathway in tumor immunotherapy. Imidazoquinolines like R837 and stimulatory ssRNA oligonucleotides both trigger TLR7-mediated immune activation, but little is known about their comparative ability to promote immunity induction. We investigated differences in innate immune activation and adjuvant activity between the imidazoquinoline R848 and the ssRNA TLR7 agonist polyUs21. In contrast to R848, polyUs21 induced detectable levels of intracellular interferon-alpha (IFN-alpha) in plasmacytoid dendritic cells (PDCs). In immunization studies, only polyUs21 led to robust priming of type 1 T helper cells and cytotoxic T lymphocytes, and it was more efficient in inducing antitumor immunity than R848. Notably, exogenous IFN-alpha augmented the adjuvant activity of R848, whereas depletion of PDC abrogated the adjuvanticity of polyUs21. This study, therefore, identifies sufficient IFN-alpha production by PDC as an important determinant of vaccine efficacy.

Type I Interferon as a Link Between Innate and Adaptive Immunity through Dendritic Cell Stimulation

Type I interferon (IFN-alpha/beta) is expressed rapidly after infection and plays a key role in innate defense against pathogens. Recent studies have shown that a connection exists between IFN-alpha/beta and antigen-presenting dendritic cells (DCs) at two levels. Firstly, a specific DC precursor, the plasmacytoid pre-DC (p-preDC), was identified as a cell type able to secrete very high amounts of IFN-alpha/beta following stimulation with infectious agents. Secondly, IFN-alpha/beta has been shown to act as a differentiation/maturation factor for DCs. These findings will be discussed in association with evidence indicating that IFN-alpha/beta can enhance and modulate immune responses in vivo. Taken together, the available data suggest that IFN-alpha/beta serves as a link between the innate response to infection and the adaptive immune response.

Modulation of the allergic asthma transcriptome following resiquimod treatment

Resiquimod is a compound belonging to the imidazoquinoline family of compounds known to signal through Toll-like receptor 7. Resiquimod treatment has been demonstrated to inhibit the development of allergen induced asthma in experimental models. The aim of the present study was to elucidate the molecular processes that were altered following resiquimod treatment and allergen challenge in a mouse model of allergic asthma. Employing microarray analysis, we have characterized the "asthmatic" transcriptome of the lungs of A/J and C57BL/6 mice and determined that it includes genes involved in the control of cell cycle progression, the complement and coagulation cascades, and chemokine signaling. Our results demonstrated that resiquimod treatment resulted in the normalization of the expression of genes involved with airway remodeling, and generally, chemokine signaling. Resiquimod treatment also altered the expression of cell adhesion molecules, and molecules involved in natural killer (NK) cell-mediated cytotoxicity. Furthermore, we have demonstrated that systemic resiquimod administration resulted in the recruitment of NK cells to the lungs and livers of the mice, although no causal relationship between NK cell recruitment and treatment efficacy was found. Overall, our findings identified several genes, important in the development of asthma pathology, that were normalized following resiquimod treatment, thus improving our understanding of the molecular consequences of resiquimod treatment in the lung milieu. The recruitment of NK cells to the lungs may also have application in the treatment of virally induced asthma exacerbations.

The in vitro and in ovo responses of chickens to TLR9 subfamily ligands

Although Toll-like receptors (TLRs) have been well characterised in mammals, less work has been carried out in non-mammalian species, such as chickens. In this study the response of chicken cells to the TLR9 subfamily of ligands was characterised in vitro and in ovo. It was found that even though chickens appear to have only one functional receptor to represent the TLR9 subfamily, stimulation of chicken splenocytes with TLR7 and TLR9 ligands induced proinflammatory cytokine production and cell proliferation, similar to that observed when the homologous mammalian receptors are stimulated. Furthermore, we demonstrated that the in ovo administration of these TLR ligands elicits a response, such as cytokine production, that can be detected post-hatch. The current knowledge of the action of TLR ligands in mammals, in conjunction with their immunomodulating ability shown in this study, draws attention to their potential use as therapeutic agents for the poultry industry.

Clinical investigations of Toll-like receptor agonists

BACKGROUND

Toll-like receptors (TLR) represent a family of surface molecules that function as primary sensors of the innate immune system to recognize microbial pathogens. Ligand binding to TLR results in activation of cellular signaling pathways that regulate expression of genes involved in inflammation and immunity.

OBJECTIVE

Use of synthetic TLR ligands (agonists) for treatment and prevention of infectious and neoplastic diseases.

METHODS

Review of literature about clinical investigations of agonists of TLR 4, 7, 8, and 9.

RESULTS/CONCLUSIONS

Imiquimod was the first TLR agonist approved for treatment of anogenital warts, actinic keratosis and superficial basal cell carcinoma in humans. Several other agonists of TLRs 4, 7, 8 and 9 were also shown to be effective for treatment of infections and cancers and, furthermore, were used as adjuvants for vaccination. Based on safety and efficacy of the TLR agonists used to date, applications are likely to increase in the future.

Imiquimod: mode of action

OBJECTIVE

Since imiquimod, a nucleoside analogue of the imidazoquinoline family, has shown efficacy against many tumour entities, its mode of action has become a focus of scientific interest.

RESULTS

The major biologic effects of imiquimod are mediated through agonistic activity towards toll-like receptors (TLR) 7 and 8, and consecutively, activation of nuclear factor-kappa B (NF-kappaB). The result of this activity is the induction of pro-inflammatory cytokines, chemokines and other mediators leading to activation of antigen-presenting cells and other components of innate immunity and, eventually, the mounting of a profound T-helper (Th1)-weighted antitumoral cellular immune response. Several secondary effects on the molecular and cellular level may also be explained, at least in part, by the activation of NF-kappaB. Moreover, independent of TLR-7 and TLR-8, imiquimod appears to interfere with adenosine receptor signalling pathways, and the compound causes receptor-independent reduction of adenylyl cyclase activity. This novel mechanism may augment the pro-inflammatory activity of the compound through suppression of a negative regulatory feedback mechanism which normally limits inflammatory responses. Finally, imiquimod induces apoptosis of tumour cells at higher concentrations. The pro-apoptotic activity of imiquimod involves caspase activation and appears to depend on B cell lymphoma/leukemia protein (Bcl)-2 proteins.

CONCLUSIONS

Overall, imiquimod acts on several levels, which appear to synergistically underlie the profound antitumoral activity of the compound.

TLR7 and TLR8 as targets in cancer therapy

Small-molecule agonists at Toll-like receptor 7 (TLR7) and TLR8 have sparked a vivid interest in cancer research owing to their profound antitumoral activity. The lead compound of the imidazoquinoline family, imiquimod, is marketed as a topical formulation. It is efficacious against many primary skin tumors and cutaneous metastases. Using different imidazoquinoline species, distinct functions of TLR7 and TLR8 have been discovered. The predominant antitumoral mode of action of these agents is TLR7/8-mediated activation of the central transcription factor nuclear factor-kappaB, which leads to induction of proinflammatory cytokines and other mediators. Cutaneous dendritic cells are the primary responsive cell type and initiate a strong Th1-weighted antitumoral cellular immune response. Recent research has shown that dendritic cells themselves acquire direct antitumoral activity upon stimulation by imiquimod. In addition, there are a number of secondary effects on the molecular and cellular level that can be explained through the activation of TLR7/8. The proinflammatory activity of imiquimod, but not resiquimod, appears to be augmented by suppression of a regulatory mechanism, which normally limits inflammatory responses. This is achieved independently of TLR7/8 through interference with adenosine receptor signaling pathways. Finally, at higher concentrations imiquimod exerts Bcl-2- and caspase-dependent proapoptotic activity against tumor cells.

Resiquimod and other immune response modifiers as vaccine adjuvants

Synthetic immune response modifiers, such as resiquimod, are Toll-like receptor 7 and 8 agonists that act as vaccine adjuvants, enhancing antigen-specific antibody production and skewing immunity towards a Th1 response. These compounds stimulate dendritic cells to secrete cytokines, upregulate costimulatory molecule expression and enhance antigen presentation to T cells. The compounds have demonstrated vaccine adjuvant properties in a number of animal models. The adjuvant effects can be enhanced by measures that allow the drug to stay localized with the vaccine without quickly entering the systemic circulation. Clinical studies demonstrate that topical application of resiquimod and analogs is safe and effective at activating the local immune response. For injection, resiquimod or a similar compound may need to be formulated to allow for local immune activation without induction of systemic cytokines.

Recognition of nucleic acid and nucleic acid analogs by Toll-like receptors 7, 8 and 9

The mammalian immune system senses pathogens through pattern recognition receptors (PRR) and responds with activation. Toll-like receptors (TLRs) that are expressed on immune and non-immune cells play a critical role in this process. As part of the innate immune response, TLRs lead to cellular activation and cytokine production with subsequent initiation of an adaptive immune response. TLR7-9 recognize single-stranded RNA, nucleoside analogs and single-stranded CpG-DNA, respectively, and their activation initiates the immune response against viruses and bacteria. Furthermore, the stimulation of these TLRs may be exploited for adjuvant therapy, vaccination and anti-tumor responses. However, a role in the generation or perpetuation of autoimmune diseases such as systemic lupus erythematosus (SLE) has also been suggested.

Effect of resiquimod 0.01% gel on lesion healing and viral shedding when applied to genital herpes lesions

Resiquimod, a Toll-like receptor 7/8 agonist developed as a topical treatment to decrease recurrences of anogenital herpes, induces proinflammatory cytokines that may delay lesion healing. Adults with frequently recurring anogenital herpes were randomized within 24 h of onset of a recurrence to vehicle or resiquimod 0.01% gel two times per week for 3 weeks. Subjects underwent daily lesion assessments and sampling for herpes simplex virus DNA PCR for 21 days or until investigator-determined healing of lesion(s). Eighty-two subjects with a mean age of 39 +/- 10.5 years and a median of seven recurrences per year were enrolled in the study. The qualifying recurrence was positive by PCR for herpes simplex virus in 68% of subjects. No difference was observed between the vehicle (39 subjects) and resiquimod (43 subjects) groups with respect to time to healing (median of 7.0 days versus median of 6.5 days, respectively; Cox proportional hazard model ratio of 1.229; 95% confidence interval, 0.778 to 1.942; P = 0.376). The distributions of maximum severity scores for any investigator-assessed local skin signs and for subject-assessed local symptoms were similar between treatment groups (P = 0.807 and P = 0.103, respectively). For subjects with at least one positive PCR result, no difference was observed for time to cessation of viral shedding (median of 7 days versus median of 5 days for vehicle and resiquimod groups, respectively; Cox proportional hazard model ratio of 1.471; 95% confidence interval, 0.786 to 2.754; P = 0.227). Application of resiquimod 0.01% two times per week for 3 weeks did not delay the healing of genital herpes lesions or reduce acute viral shedding.

The pharmacology of endosomal TLR agonists in viral disease

The discovery of endosomal TLRs (Toll-like receptors) and their natural ligands has accelerated efforts to exploit them for therapeutic benefit. Importantly, this was preceded by clinical exploration of agents now known to be endosomal TLR agonists. Clinical effects in viral disease have been reported with agonists of TLR3, TLR7, TLR7/8 and TLR9, and the TLR7 agonist imiquimod is marketed for topical use against warts, a papillomavirus disease. The observed pre-clinical and clinical profiles of agonists of each of these TLRs suggest induction of a multifaceted innate immune response, with biomarker signatures indicative of type 1 interferon induction. However, these agents differ in both their pharmaceutical characteristics and the cellular distribution of their target TLRs, suggesting that drugs directed to these targets will display differences in their overall pharmacological profiles.

TLR7 imidazoquinoline ligand 3M-019 is a potent adjuvant for pure protein prototype vaccines

Cancer vaccines, while theoretically attractive, present difficult challenges that must be overcome to be effective. Cancer vaccines are often poorly immunogenic and may require augmentation of immunogenicity through the use of adjuvants and/or immune response modifiers. Toll-like receptor (TLR) ligands are a relatively new class of immune response modifiers that may have great potential in inducing and augmenting both cellular and humoral immunity to vaccines. TLR7 ligands produce strong cellular responses and specific IgG2a and IgG2b antibody responses to protein immunogens. This study shows that a new TLR7 ligand, 3M-019, in combination with liposomes produces very strong immune responses to a pure protein prototype vaccine in mice. Female C57BL/6 mice were immunized subcutaneously with ovalbumin (OVA, 0.1 mg/dose) weekly 4x. Some groups were immunized to OVA plus 3M-019 or to OVA plus 3M-019 encapsulated in liposomes. Both antibody and cellular immune responses against OVA were measured after either two or four immunizations. Anti-OVA IgG antibody responses were significantly increased after two immunizations and were substantially higher after four immunizations in mice immunized with OVA combined with 3M-019. Encapsulation in liposomes further augmented antibody responses. IgM responses, on the other hand, were lowered by 3M-019. OVA-specific IgG2a levels were increased 625-fold by 3M-019 in liposomes compared to OVA alone, while anti-OVA IgG2b levels were over 3,000 times higher. In both cases encapsulation of 3M-019 in liposomes was stronger than either liposomes alone or 3M-019 without liposomes. Cellular immune responses were likewise increased by 3M-019 but further enhanced when it was encapsulated in liposomes. The lack of toxicity also indicates that this combination may by safe, effective method to boost immune response to cancer vaccines.

Administration of a dual toll-like receptor 7 and toll-like receptor 8 agonist protects against influenza in rats

Toll-like receptors (TLR) detect conserved molecular patterns expressed by pathogens. Detection of the "molecular signature" for RNA viruses including influenza has been attributed to TLR3, TLR7, and TLR8. In the present study, compound 3M-011 was shown to be a synthetic human TLR7/8 agonist and cytokine inducer. 3M-011 was investigated as a stand-alone immune response modifier in a rat model of human influenza. Intranasal (IN) administration of 3M-011 significantly inhibited H3N2 influenza viral replication in the nasal cavity when administered from 72 h before IN viral inoculation to 6h after inoculation. Viral inhibition correlated with the ability of the TLR7/8 agonist to stimulate type I interferon (IFN) and other cytokines such as tumor necrosis factor-alpha, interleukin-12, and IFN-gamma from rat peripheral blood mononuclear cells. Prophylactic administration of TLR7/8 agonist also suppressed influenza viral titers in the lung, which corresponded with local IFN production. The activity of the TLR7/8 agonist resulted in greater inhibition of viral titers compared to rat recombinant IFN-alpha administered in a comparable dosing regimen. These studies indicate that TLR7/8 agonists may have prophylactic and therapeutic benefits in the treatment of respiratory viral infections, such as influenza, when administered prior to or shortly after viral inoculation.