Effect of food on the pharmacokinetics and bioavailability of oral imiquimod relative to a subcutaneous dose

TLR7 Agonist-Loaded Gadolinium Oxide Nanotubes Promote Anti-Tumor Immunity by Activation of Innate and Adaptive Immune Responses

Improving the delivery of biomolecules to DCs and lymph nodes is critical to increasing their anti-tumor efficacy, reducing their off-target side effects, and improving their safety. In this study, Gd2O3 nanotubes with lengths of 70-80 nm, diameters of 20-30 nm, and pore sizes of up to 18 nm were synthesized using a facile one-pot solvothermal method. The Gd2O3 nanotubes showed good adsorption capacity of OVA and TLR7a, with a loading efficiency of about 100%. The Gd2O3 nanotubes showed pH-sensitive degradation and biomolecule release properties; the release of gadolinium ions, OVA, and TLR7a was slow at pH 7.4 and fast at pH 5. The Gd2O3 nanotubes showed 2.6-6.0 times higher payload retention around the injection site, 3.1 times higher cellular uptake, 1.7 times higher IL1β secretion, 1.4 times higher TNFα secretion by BMDCs, and markedly enhanced draining lymph node delivery properties. The combination of OVA, TLR7a, and Gd2O3 nanotubes significantly inhibited tumor growth and increased survival rate compared with only OVA-TLR7a, only OVA, and saline. The Gd2O3 nanotubes are biocompatible and can also be used as radiation sensitizers.

Immunogenicity of Recombinant Lipid-Based Nanoparticle Vaccines: Danger Signal vs. Helping Hand

Infectious diseases are a predominant problem in human health. While the incidence of many pathogenic infections is controlled by vaccines, some pathogens still pose a challenging task for vaccine researchers. In order to face these challenges, the field of vaccine development has changed tremendously over the last few years. For non-replicating recombinant antigens, novel vaccine delivery systems that attempt to increase the immunogenicity by mimicking structural properties of pathogens are already approved for clinical applications. Lipid-based nanoparticles (LbNPs) of different natures are vesicles made of lipid layers with aqueous cavities, which may carry antigens and other biomolecules either displayed on the surface or encapsulated in the cavity. However, the efficacy profile of recombinant LbNP vaccines is not as high as that of live-attenuated ones. This review gives a compendious picture of two approaches that affect the immunogenicity of recombinant LbNP vaccines: (i) the incorporation of immunostimulatory agents and (ii) the utilization of pre-existing or promiscuous cellular immunity, which might be beneficial for the development of tailored prophylactic and therapeutic LbNP vaccine candidates.

New In Vitro-In Silico Approach for the Prediction of In Vivo Performance of Drug Combinations

Pharmacokinetic (PK) studies improve the design of dosing regimens in preclinical and clinical settings. In complex diseases like cancer, single-agent approaches are often insufficient for an effective treatment, and drug combination therapies can be implemented. In this work, in silico PK models were developed based on in vitro assays results, with the goal of predicting the in vivo performance of drug combinations in the context of cancer therapy. Combinations of reference drugs for cancer treatment, gemcitabine and 5-fluorouracil (5-FU), and repurposed drugs itraconazole, verapamil or tacrine, were evaluated in vitro. Then, two-compartment PK models were developed based on the previous in vitro studies and on the PK profile reported in the literature for human patients. Considering the quantification parameter area under the dose-response-time curve (AUC_effect) for the combinations effect, itraconazole was the most effective in combination with either reference anticancer drugs. In addition, cell growth inhibition was itraconazole-dose dependent and an increase in effect was predicted if itraconazole administration was continued (24-h dosing interval). This work demonstrates that in silico methods and AUC_effect are powerful tools to study relationships between tissue drug concentration and the percentage of cell growth inhibition over time.

Immunological Mechanism and Clinical Application of PAMP Adjuvants

BACKGROUND

The host innate immune system can recognize Pathogen-Associated Molecular Patterns (PAMPs) through Pattern Recognition Receptors (PRRs), thereby initiating innate immune responses and subsequent adaptive immune responses. PAMPs can be developed as a vaccine adjuvant for modulating and optimizing antigen-specific immune responses, especially in combating viral infections and tumor therapy. Although several PAMP adjuvants have been successfully developed they are still lacking in general, and many of them are in the preclinical exploration stage.

OBJECTIVE

This review summarizes the research progress and development direction of PAMP adjuvants, focusing on their immune mechanisms and clinical applications.

METHODS

PubMed, Scopus, and Google Scholar were screened for this information. We highlight the immune mechanisms and clinical applications of PAMP adjuvants.

RESULTS

Because of the differences in receptor positions, specific immune cells targets, and signaling pathways, the detailed molecular mechanism and pharmacokinetic properties of one agonist cannot be fully generalized to another agonist, and each PAMP should be studied separately. In addition, combination therapy and effective integration of different adjuvants can increase the additional efficacy of innate and adaptive immune responses.

CONCLUSION

The mechanisms by which PAMPs exert adjuvant functions are diverse. With continuous discovery in the future, constant adjustments should be made to build new understandings. At present, the goal of therapeutic vaccination is to induce T cells that can specifically recognize and eliminate tumor cells and establish long-term immune memory. Following immune checkpoint modulation therapy, cancer treatment vaccines may be an option worthy of clinical testing.

Development of immune memory to glial brain tumors after tumor regression induced by immunotherapeutic Toll-like receptor 7/8 activation

The efficacy of immunotherapeutic TLR7/8 activation by resiquimod (R848) was evaluated in vivo, in the CNS-1 rat glioma model syngeneic to Lewis rats. The immune treatment was compared with cytotoxic cyclophosphamide chemotherapy, and as well, was compared with the combination cytotoxic and immunotherapeutic treatments. We found that parenteral treatment with the TLR7/8 agonist, resiquimod, eventually induced complete tumor regression of CNS-1 glioblastoma tumors in Lewis rats. Cyclophosphamide (CY) treatment also resulted in dramatic CNS-1 remission, while the combined treatment showed similar antitumor effects. The resiquimod efficacy appeared not to be associated with direct injury to CNS-1 growth, while CY proved to exert tumoricidal cytotoxicity to the tumor cells. Rats that were cured by treatment with the innate immune response modifier resiquimod proved to be fully immune to secondary CNS-1 tumor rechallenge. They all remained tumor-free and survived. In contrast, rats that controlled CNS-1 tumor growth as a result of CY treatment did not develop immune memory, as demonstrated by their failure to reject a secondary CNS-1 tumor challenge; they showed a concomittant outgrowth of the primary tumor upon secondary tumor exposure. Rechallenge of rats that initially contained tumor growth by combination chemo-immunotherapy also failed to reject secondary tumor challenge, indicating that the cytotoxic effect of the CY likely extended to the endogenous memory immune cells as well as to the tumor. These data demonstrate strong therapeutic antitumor efficacy for the immune response modifier resiquimod leading to immunological memory, and suggest that CY treatment, although effective as chemotherapeutic agent, may be deleterious to maintenance of long-term antitumor immune memory. These data also highlight the importance of the sequence in which a multi-modal therapy is administered.

Imiquimod - A toll like receptor 7 agonist - Is an ideal option for management of COVID 19

According to numerous recent publications, the COVID-19 patients have lymphopenia, higher infection-related biomarkers and several elevated inflammatory cytokines (i.e. tumor necrosis factor (TNF)-α, interleukin IL-2R and IL-6). The total number of B cells, T cells and NK cells are significantly decreased. RNA viruses, SARS-CoV-2 included, hit the innate immune system in order to cause infection, through TLRs 3, 7 and 8. Imiquimod is an immune-stimulator that activates TLR 7 and can be used to enhance the innate and adaptive immunity. Preclinical and clinical trials are proposed.

Pre-activation with TLR7 in combination with thioridazine and loratadine promotes tumoricidal T-cell activity in colorectal cancer

Colorectal cancer (CRC) is the third most common malignancy worldwide. Our previous studies have shown that combinatorial treatment with thioridazine and loratadine may effectively inhibit CRC. However, the translation of these research findings to clinical practice was impaired by issues related to a lack of therapeutic specificity and to immune evasion. Toll-like receptor (TLR) agonists have been used as adjuvants to enhance the effectiveness of cancer vaccines. The aim of this study was to evaluate the therapeutic efficiency of immunotherapy with thioridazine and loratadine in combination with resiqumiod (R848), a small-molecule TLR7 agonist, in suppressing CRC growth in a mouse model. Twenty-four BALB/c mice were randomly assigned to treatment with PBS, R848, thioridazine + loratadine, or thioridazine + loratadine + R848. Cytokine levels were measured with ELISA. Overall survival, as well as tumor volume and tumor weight, was recorded. Cytotoxicity was measured by counting the numbers of CD8 and CD3-positive (CD8CD3) or CD4 and CD3-positive (CD3CD4) T-cells. The immune response induced by cytokines (as interferon-γ, interleukin-6, and tumor necrosis factor-α) was significantly stronger in mice treated with thioridazine + loratadine + R848. Moreover, thioridazine + loratadine + R848 significantly delayed tumor development and prolonged survival, which was associated with enhanced immune response and dendritic cell maturation. This study suggested that thioridazine + loratadine + R848 combinatorial treatment may be effective in overcoming immune evasion by tumor cells, with promising therapeutic potential in CRC.

A novel TLR7 agonist as adjuvant to stimulate high quality HBsAg-specific immune responses in an HBV mouse model

Background

The global burden of hepatitis B virus (HBV) infection in terms of morbidity and mortality is immense. Novel treatments that can induce a protective immune response are urgently needed to effectively control the HBV epidemic and eventually eradicate chronic HBV infection.

Methods

We designed and evaluated an HBV therapeutic vaccine consisting of a novel Toll-like receptor 7 (TLR7) agonist T7-EA, an Alum adjuvant and a recombinant HBsAg protein. We used RNA-seq, ELISA and hTLR7/8 reporting assays to characterize T7-EA in vitro and real-time PCR to evaluate the tissue-retention characteristics in vivo. To evaluate the adjuvant potential, we administrated T7-EA intraperitoneally in a formulation with an Alum adjuvant and HBsAg in normal and HBV mice, then, we evaluated the HBsAg-specific immune responses by ELISA and Elispot assays.

Results

T7-EA acted as an hTLR7-specific agonist and induced a similar gene expression pattern as an unmodified TLR7 ligand when Raw 264.7 cells were exposed to T7-EA; however, T7-EA was more potent than the unmodified TLR7 ligand. In vivo studies showed that T7-EA had tissue-retaining activity with stimulating local cytokine and chemokine expression for up to 7 days. T7-EA could induce Th1-type immune responses, as evidenced by an increased HBsAg-specific IgG2a titer and a T-cell response in normal mice compared to mice received traditional Alum-adjuvant HBV vaccine. Importantly, T7-EA could break immune tolerance and induce persistent HBsAg-specific antibody and T-cell responses in an HBV mouse model.

Conclusions

T7-EA might be a candidate adjuvant in a prophylactic and therapeutic HBV vaccine.

Impact of Polymer-TLR-7/8 Agonist (Adjuvant) Morphology on the Potency and Mechanism of CD8 T Cell Induction

Small molecule Toll-like receptor-7 and -8 agonists (TLR-7/8a) can be used as vaccine adjuvants to induce CD8 T cell immunity but require formulations that prevent systemic toxicity and focus adjuvant activity in lymphoid tissues. Here, we covalently attached TLR-7/8a to polymers of varying composition, chain architecture and hydrodynamic behavior (∼300 nm submicrometer particles, ∼10 nm micelles and ∼4 nm flexible random coils) and evaluated how these parameters of polymer-TLR-7/8a conjugates impact adjuvant activity in vivo. Attachment of TLR-7/8a to any of the polymer compositions resulted in a nearly 10-fold reduction in systemic cytokines (toxicity). Moreover, both lymph node cytokine production and the magnitude of CD8 T cells induced against protein antigen increased with increasing polymer-TLR-7/8a hydrodynamic radius, with the submicrometer particle inducing the highest magnitude responses. Notably, CD8 T cell responses induced by polymer-TLR-7/8a were dependent on CCR2+ monocytes and IL-12, whereas responses by a small molecule TLR-7/8a that unexpectedly persisted in vaccine-site draining lymph nodes (T1/2 = 15 h) had less dependence on monocytes and IL-12 but required Type I IFNs. This study shows how modular properties of synthetic adjuvants can be chemically programmed to alter immunity in vivo through distinct immunological mechanisms.

Therapy with transcutaneous administration of imiquimod combined with oral administration of sorafenib suppresses renal cell carcinoma growing in an orthotopic mouse model

Imiquimod is an imidazoquinoline immune response modifier that is used in antiviral and antiallergic creams. Combination therapy using transcutaneous imiquimod and oral sorafenib was previously demonstrated to reduce the tumor burden of renal cell carcinoma growing cutaneously in a mouse model. In the present study, an orthotopic mouse model was used to investigate whether combined treatment with oral sorafenib and transcutaneous imiquimod inhibited renal cell carcinoma growing in the kidney. Kidneys of female BALB/c mice were orthotopically implanted with RENCA mouse kidney cancer cells, and the mice were transcutaneously treated with cream containing imiquimod and/or with orally administered sorafenib 5 days following cell implantation. Tumor burden and incidence were determined 28 days following the start of therapy. Splenocyte activity was quantified using the ⁵¹Cr release assay and the fluorescence-activated cell sorting assay with cluster of differentiation (CD) 4 and CD8 antibodies. Imiquimod, sorafenib and combination therapy were tolerated well. A combination of transcutaneous imiquimod and oral sorafenib inhibited the growth of RENCA tumors in the kidney significantly compared with the control. The ⁵¹Cr release assay demonstrated that transcutaneous imiquimod therapy significantly induced the release of ⁵¹Cr from RENCA cells compared with the control. The fluorescence-activated cell sorting assay demonstrated that transcutaneous imiquimod therapy induced CD8⁺ and CD4^- splenocytes compared with the control. In summary, the results of the present study demonstrated that combined treatment with transcutaneous imiquimod and oral sorafenib may be a promising strategy for the treatment of patients with renal cell carcinoma.

Fatty Acid-Mimetic Micelles for Dual Delivery of Antigens and Imidazoquinoline Adjuvants

Vaccine design has undergone a shift towards the use of purified protein subunit vaccines, which offer increased safety and greater control over antigen specificity, but at the expense of immunogenicity. Here we report the development of a new polymer-based vaccine delivery platform engineered to enhance immunity through the co-delivery of protein antigens and the Toll-like receptor 7 (TLR7) agonist imiquimod (IMQ). Owing to the preferential solubility of IMQ in fatty acids, a series of block copolymer micelles with a fatty acid-mimetic core comprising lauryl methacrylate (LMA) and methacrylic acid (MAA), and a poly(ethylene glycol) methyl ether methacrylate (PEGMA) corona decorated with pyridyl disulfide ethyl methacrylate (PDSM) moieties for antigen conjugation were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Carriers composed of 50 mole% LMA (LMA50) demonstrated the highest IMQ loading (2.2 w/w%) and significantly enhanced the immunostimulatory capacity of IMQ to induce dendritic cell maturation and proinflammatory cytokine production. Conjugation of a model antigen, ovalbumin (OVA), to the corona of IMQ-loaded LMA50 micelles enhanced in vitro antigen uptake and cross-presentation on MHC class I (MHC-I). A single intranasal (IN) immunization of mice with carriers co-loaded with IMQ and OVA elicited significantly higher pulmonary and systemic CD8+ T cell responses and increased serum IgG titer relative to a soluble formulation of antigen and adjuvant. Collectively, these data demonstrate that rationally designed fatty acid-mimetic micelles enhance intracellular antigen and IMQ delivery and have potential as synthetic vectors for enhancing the immunogenicity of subunit vaccines.

The link between TLR7 signaling and hepatitis B virus infection

Toll-Like Receptors (TLRs) play crucial roles in recognition and induction of appropriate immune responses against viral infections, including hepatitis B. TLR7 detects intracellular viral single strand RNA which leads to the activation of several pro-inflammatory transcription factors via the MYD88 dependent pathway. Patients with prolonged infectious forms of hepatitis B, including active and inactive chronic forms, are unable to clear HBV from hepatocytes completely. It is believed that the differences in genetic and immunological parameters of the patients and clearance subjects, who successfully clear HBV infections, are the main factors responsible for allowing the long term infections to persist. It appears that defective expression of TLR7 may result in impaired immune responses against HBV. The aim of this review is to address the recent information regarding the crucial roles played by TLR7 in hepatitis B infection and also the main mechanisms used by HBV to escape from recognition by TLR7 in prolonged HBV infected patients. Considering that chronic hepatitis B infection is not yet curable, it could be possible to activate TLR7-related immunological pathways as a therapy directed towards persistent HBV infection. Hence, another aim of this study is to present recent developments of TLR7 agonists as a therapeutic strategy for chronic hepatitis B.

Pharmacokinetic, Pharmacodynamic, and Activity Evaluation of TMX-101 in a Multicenter Phase 1 Study in Patients With Papillary Non-Muscle-Invasive Bladder Cancer

INTRODUCTION/BACKGROUND

Non-muscle-invasive bladder cancer (NMIBC) has a strong tendency to recur despite adjuvant instillations. TMX-101 is a new liquid form of imiquimod for intravesical instillation and has activity in vitro against urothelial carcinoma. The purpose was to analyze the activity of TMX-101 in low-grade NMIBC. Furthermore, pharmacokinetic and pharmacodynamic characteristics and adverse events were evaluated.

PATIENTS AND METHODS

A multicenter, prospective phase 1 trial in 7 patients with low-grade NMIBC was conducted. All patients underwent a marker lesion transurethral resection of the bladder tumor and 6 weekly instillations with TMX-101 0.2% or 0.4%. Cystoscopy 2 to 4 weeks after the last instillation evaluated the effect of TMX-101.

RESULTS

The effective biologic dose (EBD = complete response [CR] in > 2 patients) could not be defined because none of the patients experienced CR. Maximum plasma concentration was 75.1 ng/mL in the 0.4% dose group. No drug accumulation was observed. In the pharmacodynamic analysis, urinary interleukin 1 receptor agonist (IL-1ra) represents the most sensitive and uniform response after TMX-101 instillation. A total of 87.0% reported at least 1 adverse event. All events were of grade 2 severity or less (Common Terminology Criteria of Adverse Events version 4.02). No clinically significant changes in laboratory parameters or vital signs were observed during or after treatment.

CONCLUSION

Toll-like receptor 7 (TLR-7) agonists are effective in urothelial carcinoma in preclinical research. The EBD in this phase 1 study could not be determined because no patient experienced CR. IL-1ra could be valuable as a urinary biomarker in future developments. The safety of TMX-101 has been reconfirmed. New doses, other schedules, and NMIBC subgroups should be tested to define the EBD. A pilot study in carcinoma-in-situ patients is currently ongoing and results are expected shortly.

Results of a phase 1 dose escalation study of intravesical TMX-101 in patients with nonmuscle invasive bladder cancer

PURPOSE

Imiquimod, a toll like receptor 7 (TLR-7) agonist, is effective as a topical treatment for skin malignancies. TMX-101 is a liquid formulation of imiquimod. In this study we establish a safety profile of TMX-101 in patients with nonmuscle invasive bladder cancer.

MATERIALS AND METHODS

We conducted a multicenter phase 1 dose escalation study in patients with nonmuscle invasive bladder cancer. Patients were included in 1 of 4 dose groups (0.05%, 0.1%, 0.2% or 0.4%) and treated with 6 weekly instillations of TMX-101, starting 2 weeks after transurethral resection of bladder tumor. Patients were evaluated weekly, and pharmacokinetic and pharmacodynamic parameters were measured.

RESULTS

A total of 16 patients were included in the study with 4 per dose group. Two patients dropped out after instillation 2 in dose groups 1 and 2. Overall, 88 instillations were administered without serious adverse events. There were 118 adverse events, of which 84 were related to the study drug. All adverse events were mild or moderate and number or severity was not correlated with dose group. Of the related adverse events 70% were confined to the genitourinary tract and resolved without intervention. There was a dose dependent systemic uptake with low plasma levels up to dose group 3 (0.2%, 100 mg). Maximum plasma concentration in dose group 4 (0.4%, 200 mg) was 71.7 ng/ml. This is below plasma concentrations of 123 and 128 ng/ml without significant side effects measured in healthy volunteers after subcutaneous (30 mg) or oral intake (100 mg) of imiquimod, respectively.

CONCLUSIONS

Intravesical treatment with TMX-101 is safe. The side effects are common but mild and mostly limited to the genitourinary tract. There is a low systemic uptake.

The pharmacokinetics of Toll-like receptor agonists and the impact on the immune system

Toll-like receptor (TLR) ligation activates both the innate and adaptive immune systems, and plays an important role in antiviral and anti-tumor immunity. Therefore, a significant amount of effort has been devoted to exploit the therapeutic potential of TLR agonists. Depending on the therapeutic purpose, either as adjuvants to vaccine, chemotherapy or standalone therapy, TLR agonists have been administered via different routes. Both preclinical and clinical studies have suggested that the route of administration has significant effects on pharmacokinetics, and that understanding these effects is critical to the success of TLR agonist drug development. This article will summarize the pharmacokinetics of TLR agonists with different administration routes, with an emphasis on clinical studies of TLR ligands in oncologic applications.

Pharmacokinetics of daily self-application of imiquimod 3.75% cream in adult patients with external anogenital warts

Imiquimod 3.75% cream is a new formulation intended for daily self-application. The objective of this study was to characterize serum imiquimod pharmacokinetics under maximal use conditions. Adults with ≥8 warts or total wart area ≥100 mm² applied up to 1 packet of imiquimod 3.75% cream (250 mg cream, 9.375 mg imiquimod) once daily for 3 weeks. Blood was obtained prior to doses 1, 7, 14, and 21 and at selected time points after doses 1 and 21. Eighteen patients (13 men and 5 women) with a median wart count of 16 and total wart area of 60 mm² were enrolled. Day 21 mean (SD) serum C(max) was 0.49 (0.37) ng/mL, AUC₀₋₂₄ 6.80 (3.59) ng·h/mL, and t(1/2) 24.1 (12.4) hours. Steady state was achieved by day 7 with ~2-fold increase in C(max) and AUC after multiple dosing. Overall, C(max) was higher and t(max) shorter in women, with comparable AUC₀₋₂₄. Imiquimod metabolites were sporadically quantifiable. No patients discontinued for adverse events; 1 interrupted dosing for an application site ulcer. Treatment-related adverse events occurred in 16.7% of the patients. In conclusion, serum imiquimod concentrations were low after daily self-application to external anogenital warts of up to 1 packet of imiquimod 3.75% cream for 21 days.

Toll-like receptors 3 and 7 agonists enhance tumor cell lysis by human gammadelta T cells

Toll-like receptor (TLR) agonists are considered adjuvants in clinical trials of cancer immunotherapy. Here, we investigated the modulation of gammadelta T cell-mediated tumor cell lysis by TLR ligands. gammadelta T-cell cytotoxicity and granzyme A/B production were enhanced after pretreatment of tumor cells with TLR3 [poly(I:C)] or TLR7 ligand (imiquimod). We examined TLR3- and TLR7-expressing pancreatic adenocarcinomas, squamous cell carcinomas of head and neck and lung carcinomas. Poly(I:C) treatment of pancreatic adenocarcinomas followed by coculture with gammadelta T cells resulted in an upregulation of CD54 on the tumor cells. The interaction of CD54 and the corresponding ligand CD11a/CD18 expressed on gammadelta T cells is responsible for triggering effector function in gammadelta T cells. Moreover, treatment with imiquimod downregulated MHC class I molecules on tumor cells possibly resulting in a reduced binding affinity for inhibitory receptor NKG2A expressed on gammadelta T cells. These results indicate that TLR3 or TLR7 ligand stimulation of tumor cells enhances the cytotoxic activity of expanded gammadelta T cells of cancer patients in vitro.

First in human phase I trial of 852A, a novel systemic toll-like receptor 7 agonist, to activate innate immune responses in patients with advanced cancer

PURPOSE

Recent advances in the understanding of innate immunity suggest that an orchestrated sequence of events is required to elicit a productive immune response against cancer. We studied the systemic administration of the Toll-like receptor 7 agonist 852A, a small-molecule imidazoquinoline, in patients with advanced cancer. Preclinical studies showed that 852A stimulates plasmacytoid dendritic cells to produce multiple cytokines, such as IFN-alpha, interleukin-1 receptor antagonist, and IFN-inducible protein-10. Our goal was to define the tolerated dose, pharmacokinetics, pharmacodynamics, and immunologic effects of 852A in humans.

EXPERIMENTAL DESIGN

Eligible adult patients with refractory solid organ tumors received i.v. 852A thrice weekly for 2 weeks. Patients who had responses or stable disease were eligible for additional cycles.

RESULTS

Twenty-five patients (median age, 55.0 years; 72% male) were enrolled in six cohorts at dose levels of 0.15 to 2.0 mg/m(2). Serum drug levels showed dose proportionality and no evidence of drug accumulation. The maximum tolerated dose was 1.2 mg/m(2); higher doses were limited by fatigue and constitutional symptoms. Increases in IFN-alpha, interleukin-1 receptor antagonist, and IFN-inducible protein-10, immunologic activity, and clinical symptoms were observed in all patients receiving dose levels > or =0.6 mg/m(2). Significant correlations were found between pharmacodynamic biomarkers and pharmacokinetic variables, and an objective clinical response was seen.

CONCLUSIONS

852A was safely administered i.v. at doses up to 1.2 mg/m(2) thrice weekly for 2 weeks with transient or reversible adverse effects. This novel Toll-like receptor 7 agonist is biologically active and holds promise for stimulating innate immune responses. Future trials are warranted to assess its therapeutic role in patients with cancer.

Pharmacokinetics of 852A, an imidazoquinoline Toll-like receptor 7-specific agonist, following intravenous, subcutaneous, and oral administrations in humans

852A is an imidazoquinoline Toll-like receptor 7 agonist undergoing evaluation for the systemic treatment of cancer. 852A was administered to 6 healthy subjects as 3 rising subcutaneous doses (0.5 to 1.0 to 2.0 mg), to 6 subjects as 3 oral doses (10.0 to 20.0 to 15.0 mg, the third dose being a de-escalation), and to 6 subjects as a 2.0-mg dose by the subcutaneous, intravenous, and oral routes in crossover fashion. The subcutaneous and intravenous doses were well tolerated. One subject withdrew following the 20.0-mg oral dose because of hypotension. The 2.0-mg subcutaneous dose had 80.5% +/- 12.8% (mean +/- SD) bioavailability and gave serum concentrations comparable to intravenous administration by 30 minutes. Linear kinetics and an interferon-alpha dose response were observed for the 3 subcutaneous doses. Serum concentrations following the 2.0-mg oral dose were always lower than those following the same intravenous dose, and the oral route had a bioavailability of 26.5% +/- 7.84%. Concentrations appeared to increase with oral dose; however, large variabilities in both the rate and extent of absorption were seen between individuals. Approximately 40% of an absorbed dose was excreted unchanged in the urine. Overall, the study suggests that subcutaneous administration may be an acceptable method to deliver 852A for systemic applications.

Predicting effect of food on extent of drug absorption based on physicochemical properties

PURPOSE

To develop a statistical model for predicting effect of food on the extent of absorption (area under the curve of time-plasma concentration profile, AUC) of drugs based on physicochemical properties.

MATERIALS AND METHODS

Logistic regression was applied to establish the relationship between the effect of food (positive, negative or no effect) on AUC of 92 entries and physicochemical parameters, including clinical doses used in the food effect study, solubility (pH 7), dose number (dose/solubility at pH 7), calculated Log D (pH 7), polar surface area, total surface area, percent polar surface area, number of hydrogen bond donor, number of hydrogen bond acceptors, and maximum absorbable dose (MAD).

RESULTS

For compounds with MAD >or= clinical dose, the food effect can be predicted from the dose number category and Log D category, while for compounds with MAD < clinical dose, the food effect can be predicted from the dose number category alone. With cross validation, 74 out of 92 entries (80%) were predicted into the correct category. The correct predictions were 97, 79 and 68% for compounds with positive, negative and no food effect, respectively.

CONCLUSIONS

A logistic regression model based on dose, solubility, and permeability of compounds is developed to predict the food effect on AUC. Statistically, solubilization effect of food primarily accounted for the positive food effect on absorption while interference of food with absorption caused negative effect on absorption of compounds that are highly hydrophilic and probably with narrow window of absorption.

Design and physicochemical characterisation of a bioadhesive patch for dose-controlled topical delivery of imiquimod

Clinical use of the imidazoquinoline immunomodulator imiquimod for the topical treatment of dysplastic and neoplastic lesions has increased markedly in recent years. However, despite guidance from the manufacturer of the proprietary imiquimod cream, there seems to be little consensus between clinicians as to the topically applied dose. Given that patients often apply the cream themselves at home, further dosing variability is expected and, consequently, accurate comparison of the results of different published studies is difficult. This paper describes, for the first time, the formulation and physicochemical characterisation of a bioadhesive patch for dose-controlled topical delivery of imiquimod as well as a new HPLC method for sensitive fluorescence determination of imiquimod released from such systems. Patches containing imiquimod loadings of 4.75, 9.50 and 12.50 mg cm(-2) all released significantly more drug across a model membrane than the proprietary cream over a period of 6h. Inclusion of imiquimod in patches did not adversely affect their physicochemical properties. Of major importance, patches contained defined drug loadings per unit area; therefore, their use could reduce inter-clinician variability. This would make critical comparison of clinical studies and determination of an appropriate imiquimod dose for successful treatment much simpler. Since bioadhesive formulations are capable of adhering to body tissues in moist environments, the use of a bioadhesive patch system may allow extension of the clinical uses of imiquimod to the treatment of neoplastic conditions of the oral cavity and cervix, as well as the vulva.

Effects of Food on the Clinical Pharmacokinetics of Anticancer Agents

Pharmacokinetic interactions between food and orally administered drugs involve changes mainly in the absorption and metabolism of a drug, and may have clinical implications. Such interactions, in particular, may be of major clinical significance for cancer chemotherapy since the majority of anticancer agents are toxic, have a low therapeutic index and are administered long term, most often in combination with other cytotoxic agents. The purpose of this review is to compare the pharmacokinetic profiles of various anticancer drugs, including chemopreventive agents that have been examined previously in fasted and fed conditions, and to discuss the underlying basis/mechanisms of food effect in light of a drug's physicochemical and pharmacokinetic properties. Clinical pharmacokinetic parameters such as maximum concentration, area under the concentration-time curve, time to maximum concentration and half-life for each drug are compared in fasted and fed states, and specific dietary recommendations are summarised accordingly. In addition, the effects of food on the metabolite kinetics and pharmacodynamic responses, and the potential role of food effect in the modulation of oral biovariability and multidrug resistance have been extensively discussed. Overall, this comprehensive pharmacokinetic analysis indicates that a broad spectrum of food effects is seen among anticancer agents because of diverse factors regulating each drug's oral bioavailability and its interactions with food. The consideration of such effects is important, as it could lead to more rational pharmacological monitoring and possibly improve the oral chemotherapy of cancer in children, adults and the elderly.