Trifluridine: a review of its antiviral activity and therapeutic use in the topical treatment of viral eye infections

Combination therapy synergism prediction for virus treatment using machine learning models

Combining different drugs synergistically is an essential aspect of developing effective treatments. Although there is a plethora of research on computational prediction for new combination therapies, there is limited to no research on combination therapies in the treatment of viral diseases. This paper proposes AI-based models for predicting novel antiviral combinations to treat virus diseases synergistically. To do this, we assembled a comprehensive dataset comprising information on viral strains, drug compounds, and their known interactions. As far as we know, this is the first dataset and learning model on combination therapy for viruses. Our proposal includes using a random forest model, an SVM model, and a deep model to train viral combination therapy. The machine learning models showed the highest performance, and the predicted values were validated by a t-test, indicating the effectiveness of the proposed methods. One of the predicted combinations of acyclovir and ribavirin has been experimentally confirmed to have a synergistic antiviral effect against herpes simplex type-1 virus, as described in the literature.

Ocular manifestations of mpox

PURPOSE OF REVIEW

To highlight the clinical features of mpox with an emphasis on ocular manifestations and to review treatment options for this re-emerging infectious disease.

RECENT FINDINGS

Ocular involvement of mpox varies by clade. The most recent 2022 outbreak appears to be associated with fewer conjunctivitis cases compared to previous outbreaks. However, the ocular findings occurring during this newly emerging clade can be visually threatening and include cases of keratitis, rapidly progressing scleritis, and necrotizing periorbital rashes.

SUMMARY

Ocular mpox is an important clinical feature of systemic mpox virus (MPXV) infection. Heightened clinical suspicion allows for a timely diagnosis and the initiation of antiviral treatment, when appropriate. Randomized clinical trials for mpox systemic and ocular treatment efficacy are lacking. Prior clinical experience with smallpox and in-vitro mpox data support the use of systemic antivirals such as tecovirimat, cidofovir, brincidofovir and topical use of trifluridine in ocular mpox management, though treatment-resistant infection can occur and portend a poor prognosis.

The immunobiology of corneal HSV-1 infection and herpetic stromal keratitis

SUMMARYHuman alphaherpesvirus 1 (HSV-1) is a highly successful neurotropic pathogen that primarily infects the epithelial cells lining the orofacial mucosa. After primary lytic replication in the oral, ocular, and nasal mucosal epithelial cells, HSV-1 establishes life-long latency in neurons within the trigeminal ganglion. Patients with compromised immune systems experience frequent reactivation of HSV-1 from latency, leading to virus entry in the sensory neurons, followed by anterograde transport and lytic replication at the innervated mucosal epithelial surface. Although recurrent infection of the corneal mucosal surface is rare, it can result in a chronic immuno-inflammatory condition called herpetic stromal keratitis (HSK). HSK leads to gradual vision loss and can cause permanent blindness in severe untreated cases. Currently, there is no cure or successful vaccine to prevent latent or recurrent HSV-1 infections, posing a significant clinical challenge to managing HSK and preventing vision loss. The conventional clinical management of HSK primarily relies on anti-virals to suppress HSV-1 replication, anti-inflammatory drugs (such as corticosteroids) to provide symptomatic relief from pain and inflammation, and surgical interventions in more severe cases to replace damaged cornea. However, each clinical treatment strategy has limitations, such as local and systemic drug toxicities and the emergence of anti-viral-resistant HSV-1 strains. In this review, we summarize the factors and immune cells involved in HSK pathogenesis and highlight alternate therapeutic strategies for successful clinical management of HSK. We also discuss the therapeutic potential of immunoregulatory cytokines and immunometabolism modulators as promising HSK therapies against emerging anti-viral-resistant HSV-1 strains.

Insights into the Transmission, Host Range, Genomics, Vaccination, and Current Epidemiology of the Monkeypox Virus

This review delves into the historical context, current epidemiological landscape, genomics, and pathobiology of monkeypox virus (MPXV). Furthermore, it elucidates the present vaccination status and strategies to curb the spread of monkeypox. Monkeypox, caused by the Orthopoxvirus known as MPXV, is a zoonotic ailment. MPXV can be transmitted from person to person through respiratory droplets during prolonged face-to-face interactions. While many cases of monkeypox are self-limiting, vulnerable groups such as young children, pregnant women, and immunocompromised individuals may experience severe manifestations. Diagnosis predominantly relies on clinical presentations, complemented by laboratory techniques like RT-PCR. Although treatment is often not required, severe cases necessitate antiviral medications like tecovirimat, cidofovir, and brincidofovir. Vaccination, particularly using the smallpox vaccine, has proven instrumental in outbreak control, exhibiting an efficacy of at least 85% against mpox as evidenced by data from Africa. Mitigating transmission requires measures like wearing surgical masks, adequately covering skin lesions, and avoiding handling wild animals.

Synthesis of Fluorinated Nucleosides/Nucleotides and Their Antiviral Properties

The FDA has approved several drugs based on the fluorinated nucleoside pharmacophore, and numerous drugs are currently in clinical trials. Fluorine-containing nucleos(t)ides offer significant antiviral and anticancer activity. The insertion of a fluorine atom, either in the base or sugar of nucleos(t)ides, alters its electronic and steric parameters and transforms the lipophilicity, pharmacodynamic, and pharmacokinetic properties of these moieties. The fluorine atom restricts the oxidative metabolism of drugs and provides enzymatic metabolic stability towards the glycosidic bond of the nucleos(t)ide. The incorporation of fluorine also demonstrates additional hydrogen bonding interactions in receptors with enhanced biological profiles. The present article discusses the synthetic methodology and antiviral activities of FDA-approved drugs and ongoing fluoro-containing nucleos(t)ide drug candidates in clinical trials.

Tolerability, pharmacokinetics, and anti-herpetic activity of orally administered BX795

Herpes simplex viruses type-1 (HSV-1) and type-2 (HSV-2) are ubiquitous human pathogens causing serious pathologies in the ocular, orofacial and anogenital regions. While current treatments such as nucleoside analogs are effective in most cases, the emergence of drug resistance necessitates the development of newer antivirals with different mechanisms of action. In this regard, BX795, a small molecule inhibitor has shown significant benefit in the treatment of herpesvirus infections previously when dosed topically. However, the efficacy of BX795's systemic dosage remains to be tested. In this study, we evaluated acute and short-term toxicity of orally administered BX795 at a concentration of 400 and 100 mg/kg respectively in mice. This was followed by an evaluation of pharmacokinetics and tissue distribution of BX795 on intravenous and oral administration. Based on these studies, we performed an in vivo antiviral study using murine models of ocular HSV-1 and genital HSV-2 infection. Our results indicate that orally administered BX795 is very well tolerated, had oral bioavailability of 56%, and reached ocular and genital tissues within the first 15 min of dosing. Our studies indicate that BX795 administered orally can significantly reduce herpesvirus replication in the ocular and genital tissue.

Identification of IMP Dehydrogenase as a Potential Target for Anti-Mpox Virus Agents

Mpox virus (formerly monkeypox virus [MPXV]) is a neglected zoonotic pathogen that caused a worldwide outbreak in May 2022. Given the lack of an established therapy, the development of an anti-MPXV strategy is of vital importance. To identify drug targets for the development of anti-MPXV agents, we screened a chemical library using an MPXV infection cell assay and found that gemcitabine, trifluridine, and mycophenolic acid (MPA) inhibited MPXV propagation. These compounds showed broad-spectrum anti-orthopoxvirus activities and presented lower 90% inhibitory concentrations (0.026 to 0.89 μM) than brincidofovir, an approved anti-smallpox agent. These three compounds have been suggested to target the postentry step to reduce the intracellular production of virions. Knockdown of IMP dehydrogenase (IMPDH), the rate-limiting enzyme of guanosine biosynthesis and a target of MPA, dramatically reduced MPXV DNA production. Moreover, supplementation with guanosine recovered the anti-MPXV effect of MPA, suggesting that IMPDH and its guanosine biosynthetic pathway regulate MPXV replication. By targeting IMPDH, we identified a series of compounds with stronger anti-MPXV activity than MPA. This evidence shows that IMPDH is a potential target for the development of anti-MPXV agents. IMPORTANCE Mpox is a zoonotic disease caused by infection with the mpox virus, and a worldwide outbreak occurred in May 2022. The smallpox vaccine has recently been approved for clinical use against mpox in the United States. Although brincidofovir and tecovirimat are drugs approved for the treatment of smallpox by the U.S. Food and Drug Administration, their efficacy against mpox has not been established. Moreover, these drugs may present negative side effects. Therefore, new anti-mpox virus agents are needed. This study revealed that gemcitabine, trifluridine, and mycophenolic acid inhibited mpox virus propagation and exhibited broad-spectrum anti-orthopoxvirus activities. We also suggested IMP dehydrogenase as a potential target for the development of anti-mpox virus agents. By targeting this molecule, we identified a series of compounds with stronger anti-mpox virus activity than mycophenolic acid.

Antiviral activities of two nucleos(t)ide analogs against vaccinia, mpox, and cowpox viruses in primary human fibroblasts

Many poxviruses are significant human and animal pathogens, including viruses that cause smallpox and mpox (formerly monkeypox). Identifying novel and potent antiviral compounds is critical to successful drug development targeting poxviruses. Here we tested two compounds, nucleoside trifluridine, and nucleotide adefovir dipivoxil, for antiviral activities against vaccinia virus (VACV), mpox virus (MPXV), and cowpox virus (CPXV) in physiologically relevant primary human fibroblasts. Both compounds potently inhibited the replication of VACV, CPXV, and MPXV (MA001 2022 isolate) in plaque assays. In our recently developed assay based on a recombinant VACV expressing secreted Gaussia luciferase, they both exhibited high potency in inhibiting VACV replication with EC₅₀s in the low nanomolar range. In addition, both trifluridine and adefovir dipivoxil inhibited VACV DNA replication and downstream viral gene expression. Our results characterized trifluridine and adefovir dipivoxil as strong poxvirus antiviral compounds and further validate the VACV Gaussia luciferase assay as a highly efficient and reliable reporter tool for identifying poxvirus inhibitors. Given that both compounds are FDA-approved drugs, and trifluridine is already used to treat ocular vaccinia, further development of trifluridine and adefovir dipivoxil holds great promise in treating poxvirus infections, including mpox.

Pharmacological treatment and vaccines in monkeypox virus: a narrative review and bibliometric analysis

Mpox (earlier known as monkeypox) virus infection is a recognized public health emergency. There has been little research on the treatment options. This article reviews the specific drugs used to treat mpox virus infection and the vaccines used here. Instead of focusing on the mechanistic basis, this review narrates the practical, real-life experiences of individual patients of mpox virus disease being administered these medicines. We conducted a bibliometric analysis on the treatment of the mpox virus using data from several databases like PubMed, Scopus, and Embase. The research on this topic has grown tremendously recently but it is highly concentrated in a few countries. Cidofovir is the most studied drug. This is because it is indicated and also used off-label for several conditions. The drugs used for mpox virus infection include tecovirimat, cidofovir, brincidofovir, vaccinia immune globulin, and trifluridine. Tecovirimat is used most frequently. It is a promising option in progressive mpox disease in terms of both efficacy and safety. Brincidofovir has been associated with treatment discontinuation due to elevated hepatic enzymes. Cidofovir is also not the preferred drug, often used because of the unavailability of tecovirimat. Trifluridine is used topically as an add-on agent along with tecovirimat for ocular manifestations of mpox virus disease. No study reports individual patient data for vaccinia immune globulin. Though no vaccine is currently approved for mpox virus infection, ACAM 2000 and JYNNEOS are the vaccines being mainly considered. ACAM 2000 is capable of replicating and may cause severe adverse reactions. It is used when JYNNEOS is contraindicated. Several drugs and vaccines are under development and have been discussed alongside pragmatic aspects of mpox virus treatment and prevention. Further studies can provide more insight into the safety and efficacy of Tecovirimat in actively progressing mpox virus disease.

Bioinformatics analysis of the pathogenic link between Epstein-Barr virus infection, systemic lupus erythematosus and diffuse large B cell lymphoma

Epstein-Barr virus (EBV) is a risk factor for diffuse large B-cell lymphoma (DLBCL) and systemic lupus erythematosus (SLE). While prior research has suggested a potential correlation between SLE and DLBCL, the molecular mechanisms remain unclear. The present study aimed to explore the contribution of EBV infection to the pathogenesis of DLBCL in the individuals with SLE using bioinformatics approaches. The Gene Expression Omnibus database was used to compile the gene expression profiles of EBV-infected B cells (GSE49628), SLE (GSE61635), and DLBCL (GSE32018). Altogether, 72 shared common differentially expressed genes (DEGs) were extracted and enrichment analysis of the shared genes showed that p53 signaling pathway was a common feature of the pathophysiology. Six hub genes were selected using protein-protein interaction (PPI) network analysis, including CDK1, KIF23, NEK2, TOP2A, NEIL3 and DEPDC1, which showed preferable diagnostic values for SLE and DLBCL and involved in immune cell infiltration and immune responses regulation. Finally, TF-gene and miRNA-gene regulatory networks and 10 potential drugs molecule were predicted. Our study revealed the potential molecular mechanisms by which EBV infection contribute to the susceptibility of DLBCL in SLE patients for the first time and identified future biomarkers and therapeutic targets for SLE and DLBCL.

Development of FRET and Stress Granule Dual-Based System to Screen for Viral 3C Protease Inhibitors

3C proteases (3Cpros) of picornaviruses and 3C-like proteases (3CLpros) of coronaviruses and caliciviruses represent a group of structurally and functionally related viral proteases that play pleiotropic roles in supporting the viral life cycle and subverting host antiviral responses. The design and screening for 3C/3CLpro inhibitors may contribute to the development broad-spectrum antiviral therapeutics against viral diseases related to these three families. However, current screening strategies cannot simultaneously assess a compound’s cytotoxicity and its impact on enzymatic activity and protease-mediated physiological processes. The viral induction of stress granules (SGs) in host cells acts as an important antiviral stress response by blocking viral translation and stimulating the host immune response. Most of these viruses have evolved 3C/3CLpro-mediated cleavage of SG core protein G3BP1 to counteract SG formation and disrupt the host defense. Yet, there are no SG-based strategies screening for 3C/3CLpro inhibitors. Here, we developed a fluorescence resonance energy transfer (FRET) and SG dual-based system to screen for 3C/3CLpro inhibitors in living cells. We took advantage of FRET to evaluate the protease activity of poliovirus (PV) 3Cpro and live-monitor cellular SG dynamics to cross-verify its effect on the host antiviral response. Our drug screen uncovered a novel role of Telaprevir and Trifluridine as inhibitors of PV 3Cpro. Moreover, Telaprevir and Trifluridine also modulated 3Cpro-mediated physiological processes, including the cleavage of host proteins, inhibition of the innate immune response, and consequent facilitation of viral replication. Taken together, the FRET and SG dual-based system exhibits a promising potential in the screening for inhibitors of viral proteases that cleave G3BP1.

Antiviral activities of two nucleos(t)ide analogs against vaccinia and mpox viruses in primary human fibroblasts

Many poxviruses are significant human and animal pathogens, including viruses that cause smallpox and mpox. Identification of inhibitors of poxvirus replication is critical for drug development to manage poxvirus threats. Here we tested two compounds, nucleoside trifluridine and nucleotide adefovir dipivoxil, for antiviral activities against vaccinia virus (VACV) and mpox virus (MPXV) in physiologically relevant primary human fibroblasts. Both trifluridine and adefovir dipivoxil potently inhibited replication of VACV and MPXV (MA001 2022 isolate) in a plaque assay. Upon further characterization, they both conferred high potency in inhibiting VACV replication with half maximal effective concentrations (EC ₅₀ ) at low nanomolar levels in our recently developed assay based on a recombinant VACV secreted Gaussia luciferase. Our results further validated that the recombinant VACV with Gaussia luciferase secretion is a highly reliable, rapid, non-disruptive, and simple reporter tool for identification and chracterization of poxvirus inhibitors. Both compounds inhibited VACV DNA replication and downstream viral gene expression. Given that both compounds are FDA-approved drugs, and trifluridine is used to treat ocular vaccinia in medical practice due to its antiviral activity, our results suggest that it holds great promise to further test trifluridine and adefovir dipivoxil for countering poxvirus infection, including mpox.

Role of Innate Interferon Responses at the Ocular Surface in Herpes Simplex Virus-1-Induced Herpetic Stromal Keratitis

Herpes simplex virus type 1 (HSV-1) is a highly successful pathogen that primarily infects epithelial cells of the orofacial mucosa. After initial lytic replication, HSV-1 enters sensory neurons and undergoes lifelong latency in the trigeminal ganglion (TG). Reactivation from latency occurs throughout the host’s life and is more common in people with a compromised immune system. HSV-1 causes various diseases depending on the site of lytic HSV-1 replication. These include herpes labialis, herpetic stromal keratitis (HSK), meningitis, and herpes simplex encephalitis (HSE). HSK is an immunopathological condition and is usually the consequence of HSV-1 reactivation, anterograde transport to the corneal surface, lytic replication in the epithelial cells, and activation of the host’s innate and adaptive immune responses in the cornea. HSV-1 is recognized by cell surface, endosomal, and cytoplasmic pattern recognition receptors (PRRs) and activates innate immune responses that include interferons (IFNs), chemokine and cytokine production, as well as the recruitment of inflammatory cells to the site of replication. In the cornea, HSV-1 replication promotes type I (IFN-α/β) and type III (IFN-λ) IFN production. This review summarizes our current understanding of HSV-1 recognition by PRRs and innate IFN-mediated antiviral immunity during HSV-1 infection of the cornea. We also discuss the immunopathogenesis of HSK, current HSK therapeutics and challenges, proposed experimental approaches, and benefits of promoting local IFN-λ responses.

Treatment of ocular-involving monkeypox virus with topical trifluridine and oral tecovirimat in the 2022 monkeypox virus outbreak

Purpose

To report a case of ocular involving monkeypox infection in the United States during the 2022 outbreak, and to review the literature regarding its clinical manifestations and management known to date.

Observations

A 36-year-old man with well controlled HIV presented to the emergency department with anal pain, diffuse rash, right eye pain, and right eye redness after he tested positive for monkeypox one week prior. Ocular examination showed bilateral periorbital vesicular lesions, right eye conjunctival injection, and a single white plaque on his right medial bulbar conjunctiva. Macular, vesicular, and pustular lesions were noted throughout his body, including the genital and perianal region. His ocular and systemic symptoms completely resolved after treatment with a ten-day course of 1% trifluridine and moxifloxacin drops in both eyes, as well as two weeks of oral tecovirimat.

Conclusion and Importance

In July of 2022, monkeypox virus was declared a global health emergency by the World Health Organization; however, there are no standard guidelines for monkeypox treatment. Data on its clinical presentation and course, especially pertaining to ocular manifestations, is limited. We highlight the importance of recognizing ophthalmic manifestations of monkeypox virus and a possible therapeutic approach to help guide the management of these patients.

The use of antivirals in the treatment of human monkeypox outbreaks: a systematic review

OBJECTIVES

Human monkeypox virus (MPXV) infection is a recently declared public health emergency of international concern by the World Health Organization. Besides, there is scant literature available on the use of antivirals in MPXV infection. This systematic review compiles all evidence of various antivirals used on their efficacy and safety and summarizes their mechanisms of action.

METHODS

A review was done of all original studies mentioning individual patient data on the use of antivirals in patients with MPXV infection.

RESULTS

Of the total 487 non-duplicate studies, 18 studies with 71 individuals were included. Tecovirimat was used in 61 individuals, followed by cidofovir in seven and brincidofovir (BCV) in three individuals. Topical trifluridine was used in four ophthalmic cases in addition to tecovirimat. Of the total, 59 (83.1%) were reported to have complete resolution of symptoms; one was experiencing waxing and waning of symptoms, only one (1.8%) had died, and the others were having a resolution of symptoms. The death was thought unrelated to tecovirimat. Elevated hepatic panels were reported among all individuals treated with BCV (leading to treatment discontinuation) and five treated with tecovirimat.

CONCLUSION

Tecovirimat is the most used and has proven beneficial in several aggravating cases. No major safety concerns were detected upon its use. Topical trifluridine was used as an adjuvant treatment option along with tecovirimat. BCV and cidofovir were seldom used, with the latter often being used due to the unavailability of tecovirimat. BCV was associated with treatment discontinuation due to adverse events.

Antiviral Drugs in Adenovirus-Induced Keratoconjunctivitis

Human adenovirus (HAdV) is one of the most common causes of conjunctivitis worldwide. Depending on specific serotypes and other factors, it can lead to several ocular manifestations, ranging from isolated, self-limited disease to epidemic and potentially sight-threatening keratoconjunctivitis. To date, no antiviral agent against ocular adenovirus has been licensed, and its management is still based on hygienic and supportive measures alone. In this review, a literature search up to August 2021 was performed to find peer-reviewed articles, with the primary aim to investigate drugs or other compounds with any antiviral activity against adenovirus. Finally, we included 70 articles, consisting of both in vitro, and in vivo studies on animal models and clinical trials of any phase, as well as a case-report, and analyzed each compound separately. Many antiviral agents proved to be effective on in vivo and in vitro studies on animal models, and in pre-clinical trials, but lacked reliability in large, controlled clinical investigations. The design of such studies, though, presented several hurdles, due to the nature and the specific characteristics of adenovirus-induced ocular diseases. Nevertheless, some promising compounds are currently under study, and further investigations are needed to prove their efficacy in the management of adenovirus conjunctivitis.

Uracil derivatives as HIV-1 capsid protein inhibitors: design, in silico, in vitro and cytotoxicity studies

A series of novel uracil derivatives such as bispyrimidine dione and tetrapyrimidine dione derivatives were designed based on the existing four-point pharmacophore model as effective HIV capsid protein inhibitors. The compounds were initially docked with an HIV capsid protein monomer to rationalize the ideas of design and to find the potential binding modes. The successful design and computational studies led to the synthesis of bispyrimidine dione and tetrapyrimidine dione derivatives from uracil and aromatic aldehydes in the presence of HCl using novel methodology. The in vitro evaluation in HIV p24 assay revealed five potential uracil derivatives with IC₅₀ values ranging from 191.5 μg ml⁻¹ to 62.5 μg ml⁻¹. The meta-chloro substituted uracil compound 9a showed promising activity with an IC₅₀ value of 62.5 μg ml⁻¹ which is well correlated with the computational studies. As expected, all the active compounds were noncytotoxic in BA/F3 and Mo7e cell lines highlighting the thoughtful design. The structure activity relationship indicates the position priority and lower log P values as the possible cause of inhibitory potential of the uracil compounds.

The paper describes the design, synthesis, computational and biological validation of a series of novel uracil derivatives as effective HIV capsid protein inhibitors.

A proof-of-concept study for the efficacy of dispirotripiperazine PDSTP in a rabbit model of herpes simplex epithelial keratitis

Herpes simplex keratitis is an important infectious cause of blindness worldwide. The mainstay of antiviral therapy is treatment with long-established nucleoside analogues orally or topically. However, the emergence of resistant strains may become a major health concern in the future. Therefore, the development of backup antiherpetic medicines is urgently needed. Small molecule PDSTP is known to be active against herpes simplex type 1 strains in vitro, affecting early host-pathogen interactions. Here, we evaluated its preclinical efficacy in a rabbit model of herpes simplex epithelial keratitis. The mean course of keratitis and the corneal lesions in the 1.0% PDSTP gel group was statistically significantly less than in the negative control group and was comparable to that in the aciclovir group. These findings open up new opportunities for the development of antiherpetic drugs with an original mechanism of action.

Machine learning to predict metabolic drug interactions related to cytochrome P450 isozymes

Drug–drug interaction (DDI) often causes serious adverse reactions and thus results in inestimable economic and social loss. Currently, comprehensive DDI evaluation has become a major challenge in pharmaceutical research due to the time-consuming and costly process of the experimental assessment and it is of high necessity to develop effective in silico methods to predict and evaluate DDIs accurately and efficiently. In this study, based on a large number of substrates and inhibitors related to five important CYP450 isozymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4), a series of high-performance predictive models for metabolic DDIs were constructed by two machine learning methods (random forest and XGBoost) and 4 different types of descriptors (MOE_2D, CATS, ECFP4 and MACCS). To reduce the uncertainty of individual models, the consensus method was applied to yield more reliable predictions. A series of evaluations illustrated that the consensus models were more reliable and robust for the DDI predictions of new drug combination. For the internal validation, the whole prediction accuracy and AUC value of the DDI models were around 0.8 and 0.9, respectively. When it was applied to the external datasets, the model accuracy was 0.793 and 0.795 for multi-level validation and external validation, respectively. Furthermore, we also compared our model with some recently published tools and then applied the final model to predict FDA-approved drugs and proposed 54,013 possible drug pairs with potential DDIs. In summary, we developed a powerful DDI predictive model from the perspective of the CYP450 enzyme family and it will help a lot in the future drug development and clinical pharmacy research.

FDA-Approved Small Molecule Compounds as Drugs for Solid Cancers from Early 2011 to the End of 2021

Solid cancers are the most common types of cancers diagnosed globally and comprise a large number of deaths each year. The main challenge currently in drug development for tumors raised from solid organs is to find more selective compounds, which exploit specific molecular targets. In this work, the small molecule drugs registered by the Food and Drug Administration (FDA) for solid cancers treatment between 2011 and 2022 were identified and analyzed by investigating a type of therapy they are used for, as well as their structures and mechanisms of action. On average, 4 new small molecule agents were introduced each year, with a few exceptions, for a total of 62 new drug approvals. A total of 50 of all FDA-approved drugs have also been authorized for use in the European Union by the European Medicines Agency (EMA). Our analysis indicates that many more anticancer molecules show a selective mode of action, i.e., 49 targeted agents, 5 hormone therapies and 3 radiopharmaceuticals, compared to less specific cytostatic action, i.e., 5 chemotherapeutic agents. It should be emphasized that new medications are indicated for use mainly for monotherapy and less for a combination or adjuvant therapies. The comprehensive data presented in this review can serve for further design and development of more specific targeted agents in clinical usage for solid tumors.

Safety, efficacy and delivery of multiple nucleoside analogs via drug encapsulated carbon (DECON) based sustained drug release platform

Acyclovir and similar nucleoside analogs form an essential frontline treatment for various herpesvirus infections of the eye. However, these drugs have low ocular retention when delivered topically and need to be administered several times every day. We have previously demonstrated that acyclovir loaded into activated carbon can be used to significantly decrease dosage frequency in a murine model of ocular infection. In this study, we demonstrate that other nucleoside analogs such as ganciclovir, penciclovir and famciclovir have excellent loading and release profile similar to acyclovir. Similarly we also demonstrate that nucleoside analog loaded carbons termed DECON are effective at very low concentrations in treating active viral infection of human corneal epithelial cells. In this study, using a variety of techniques to evaluate corneal dryness, nerve sensitivity, intraocular pressure, corneal thickness, and somatic inflammation, we report that DECON is well tolerated after administration three times daily over the course of four weeks.

Microwave Assisted Cu-Mediated Trifluoromethylation of Pyrimidine Nucleosides

Trifluoromethylated nucleosides, such as trifluridine, have widespread applications in pharmaceuticals as anticancer and antiviral agents. However, site-selective addition of a trifluoromethyl group onto a nucleobase typically requires either inconvenient multi-step synthesis or expensive trifluoromethylation reagents, or results in low yield. This article describes a simple, scalable, and high-yielding protocol for late-stage direct trifluoromethylation of pyrimidine nucleosides via a microwave-irradiated pathway. First, 5-iodo pyrimidine nucleosides undergo complete benzoylation to obtain N³ -benzoyl-3',5'-di-O-benzoyl-5-iodo-pyrimidine nucleosides as key precursors. Next, trifluoromethylation is carried out under both conventional and microwave heating using an inexpensive and commercially accessible Chen's reagent, i.e., methyl fluorosulfonyldifluoroacetate, to produce N³ -benzoyl-3',5'-di-Obenzoyl-5-trifluoromethyl-pyrimidine nucleosides. The microwave-assisted transformation accentuates its simplicity, mild reaction conditions, and dominance, providing a facile route to access trifluoromethylation. Finally, the envisioned 5-trifluoromethyl pyrimidine nucleosides are obtained by a routine debenzoylation procedure. This concludes a convenient three-step synthesis to obtain trifluridine and its 2'-modified analogs on a gram scale with consistently high yields, starting from their respective iodo-precursors, and requires only one chromatographic purification at the trifluoromethylation step. Furthermore, this operationally simple protocol can be utilized as a definitive methodology to produce various other trifluoromethylated therapeutics. © 2021 Wiley Periodicals LLC. Basic Protocol: Synthesis of 5-trifluoromethyl pyrimidine nucleosides 4a-c Alternate Protocol: Conventional trifluoromethylation: Synthesis of N3-benzoyl-3',5'-di-O-benzoyl-5-trifluoromethyl pyrimidine nucleosides (3a-c).

Pathobiology and treatment of viral keratitis

Keratitis is one of the most prevalent ocular diseases manifested by partial or total loss of vision. Amongst infectious (viz., microbes including bacteria, fungi, amebae, and viruses) and non-infectious (viz., eye trauma, chemical exposure, and ultraviolet exposure, contact lens) risk factors, viral keratitis has been demonstrated as one of the leading causes of corneal opacity. While many viruses have been shown to cause keratitis (such as rhabdoviruses, coxsackieviruses, etc.), herpesviruses are the predominant etiologic agent of viral keratitis. This chapter will summarize current knowledge on the prevalence, diagnosis, and pathobiology of viral keratitis. Virus-mediated immunomodulation of host innate and adaptive immune components is critical for viral persistence, and dysfunctional immune responses may cause destruction of ocular tissues leading to keratitis. Immunosuppressed or immunocompromised individuals may display recurring disease with pronounced severity. Early diagnosis of viral keratitis is beneficial for disease management and response to treatment. Finally, we have discussed current and emerging therapies to treat viral keratitis.

Therapeutic potential of uracil and its derivatives in countering pathogenic and physiological disorders

Uracil is one of the most notable pharmacophores in medicinal chemistry as the pyrimidine nucleobase forms an integral part of many commercial drugs. Though the name uracil is usually associated with cancer drugs, there are many uracil-based compounds which can treat different diseases when they are employed. So far, there has been no in-depth review concerning uracil drugs in the market, or in the different stages of clinical trials, including those approved or discontinued. The current work focuses on the importance of uracil and its derivatives in treating different diseases. The use of uracil compounds in treating viral infections, cancer, diabetic, thyroid and autosomal recessive disorders are discussed in the review. The mechanism of action of each uracil drug with emphasis on their structure and properties are discussed in detail. The targeted action of these drugs on sites or on the different stages of a disorder/pathogenic life cycle are also discussed. This review encompasses uracil drugs approved as well as those in development from the 1950's onwards. The utility of uracil in drug discovery and its association with a wide range of diseases is brought forth within this review to demonstrate its potential to a wider audience.

Antiviral Drugs in Newborn and Children

This article focuses on the clinically relevant approved antiviral medications available for the treatment of infants and children. A brief overview of drug categories, mechanism of action, resistance, pharmacokinetics, and side effects is provided for the more commonly prescribed antivirals. The patient categories addressed are treatment and prophylaxis of influenza, neonatal herpes simplex virus and congenital cytomegalovirus, treatment and prophylaxis of viral disease in the immunocompromised host, and a brief introduction to the antivirals available to treat hepatitis B and hepatitis C in children.

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

The amide moiety of peptides can be replaced for example by a triazole moiety, which is considered to be bioisosteric. Therefore, the carbonyl moiety of an amino acid has to be replaced by an alkyne in order to provide a precursor of such peptidomimetics. As most amino acids have a chiral center at Cα, such amide bond surrogates need a chiral moiety. Here the asymmetric synthesis of a set of 24 N-sulfinyl propargylamines is presented. The condensation of various aldehydes with Ellman's chiral sulfinamide provides chiral N-sulfinylimines, which were reacted with (trimethylsilyl)ethynyllithium to afford diastereomerically pure N-sulfinyl propargylamines. Diverse functional groups present in the propargylic position resemble the side chain present at the Cα of amino acids. Whereas propargylamines with (cyclo)alkyl substituents can be prepared in a direct manner, residues with polar functional groups require suitable protective groups. The presence of particular functional groups in the side chain in some cases leads to remarkable side reactions of the alkyne moiety. Thus, electron-withdrawing substituents in the Cα-position facilitate a base induced rearrangement to α,β-unsaturated imines, while azide-substituted propargylamines form triazoles under surprisingly mild conditions. A panel of propargylamines bearing fluoro or chloro substituents, polar functional groups, or basic and acidic functional groups is accessible for the use as precursors of peptidomimetics.

A novel antimetabolite: TAS-102 for metastatic colorectal cancer

TAS-102 is a new oral anti-tumor drug, composed of a thymidine-based nucleoside analog (trifluridine: FTD) and a thymidine phosphorylase inhibitor (tipiracil hydrochloride: TPI). TAS-102 has been shown to significantly improve overall survival and progression-free survival in patients with refractory metastatic colorectal cancer (mCRC) in placebo-controlled randomized phase II and III trials. The current review summarizes mechanisms of action, pharmacokinetics/dynamics and preclinical and clinical data of TAS-102 in colorectal cancer. TAS-102 is a new salvage-line treatment option for patients with mCRC. TAS-102 is well tolerated and has great potential in future clinical drug combination therapies.

3,3-Dibromo-2-trifluoromethyl acrylic acid ethyl ester: a versatile platform for the stereoselective preparation of functionalized-α-trifluoromethyl α,β-unsaturated lactones and trifluoromethyl pyrazolinones

Synthetic routes to multi-functionalized-α-trifluoromethyl α,β-unsaturated lactones and trifluoromethyl pyrazolinones.

Therapeutic potential of TAS-102 in the treatment of gastrointestinal malignancies

Fluoropyrimidines form the mainstay in treatment of gastrointestinal malignancies. For decades 5-fluorouracil (5FU), was the major fluoropyrimidine. Currently it is usually given in a combination with leucovorin and oxaliplatin, i.e. FOLFOX, or irinotecan, i.e. FOLFIRI, or all three, i.e. FOLFIRINOX, but gradually it has been replaced by oral fluoropyrimidine prodrug formulations, such as tegafur-uracil and S-1 (both contain ftorafur), and capecitabine (Xeloda®). Novel drugs such as the antivascular endothelial growth factor antibody, bevacizumab, and the anti-epidermal growth factor receptor antibody, cetuximab, are often combined with one of these treatment options. However, when resistance emerged, no alternatives were available. TAS-102, a combination of trifluorothymidine and the thymidine phosphorylase inhibitor TPI in a 1:0.5 ratio, is a novel oral formulation, which is active in 5FU-resistant models, both in vitro and in xenograft models. In addition to inhibition of thymidylate synthase, the major mechanism of action of classical fluoropyrimidines, TAS-102's major mechanism of action is incorporation into DNA, thereby causing DNA damage. TAS-102 also follows an alternative activation pathway via thymidine kinase, and is not a substrate for dihydropyrimidine dehydrogenase. All together this explains the efficacy in 5FU-resistant models. In early clinical studies, the twice-daily schedule (5 days on, 2 days rest) for 2 weeks every 4 weeks, led to a significant disease control rate in various malignancies. This schedule showed consistent activity in two randomized trials on fluoropyrimidine refractory colorectal cancer patients, reflected by an increase of 2-3 months in overall survival in the TAS-102 group compared with placebo. Considering the impressive preclinical potential of various combinations TAS-102 has the promise to become an alternative for 5FU-resistant cancer.

Trifluridine Induces p53-Dependent Sustained G2 Phase Arrest with Its Massive Misincorporation into DNA and Few DNA Strand Breaks

Trifluridine (FTD) is a key component of the novel oral antitumor drug TAS-102, which consists of FTD and a thymidine phosphorylase inhibitor. Like 5-fluoro-2'-deoxyuridine (FdUrd), a deoxynucleoside form of 5-fluorouracil metabolite, FTD is sequentially phosphorylated and not only inhibits thymidylate synthase activity, but is also incorporated into DNA. Although TAS-102 was effective for the treatment of refractory metastatic colorectal cancer in clinical trials, the mechanism of FTD-induced cytotoxicity is not completely understood. Here, we show that FTD as well as FdUrd induce transient phosphorylation of Chk1 at Ser345, and that this is followed by accumulation of p53 and p21 proteins in p53-proficient human cancer cell lines. In particular, FTD induced p53-dependent sustained arrest at G2 phase, which was associated with a proteasome-dependent decrease in the Cyclin B1 protein level and the suppression of CCNB1 and CDK1 gene expression. In addition, a p53-dependent increase in p21 protein was associated with an FTD-induced decrease in Cyclin B1 protein. Although numerous ssDNA and dsDNA breaks were induced by FdUrd, few DNA strand breaks were detected in FTD-treated HCT-116 cells despite massive FTD misincorporation into genomic DNA, suggesting that the antiproliferative effect of FTD is not due to the induction of DNA strand breaks. These distinctive effects of FTD provide insights into the cellular mechanism underlying its antitumor effect and may explain the clinical efficacy of TAS-102.

Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Eye disease due to herpes simplex virus (HSV) commonly presents as epithelial keratitis which, though usually self-limiting, may persist or progress without treatment.

OBJECTIVES

To compare the relative effectiveness of antiviral agents, interferon, and corneal debridement in the treatment of HSV epithelial keratitis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 12), PubMed (January 1946 to 31 December 2014), EMBASE (January 1980 to 31 December 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to 31 December 2014), System for Information on Grey Literature in Europe (OpenGrey) (January 1995 to 31 December 2014), BIOSIS (January 1926 to 5 May 2014), Scopus (January 1966 to 31 December 2014), Japan Science and Technology Institute (J-Global) (January 1975 to 31 December 2014), China National Knowledge Infrastructure (CNKI) (January 1979 to 31 December 2014), British Library's Electronic Table of Contents (Zetoc) (January 1993 to 7 May 2014). We looked for trials listed on the the metaRegister of Controlled Trials (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en), Chinese Clinical Trial Registry, the U.S. Food and Drug Administration (FDA) (www.fda.gov/), National Institute for Health and Clinical Excellence (NICE) (www.

EVIDENCE

nhs.uk) and the European Medicines Agency (EMA) (www.ema.europa.eu/ema/) as of 31 December 2014. There were no language or date restrictions in the search for trials. We also culled literature digests and conference proceedings as of 15 April 2014. There were no language or date restrictions in the search for trials.

SELECTION CRITERIA

Randomised and quasi-randomised trials of HSV dendritic or geographic epithelial keratitis were included that reported the proportion of eyes healed at one week, two weeks, or both after enrolment.

DATA COLLECTION AND ANALYSIS

We tabulated data on study characteristics, risk of bias, and outcomes and used direct comparisons to estimate a risk ratio (RR) and, when feasible, a hazard ratio (HR) with a 95% confidence interval (CI). Heterogeneity was assessed by an inconsistency index. A multiple treatment comparison meta-analysis consolidated direct and indirect comparisons of relative healing at 14 days.

MAIN RESULTS

One hundred thirty-seven studies involving 8333 eyes met the inclusion criteria. Placebo-controlled studies were heterogeneous in comparison with idoxuridine (RR 1.74; 95% CI 1.03 to 2.91) and few in number for vidarabine (RR 1.81; 95% CI 1.09 to 3.01), interferon (RR 1.32; 95% CI 1.06 to 1.64), and debridement. Vidarabine (RR 1.13; 95% CI 1.02 to 1.25), trifluridine (RR 1.30; 95% CI 1.18 to 1.43), acyclovir (RR 1.23; 95% CI 1.14 to 1.34), and brivudine (RR 1.34; 95% CI 1.18 to 1.51) were more effective than idoxuridine. Trifluridine (RR 1.17; 95% CI 1.03 to 1.32) and acyclovir (RR 1.11; 95% CI 1.03 to 1.19) were more effective than vidarabine. No significant differences in healing emerged among trifluridine, acyclovir, brivudine, and foscarnet although few studies compared brivudine or foscarnet with other antivirals. Any potential advantage of ganciclovir compared to acyclovir was mitigated by study heterogeneity and possible publication bias. Only one study evaluated the joint use of two topical antivirals. In a limited number of studies, oral acyclovir (RR 0.92; 95% CI 0.79 to 1.07) or the combination of oral acyclovir with a topical antiviral (RR 1.36; 95% CI 0.68 to 2.74) appeared as effective as a single topical antiviral agent. Compared to topical antiviral monotherapy, the combination of an antiviral with either interferon or debridement had inconsistent effects on expediting healing and improving outcome.

AUTHORS' CONCLUSIONS

Placebo-controlled studies of HSV epithelial keratitis are limited to superseded interventions. Trifluridine and acyclovir are more effective than idoxuridine or vidarabine and similar in therapeutic effectiveness. Brivudine and foscarnet do not substantially differ in effectiveness from trifluridine or acyclovir. Ganciclovir is at least as effective as acyclovir. The addition of interferon to a nucleoside antiviral agent and the combination of debridement with antiviral treatment need to be further assessed to substantiate any possible advantage in healing.

Fluorine-Containing Diazines in Medicinal Chemistry and Agrochemistry

The combination of a fluorine atom and a diazine ring, which both possess unique structural and chemical features, can generate new relevant building blocks for the discovery of efficient fluorinated biologically active agents. Herein we give a comprehensive review on the biological activity and synthesis of fluorine containing, pyrimidine, pyrazine and pyridazine derivatives with relevance to medicinal and agrochemistry.

In vitro synergism of trifluorothymidine and ganciclovir against HSV-1

PURPOSE

To determine whether trifluorothymidine (TFT) and ganciclovir (GCV) are synergistic against herpes simplex virus type 1 (HSV-1).

METHODS

TFT and GCV activity against 12 strains of HSV-1 (including an acyclovir-resistant strain) was measured by plaque-forming unit (PFU) inhibition. Cellular toxicity was assessed with an MTT dye reduction assay. Synergism was determined by calculating fractional inhibitory concentration (FIC indices) based on PFU reduction.

RESULTS

Concentrations of TFT resulting in 50% inhibition of PFUs (IC(50)) of acyclovir-susceptible HSV-1 strains ranged from 3.07 ± 0.36 to 12.52 ± 0.61 μM. GCV IC(50) values ranged from 0.40 ± 0.02 to 1.59 ± 0.14 μM. IC(50) values of TFT and GCV against the acyclovir-resistant strain were 15.40 ± 3.17 and 93.00 ± 9.64 μM, respectively. Concentrations of TFT or GCV resulting in 50% cell cytotoxicity (CC(50)) were 0.99 ± 0.01 and 92.91 ± 8.92 μM, respectively. TFT and GCV combined (10:1) were 10 times more potent against all acyclovir-susceptible HSV-1 strains. For 8 of 12 HSV-1 strains, the IC(50) of TFT and GCV combined was lower than the CC(50) of either drug. For acyclovir-susceptible HSV-1 strains, TFT and GCV combined generated a FIC index of <0.5, suggesting strong synergism between the two drugs. The FIC value for TFT and GCV combined against the acyclovir-resistant HSV-1 strain was 0.84, indicating nonantagonism.

CONCLUSIONS

TFT and GCV are synergistic against acyclovir-susceptible HSV-1 at concentrations significantly less toxic than if each antiviral were used as a sole agent.

Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Eye disease due to herpes simplex virus (HSV) commonly presents as epithelial keratitis.

OBJECTIVES

To compare the relative effectiveness of antiviral agents, interferon, and corneal débridement in the treatment of acute HSV epithelial keratitis.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2010, Issue 4), MEDLINE (January 1950 to October 2010), EMBASE (January 1980 to October 2010), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2010), Zetoc (British Library's Electronic Table of Contents), System for Information on Grey Literature in Europe (openSIGLE), Biosciences Information Service (BIOSIS), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), Japan Information Center of Science and Technology (JICST-EPlus), and China Academic Journals database (CAJ) via China National Knowledge Infrastructure (CNKI) with citations confirmed using China/Asia On Demand (COAD). There were no language or date restrictions in the search for trials. All databases except CNKI and COAD were last searched on 27 October 2010, CNKI and COAD were searched on 1 April 2010. We also searched literature digests, conference proceedings and reference lists.

SELECTION CRITERIA

Of 152 eligible studies,106 comparative treatment trials involving 5872 eyes with dendritic or geographic epithelial keratitis were analysed for corneal healing over two weeks.

DATA COLLECTION AND ANALYSIS

Interventions were compared at 14 days after trial enrolment by calculating a risk ratio (RR) that was adjusted with indirect RR, assessed by an inconsistency index (I(2) ) and supplemented by a seven-day RR and a hazard ratio (HR).

MAIN RESULTS

Idoxuridine, though uncertainly better in healing outcome than control because of few trials with 14-day follow up, allowed earlier corneal re-epithelialisation. Vidarabine resulted in a significantly better outcome than placebo in one trial (RR 1.96; 95% CI 1.10 to 3.49). Compared to idoxuridine, in combined direct and indirect analyses, vidarabine (RR 1.11; 95% CI 1.03 to 1.19), trifluridine (RR 1.31; 95% CI 1.20 to 1.42), acyclovir (RR 1.23; 95% CI 1.16 to 1.31), brivudine (RR 1.38; 95% CI 1.18 to 1.61), and ganciclovir (RR 1.40; 95% CI 1.25 to 1.57) were significantly more effective. Trifluridine (RR 1.12; 95% CI 1.04 to 1.21) and acyclovir (RR 1.11; 95% CI 1.05 to 1.19) appeared more effective than vidarabine. No significant differences were found in comparisons between acyclovir, trifluridine and brivudine. The comparison of ganciclovir to acyclovir was limited by heterogeneity and possible publication bias. The joint use of two topical antivirals (RR 1.00; 95% CI 0.89 to 1.12) and the use of oral acyclovir alone (RR 0.92; 95% CI 0.79 to 1.07) or combined with a topical antiviral (RR 1.08; 95% CI 0.99 to 1.17) appeared as effective as topical antiviral therapy. Compared to antiviral monotherapy, the combination of an antiviral with interferon (RR 1.03; 95% CI 0.99 to 1.07) or with débridement (RR 1.04; 95% CI 0.95 to 1.14) did not yield significantly better outcomes but may have accelerated healing. The corneal epithelial healing outcome was improved when antiviral therapy was added to débridement (RR 1.21; 95% CI 1.04 to 1.42).

AUTHORS' CONCLUSIONS

Trifluridine and acyclovir are more effective than idoxuridine or vidarabine, and similar in therapeutic effectiveness. Brivudine and ganciclovir are at least as effective as acyclovir. While not improving outcome, the combination of interferon and an antiviral agent may speed healing. The effectiveness of corneal epithelial débridement is improved by an antiviral agent.

Structural modifications of nucleosides in ionic liquids

Nucleoside chemistry represents an important research area for drug discovery, as many nucleoside analogs are prominent drugs and have been widely applied for cancer and viral chemotherapy. However, the synthesis of modified nucleosides presents a major challenge, which is further aggravated by poor solubility of these compounds in common organic solvents. Most of the currently available methods for nucleoside modification employ toxic high boiling solvents; require long reaction time and tedious workup methods. As such, there is constant effort to develop process chemistry in alternative medium to limit the use of organic solvents that are hazardous to the environment and can be deleterious to human health. One such approach is to use ionic liquids, which are 'designer materials' with unique and tunable physico-chemical properties. Studies have shown that methodologies using ionic liquids are highly efficient and convenient for the synthesis of nucleoside analogs, as demonstrated by the preparation of pharmaceutically important anti-viral drugs. This article summarizes recent efforts on nucleoside modification using ionic liquids.

Therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Many clinical trials have been performed on the acute treatment of dendritic epithelial keratitis. Surveys of ocular antiviral pharmacology and of herpes simplex virus (HSV) eye disease have evaluated different interventions, but a systematic review of all comparative clinical studies has not previously been undertaken.

OBJECTIVES

The objective of this review was to compare the effects of various therapeutic interventions for dendritic or geographic HSV epithelial keratitis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library (Issue 3, 2007), MEDLINE (1966 to September 2007), EMBASE (1980 to September 2007), LILACS (up to September 2007), SIGLE (1980 to September 2007), ZETOC (21 September 2007), BIOSIS (up to 2005), JICT-EPlus (up to 2005), Index Medicus (1960 to 1965), Excerpta Medica Ophthalmology (1960 to 1973), reference lists of primary reports and review articles, and conference proceedings pertaining to ocular virology.

SELECTION CRITERIA

This review included comparative clinical trials that assessed one-week or two-week healing rates of topical ophthalmic or oral antiviral agents and or physical or chemical debridement in people with active epithelial keratitis.

DATA COLLECTION AND ANALYSIS

The review author extracted data and assessed trial quality. Interventions were compared by the proportions of participants healed at seven days and at fourteen days after trial enrolment.

MAIN RESULTS

This review included data from 99 trials that randomised a total of 5363 participants. The topical application of vidarabine, trifluridine, acyclovir or ganciclovir resulted in a high proportion of participants healing within one week of treatment. Among these antiviral agents, no treatment emerged as significantly better for the therapy of dendritic epithelial keratitis. Insufficient placebo-controlled studies were available to assess debridement and other physical or physicochemical methods of treatment. Interferon monotherapy had a slight beneficial effect on dendritic epithelial keratitis but was not better than other antiviral agents. Interferon was very effective when combined with another antiviral agent such as trifluridine.

AUTHORS' CONCLUSIONS

Currently available antiviral agents are effective and nearly equivalent. The combination of a nucleoside antiviral with either debridement or with interferon seems to speed healing. Future trials of the acute treatment of HSV epithelial keratitis must aim to achieve adequate statistical power for assessing the primary outcome of epithelial healing and should consider the effect of lesion size and other characteristics on treatment response.

Therapeutic potential of the dual-targeted TAS-102 formulation in the treatment of gastrointestinal malignancies

Current treatment modalities for cancer combine cytotoxic drugs against DNA and novel targeted drugs affecting signal transduction pathways, which are required for growth progression and metastasizing tumors. Classical chemotherapeutic regimens for gastro-intestinal tumors include antimetabolites based on 5-fluorouracil (5FU), the platinum analog oxaliplatin and the topoisomerase inhibitor irinotecan. The thymidine analog trifluorothymidine (TFT) has been shown to bypass resistance pathways for 5FU derivatives (S-1, UFT, Xeloda) in model systems, while concurrent application with a thymidine phosphorylase inhibitor (TPI) increases the bioavailability of TFT, thereby potentiating the in vivo efficacy of TFT. The formulation TAS-102 is given orally in a 1.0:0.5 molar ratio (TFT:TPI). The formulation is dual-targeted due to the cytotoxic effect of TFT, which is enhanced by TPI, while TPI also exerts antiangiogenic effects by inhibiting thymidine phosphorylase (TP), also known as platelet-derived endothelial cell growth factor. Evidence is accumulating from in vitro and in vivo preclinical studies that these properties favor further combinations with other cytotoxic agents currently being used in the treatment of gastro-intestinal tumors. Also treatment with targeted agents will synergistically down-regulate signal transduction pathways responsible for growth and progression of tumors. In this review, we summarize the available information on (clinical) pharmacology, mechanisms of action, pharmacodynamic and pharmacokinetic properties, early clinical trials and future directions of the new potent combination drug TAS-102.

Therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Many clinical trials have been performed on the acute treatment of dendritic epithelial keratitis. Surveys of ocular antiviral pharmacology and of herpes simplex virus (HSV) eye disease have evaluated different interventions, but a systematic review of all comparative clinical studies has not previously been undertaken.

OBJECTIVES

The objective of this review was to compare the effects of various therapeutic interventions for dendritic or geographic HSV epithelial keratitis.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) in The Cochrane Library (Issue 3, 2006), MEDLINE (1966 to July 2006, week 3), EMBASE (1980 to 2006, week 30), LILACS (up to August 2006), SIGLE (1980 to March 2005), ZETOC (1 August 2006), BIOSIS (up to 2005), JICT-EPlus (up to 2005), Index Medicus (1960 to 1965), Excerpta Medica Ophthalmology (1960 to 1973), reference lists of primary reports and review articles, and conference proceedings pertaining to ocular virology.

SELECTION CRITERIA

This review included comparative clinical trials that assessed one-week or two-week healing rates of topical ophthalmic or oral antiviral agents and or physical or chemical debridement in people with active epithelial keratitis.

DATA COLLECTION AND ANALYSIS

The review author extracted data and assessed trial quality. Interventions were compared by the proportions of participants healed at seven days and at fourteen days after trial enrolment.

MAIN RESULTS

This review included data from 98 trials that randomised a total of 5211 participants. Compared to idoxuridine, the topical application of vidarabine, trifluridine, or acyclovir resulted in a significantly greater proportion of participants healing within one week of treatment. Among these latter three antiviral agents, no treatment emerged as significantly better for the therapy of dendritic epithelial keratitis. Insufficient placebo-controlled studies were available to assess debridement and other physical or physicochemical methods of treatment. Interferon monotherapy had a slight beneficial effect on dendritic epithelial keratitis but was not better than other antiviral agents. Interferon was very effective when combined with another antiviral agent such as trifluridine.

AUTHORS' CONCLUSIONS

Currently available antiviral agents are effective and nearly equivalent. The combination of a nucleoside antiviral with either debridement or with interferon seems to speed healing. Future trials of the acute treatment of HSV epithelial keratitis must aim to achieve adequate statistical power for assessing the primary outcome of epithelial healing and should consider the effect of lesion size and other characteristics on treatment response.

A method to distinguish between the de novo induction of thymidine kinase mutants and the selection of pre-existing thymidine kinase mutants in the mouse lymphoma assay

The mouse lymphoma assay (MLA) is the most widely used in vitro mammalian gene mutation assay. It detects various mutation events involving the thymidine kinase (Tk) gene in L5178Y/Tk+/- -3.7.2C mouse lymphoma cells. Mutants are detected using a thymidine analogue that arrests the growth of cells containing a functional Tk gene. However, there are a number of potential test chemicals that are thymidine analogues, and there is a problem when using the MLA to evaluate the mutagenicity of these chemicals. Thymidine analogues are activated by Tk before eliciting their toxicity. Therefore, any pre-existing Tk-/- mutants may avoid the toxicity of the test chemical and obtain a growth advantage over the Tk+/- cells, increasing the Tk mutant frequency (MF) in the culture via a selection mechanism. This potential mutant selection effect needs to be distinguished from de novo mutant induction in order to properly evaluate the mutagenicity of these chemicals. Here we describe a simple MLA study design that can differentiate between the selection of pre-existing mutants and de novo mutant induction. Trifluorothymidine (TFT), a thymidine analogue and the selection agent normally used in the MLA, and 4-nitroquinoline-1-oxide (4-NQO), a potent mutagen, were used to treat cells from two different Tk+/- mouse lymphoma cell cultures with different background MFs (approximately 112 and 305x10(-6)). Both agents significantly increased the Tk MFs in both the normal and high background cultures (p<0.01). In 4-NQO-treated cultures, the induced MFs (MF of treated culture-MF of control) for the cultures with different background MFs were about the same (p>0.1), while in TFT-treated cultures, they were significantly different (p<0.01). In TFT-treated cultures, the fold-increases of MF (MF of treated culture/MF of control) for the cultures with different background MFs were about the same (p>0.1), while in 4-NQO-treated cultures, they were significantly different (p<0.01). This study confirms that, when de novo mutations are induced, the induced MF is the same for cultures with normal and artificially high background MFs. In situations where the increase in MF is due solely to selection of pre-existing mutants, the "induced" MF will be a multiple of the background MF and the magnitude of the increase of the induced MF will depend upon the magnitude of the background MF. Our results demonstrate that it is possible, using this experimental design, to distinguish between chemicals acting primarily via the selection of pre-existing Tk mutants and those inducing de novo mutants in the MLA.

RCM-Mediated Synthesis of Trifluoromethyl-Containing Nitrogen Heterocycles

A ring-closing metathesis mediated pathway to trifluoromethyl-containing piperidines is detailed. This involves the development of a synthetic route to a new (trifluoromethyl)allylating reagent via a Diels-Alder/retro-Diels-Alder strategy, its application in the synthesis of a series of trifluormethyl-substituted diolefin precursors for ring-closing metathesis, and eventually the successful cyclization of these precursor molecules into the corresponding functionalized piperidines.