Tumor Regression upon Intratumoral and Subcutaneous Dosing of the STING Agonist ALG-031048 in Mouse Efficacy Models.

Stimulator of interferon genes (STING) agonists have shown potent anti-tumor efficacy in various mouse tumor models and have the potential to overcome resistance to immune checkpoint inhibitors (ICI) by linking the innate and acquired immune systems. First-generation STING agonists are administered intratumorally; however, a systemic delivery route would greatly expand the clinical use of STING agonists. Biochemical and cell-based experiments, as well as syngeneic mouse efficacy models, were used to demonstrate the anti-tumoral activity of ALG-031048, a novel STING agonist. In vitro, ALG-031048 is highly stable in plasma and liver microsomes and is resistant to degradation via phosphodiesterases. The high stability in biological matrices translated to good cellular potency in a HEK 293 STING R232 reporter assay, efficient activation and maturation of primary human dendritic cells and monocytes, as well as long-lasting, antigen-specific anti-tumor activity in up to 90% of animals in the CT26 mouse colon carcinoma model. Significant reductions in tumor growth were observed in two syngeneic mouse tumor models following subcutaneous administration. Combinations of ALG-031048 and ICIs further enhanced the in vivo anti-tumor activity. This initial demonstration of anti-tumor activity after systemic administration of ALG-031048 warrants further investigation, while the combination of systemically administered ALG-031048 with ICIs offers an attractive approach to overcome key limitations of ICIs in the clinic.

Synthesis and Anti-HCV Activities of 4'-Fluoro-2'-Substituted Uridine Triphosphates and Nucleotide Prodrugs: Discovery of 4'-Fluoro-2'- C-methyluridine 5'-Phosphoramidate Prodrug (AL-335) for the Treatment of Hepatitis C Infection.

We report the synthesis and biological evaluation of a series of 4'-fluoro-2'- C-substituted uridines. Triphosphates of the uridine analogues exhibited a potent inhibition of hepatitis C virus (HCV) NS5B polymerase with IC50 values as low as 27 nM. In an HCV subgenomic replicon assay, the phosphoramidate prodrugs of these uridine analogues demonstrated a very potent activity with EC50 values as low as 20 nM. A lead compound AL-335 (53) demonstrated high levels of the nucleoside triphosphate in vitro in primary human hepatocytes and Huh-7 cells as well as in dog liver following a single oral dose. Compound 53 was selected for the clinical development where it showed promising results in phase 1 and 2 trials.

Structure-activity relationship analysis of mitochondrial toxicity caused by antiviral ribonucleoside analogs.

Recent cases of severe toxicity during clinical trials have been associated with antiviral ribonucleoside analogs (e.g. INX-08189 and balapiravir). Some have hypothesized that the active metabolites of toxic ribonucleoside analogs, the triphosphate forms, inadvertently target human mitochondrial RNA polymerase (POLRMT), thus inhibiting mitochondrial RNA transcription and protein synthesis. Others have proposed that the prodrug moiety released from the ribonucleoside analogs might instead cause toxicity. Here, we report the mitochondrial effects of several clinically relevant and structurally diverse ribonucleoside analogs including NITD-008, T-705 (favipiravir), R1479 (parent nucleoside of balapiravir), PSI-7851 (sofosbuvir), and INX-08189 (BMS-986094). We found that efficient substrates and chain terminators of POLRMT, such as the nucleoside triphosphate forms of R1479, NITD-008, and INX-08189, are likely to cause mitochondrial toxicity in cells, while weaker chain terminators and inhibitors of POLRMT such as T-705 ribonucleoside triphosphate do not elicit strong in vitro mitochondrial effects. Within a fixed 3'-deoxy or 2'-C-methyl ribose scaffold, changing the base moiety of nucleotides did not strongly affect their inhibition constant (Ki) against POLRMT. By swapping the nucleoside and prodrug moieties of PSI-7851 and INX-08189, we demonstrated that the cell-based toxicity of INX-08189 is mainly caused by the nucleoside component of the molecule. Taken together, these results show that diverse 2' or 4' mono-substituted ribonucleoside scaffolds cause mitochondrial toxicity. Given the unpredictable structure-activity relationship of this ribonucleoside liability, we propose a rapid and systematic in vitro screen combining cell-based and biochemical assays to identify the early potential for mitochondrial toxicity.

Nebulized Fentanyl for Dyspnea in a Hospice Patient with True Allergy to Morphine and Hydromorphone.

An 86-year-old white female was admitted to hospice care with lung cancer. Even with optimal medical management, she suffered from dyspnea and required opioid therapy. However, the patient had a true morphine and hydromorphone allergy. She was administered nebulized fentanyl for symptomatic relief of dyspnea with good effect and she did not experience any allergic response.

Biochemical study of the comparative inhibition of hepatitis C virus RNA polymerase by VX-222 and filibuvir.

Filibuvir and VX-222 are nonnucleoside inhibitors (NNIs) that bind to the thumb II allosteric pocket of the hepatitis C virus (HCV) RNA-dependent RNA polymerase. Both compounds have shown significant promise in clinical trials and, therefore, it is relevant to better understand their mechanisms of inhibition. In our study, filibuvir and VX-222 inhibited the 1b/Con1 HCV subgenomic replicon, with 50% effective concentrations (EC(50)s) of 70 nM and 5 nM, respectively. Using several RNA templates in biochemical assays, we found that both compounds preferentially inhibited primer-dependent RNA synthesis but had either no or only modest effects on de novo-initiated RNA synthesis. Filibuvir and VX-222 bind to the HCV polymerase with dissociation constants of 29 and 17 nM, respectively. Three potential resistance mutations in the thumb II pocket were analyzed for effects on inhibition by the two compounds. The M423T substitution in the RNA polymerase was at least 100-fold more resistant to filibuvir in the subgenomic replicon and in the enzymatic assays. This resistance was the result of a 250-fold loss in the binding affinity (K(d)) of the mutated enzyme to filibuvir. In contrast, the inhibitory activity of VX-222 was only modestly affected by the M423T substitution but more significantly affected by an I482L substitution.

The design, synthesis, and antiviral activity of monofluoro and difluoro analogues of 4'-azidocytidine against hepatitis C virus replication: the discovery of 4'-azido-2'-deoxy-2'-fluorocytidine and 4'-azido-2'-dideoxy-2',2'-difluorocytidine.

The discovery of 4'-azidocytidine (3) (R1479) (J. Biol. Chem. 2006, 281, 3793; Bioorg. Med. Chem. Lett. 2007, 17, 2570) as a potent inhibitor of RNA synthesis by NS5B (EC(50) = 1.28 microM), the RNA polymerase encoded by hepatitis C virus (HCV), has led to the synthesis and biological evaluation of several monofluoro and difluoro derivatives of 4'-azidocytidine. The most potent compounds in this series were 4'-azido-2'-deoxy-2',2'-difluorocytidine and 4'-azido-2'-deoxy-2'-fluoroarabinocytidine with antiviral EC(50) of 66 nM and 24 nM in the HCV replicon system, respectively. The structure-activity relationships within this series were discussed, which led to the discovery of these novel nucleoside analogues with the most potent compound, showing more than a 50-fold increase in antiviral potency as compared to 4'-azidocytidine (3).

First example of phosphoramidate approach applied to a 4'-substituted purine nucleoside (4'-azidoadenosine): conversion of an inactive nucleoside to a submicromolar compound versus hepatitis C virus.

We report on the synthesis of the anti hepatitis C virus (HCV) agent 4'-azidoadenosine (1) and the application of the phosphoramidate ProTide technology to this nucleoside. The synthesis of 1 was achieved through an epoxide intermediate followed by regio- and stereoselective ring opening by azidotrimethylsilane in the presence of a Lewis acid. Compound 1 did not inhibit HCV replication in cell culture at concentrations up to 0.1 mM. However, a submicromolar active agent could be derived from 1 by the application of the ProTide technology. All the phosphoramidates prepared were L-alanine derivatives with variations in the aryl moiety and in the ester part of the amino acid. The benzyl ester and the l-naphthyl phosphate (18) had the best activity in replicon assay. Phosphoramidates (18-21) achieved a significant improvement in antiviral potency over the parent nucleoside (1) with no increase in cytotoxicity.

Adjuvant therapy for pancreatic cancer.

Ductal adenocarcinoma of the pancreas is one of the leading causes of cancer death in the UK, Europe and US, with incidence closely paralleling mortality. Until recently, enthusiasm for treating these patients was limited for a number of reasons: the majority of patients undergoing surgery would relapse early, adjuvant treatment was of unproven value and systemic therapy in advanced disease had only a small chance of a short-term benefit. More recently, however, it has become recognised that specialist surgery can improve results and there is evidence that adjuvant chemotherapy has a significant advantage in terms of 5-year survival. In particular adjuvant systemic 5-fluorouracil with folinic acid can result in 5-year survival of < or = 29% (compared with 11% for controls) and adjuvant gemcitabine can improve disease-free survival to 13.4 months from a median of 6.9 months in controls, but not overall survival. In contrast the role of adjuvant chemoradiation in addition to chemotherapy remains unproven and the survival results appear to be inferior to systemic chemotherapy alone. New agents, such as capecitabine and erlotinib, are emerging with some activity in this dismal disease signalling hope for the future.

Different strategies of sequential and combination chemotherapy for patients with poor prognosis advanced colorectal cancer (MRC FOCUS): a randomised controlled trial.

BACKGROUND: In the non-curative setting, the sequence in which anticancer agents are used, singly or in combination, may be important if patients are to receive the maximum period of disease control with the minimum of adverse effects. We compared sequential and combination chemotherapy strategies in patients with unpretreated advanced or metastatic colorectal cancer, who were regarded as not potentially curable irrespective of response. METHODS: We studied patients with advanced colorectal cancer, starting treatment with non-curative intent. 2135 unpretreated patients were randomly assigned to three treatment strategies in the ratio 1:1:1. Strategy A (control group) was single-agent fluorouracil (given with levofolinate over 48 h every 2 weeks) until failure, then single-agent irinotecan. Strategy B was fluorouracil until failure, then combination chemotherapy. Strategy C was combination chemotherapy from the outset. Within strategies B and C, patients were randomly assigned to receive, as the combination regimen, fluorouracil plus irinotecan (groups B-ir and C-ir) or fluorouracil plus oxaliplatin (groups B-ox and C-ox). The primary endpoint was overall survival, analysed by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN 79877428. RESULTS: Median survival of patients allocated to control strategy A was 13.9 months. Median survival of each of the other groups was longer (B-ir 15.0, B-ox 15.2, C-ir 16.7, and C-ox 15.4 months). However, log-rank comparison of each group against control showed that only C-ir--the first-line combination strategy including irinotecan--satisfied the statistical test for superiority (p=0.01). Overall comparison of strategy B with strategy C was within the predetermined non-inferiority boundary of HR=1.18 or less (HR=1.06, 90% CI 0.97-1.17). INTERPRETATION: Our data challenge the assumption that, in this non-curative setting, maximum tolerable treatment must necessarily be used first-line. The staged approach of initial single-agent treatment upgraded to combination when required is not worse than first-line combination, and is an alternative option for discussion with patients.

Application of the phosphoramidate ProTide approach to 4'-azidouridine confers sub-micromolar potency versus hepatitis C virus on an inactive nucleoside.

We report the application of our phosphoramidate ProTide technology to the ribonucleoside analogue 4'-azidouridine to generate novel antiviral agents for the inhibition of hepatitis C virus (HCV). 4'-Azidouridine did not inhibit HCV, although 4'-azidocytidine was a potent inhibitor of HCV replication under similar assay conditions. However 4'-azidouridine triphosphate was a potent inhibitor of RNA synthesis by HCV polymerase, raising the question as to whether our phosphoramidate ProTide approach could effectively deliver 4'-azidouridine monophosphate to HCV replicon cells and unleash the antiviral potential of the triphosphate. Twenty-two phosphoramidates were prepared, including variations in the aryl, ester, and amino acid regions. A number of compounds showed sub-micromolar inhibition of HCV in cell culture without detectable cytotoxicity. These results confirm that phosphoramidate ProTides can deliver monophosphates of ribonucleoside analogues and suggest a potential path to the generation of novel antiviral agents against HCV infection. The generic message is that ProTide synthesis from inactive parent nucleosides may be a warranted drug discovery strategy.

Capecitabine: an evidence-based review of its effectiveness in the treatment of carcinoma of the pancreas.

INTRODUCTION: More than 90% of patients with pancreatic cancer present either with incurable locally advanced or metastatic disease or relapse following surgery. For these patients systemic therapy offers the only prospect of salvage, but pancreatic cancer is one of the most chemoresistant of tumors; current chemotherapy can only delay progression in a limited proportion of patients and survival rates are poor. There is therefore a pressing need for more effective therapy. Capecitabine is a new oral prodrug of fluorouracil, which has shown activity in pancreatic cancer particularly when used in combination with gemcitabine. AIMS: To review the emerging evidence for the clinical effectiveness of capecitabine in the management of carcinoma of the pancreas. EVIDENCE REVIEW: There is evidence from phase II testing that capecitabine is active in pancreatic cancer. The Swiss Group for Clinical Cancer Research/Central European Cooperative Oncology Group (SAKK/CECOG) phase III trial found that the combination of gemcitabine and capecitabine did not improve overall median survival as compared with gemcitabine alone (8.4 vs 7.3 months, respectively; P=0.314) but subgroup analysis in patients with good performance score [Karnofsky Performance Scores (KPS) ≥90] revealed a significant survival improvement with the combination arm (10.1 months) compared with single-agent gemcitabine (7.5 months; P=0.033). Preliminary data from the GemCap phase III trial indicated significantly improved response rates and survival for the combination of gemcitabine with capecitabine (7.4 months) compared with gemcitabine alone (6 months; P=0.026) but analysis of the mature data with adequate follow-up awaits reporting. CLINICAL POTENTIAL: The addition of capecitabine to gemcitabine may represent a small step forward in the management of advanced pancreatic cancer but further data are required in order to determine its full impact.

Capecitabine in carcinoma of the pancreas.

Capecitabine is an oral prodrug of 5-fluorouracil, which is converted to 5-fluorouracil by three sequential enzymatic reactions. The final requisite enzyme, thymidine phosphorylase, is present at consistently higher levels in tumours compared with normal tissues, thereby suggesting that 5-fluorouracil that is delivered in this way may benefit from an element of tumour targeting and thus enhanced selectivity and better tolerability. Capecitabine has been shown to have single-agent activity in advanced carcinoma of the pancreas and to improve response rates and survival when administered in combination with gemcitabine compared with gemcitabine alone. This paper reviews the pharmacology and clinical data that are relevant to the use of capecitabine in pancreatic cancer.

Perioperative chemotherapy versus surgery alone for resectable gastroesophageal cancer.

BACKGROUND: A regimen of epirubicin, cisplatin, and infused fluorouracil (ECF) improves survival among patients with incurable locally advanced or metastatic gastric adenocarcinoma. We assessed whether the addition of a perioperative regimen of ECF to surgery improves outcomes among patients with potentially curable gastric cancer. METHODS: We randomly assigned patients with resectable adenocarcinoma of the stomach, esophagogastric junction, or lower esophagus to either perioperative chemotherapy and surgery (250 patients) or surgery alone (253 patients). Chemotherapy consisted of three preoperative and three postoperative cycles of intravenous epirubicin (50 mg per square meter of body-surface area) and cisplatin (60 mg per square meter) on day 1, and a continuous intravenous infusion of fluorouracil (200 mg per square meter per day) for 21 days. The primary end point was overall survival. RESULTS: ECF-related adverse effects were similar to those previously reported among patients with advanced gastric cancer. Rates of postoperative complications were similar in the perioperative-chemotherapy group and the surgery group (46 percent and 45 percent, respectively), as were the numbers of deaths within 30 days after surgery. The resected tumors were significantly smaller and less advanced in the perioperative-chemotherapy group. With a median follow-up of four years, 149 patients in the perioperative-chemotherapy group and 170 in the surgery group had died. As compared with the surgery group, the perioperative-chemotherapy group had a higher likelihood of overall survival (hazard ratio for death, 0.75; 95 percent confidence interval, 0.60 to 0.93; P=0.009; five-year survival rate, 36 percent vs. 23 percent) and of progression-free survival (hazard ratio for progression, 0.66; 95 percent confidence interval, 0.53 to 0.81; P<0.001). CONCLUSIONS: In patients with operable gastric or lower esophageal adenocarcinomas, a perioperative regimen of ECF decreased tumor size and stage and significantly improved progression-free and overall survival. (Current Controlled Trials number, ISRCTN93793971 [controlled-trials.com].).

Arsenic, cadmium, lead, and mercury in surface soils, Pueblo, Colorado: implications for population health risk.

Decades of intensive industrial and agricultural practices as well as rapid urbanization have left communities like Pueblo, Colorado facing potential health threats from pollution of its soils, air, water and food supply. To address such concerns about environmental contamination, we conducted an urban geochemical study of the city of Pueblo to offer insights into the potential chemical hazards in soil and inform priorities for future health studies and population interventions aimed at reducing exposures to inorganic substances. The current study characterizes the environmental landscape of Pueblo in terms of heavy metals, and relates this to population distributions. Soil was sampled within the city along transects and analyzed for arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb). We also profiled Pueblo's communities in terms of their socioeconomic status and demographics. ArcGIS 9.0 was used to perform exploratory spatial data analysis and generate community profiles and prediction maps. The topsoil in Pueblo contains more As, Cd, Hg and Pb than national soil averages, although average Hg content in Pueblo was within reported baseline ranges. The highest levels of As concentrations ranged between 56.6 and 66.5 ppm. Lead concentrations exceeded 300 ppm in several of Pueblo's residential communities. Elevated levels of lead are concentrated in low-income Hispanic and African-American communities. Areas of excessively high Cd concentration exist around Pueblo, including low income and minority communities, raising additional health and environmental justice concerns. Although the distribution patterns vary by element and may reflect both industrial and non-industrial sources, the study confirms that there is environmental contamination around Pueblo and underscores the need for a comprehensive public health approach to address environmental threats in urban communities.