Elucidating the mechanisms responsible for the previous failure of phase III clinical trials with eniluracil (EU) and development of a novel scheduling approach to optimize the efficacy of EU/5-fluorouracil (5-FU) combination therapy

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 2557-2557
Author(s):  
V. Guarcello ◽  
J. Fourie ◽  
M. J. Lawton ◽  
W. W. Peters ◽  
M. J. Heslin ◽  
...  
Keyword(s):  
Tumor Tissue ◽  
Competitive Inhibition ◽  
Dihydropyrimidine Dehydrogenase ◽  
Phase Iii ◽  
Clinical Failure ◽  
Peripheral Blood Mononuclear ◽  
Phase Iii Clinical Trials ◽  
Phase Iii Trials ◽  
Dosing Regimens

2557 Background: Irreversible inhibition of dihydropyrimidine dehydrogenase (DPD) by EU blocks 5-FU catabolism allowing for oral 5-FU administration with complete bioavailability. Unfortunately, phase III trials with co-administered EU/5-FU showed inferiority vs. 5-FU/leucovorin, and were discontinued. We recently reported that competitive inhibition of human uridine phosphorylase (UP) and thymidine phosphorylase (TP) 5-FU-anabolic enzymes by EU is an important mechanism potentially responsible for clinical failure of the combined EU/5- FU regimen. We hypothesize that EU inhibition of UP and TP is transient, while that of DPD is prolonged, allowing for novel schedule dependent optimization of EU/5-FU dosing regimens with improved efficacy. Methods: In this phase I study, five patients received a single oral dose (2 mg, 5 mg or 10 mg) of EU 12–14 hours prior to scheduled resection of primary/metastatic colorectal cancer. Dosage was as follows: Two patients received the 2 mg dose, one patient received the 5 mg dose and two patients received the 10 mg dose. Matched normal and tumor tissue biopsies were immediately snap frozen and subsequently UP, TP and DPD activity was measured in vitro via HPLC detection of [6- 14C]-5-FU catabolites/anabolites. Peripheral blood mononuclear cell (PBMC) DPD activity was determined at baseline prior to EU administration, 30 min prior to surgery (Day 1), and on Days 2, 5 and 14 following EU administration. Results: At 12–14 hours following EU administration, there was an absence of inhibition of UP and TP, while DPD was significantly inhibited in matched tumor and normal tissue. Importantly, PBMC DPD activity was significantly inhibited by EU on Day 1 (12–14 hours after EU administration) and Day 2 (36 hours after EU administration) at 0 ± 0% and 17 ± 11% (mean ± SD) of baseline, respectively. Conclusions: These data demonstrate a differential recovery time of EU mediated inhibition of UP and TP compared to DPD, which permits future schedule dependent optimization of EU/5-FU therapy. No significant financial relationships to disclose.

Dose dependent inhibition of uridine phosphorylase (UP) by eniluracil (EU): Was the clinical inferiority of the EU/5-fluorouracil (5-FU) phase III trials due to an unrecognized inhibition of 5-FU anabolism?

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 2058-2058 ◽  
Author(s):  
J. Fourie ◽  
V. Guarcello ◽  
R. B. Diasio
Keyword(s):  
Phosphate Buffer ◽  
Competitive Inhibition ◽  
Dihydropyrimidine Dehydrogenase ◽  
Phase Iii ◽  
Uridine Phosphorylase ◽  
Dose Ratio ◽  
Hek 293 ◽  
Phase Iii Trials ◽  
Dose Dependent ◽  
The Eu

2058 Background: Eniluracil (EU) is an irreversible inactivator of dihydropyrimidine dehydrogenase (DPD). EU inhibits DPD dependent 5-fluorouracil (5-FU) catabolism, allowing for oral 5-FU administration with essentially complete bioavailability. Although earlier murine studies suggested an increased antitumor effect when EU was administered before 5-FU, clinical studies used co-administered EU and 5-FU (ratio: 10 EU:1 5-FU) (b.i.d.). These phase III trials demonstrated inferiority compared to a regimen of 5-FU/leukovorin, leading to discontinuation of EU development. We hypothesize that the clinical failure of this EU/5-FU schedule may have resulted from competitive inhibition of 5-FU anabolic (ANA) activation by EU. In this study we examined whether EU could competitively inhibit uridine phosphorylase (UP) or orotate phosphoribosyl transferase (OPRT), the primary ANA enzymes of 5-FU. Methods: The cytoplasmic fraction of human embryonic kidney cells (HEK-293) was used as the source of UP and OPRT. Reverse phase HPLC with radioactivity detection was used to quantify [2-14C]-uracil formation from [2-14C]-uridine (UP activity) and to quantify [6-14C]-FUMP formation from [6-14C]-5-FU (OPRT activity). For UP activity, reaction mixtures consisted of increasing concentrations of EU in phosphate buffer containing 150 μM [2-14C]-uridine. For OPRT activity, reaction mixtures consisted of increasing concentrations of EU in phosphate buffer containing 5 μM [6-14C]-FU and 100 μM benzylacyclouridine (UP inhibitor). Reactions were initiated with addition of UP/OPRT enzyme source and allowed to proceed for 30 min at 37°C. Results: EU displayed dose-dependent competitive inhibition of UP activity (IC50 = 0.375 mM). In particular, the EU/5-FU ratio of 2.5:1 produced approximately 50% inhibition of UP activity. In contrast, EU did not inhibit OPRT activity. Conclusions: This study demonstrates that EU competitively inhibits UP, an important enzyme in 5-FU ANA activation, and suggests that changing the dose ratio and/or increasing the interval between EU and 5-FU administration may be useful in optimizing 5-FU antitumor efficacy. [Table: see text]

In Vitro Activity of Gepotidacin Against Gram-negative and Gram-positive Anaerobes

2021 ◽  
Author(s):  
Meredith A. Hackel ◽  
James A. Karlowsky ◽  
Michele A. Canino ◽  
Daniel F. Sahm ◽  
Nicole E. Scangarella-Oman
Keyword(s):  
Clinical Trials ◽  
Vitro Activity ◽  
Phase Iii ◽  
In Vitro Activity ◽  
Gram Positive ◽  
Gram Negative ◽  
Phase Iii Clinical Trials ◽  
Agar Dilution

Gepotidacin (formerly GSK2140944) is a first in class triazaacenaphthylene antibacterial currently in Phase III clinical trials. When tested against Gram-negative ( n =333) and Gram-positive ( n =225) anaerobes by agar dilution, gepotidacin inhibited 90% of isolates (MIC 90 ) at concentrations of 4 and 2 μg/ml, respectively. Given gepotidacin’s in vitro activity against the anaerobic isolates tested, further study is warranted to better understand gepotidacin’s utility in the treatment of infections caused by clinically relevant anaerobic organisms.

Activities of Tobramycin and Six Other Antibiotics against Pseudomonas aeruginosa Isolates from Patients with Cystic Fibrosis

1999 ◽  
Vol 43 (12) ◽  
pp. 2877-2880 ◽  
Author(s):  
Ribhi M. Shawar ◽  
David L. MacLeod ◽  
Richard L. Garber ◽  
Jane L. Burns ◽  
Jenny R. Stapp ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Active Drug ◽  
Resistance Mechanisms ◽  
Phase Iii ◽  
In Vitro Activity ◽  
Phase Iii Clinical Trials ◽  
Multiple Antibiotics

ABSTRACT The in vitro activity of tobramycin was compared with those of six other antimicrobial agents against 1,240 Pseudomonas aeruginosa isolates collected from 508 patients with cystic fibrosis during pretreatment visits as part of the phase III clinical trials of tobramycin solution for inhalation. The tobramycin MIC at which 50% of isolates are inhibited (MIC50) and MIC90 were 1 and 8 μg/ml, respectively. Tobramycin was the most active drug tested and also showed good activity against isolates resistant to multiple antibiotics. The isolates were less frequently resistant to tobramycin (5.4%) than to ceftazidime (11.1%), aztreonam (11.9%), amikacin (13.1%), ticarcillin (16.7%), gentamicin (19.3%), or ciprofloxacin (20.7%). For all antibiotics tested, nonmucoid isolates were more resistant than mucoid isolates. Of 56 isolates for which the tobramycin MIC was ≥16 μg/ml and that were investigated for resistance mechanisms, only 7 (12.5%) were shown to possess known aminoglycoside-modifying enzymes; the remaining were presumably resistant by an incompletely understood mechanism often referred to as “impermeability.”

scholarly journals A Review of Phase III Clinical Trials of Prostate Cancer Chemoprevention

2007 ◽  
Vol 89 (3) ◽  
pp. 207-211 ◽  
Author(s):  
JF Thorpe ◽  
S Jain ◽  
TH Marczylo ◽  
AJ Gescher ◽  
WP Steward ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Clinical Trial ◽  
Clinical Trials ◽  
Cancer Prevention ◽  
Age Of Onset ◽  
Cancer Chemoprevention ◽  
Phase Iii ◽  
Phase Iii Clinical Trials ◽  
Prostate Cancer Prevention ◽  
Phase Iii Trials

INTRODUCTION Prostate cancer is an excellent target for chemoprevention strategies; given its late age of onset, any delay in carcinogenesis would lead to a reduction in its incidence. This article reviews all the completed and on-going phase III trials in prostate cancer chemoprevention. PATIENTS AND METHODS All phase III trials of prostate cancer chemoprevention were identified within a Medline search using the keywords ‘clinical trial, prostate cancer, chemoprevention’. RESULTS In 2003, the Prostate Cancer Prevention Trial (PCPT) became the first phase III clinical trial of prostate cancer prevention. This landmark study was terminated early due to the 24.8% reduction of prostate cancer prevalence over a 7-year period in those men taking the 5α-reductase inhibitor, finasteride. This article reviews the PCPT and the interpretation of the excess high-grade prostate cancer (HGPC) cases in the finasteride group. The lack of relationship between cumulative dose and the HGPC cases, and the possible sampling error of biopsies due to gland volume reduction in the finasteride group refutes the suggestion that this is a genuine increase in HGPC cases. The other on-going phase III clinical trials of prostate cancer chemoprevention – the REDUCE study using dutasteride, and the SELECT study using vitamin E and selenium – are also reviewed. CONCLUSIONS At present, finasteride remains the only intervention shown in long-term prospective phase III clinical trials to reduce the incidence of prostate cancer. Until we have the results of trials using alternative agents including the on-going REDUCE and SELECT trials, the advice given to men interested in prostate cancer prevention must include discussion of the results of the PCPT. The increased rate of HGPC in the finasteride group continues to generate debate; however, finasteride may still be suitable for prostate cancer prevention, particularly in men with lower urinary tract symptoms.

scholarly journals Evaluating Intermittent Androgen-Deprivation Therapy Phase III Clinical Trials: The Devil Is in the Details

2016 ◽  
Vol 34 (3) ◽  
pp. 280-285 ◽  
Author(s):  
Maha Hussain ◽  
Catherine Tangen ◽  
Celestia Higano ◽  
Nicholas Vogelzang ◽  
Ian Thompson
Keyword(s):  
Prostate Cancer ◽  
Statistical Power ◽  
Progression Free Survival ◽  
Androgen Deprivation ◽  
Phase Iii ◽  
End Point ◽  
Phase Iii Clinical Trials ◽  
Noninferiority Trials ◽  
Phase Iii Trials

Purpose Intermittent androgen deprivation (IAD) has been widely tested in prostate cancer. However, phase III trials testing continuous androgen deprivation (CAD) versus IAD have reached inconclusive and seemingly contradictory results. Different design and conduct issues must be critically evaluated to better interpret the results. Patients and Methods Seven published phase III trials were examined for prespecified design and outcomes. Treatment specifications; primary end point; superiority versus noninferiority design assumptions, including magnitude of assumed versus observed noninferiority margin (NIM); duration of follow-up; and quality-of-life (QOL) outcomes were considered in terms of the results and conclusions reported. Results Five trials had a superiority and three had a noninferiority primary hypothesis. Only three trials had a uniform population and overall survival (OS) end point. All trials observed better outcomes in terms of OS and progression-free survival (PFS) than assumed at time of study design, translating into prespecified NIMs or hazard ratios that reflected larger absolute differences in OS or PFS between arms. Lower-than-expected event rates also reduced statistical power for the trials. Other factors, including length of follow-up, cause of death, QOL, and primary end point, and their impact on trial interpretation are discussed. Conclusion No trial to date has demonstrated survival superiority of IAD compared with CAD. Trials concluding IAD is noninferior to CAD were based on wide NIMs that included clinically important survival differences, not likely to be considered comparable by physicians or patients. Interim analyses relying on short follow-up and including a majority of non–prostate cancer deaths will favor a noninferiority conclusion and should be interpreted cautiously. Adequate follow-up is required to ensure capture of prostate cancer deaths in both superiority and noninferiority trials.

scholarly journals Microbiology and Preclinical Review of Omadacycline

2019 ◽  
Vol 69 (Supplement_1) ◽  
pp. S6-S15 ◽  
Author(s):  
James A Karlowsky ◽  
Judith Steenbergen ◽  
George G Zhanel
Keyword(s):  
Legionella Pneumophila ◽  
Animal Studies ◽  
Action Spectrum ◽  
Binding Activity ◽  
Phase Iii ◽  
Phase Iii Clinical Trials ◽  
Clostridioides Difficile ◽  
Semisynthetic Derivative

AbstractOmadacycline is a novel aminomethylcycline antimicrobial and semisynthetic derivative of tetracycline. In vitro, omadacycline displays potent activity against gram-positive and many gram-negative bacteria, including methicillin-resistant Staphylococcus aureus, Streptococcus pneumoniae, β-hemolytic streptococci, vancomycin-resistant Enterococcus, and Enterobacteriaceae. Omadacycline is also active against atypical and anaerobic pathogens, including Legionella pneumophila, Mycoplasma spp., Ureaplasma spp., Bacteroides spp., and Clostridioides difficile. This review outlines the microbiology and preclinical studies of omadacycline, including its mechanism of action; spectrum of activity; protein binding; activity in the presence of surfactant, serum, normal, and pH-adjusted urine, or bacterial biofilms; postantibiotic effect; pharmacodynamic properties; and in vitro and in vivo efficacy. The results of in vitro and in vivo animal studies support the observations made in phase III clinical trials and the clinical development of omadacycline.

scholarly journals Individualising Anticoagulant Therapy in Atrial Fibrillation Patients

2016 ◽  
Vol 5 (2) ◽  
pp. 102 ◽  
Author(s):  
Marco Alings ◽  
Keyword(s):  
Atrial Fibrillation ◽  
Oral Anticoagulants ◽  
Vitamin K Antagonist ◽  
The Other ◽  
Phase Iii ◽  
European Medicines Agency ◽  
Efficacy And Safety ◽  
Pivotal Phase ◽  
Phase Iii Clinical Trials ◽  
Dosing Regimens

Non-vitamin K antagonist (VKA) oral anticoagulants (NOACs) have emerged as alternatives to VKAs for the prevention of stroke in patients with non-valvular atrial fibrillation. Four NOACs: dabigatran, apixaban, rivaroxaban and edoxaban, have received regulatory approval in Europe from the European Medicines Agency. Numerous factors can influence the decision to prescribe a NOAC, the most important of which are assessment of stroke and bleeding risks. Given the variation in design of the pivotal phase III clinical trials investigating the efficacy and safety of NOACs, and in the absence of head-to-head comparative data, it is impossible to recommend one NOAC over the other. However, NOACs offer the opportunity for individualised therapy based on factors such as renal function, age or patient/doctor preference for once- or twice-daily dosing regimens. Dose reduction of some NOACs should be considered in at-risk patient populations.

Improvements in first-line systemic mRCC therapy: Challenging insights from a cross trial comparison of overall survival and subsequent therapies in recent phase III trials.

2020 ◽  
Vol 38 (6_suppl) ◽  
pp. 705-705
Author(s):  
Jochen Casper ◽  
Samantha Henderson ◽  
Hannah Casper ◽  
Claus-Henning Kohne
Keyword(s):  
Overall Survival ◽  
Phase Iii ◽  
Lower Percentage ◽  
Primary Study ◽  
Special Focus ◽  
The Sun ◽  
Phase Iii Clinical Trials ◽  
Phase Iii Trials ◽  
Risk Patients ◽  
Recent Phase

705 Background: Using sunitinib (SUN) as the comparator, two out of three recent phase III clinical trials have shown an overall survival (OS) benefit in the alternative treatment arm (Checkmate 214 (C), Keynote 426 (K)). The Javelin 101(J) trial has yet to show a significant improvement. Methods: A cross-study comparison of OS for the sunitinib arms of C, K and J was carried out. Special focus was given to risk group stratification and subsequent therapies. Data from the SUN pivotal trial (SP) was also taken into account. Results: Across the C, K and SP trials, OS was similar at approximately 78%. Despite a lower percentage of favourable risk patients compared to K and SP, an OS of 82% was observed in J. At 18 months, OS survival curves split ranging from 65% ©, 72.1% (K) to 76% (J). OS in the SUN arm in J at 18 months was comparable to OS of Nivolumab/Ipilimumab in C (78%). The rate of subsequent therapies ranged from 34.3% (K), 39.2% (J) to 54% (C) in the SUN arms. At the time of the SP trial almost no subsequent therapy options existed. In the experimental arms, the rate of subsequent therapies was 51.8% ©, 20.5% (K) and 20.8% (J). The existing data give no clear evidence of a correlation between subsequent therapies and OS. However, an analysis of the subsequent therapies/patients discontinuing therapy ratio (ST/DIS) and type of subsequent therapy (PD1/L1 directed or therapy with proven OS benefit (pOS) in randomized trials) in the SUN arms may be more conclusive (see table). The rate of subsequent therapies (ST/DIS) as well as PD(L)1 or pOS therapies were highest in J, followed by K and C. Conclusions: Despite the difficulties of a cross trial comparison, this data should raise awareness of the influence of a more intense subsequent therapy. It points to the necessity to standardize subsequent therapies in 1st line trials if OS is a primary study aim. Given this analysis, it may be pertinent to ask if an optimal or near optimal subsequent therapy following SUN might be equal to a 1st line IO/IO therapy with regards to OS.[Table: see text]

scholarly journals Inhibiting Mycobacterium tuberculosis within and without

2016 ◽  
Vol 371 (1707) ◽  
pp. 20150506 ◽  
Author(s):  
Stewart T. Cole
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Drug Development ◽  
Cholesterol Metabolism ◽  
Treatment Options ◽  
Scientific Progress ◽  
Phase Iii ◽  
Phase Iii Trials ◽  
Shorten Treatment Duration ◽  
Drug Resistant Strains

Tuberculosis remains a scourge of global health with shrinking treatment options due to the spread of drug-resistant strains of Mycobacterium tuberculosis . Intensive efforts have been made in the past 15 years to find leads for drug development so that better, more potent drugs inhibiting new targets could be produced and thus shorten treatment duration. Initial attempts focused on repurposing drugs that had been developed for other therapeutic areas but these agents did not meet their goals in clinical trials. Attempts to find new lead compounds employing target-based screens were unsuccessful as the leads were inactive against M. tuberculosis . Greater success was achieved using phenotypic screening against live tubercle bacilli and this gave rise to the drugs bedaquiline, pretomanid and delamanid, currently in phase III trials. Subsequent phenotypic screens also uncovered new leads and targets but several of these targets proved to be promiscuous and inhibited by a variety of seemingly unrelated pharmacophores. This setback sparked an interest in alternative screening approaches that mimic the disease state more accurately. Foremost among these were cell-based screens, often involving macrophages, as these should reflect the bacterium's niche in the host more faithfully. A major advantage of this approach is its ability to uncover functions that are central to infection but not necessarily required for growth in vitro . For instance, inhibition of virulence functions mediated by the ESX-1 secretion system severely attenuates intracellular M. tuberculosis , preventing intercellular spread and ultimately limiting tissue damage. Cell-based screens have highlighted the druggability of energy production via the electron transport chain and cholesterol metabolism. Here, I review the scientific progress and the pipeline, but warn against over-optimism due to the lack of industrial commitment for tuberculosis drug development and other socio-economic factors. This article is part of the themed issue ‘The new bacteriology’.

scholarly journals Killing of Borrelia burgdorferi by Antibody Elicited by OspA Vaccine Is Inefficient in the Absence of Complement

1999 ◽  
Vol 67 (1) ◽  
pp. 443-445 ◽  
Author(s):  
Jena M. Nowling ◽  
Mario T. Philipp
Keyword(s):  
Borrelia Burgdorferi ◽  
Antibody Titer ◽  
Vaccine Efficacy ◽  
Rhesus Monkeys ◽  
Phase Iii ◽  
Tick Saliva ◽  
Tick Vector ◽  
Lyme Disease Vaccine ◽  
Phase Iii Trials

ABSTRACT A Lyme disease vaccine, based on the Borrelia burgdorferi lipoprotein OspA, has recently undergone phase III trials in humans. The results of one of these trials indicate that vaccine efficacy positively correlates with anti-OspA antibody titer. Spirochete killing within the tick vector midgut, upon which vaccine efficacy appears to depend, may occur chiefly via a mechanism that involves antibody alone, as it has been reported that complement is degraded by tick saliva decomplementing factors. We compared the in vitro killing efficiencies of anti-OspA antibody elicited in rhesus monkeys by the OspA vaccine, in the presence and in the absence of monkey complement. Killing in the absence of complement was between 14 and 3,800 times less efficient than with complement present, depending on the spirochete strain. The relative inefficiency of the complement-independent killing mechanism by anti-OspA antibody may explain why OspA vaccine efficacy is critically dependent on antibody titer.

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