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Biomedical subjects

D J Kerr

Publications and source records attributed to D J Kerr.

At least 19 recordsLinked to original sources
PubMed2005

A phase I/II and pharmacokinetic study of irinotecan in combination with capecitabine as first-line therapy for advanced colorectal cancer.

PURPOSE: The aim of this study was to determine in patients with previously untreated advanced colorectal cancer the maximum tolerated dose (MTD) and safety profile of irinotecan in combination with capecitabine, to identify a recommended dose and to determine the response rate and time to disease progression. In addition, we aimed to explore the pharmacokinetic parameters of irinotecan and capecitabine when used in different sequences of administration, with irinotecan infusion either prior to or after the first intake of capecitabine. PATIENTS AND METHODS: One hundred patients were included: 43 patients were recruited into an extended phase I trial of alternating escalation in dose of both drugs where irinotecan was administered intravenously (i.v) on day 1 after first intake of capecitabine taken from days 1-14 twice daily, with cycles repeated every 3 weeks. After the determination of recommended dose a further 57 patients were treated in a phase II evaluation with the reverse sequence of drugs on day 1. Pharmacokinetic analysis was performed in patients treated at the recommended dose in two cohorts of patients in which the sequence of the first administration of each drug was reversed. RESULTS: The MTD of the combination was determined as irinotecan 300 mg/m2, with capecitabine 2000 mg/m2/day. Dose limiting toxicities were neutropenia and diarrhoea. The recommended dose is irinotecan intravenous (i.v.) 250 mg/m2 day 1 and capecitabine 2000 mg/m2/day days 1-14, every 3 weeks. Treatment was well tolerated, with diarrhoea the most common serious toxicity. Response rate in the phase II cohort was 42% [95% confidence interval (CI) 29% to 56%]. Median duration of response was 7.7 months (95% CI 7.5-8.9). Median time to progression was 8.3 months (95% CI 5.8-10). No significant effect on irinotecan pharmacokinetics was observed whatever the intake of capecitabine before or after irinotecan infusion. An effect of irinotecan on capecitabine and some capecitabine metabolites was observed, but irinotecan did not effect 5-fluorouracil (5-FU) pharmacokinetics. CONCLUSIONS: Irinotecan in combination with capecitabine is a well tolerated regimen with an activity comparable to, but more convenient than, irinotecan-5-FU i.v. combinations in patients with previously untreated advanced colorectal cancer. The pharmacokinetic data suggest that the sequence of administration does not impact significantly on the metabolism of the two drugs.

Adult↗
PubMed2005

Inhibition of NF-kappaB enhances the cytotoxicity of virus-directed enzyme prodrug therapy and oncolytic adenovirus cancer gene therapy.

Virus-directed enzyme prodrug therapy utilizing the bacterial enzyme nitroreductase delivered by a replication-defective adenovirus vector to activate the prodrug CB1954 is a promising strategy currently undergoing clinical trials in patients with a range of cancers. Similarly, selectively replicating oncolytic adenoviruses are entering clinical trials. An understanding of interactions between vector and target cell are critical to the development of these strategies. We demonstrate that adenovirus vectors activate cellular pathways that promote cell survival in an NF-kappaB-dependent manner, and consequently have a negative effect on the efficacy of cell killing induced by cancer gene therapy strategies. This provides a potential therapeutic target to enhance the cytotoxicity of these approaches.

Adenoviridae↗
PubMed2004

Enhanced efficacy of Escherichia coli nitroreductase/CB1954 prodrug activation gene therapy using an E1B-55K-deleted oncolytic adenovirus vector.

Viruses that replicate selectively in cancer cells constitute an exciting new class of anticancer agent. The conditionally replicating adenovirus (CRAd) dl1520, which lacks the E1B-55K gene, has elicited significant clinical responses in humans when used in combination with chemotherapy. A convergent development has been to use replication-defective viruses to express prodrug-activating enzymes in cancer cells. This can sensitize the cancer to prodrug, but depends upon achieving sufficient level, distribution and specificity of enzyme expression within the tumour. In this study, we have expressed the prodrug-activating enzyme nitroreductase (NTR) in the context of an E1B-55K-deleted adenovirus, CRAd-NTR(PS1217H6). We show that CRAd-NTR(PS1217H6) retains oncolytic growth properties, and expresses substantially more NTR than a comparable, replication-defective adenovirus. The combination of viral oncolysis and NTR expression results in significantly greater sensitization of SW480 and WiDr colorectal cancer cells to the prodrug CB1954 in vitro. In vivo, CRAd-NTR(PS1217H6) was shown to replicate in subcutaneous SW480 tumour xenografts in immunodeficient mice, resulting in more NTR expression and greater sensitization to CB1954 than with replication-defective virus. Combination therapy of CRAd-NTR(PS1217H6) with CB1954 reduced tumour growth from 13.5- to 2.8-fold over 5 weeks, and extended median survival from 42 to 81 days, compared with no treatment.

Adenoviridae↗
PubMed2003

Mechanism of cell death induced by the novel enzyme-prodrug combination, nitroreductase/CB1954, and identification of synergism with 5-fluorouracil.

Virus-directed enzyme prodrug therapy (VDEPT) utilising the bacterial enzyme nitroreductase delivered by a replication-defective adenovirus vector to activate the prodrug CB1954 is a promising strategy currently undergoing clinical trials in patients with a range of cancers. An understanding of the mechanism of tumour cell death induced by activated CB1954 will facilitate this clinical development. Here, we report that activated CB1954 kills cells predominantly by caspase-dependent apoptosis. This may have important implications for the generation of immune-mediated bystander effects. Further, the use of a replication-defective adenovirus vector to deliver nitroreductase may negatively affect cellular apoptotic pathways stimulated by activated CB1954. Finally, examination of nitroreductase/CB1954 in combination with conventional chemotherapy reveals a synergistic interaction with 5-fluorouracil. These data will facilitate the further development and future clinical trial design of this novel therapy.

Adenoviridae↗
PubMed2003

Comparison of intermittent and continuous palliative chemotherapy for advanced colorectal cancer: a multicentre randomised trial.

BACKGROUND: Policies of UK clinicians regarding the duration of chemotherapy for patients with advanced colorectal cancer are not consistent. We aimed to compare effectiveness of continuous and intermittent chemotherapy in such patients. METHODS: Patients who responded or had stable disease after receiving 12 weeks of the regimens described by de Gramont and Lokich, or raltitrexed chemotherapy, were randomised to either intermittent (a break in chemotherapy, re-starting on the same drug on progression), or continuous chemotherapy until progression. FINDINGS: 354 patients (178 intermittent, 176 continuous) were enrolled from 42 UK centres. At randomisation, 41% of participants had part or complete response; 59% were stable. Only 66 (37%) patients allocated to intermittent treatment restarted as planned, after a median of 130 days. Median time on treatment after restarting was 84 days. Patients in the continuous group remained on treatment for a median of a further 92 days. Similar proportions of patients in both groups received second-line therapy. Patients on intermittent chemotherapy had significantly fewer toxic effects and serious adverse events than those in the continuous group. There was no clear evidence of a difference in overall survival (hazard ratio 0.87 favouring intermittent, 95% CI 0.69-1.09, p=0.23). INTERPRETATION: Our findings provided no clear evidence of a benefit in continuing therapy indefinitely until disease progression. They showed that it is safe to stop chemotherapy after 12 weeks and re-start the same treatment on progression in patients with chemosensitive advanced colorectal cancer.

Adult↗
PubMed2003

Effect of specimen length: are the mechanics of individual motion segments comparable in functional spinal units and multisegment specimens?

Functional spinal units (FSUs) are frequently used for in vitro mechanical testing. This approach assumes that the mechanical behavior of the FSUs is equivalent to the mechanics of these segments within the intact spine. The purpose of this study was to determine whether normal spinal mechanics are compromised in FSU preparations. Flexion-extension pure-moment flexibility testing was performed on 13 L2-L5 porcine specimens. The moment-angle relationship of the L3/L4 segment was recorded, and then the multisegment specimens were cut down to L3/L4 FSUs and retested. Comparisons of stiffness, range of motion, and laxity zone were made between conditions. The neutral zone and range of motion parameters were significantly larger in the L3/L4 motion segment compared to the L3/L4 segment tested within the multisegment specimen; the stiffness was not significantly different. These differences were attributed to cutting the supraspinous ligament as this ligament spans several vertebral levels. Flexion mechanical tests performed on FSUs should be interpreted cautiously as the biomechanics of FSUs is altered from normal. Although the choice of spine length depends on the experimental purpose, spinal flexion studies should be performed on multisegment specimens to appropriately represent the anatomical boundary conditions.

Animals↗
PubMed2003

A pilot study of adjuvant intraperitoneal 5-fluorouracil using 4% icodextrin as a novel carrier solution.

AIM: This pilot study utilised the sustained intraperitoneal (i.p.) dwell properties of an iso-osmotic solution of 4% icodextrin to investigate the tolerability, toxicity and feasibility of home-based i.p. 5FU adjuvant chemotherapy following resective surgery for colorectal cancer. METHODS: Twenty eligible patients (Dukes' stage B and C with potentially curative resection) underwent perioperative Tenckhoff catheter placement. Ten (6 male, 4 female, aged 46-85; mean 67.5 years) received 5FU chemotherapy. After initial flushing and gradual increase in volumes of 4% icodextrin alone, patients received home-based i.p. 5FU (150-300 mg/m(2)/day given as equal doses at 12-hourly intervals) for 14 days, with a 14-day recovery period, for a maximum of 6 courses. Two incurable patients, treated on compassionate grounds, provided further safety data. RESULTS: Nine of the 10 patients became proficient in self-treatment with 5FU and two completed 6 courses. Frequent abdominal pain was the main dose-limiting toxicity of 5FU, causing withdrawal of three patients after a high (300 mg/m(2)/day) first course and one following a third course at lower doses. I.p. 5FU concentrations (mean>30000 ngml(-1)) were 1000 fold higher than systemic venous levels. Bacterial peritonitis led to two withdrawals but was not a frequent event (microbiologically confirmed incidence of 1 per 27 catheter-months). CONCLUSIONS: Home-based i.p. adjuvant chemotherapy is a feasible treatment option in patients with surgically resected colorectal carcinoma.

Adenocarcinoma↗
PubMed2003

Gene therapy for colorectal cancer.

Colorectal cancer is an important public health problem worldwide. Gene therapy has therapeutic potential for patients with advanced or recurrent colorectal cancer, incurable by conventional treatments. To date, many strategies of gene therapy have been explored, including mutant gene correction, prodrug activation, immune stimulation and genetically-modified oncolytic viruses. Although the preclinical results of gene therapy for colorectal cancer have shown promise, gene therapy is still at an early stage of clinical development and has not yet shown a significant therapeutic benefit for patients. The main obstacles for introduction of gene therapy to patients are poor targeting selectivity of the vectors and inefficient gene transfer. As the science supporting tumour-selective vectors evolves, gene therapy may expand rapidly in the clinical practice of colorectal cancer treatment.

Animals↗
PubMed2002

Comparison of survival, palliation, and quality of life with three chemotherapy regimens in metastatic colorectal cancer: a multicentre randomised trial.

BACKGROUND: This randomised trial compared three chemotherapy regimens in the first-line treatment of advanced colorectal cancer, in terms of their effect on overall and progression-free survival; other endpoints included toxicity, symptom palliation, and quality of life. METHODS: 905 patients were randomly assigned the de Gramont regimen (n=303; folinic acid 200 mg/m(2), fluorouracil bolus 400 mg/m(2), and infusion 600 mg/m(2) on days 1 and 2, repeated every 14 days), the Lokich regimen (n=301; protracted venous infusion of fluorouracil 300 mg/m(2) daily), or raltitrexed (n=301; 3 mg/m(2) intravenously every 21 days). Analyses were by intention to treat. FINDINGS: Median follow-up of survivors was 67 weeks. For the de Gramont, Lokich, and raltitrexed groups, respectively, median survival was 294, 302, and 266 days. The hazard ratios for overall survival were 0.88 (95% CI 0.70-1.12, p=0.17) for de Gramont versus Lokich, and 0.99 (0.79-1.25, p=0.94) for de Gramont versus raltitrexed. An increase in treatment-related deaths was seen on raltitrexed (de Gramont one, Lokich two, raltitrexed 18) due to combined gastrointestinal and haematological toxicity. Patients' assessment of quality of life showed that raltitrexed was inferior to the fluorouracil-based regimens, especially in terms of palliation and functioning. INTERPRETATION: The deGramont and Lokich regimens were similar in terms of survival, quality of life, and response rates. The Lokich regimen was associated with more central line complications and hand-foot syndrome. Raltitrexed showed similar response rates and overall survival to the de Gramont regimen and was easier to administer, but resulted in greater toxicity and inferior quality of life.

Adenocarcinoma↗
PubMed2002

Induction of apoptosis by chemotherapeutic drugs: the role of FADD in activation of caspase-8 and synergy with death receptor ligands in ovarian carcinoma cells.

Although ovarian tumours initially respond to chemotherapy, they gradually acquire drug resistance. The aims of this study were to identify how chemotherapeutic drugs with diverse cellular targets activate apoptotic pathways and to investigate the mechanism by which exposure to a combination of drugs plus death receptor ligands can increase tumour cell kill. The results show that drugs with distinct cellular targets differentially up-regulate TRAIL and TNF as well CD95L, but do not require interaction of these ligands with their receptor partners to induce cell death. Factors that were critical in drug-induced apoptosis were activation of caspases, with caspase-8 being activated by diverse drugs in a FADD-independent manner. Certain drugs also demonstrated some dependence on FADD in the induction of cell death. Caspase-9 was activated more selectively by chemotherapeutic agents. Combining ligation of death receptors with exposure to drugs increased tumour cell kill in both drug resistant cell lines and primary ovarian carcinoma cells, even though these cells were not sensitive to death receptor ligation alone. CD95L was more consistent at combining with drugs than TRAIL or TNF. Investigation of the mechanism by which a combination of drugs plus CD95 ligation can increase cell death showed that caspase-8 was activated in cells exposed to a combination of cisplatin and anti-CD95, but not in cells exposed to either agent alone.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Adjuvant chemoradiotherapy and chemotherapy in resectable pancreatic cancer: a randomised controlled trial.

BACKGROUND: The role of adjuvant treatment in pancreatic cancer remains uncertain. The European Study Group for Pancreatic Cancer (ESPAC) assessed the roles of chemoradiotherapy and chemotherapy in a randomised study. METHODS: After resection, patients were randomly assigned to adjuvant chemoradiotherapy (20 Gy in ten daily fractions over 2 weeks with 500 mg/m(2) fluorouracil intravenously on days 1-3, repeated after 2 weeks) or chemotherapy (intravenous fluorouracil 425 mg/m(2) and folinic acid 20 mg/m(2) daily for 5 days, monthly for 6 months). Clinicians could randomise patients into a two-by-two factorial design (observation, chemoradiotherapy alone, chemotherapy alone, or both) or into one of the main treatment comparisons (chemoradiotherapy versus no chemoradiotherapy or chemotherapy versus no chemotherapy). The primary endpoint was death, and all analyses were by intention to treat. Findings 541 eligible patients with pancreatic ductal adenocarcinoma were randomised: 285 in the two-by-two factorial design (70 chemoradiotherapy, 74 chemotherapy, 72 both, 69 observation); a further 68 patients were randomly assigned chemoradiotherapy or no chemoradiotherapy and 188 chemotherapy or no chemotherapy. Median follow-up of the 227 (42%) patients still alive was 10 months (range 0-62). Overall results showed no benefit for adjuvant chemoradiotherapy (median survival 15.5 months in 175 patients with chemoradiotherapy vs 16.1 months in 178 patients without; hazard ratio 1.18 [95% CI 0.90-1.55], p=0.24). There was evidence of a survival benefit for adjuvant chemotherapy (median survival 19.7 months in 238 patients with chemotherapy vs 14.0 months in 235 patients without; hazard ratio 0.66 [0.52-0.83], p=0.0005). Interpretation This study showed no survival benefit for adjuvant chemoradiotherapy but revealed a potential benefit for adjuvant chemotherapy, justifying further randomised controlled trials of adjuvant chemotherapy in pancreatic cancer.

Adenocarcinoma↗
PubMed2001

Neural network and regression predictions of 5-year survival after colon carcinoma treatment.

BACKGROUND: The Commission on Cancer data from the National Cancer Data Base (NCDB) for patients with colon carcinoma was used to develop several artificial neural network and regression-based models. These models were designed to predict the likelihood of 5-year survival after primary treatment for colon carcinoma. METHODS: Two modeling methods were used in the study. Artificial neural networks were used to select the more important variables from the NCDB database and model 5-year survival. A standard parametric logistic regression also was used to model survival and the two methods compared on a prospective set of patients not used in model development. RESULTS: The neural network yielded a receiver operating characteristic (ROC) area of 87.6%. At a sensitivity to mortality of 95% the specificity was 41%. The logistic regression yielded a ROC area of 82% and at a sensitivity to mortality of 95% gave a specificity of 27%. CONCLUSIONS: The neural network found a strong pattern in the database predictive of 5-year survival status. The logistic regression produced somewhat less accurate, but good, results.

Aged↗