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Biomedical subjects

David J Kerr

Publications and source records attributed to David J Kerr.

At least 19 recordsLinked to original sources
PubMed2006

Identification of oligopeptides binding to peritoneal tumors of gastric cancer.

This is a report of in vivo intraperitoneal biopanning, and we successfully identified a novel peptide to target the multiple peritoneal tumors of gastric cancer. A phage display library was injected directly into the abdominal cavity of mice bearing peritoneal tumors of human gastric cancer, and phages associated with the tumors were subsequently reclaimed from isolated samples. The tumor-associated phages were amplified and the biopanning cycle was repeated five times to enrich for high affinity tumor-selective binding peptides. Finally, a tri-peptide motif, KLP, which showed homology with laminin 5 (a ligand for alpha3beta1 integrin), was identified as a binding peptide for peritoneal tumors of gastric cancer. Phage clones displaying the sequence KLP showed 64-fold higher binding to peritoneal tumors than control phage and were preferentially distributed in tumors rather than in normal organs after intraperitoneal injection into mice. In addition, the KLP phages were more likely to bind to cancer cells in malignant ascites derived from a patient with recurrent gastric cancer. Synthesized peptide containing the motif KLP (SWKLPPS) also showed a strong binding activity to peritoneal tumors without cancer growth effect. Liposomes conjugated with SWKLPPS peptide appeared significantly more often in tumors than control liposomes after intraperitoneal injection into mice. Furthermore, modification of liposomes with SWKLPPS peptide enhanced the antitumor activity of adriamycin on gastric cancer cells. The peptide motif KLP seems a potential targeting ligand for the treatment of peritoneal metastasis of gastric cancer.

Amino Acid Motifs↗
PubMed2005

Adjuvant chemotherapy for stage II colorectal cancer: the time is right!

Colorectal cancer is the second most common cause of cancer death in much of the developed world. Cancer-related mortality is slowly decreasing as a result of better detection and improved surgery. Adjuvant chemotherapy is now considered the standard treatment for stage III colon cancer, and has evolved recently with the introduction of infusional, combination chemotherapy. Adjuvant therapy for stage II colon cancer has been more controversial. Recent trial data suggest, however, that there is a legitimate case for discussing the advantages and limitations with individual patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Single-dose clinical pharmacokinetic studies of gefitinib.

BACKGROUND: The objective of the five clinical studies presented in this article was to investigate the single-dose pharmacokinetics of gefitinib (IRESSA, ZD1839), an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in healthy volunteers and patients with advanced cancer. METHODS: Studies 1 and 3-5 recruited healthy male volunteers aged 18-65 years; study 2 recruited male or female patients aged>or=18 years with any solid malignant tumour expressing EGFR and refractory to standard therapy. Gefitinib administration was as follows: study 1 (bioavailability in healthy volunteers; n=12)--intravenous infusion of 50 or 100 mg followed by a single oral dose of 250 mg; study 2 (bioavailability in cancer patients; n=19)--intravenous infusion of 50 mg followed by a single oral dose of 250 mg; study 3 (intrasubject variability; n=24)--two single oral doses of 250 mg; study 4 (dose-proportionality; n=15)--three single oral doses of 50-500 mg; study 5 (effect of food; n=26)--two single doses of 250 mg under either fed or fasted conditions. In all studies, venous blood samples for determination of gefitinib plasma concentrations were collected at predetermined intervals. Plasma concentrations of gefitinib were measured using liquid-liquid extraction after basification followed by high-performance liquid chromatography with tandem mass spectrometric detection. Appropriate pharmacokinetic parameters were determined by noncompartmental methods. RESULTS: Study 1: Oral bioavailability of a gefitinib 250 mg dose was 57% in healthy volunteers. Absorption was moderately slow, with geometric mean (gmean) peak plasma concentration (Cmax) of 85 ng/mL (range 43.5-110 ng/mL) reached 5 hours following an oral dose of 250 mg. Study 2: Oral bioavailability of a gefitinib 250 mg dose was 59% in patients. Absorption was again moderately slow, with gmean Cmax of 159 ng/mL (range 48.7-324 ng/mL) typically reached 3 hours (range 1-8 hours) following an oral dose of 250 mg. Study 3: Area under the plasma concentration-time curve from time zero to infinity (AUCinfinity) and Cmax were variable--up to 15-fold between subjects and 2-fold within an individual. Study 4: AUCinfinity and Cmax increased with dose across the range of 50-500 mg, and increased dose-proportionally up to 250 mg. Study 5: Small, clinically insignificant increases in AUCinfinity and Cmax were seen in the presence of food (32% and 37%, respectively). CONCLUSIONS: The gefitinib 250 mg tablet is orally bioavailable in both healthy volunteers and cancer patients; bioavailability is independent of dose and unaffected by food to any clinically significant extent. Gefitinib undergoes rapid plasma clearance and has an extensive volume of distribution, resulting in a pharmacokinetic profile supportive of a once-daily dosage regimen.

Administration, Oral↗
PubMed2004

Virus-directed enzyme prodrug therapy: intratumoral administration of a replication-deficient adenovirus encoding nitroreductase to patients with resectable liver cancer.

PURPOSE: Virus-directed enzyme prodrug therapy depends on selective delivery of virus encoding a prodrug-activating enzyme to tumor, followed by systemic treatment with prodrug to achieve high levels of the activated cytotoxic at the intended site of action. The use of the bacterial enzyme nitroreductase to activate CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide) to a short lived, highly toxic DNA cross-linking agent has been demonstrated in tumor xenografts. In this study, we report the first clinical trial investigating the feasibility, safety, and transgene expression of a replication-defective adenovirus encoding nitroreductase (CTL102) in patients with liver tumors. PATIENTS AND METHODS: Patients with resectable primary or secondary (colorectal) liver cancer received a single dose of CTL102 delivered by direct intratumoral inoculation 3 to 8 days before surgical resection. RESULTS: Eighteen patients were treated with escalating doses of CTL102 (range, 10(8)-5 x 10(11) virus particles). The vector was well tolerated with minimal side effects, had a short half-life in the circulation, and stimulated a robust antibody response. Dose-related increases in tumoral nitroreductase expression measured by immunohistochemical analysis have been observed. CONCLUSION: Direct intratumoral inoculation of CTL102 to patients with primary and secondary liver cancer is feasible and well tolerated. The high level of nitroreductase expression observed at 1 to 5 x 10(11) virus particles mandates further studies in patients with inoperable tumors who will receive CTL102 and CB1954.

Adenoviridae↗
PubMed2004

A randomized trial of chemoradiotherapy and chemotherapy after resection of pancreatic cancer.

BACKGROUND: The effect of adjuvant treatment on survival in pancreatic cancer is unclear. We report the final results of the European Study Group for Pancreatic Cancer 1 Trial and update the interim results. METHODS: In a multicenter trial using a two-by-two factorial design, we randomly assigned 73 patients with resected pancreatic ductal adenocarcinoma to treatment with chemoradiotherapy alone (20 Gy over a two-week period plus fluorouracil), 75 patients to chemotherapy alone (fluorouracil), 72 patients to both chemoradiotherapy and chemotherapy, and 69 patients to observation. RESULTS: The analysis was based on 237 deaths among the 289 patients (82 percent) and a median follow-up of 47 months (interquartile range, 33 to 62). The estimated five-year survival rate was 10 percent among patients assigned to receive chemoradiotherapy and 20 percent among patients who did not receive chemoradiotherapy (P=0.05). The five-year survival rate was 21 percent among patients who received chemotherapy and 8 percent among patients who did not receive chemotherapy (P=0.009). The benefit of chemotherapy persisted after adjustment for major prognostic factors. CONCLUSIONS: Adjuvant chemotherapy has a significant survival benefit in patients with resected pancreatic cancer, whereas adjuvant chemoradiotherapy has a deleterious effect on survival.

Aged↗
PubMed2004

Targeting angiogenesis in cancer: clinical development of bevacizumab.

The importance of vascular endothelial growth factor (VEGF) as a regulator of normal and tumor blood vessel growth has been increasingly characterized over the past two decades. VEGF increases vascular permeability and has a well established role in stimulating angiogenesis, a prerequisite of tumor growth. Numerous compounds have been developed to counteract the angiogenic effects of VEGF. One such drug, bevacizumab, a humanized anti-VEGF monoclonal antibody, received FDA approval in the US earlier this year. Results obtained from initial trials showed that this drug was generally well tolerated, and combination studies of bevacizumab and chemotherapeutic agents have been completed in patients with breast, prostate, lung, and colorectal cancers. A randomized trial of bevacizumab used in combination with capecitabine for metastatic breast patients showed no overall improvement of progression-free survival. However, this result contrasted greatly with the data obtained for patients with advanced colorectal cancer, where a combination regimen of bevacizumab, 5-fluorouracil, leucovorin and irinotecan demonstrated a significant improvement in response rates and overall survival compared with chemotherapy alone. This review highlights the key clinical trial data with bevacizumab and discusses the reasons for some of the contrasting results seen in different patient studies.

Antibodies, Monoclonal↗
PubMed2004

Nitroreductase: a prodrug-activating enzyme for cancer gene therapy.

1. The prodrug CB1954 (5-(aziridin-1-yl)-2,4-dinitrobenzamide) is activated by Escherichia coli nitroreductase (NTR) to a potent DNA-crosslinking agent. 2. Virus-mediated expression of NTR in tumour cells sensitizes them to CB1954 in vitro and in vivo, providing the basis for a strategy of cancer gene therapy. 3. A phase I trial of CB1954 in cancer patients has been completed, documenting the pharmacokinetics and establishing an acceptable dose. Subsequent trials of the replication-defective adenovirus CTL102 in patients with resectable tumours have documented expression of NTR in injected colorectal liver metastases, hepatocellular carcinoma, head and neck cancer and prostate cancer. Trials combining CTL102 and CB1954 are underway. 4. An oncolytic (replication-competent) adenovirus vector allowed increased expression of NTR in vitro and in a mouse tumour model, resulting in a greater reduction in tumour growth when combined with CB1954 treatment. 5. Alternative prodrugs may eventually prove superior to CB1954; a nitroaryl phosphoramide mustard prodrug activated by NTR shows a greater therapeutic index than CB1954 in a human ovarian carcinoma. 6. The crystal structure of NTR provided the basis for site-directed mutagenesis, which has identified a number of mutants with improved kinetics of CB1954 activation. These can provide improved cell sensitization to CB1954. Combinations of these are being tested. 7. The basis for a positive selection for improved NTR variants has been demonstrated.

Animals↗
PubMed2003

Immune enhancement of nitroreductase-induced cytotoxicity: studies using a bicistronic adenovirus vector.

The nitroreductase (NR)/CB1954 enzyme prodrug system has given promising results in preclinical studies and is currently being assessed in phase I clinical trials. It is well established that there is an immune component to the bystander effect observed with other systems such as thymidine kinase and cytosine deaminase; however, such an effect has not previously been described using NR. We have preliminary data suggesting an immune bystander effect with NR to further examine these effects and their potential enhancement by cytokines, an adenoviral vector containing CMV-NR, an internal ribosome entry site (IRES) and the gene for murine GM-CSF (mGM-CSF) was constructed. The NR-GM-CSF virus was validated in 2 experimental models and demonstrated increased therapeutic efficacy in the MC26 murine colorectal tumour model. These data illustrate that the combination of suicide gene therapy using NR and CB1954 with immune stimulation via GM-CSF gives an improved response compared to either modality alone and suggests that the immune component of this response may be beneficial in combating unresectable, metastatic disease and preventing tumour recurrence.

Adenocarcinoma↗
PubMed2003

Intrahepatic arterial versus intravenous fluorouracil and folinic acid for colorectal cancer liver metastases: a multicentre randomised trial.

BACKGROUND: The liver is the most frequent site for metastases of colorectal cancer, which is the second largest contributor to cancer deaths in Europe. We did a randomised trial to compare an intrahepatic arterial (IHA) fluorouracil and folinic acid regimen with the standard intravenous de Gramont fluorouracil and folinic acid regimen for patients with adenocarcinoma of the colon or rectum, with metastases confined to the liver. METHODS: We randomly allocated 290 patients from 16 centres to receive either intravenous chemotherapy (folinic acid 200 mg/m2, fluorouracil bolus 400 mg2 and 22-h infusion 600 mg/m2, day 1 and 2, repeated every 14 days), or IHA chemotherapy designed to be equitoxic (folinic acid 200 mg/m2, fluorouracil 400 mg/m2 over 15 mins and 22-h infusion 1600 mg/m2, day 1 and 2, repeated every 14 days). The primary endpoint was overall survival, and analysis was by intention to treat. FINDINGS: 50 (37%) patients allocated to IHA did not start their treatment, and another 39 (29%) had to stop before receiving six cycles of treatment because of catheter failure. The IHA group received a median of two cycles (0-6), compared with 8.5 (6-12) for the intravenous group. 45 (51%) IHA patients who did not start or did not receive six cycles switched to intravenous treatment. In both groups, grade 3 or 4 toxicity was uncommon. Median overall survival was 14.7 months for the IHA group and 14.8 months for the intravenous group (hazard ratio 1.04 [95% CI 0.80-1.33], log-rank test p=0.79). Similarly, there was no significant difference in progression-free survival. INTERPRETATION: Our results showed no evidence of an advantage in progression-free survival or overall survival for the IHA group; thus continued use of this regimen cannot be recommended outside of a clinical trial.

Adenocarcinoma↗
PubMed2003

Colorectal cancer.

Colorectal cancer (CRC) is one of the leading causes of mortality and accounts for approximately 200000 deaths per year in Europe and the USA. Chemotherapy and radiotherapy have established roles in the treatment of colorectal cancer and can contribute to cure rate, prolongation of survival, reduction of local rates of recurrence and enhanced quality of life in patients with advanced disease. However, over the past few years there have been major advances in our understanding of the molecular basis of this tumour and its progression from adenoma to carcinoma that hold potential for translation into novel strategies for the treatment of CRC. Furthermore, newer agents directed against different intracellular targets have also been shown to be efficacious in CRC treatment. Such improvements should continue to lead to increased cure rates in early disease and better overall survival in advanced cases. The aim of this review is to provide an overview of the pathogenesis of CRC and to present the evidence base for chemotherapy and some of the novel strategies that are currently being evaluated in phase I and II trials.

Antineoplastic Agents↗
PubMed2003

Use of a phage display library to identify oligopeptides binding to the lumenal surface of polarized endothelium by ex vivo perfusion of human umbilical veins.

Human endothelial-specific targeting peptides were identified by biopanning within freshly-obtained human umbilical cords. Umbilical veins were cleaned in situ and M13 phage display libraries were passed through the cords. Tightly bound phage were recovered following isolation of endothelial cells by collagenase digestion and homogenisation, allowing production of enriched phage libraries for subsequent rounds of panning. After five rounds of biopanning, five promising sequences were selected and the binding of the corresponding phage clones was compared in perfused umbilical veins. Each of these peptides showed substantial binding, although the clone encoding the heptapeptide KPSGLTY showed the greatest, some 89-times greater than insertless phage. Binding of this phage clone was examined to cells in vitro, where it demonstrated at least five-times greater binding to isolated human umbilical vein endothelial cells than to 911, SKOV3, B16F10 and Cos7 cells. These initial peptides may prove useful targeting agents for endothelial-selective delivery, and this powerful approach should be readily applicable to biopanning in a broad range of human vessels ex vivo.

Animals↗
PubMed2003

Immunotherapy for colorectal cancer.

There have been significant improvements in the diagnosis and treatment of colorectal cancer over the past 15 years. However, some 30% of patients with colorectal cancer have disseminated disease at presentation, and furthermore, 50% of patients initially believed to be cured by surgery subsequently relapse and die of the disease. Novel treatment concepts based on understanding the molecular signatures that separate tumor from normal epithelium, such as immunotherapy, are aimed at abolishing microscopic residual disease post standard treatment. The authors provide an overview of progress in the development of specific and nonspecific immunotherapies and explain why definition of end-points and early translation of immunotherapy into the adjuvant field are key to effective use of such agents in the clinical setting.

Animals↗
PubMed2003

CB 1954: from the Walker tumor to NQO2 and VDEPT.

CB 1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide] has been the subject of continued interest for over 30 years. As an anti-cancer agent, it represents one of the very few examples of a compound that shows real anti-tumor selectivity. Unfortunately, for the treatment of human disease, this anti-tumor selectivity was seen only in certain rat tumors. The basis for the anti-tumor selectivity of CB 1954 is that it is a prodrug that is enzymatically activated to generate a difunctional agent, which can form DNA-DNA interstrand crosslinks. The bioactivation of CB 1954 in rat cells involves the aerobic reduction of its 4-nitro group to a 4-hydroxylamine by the enzyme NQO1 (DT-diaphorase). The human form of NQO1 metabolizes CB 1954 much less efficiently than rat NQO1. Thus human tumors are insensitive to CB 1954. In view of the proven success of CB 1954 in the rat system, it would be highly desirable to re-create its anti-tumor activity in man. This has led to the development of CB 1954 analogs and other prodrugs activated by nitroreduction such, as those based on a self-immolative activation mechanism. A gene therapy-based approach for targeting cancer cells and making them sensitive to CB 1954 and related compounds has been developed. VDEPT (gene-directed enzyme prodrug therapy) has been used to express an E. coli nitroreductase in tumor cells and human tumor cells transduced to express this enzyme are very sensitive to prodrugs activated by nitroreduction. CB 1954 is in clinical trial for this application. Recently it has been shown that a latent nitroreductase is present in some human tumors. This is NQO2--an enzyme that requires for activity, the non-biogenic compound dihydronicotinamide riboside (NRH) as a cosubstrate. When active, NQO2 is 3000 times more effective than human DT-diaphorase in the reduction of CB 1954. NRH and reduced pyridinium derivatives that, like NRH, act as co-substrates for NQO2, produce a dramatic increase in the cytotoxicity of CB 1954 against human cell lines in vitro and its anti-tumor activity against certain human xenografts in vivo. NQO2 activity is substantially raised in tumor samples from colorectal and hepatoma patients (up to 14-fold). A phase I clinical trial of an NQO2 co-substrate with CB 1954 is scheduled.

Animals↗