The challenge of cancer control in Africa

While the world is focused on controlling the spread of diseases such as HIV and malaria in the developing world, another approaching epidemic has been largely overlooked. The World Heath Organization predicts that there will be 16 million new cancer cases per year in 2020 and 70% of these will be in the developing world. Many of these cancers are preventable, or treatable when detected early enough. Establishing effective, affordable and workable cancer control plans in African countries is one step in the right direction toward limiting this epidemic.

Adjuvant chemotherapy versus observation in patients with colorectal cancer: a randomised study

BACKGROUND

The aim of the QUASAR trial was to determine the size and duration of any survival benefit from adjuvant chemotherapy for patients with colorectal cancer at low risk of recurrence, for whom the indication for such treatment is unclear.

METHODS

After apparently curative resections of colon or rectal cancer, 3239 patients (2963 [91%] with stage II [node negative] disease, 2291 [71%] with colon cancer, median age 63 [IQR 56-68] years) enrolled between May, 1994, and December, 2003, from 150 centres in 19 countries were randomly assigned to receive chemotherapy with fluorouracil and folinic acid (n=1622) or to observation (with chemotherapy considered on recurrence; n=1617). Chemotherapy was delivered as six 5-day courses every 4 weeks or as 30 once-weekly courses of intravenous fluorouracil (370 mg/m2) with high-dose (175 mg) L-folinic acid or low-dose (25 mg) L-folinic acid. Until 1997, levamisole (12 courses of 450 mg over 3 days repeated every 2 weeks) or placebo was added. After 1997, patients who were assigned to receive chemotherapy were given fluorouracil and low-dose folinic acid only. The primary outcome was all-cause mortality. Analyses were done by intention to treat. This trial is registered with the International Clinical Trial Registry, number ISRCTN82375386.

FINDINGS

At the time of analysis, 61 (3.8%) patients in the chemotherapy group and 50 (3.1%) in the observation group had missing follow-up. After a median follow-up of 5.5 (range 0-10.6) years, there were 311 deaths in the chemotherapy group and 370 in the observation group; the relative risk of death from any cause with chemotherapy versus observation alone was 0.82 (95% CI 0.70-0.95; p=0.008). There were 293 recurrences in the chemotherapy group and 359 in the observation group; the relative risk of recurrence with chemotherapy versus observation alone was 0.78 (0.67-0.91; p=0.001). Treatment efficacy did not differ significantly by tumour site, stage, sex, age, or chemotherapy schedule. Eight (0.5%) patients in the chemotherapy group and four (0.25%) in the observation group died from non-colorectal cancer causes within 30 weeks of randomisation; only one of these deaths was deemed to be possibly chemotherapy related.

INTERPRETATION

Chemotherapy with fluorouracil and folinic acid could improve survival of patients with stage II colorectal cancer, although the absolute improvements are small: assuming 5-year mortality without chemotherapy is 20%, the relative risk of death seen here translates into an absolute improvement in survival of 3.6% (95% CI 1.0-6.0).

A phase I and pharmacokinetic study of lapatinib in combination with infusional 5-fluorouracil, leucovorin and irinotecan

BACKGROUND

This study determined the optimally tolerated regimen (OTR) of oral lapatinib administered in combination with infusional 5-fluorouracil (5-FU), leucovorin and irinotecan (FOLFIRI) and assessed the safety, tolerability and pharmacokinetics of the combination.

PATIENTS AND METHODS

Twenty-five patients were enrolled; 12 patients were treated at three dose levels to determine OTR; then 13 patients were treated at OTR to evaluate the pharmacokinetics of the combination.

RESULTS

The 2-weekly OTR comprised lapatinib 1250 mg/day with irinotecan 108 mg/m(2) (day 1) and leucovorin 200 mg/m(2), 5-FU bolus 240 mg/m(2) and 5-FU infusion 360 mg/m(2) (days 1 and 2); doses of 5-FU and irinotecan represent a 40% reduction in dose compared to conventional FOLFIRI. Dose-limiting toxicities were grade 3 diarrhoea and grade 4 neutropenia. Co-administration of lapatinib increased the area under the plasma concentration-time curve of SN-38, the active metabolite of irinotecan, by an average of 41%; no other pharmacokinetic interactions were observed. Of 19 patients evaluable for disease response assessment, four patients had partial response and nine patients had stable disease.

CONCLUSION

The combination of lapatinib and FOLFIRI is safe and demonstrates clinical activity; the documented PK interaction can effectively be compensated by lowering the doses of 5-FU and irinotecan. This regime may be further tested in a phase II trial.

Rofecoxib and cardiovascular adverse events in adjuvant treatment of colorectal cancer

BACKGROUND

Selective cyclooxygenase inhibitors may retard the progression of cancer, but they have enhanced thrombotic potential. We report on cardiovascular adverse events in patients receiving rofecoxib to reduce rates of recurrence of colorectal cancer.

METHODS

All serious adverse events that were cardiovascular thrombotic events were reviewed in 2434 patients with stage II or III colorectal cancer participating in a randomized, placebo-controlled trial of rofecoxib, 25 mg daily, started after potentially curative tumor resection and chemotherapy or radiotherapy as indicated. The trial was terminated prematurely owing to worldwide withdrawal of rofecoxib. To examine possible persistent risks, we examined cardiovascular thrombotic events reported up to 24 months after the trial was closed.

RESULTS

The median duration of active treatment was 7.4 months. The 1167 patients receiving rofecoxib and the 1160 patients receiving placebo were well matched, with a median follow-up period of 33.0 months (interquartile range, 27.6 to 40.1) and 33.4 months (27.7 to 40.4), respectively. Of the 23 confirmed cardiovascular thrombotic events, 16 occurred in the rofecoxib group during or within 14 days after the treatment period, with an estimated relative risk of 2.66 (from the Cox proportional-hazards model; 95% confidence interval [CI], 1.03 to 6.86; P=0.04). Analysis of the Antiplatelet Trialists' Collaboration end point (the combined incidence of death from cardiovascular, hemorrhagic, and unknown causes; of nonfatal myocardial infarction; and of nonfatal ischemic and hemorrhagic stroke) gave an unadjusted relative risk of 1.60 (95% CI, 0.57 to 4.51; P=0.37). Fourteen more cardiovascular thrombotic events, six in the rofecoxib group, were reported within the 2 years after trial closure, with an overall unadjusted relative risk of 1.50 (95% CI, 0.76 to 2.94; P=0.24). Four patients in the rofecoxib group and two in the placebo group died from thrombotic causes during or within 14 days after the treatment period, and during the follow-up period, one patient in the rofecoxib group and five patients in the placebo group died from cardiovascular causes.

CONCLUSIONS

Rofecoxib therapy was associated with an increased frequency of adverse cardiovascular events among patients with a median study treatment of 7.4 months' duration. (Current Controlled Trials number, ISRCTN98278138 [controlled-trials.com].).

Bacteriophage biopanning in human tumour biopsies to identify cancer-specific targeting ligands

Intravenous targeting of anticancer agents should improve both efficacy and therapeutic index. However, rational design of targeting constructs requires detailed definition of receptor targets and must take account of polarised tissue architecture that may restrict access to chosen receptors from the bloodstream. Bacteriophage biopanning provides a solution to this problem, identifying targeting sequences by functional selection rather than design, although reiterative panning in polarized human tumours has not previously been attempted. Here, we report an ex vivo, intra-arterial method for biopanning in freshly-resected human tumours, enabling reiterative selection of oligopeptide sequences capable of intravascular targeting to human colorectal tumours. Significant consensus was observed after two rounds of panning in tumours from different patients, and lead sequences demonstrated tumour targeting in samples from unrelated patients. This novel approach may be applicable to a wide range of settings, thus enabling iteration of consensus targeting sequences for tumour imaging and selective delivery of anticancer agents.

Identification of an Oligopeptide Binding to Hepatocellular Carcinoma

OBJECTIVES

We carried out identification of a small peptide binding to human hepatocellular carcinoma (HCC) cells with the aim of applying the peptide for future HCC-targeted therapy or imaging.

METHODS

The biopanning technique using phage peptide display libraries was performed on HCC cells in vitro, and a phage clone expressing the HCC-binding peptide motif was selected. The binding activity of the selected phage was evaluated by plaque infection assay and immunofluorescence on cell lines. In addition, the binding activity of the peptide-expressing phage was investigated using HCC specimens derived from patients who had undergone hepatectomy for HCC.

RESULTS

A heptapetide, Thr-Thr-Pro-Arg-Asp-Ala-Tyr (TTPRDAY), was identified as a motif binding to HCC. TTPRDAY bound specifically to HCC cells in comparison with other cancer cells, and the binding to HCC cells was also confirmed by immunofluorescence. In addition, the synthesized TTPRDAY peptide showed binding activity and a non-mitogenic effect on HCC cells in vitro. TTPRDAY-presenting phage showed more significant binding to HCC cells derived from specimens obtained from actual patients than to non-cancerous liver tissue.

CONCLUSION

The motif TTPRDAY, identified by the biopanning technique, shows significant binding to HCC cells.

Standard operating procedure for the collection of fresh frozen tissue samples

Studies using fresh-frozen tissue samples originating from different centres, as is often the case in EORTC related translational research, can show conflicting research results due to heterogeneity in the quality of samples and associated data from each centre. The development of infrastructure for the European Human Frozen Tumour Tissue Bank (TuBaFrost) anticipated this problem and Standard Operating Procedures (SOPs) have been developed to ensure samples collected are of consistent high quality and variation in research results is minimised. The SOPs drew on the best practice standard workflows and operating procedures employed by members of the TuBaFrost Consortium and key tissue bank initiatives worldwide. It was essential to provide workable solutions that reflect the variety in infrastructure and resources at the potential collecting centres and also the fact that it is not necessary to standardise every step of the collection and storage process in order to collect high quality tissue. Hence, the TuBaFrost SOPs detail the compulsory measures that must be implemented in order to become a TuBaFrost collecting centre and also make advisory recommendations regarding the less critical factors. Accordingly, the TuBaFrost SOPs are very flexible and to illustrate this the complete SOP for collecting, freezing and storing tissue at the Erasmus MC Tissue Bank is included. These TuBaFrost SOPs could equally be applicable to centres collecting samples for EORTC related translational research studies in order to standardise sample quality and produce reliable and reproducible research results.

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.

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.

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.

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.

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.

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.

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.