Identification of FGF receptor-binding peptides for cancer gene therapy

Linear FGF receptor-binding heptapeptides were identified by phage display using sequential rounds of biopanning against cells with displacement of phage by FGF2. The consensus motif MXXP was iterated after four to five rounds and the peptide MQLPLAT was studied in depth. Phage bearing MQLPLAT showed high levels of binding to FGF receptor positive cells, with over 90% of phage bound being eluted competitively by adding free FGF2. MQLPLAT phage showed only limited binding to Cos7 cells deficient in receptors for FGF. MQLPLAT phage bound to SKOV3 cells with a K(d) of 2.51 x 10(-10) M. Although binding could be blocked by preincubation with free FGF2, heparin could not displace the phage. Use of MQLPLAT to target polyelectrolyte gene delivery vectors in vitro in the presence of serum achieved up to 40-fold greater transgene transduction than nontargeted vectors. MQLPLAT phage were administered into gastric carcinomas via the tumor-feeding artery immediately following resection from patients. The phage showed up to 9-fold more accumulation in the tumor than in adjacent regions of normal tissue, whereas control phage showed less than 2-fold. These peptides should provide useful ligands for specific delivery of gene therapy vectors to clinically relevant targets.

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.

Capecitabine/irinotecan combination regimens in colorectal cancer

Capecitabine (Xeloda) and irinotecan (CPT-11, Camptosar) both have demonstrated single-agent activity in patients with colorectal cancer. In an analysis of pooled results of two phase III studies, capecitabine provided advantages over intravenous fluorouracil (5-FU) plus leucovorin in patients with metastatic colorectal cancer. In another analysis, metastatic colorectal cancer patients who received irinotecan along with 5-FU plus leucovorin had significantly improved overall survival as compared with those who received 5-FU plus leucovorin alone. Capecitabine and irinotecan have distinct mechanisms of action and only partially overlapping toxicities. Combinations of these agents therefore are being explored in patients with colorectal cancer. This report briefly reviews current and ongoing trials evaluating capecitabine/irinotecan combination regimens in treating this disease.

Hepatic drug targeting: phase I evaluation of polymer-bound doxorubicin

PURPOSE

Preclinical studies have shown good anticancer activity following targeting of a polymer bearing doxorubicin with galactosamine (PK2) to the liver. The present phase I study was devised to determine the toxicity, pharmacokinetic profile, and targeting capability of PK2.

PATIENTS AND METHODS

Doxorubicin was linked via a lysosomally degradable tetrapeptide sequence to N-(2-hydroxypropyl)methacrylamide copolymers bearing galactosamine. Targeting, toxicity, and efficacy were evaluated in 31 patients with primary (n = 25) or metastatic (n = 6) liver cancer. Body distribution of the radiolabelled polymer conjugate was assessed using gamma-camera imaging and single-photon emission computed tomography.

RESULTS

The polymer was administered by intravenous (i.v.) infusion over 1 hour, repeated every 3 weeks. Dose escalation proceeded from 20 to 160 mg/m(2) (doxorubicin equivalents), the maximum-tolerated dose, which was associated with severe fatigue, grade 4 neutropenia, and grade 3 mucositis. Twenty-four hours after administration, 16.9% +/- 3.9% of the administered dose of doxorubicin targeted to the liver and 3.3% +/- 5.6% of dose was delivered to tumor. Doxorubicin-polymer conjugate without galactosamine showed no targeting. Three hepatoma patients showed partial responses, with one in continuing partial remission 47 months after therapy.

CONCLUSION

The recommended PK2 dose is 120 mg/m(2), administered every 3 weeks by IV infusion. Liver-specific doxorubicin delivery is achievable using galactosamine-modified polymers, and targeting is also seen in primary hepatocellular tumors.

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.

Gene therapy for colorectal cancer

Gene therapy has been developed as a potential novel treatment modality for colorectal cancer. The preclinical data have been promising and several clinical trials are under way for colorectal cancer. Data from many phase 1 trials have proven the safety of the reagents, but have not yet demonstrated significant therapeutic benefit. In order to refine this approach, continuing efforts should be made to improve the antitumour potency, efficiency of gene delivery, and accuracy of gene targeting. It is likely that gene therapy will be integrated into pre-existing therapies including surgery, chemotherapy and radiotherapy to establish its niche in tomorrow's medicine.

Influence of resection margins on survival for patients with pancreatic cancer treated by adjuvant chemoradiation and/or chemotherapy in the ESPAC-1 randomized controlled trial

OBJECTIVE

To assess the influence of resection margins on survival for patients with resected pancreatic cancer treated within the context of the adjuvant European Study Group for Pancreatic Cancer-1 (ESPAC-1) study.

SUMMARY BACKGROUND DATA

Pancreatic cancer is associated with a poor long-term survival rate of only 10% to 15% after resection. Patients with positive microscopic resection margins (R1) have a worse survival, but it is not known how they fare in adjuvant studies.

METHODS

ESPAC-1, the largest randomized adjuvant study of resectable pancreatic cancer ever performed, set out to look at the roles of chemoradiation and chemotherapy. Randomization was stratified prospectively by resection margin status.

RESULTS

Of 541 patients with a median follow-up of 10 months, 101 (19%) had R1 resections. Resection margin status was confirmed as an influential prognostic factor, with a median survival of 10.9 months for R1 versus 16.9 months months for patients with R0 margins. Resection margin status remained an independent factor in a Cox proportional hazards model only in the absence of tumor grade and nodal status. There was a survival benefit for chemotherapy but not chemoradiation, irrespective of R0/R1 status. The median survival was 19.7 months with chemotherapy versus 14.0 months without. For patients with R0 margins, chemotherapy produced longer survival compared with to no chemotherapy. This difference was less apparent for the smaller subgroup of R1 patients, but there was no significant heterogeneity between the R0 and R1 groups.

CONCLUSIONS

Resection margin-positive pancreatic tumors represent a biologically more aggressive cancer; these patients benefit from resection and adjuvant chemotherapy but not chemoradiation. The magnitude of benefit for chemotherapy treatment is reduced for patients with R1 margins versus those with R0 margins. Patients with R1 tumors should be included in future trials of adjuvant treatments and randomization and analysis should be stratified by this significant prognostic factor.

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.

In vivo gene therapy for colon cancer using adenovirus-mediated, transfer of the fusion gene cytosine deaminase and uracil phosphoribosyltransferase

Virus-directed enzyme prodrug therapy (VDEPT) utilising cytosine deaminase (CD) converts 5-fluorocytosine (5-FC) into the chemotherapy agent, 5-fluorouracil (5-FU), and has entered into a clinical trial for metastatic colon cancer. To improve this system, a replication-deficient adenovirus, containing a bifunctional fusion gene, CD:uracil phosphoribosyltransferase (UPRT), was constructed (AdCDUPRT). UPRT enhances the conversion of 5-FU into its active metabolites, which inhibit DNA and RNA synthesis. In vitro, AdCDUPRT infection of colon cancer cells resulted in a marked increase in sensitisation to 5-FU, compared with AdCD-infected or uninfected cells. The corollary is a approximately 100-fold and approximately 10 000-fold increase in sensitisation to 5-FC in AdCDUPRT-infected cells, compared to AdCD-infected and uninfected cells, respectively. There was a strong bystander effect in vitro, 70% of tumour cells were killed by 5-FC when only 10% of cells expressed CDUPRT. In vivo, athymic mice with colon cancer xenografts treated with intratumoral AdCDUPRT and intraperitoneal 5-FC, significantly reduced tumour growth rates compared with untreated controls (P = 0.02), whereas AdCD/5-FC treated mice did not. At higher AdCDUPRT virus doses, 5-FC and 5-FU were equally effective at delaying tumour growth compared with controls. In summary, VDEPT for colon cancer utilising AdCDUPRT is more effective than AdCD and the bifunctional CDUPRT gene enables the use of either 5-FC or 5-FU as prodrugs.

Gene therapy for colorectal cancer: therapeutic potential

Colorectal cancer is a leading cause of cancer mortality in Western countries. Gene therapy has been proposed as a potential novel treatment modality for colorectal cancer, but it is still in an early stage of development. The preclinical data have been promising and numerous clinical trials are underway. This brief review aims to summarise the current status of clinical trials of different gene therapy strategies, including immune stimulation, mutant gene correction, prodrug activation and oncolytic virus therapy, for patients with colorectal cancer. Data from phase I trials have proven the safety of the reagents but have not yet demonstrated significant therapeutic benefit. In order to achieve this and extend the scope of the treatment, continuing efforts should be made to improve the antitumour potency, efficiency of gene delivery and accuracy of gene targeting.

Virus-directed, enzyme prodrug therapy with nitroimidazole reductase: a phase I and pharmacokinetic study of its prodrug, CB1954

CB1954 [5-(aziridin-1-yl)-2,4-dinitrobenzamide] is converted by the bacterial enzyme nitroimidazole reductase (NTR) into a potent cytotoxic bifunctional alkylating agent, which can be delivered to tumors in adenoviral vectors as virus-directed, enzyme prodrug therapy. This report summarizes a Phase I and pharmacokinetic study of the prodrug, CB1954. Thirty patients, ages 23-78 years (median 62 years), with predominantly gastrointestinal malignancies were treated. CB1954 was administered by i.v. injection every 3 weeks or i.p. followed by 3-weekly i.v. injections, toward a maximum of six cycles. The dose was escalated from 3 to 37.5 mg/m2. No significant toxicity was seen until 24 mg/m2 (recommended i.v. dose). Dose-limiting toxicities (DLT) were diarrhea and hepatic toxicity, seen at 37.5 mg/m2. DLT has not been observed at the current i.p. dose of 24 mg/m2. There was no alopecia, marrow suppression, or nephrotoxicity. Clearance data suggest hepatic metabolism, and <5% of CB1954 was renally excreted. There was a nonlinear relationship between i.v. dose and area under the curve (AUC). At the recommended i.v. dose of 24 mg/m2, the AUC was 5.8 microM/h. Intraperitoneal administration (24 mg/m2) achieved an AUC of 387 microM/h, giving a considerable regional advantage. In vitro, the AUC required to achieve the IC50 for CB1954, in NTR-expressing cancer cells, ranges from 10-50 microM/h. Thus, CB1954 is well tolerated at a dose of 24 mg/m2, and sufficient serum/peritoneal levels are achieved for an enzyme-prodrug approach to be feasible. We are now conducting a Phase I trial combining adenovirus-mediated NTR and i.v. CB1954 (24 mg/m2) in patients with primary and secondary liver tumors.

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.

Pre-clinical and clinical study of QC12, a water-soluble, pro-drug of quercetin

BACKGROUND

Quercetin is a naturally occurring flavonoid with many biological activities including inhibition of a number of tyrosine kinases. A phase I, dose-escalation trial of quercetin defined the maximum tolerated dose (MTD) as 1700 mg/m2 three weekly, but the vehicle, dimethyl sulphoxide (DMSO) is unsuitable for further clinical development of quercetin.

PATIENTS AND METHODS

A water-soluble, pro-drug of quercetin (3'(N-carboxymethyl)carbomyl-3,4',5,7-tetrahydroxyflavone), QC12 has been synthesised. Six cancer patients received 400 mg of QC12 (equivalent to 298 mg of quercetin), orally on day 1 and intravenously (i.v.) in normal saline on day 14.

RESULTS

Following oral administration of QC12 we were unable to detect QC12 or quercetin in plasma. After i.v. administration, we detected peak plasma concentrations of QC12 of 108.7 +/- 41.67 microMolar (microM). A two-compartment model with mean t(1/2)alpha of 0.31 +/- 0.27 hours and mean t(1/2)beta of 0.86 +/- 0.78 hours best described the concentration-time curves for QC12. The mean AUC was 44.54 +/- 13.0 microM.hour and mean volume of distribution (Vd) of 10.0 +/- 6.2 litres (l). Quercetin was found in all patients following i.v. infusion of QC12, with peak levels of quercetin 19.9 +/- 11.8 microM. The relative bioavailability of quercetin was estimated to be 20%-25% quercetin released from QC12.

CONCLUSIONS

QC12 is not orally bioavailable. This water-soluble pro-drug warrants further clinical investigation; starting with a formal phase I, IV, dose-escalation study.

Combined adenovirus-mediated nitroreductase gene delivery and CB1954 treatment: a well-tolerated therapy for established solid tumors

Gene-directed enzyme prodrug therapy (GDEPT) is a refinement of cancer chemotherapy that generates a potent cell-killing drug specifically in tumor cells by enzymatic activation of an inert prodrug. We describe in vivo studies that evaluate the efficacy and safety of intratumoral (i.t.) injection of an adenovirus vector (CTL102) expressing Escherichia coli nitroreductase (NTR) combined with systemic prodrug (CB1954) treatment. A single i.t. injection of CTL102 (7.5 x 10(9) to -2 x 10(10) particles) followed by CB1954 treatment produced clear anti-tumor effects in subcutaneous (s.c.) xenograft models of four cancers that are likely candidates for GDEPT (i.e., primary liver, head and neck, colorectal and prostate). Virus dose-response studies (s.c. liver model) revealed a steep increase and subsequent rapid plateauing of both NTR gene delivery and anti-tumor efficacy. Evidence of minor virus spread (toxicity) was observed in a s.c. head and neck xenograft model. This was eliminated by passive immunization with neutralizing anti-Ad5 antibodies prior to virus injection without reducing the magnitude of the anti-tumor effect. Preexisting anti-Ad5 neutralizing antibodies may therefore be an advantage rather than an issue in the clinical use of this new therapy.

Hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common cancer of men and eleventh most common cancer of women world-wide. However, because almost every individual who develops liver cancer dies of the disease, HCC is the third most common cause of the cancer deaths in men and seventh most common in women. The treatment of choice for hepatocellular carcinoma remains surgical resection or liver transplantation, in carefully selected cases. In patients with hepatocellular carcinoma not amenable to surgical intervention a variety of different therapeutic interventions have been investigated. These include direct ablation of the tumour using agents such as ethanol or acetic acid, transcatheter arterial chemoembolization, or systemic chemotherapy. The evaluation of their efficacy is compromised by the paucity of adequately powered randomised clinical trials. The main challenge facing the research community over the next decade is to prioritise the most promising treatments and take these forward into multicentre controlled trials. Even if these fail to improve results, they will help reduce the variation in clinical practice by eliminating anecdotal treatment.

A United Kingdom coordinating committee on cancer research study of adjuvant chemotherapy for colorectal cancer: preliminary results

Standard adjuvant chemotherapy for colorectal cancer consists of 5-fluorouracil with leucovorin or levamisole. The large, multicenter, randomized, double-blind QUASAR (Quick and Simple and Reliable) trial investigated whether treatment with a higher dose of leucovorin or the addition of levamisole to 5-fluorouracil and leucovorin improved survival. In the QUASAR study, 4,927 patients with colorectal cancer with no evidence of residual disease following resection, were randomized to receive fluorouracil (370 mg/m2) with high-dose (175 mg) or low-dose (25 mg) leucovorin and either levamisole (50 mg) or placebo. The fluorouracil and leucovorin regimen was given either monthly (as six 5-day courses with 4 weeks between the start of each course) or weekly (as 30 once-weekly doses). Levamisole or placebo was given three times daily for 3 days, repeated every 2 weeks for 12 courses. The primary endpoint was death from any cause. Survival was similar with both high- and low-dose leucovorin (70.1% v 71.0% at 3 years; P = .43) as well as recurrence rates (36.0% v 35.8%; P = .94), and with levamisole compared with placebo (69.4% v 71.5%; P = .06) as well as recurrence rates (37.0% v 34.9%; P = .16). Monthly and weekly treatments were equally effective (although this was a nonrandomized comparison), while weekly treatment was associated with significantly fewer toxic effects (neutropenia, mucositis, and diarrhea). High-dose leucovorin was not associated with a survival or recurrence benefit when compared with low-dose leucovorin. The ongoing QUASAR-1 trial aims to establish whether adjuvant chemotherapy has any worthwhile survival benefit in colorectal cancer patients with an uncertain indication following surgical resection.