New directions in the treatment of colorectal cancer: a look to the future

Triptolide inhibits proliferation and invasion of colorectal cancer cells by blocking Nrf2 expression

Triptolide (TPL), the main active ingredient of Tripterygium wilfordii, has anti-inflammatory, immunomodulatory, and antitumor actions. It can also inhibit cell proliferation and metastasis while promoting apoptosis of several tumors, such as colorectal cancer (CRC). However, the mechanism of TPL against CRC is not clear. This study was designed to investigate the effects and molecular mechanisms of TPL on the proliferation and invasion ability of CRC cells. A human CRC cell line (HT29 cell line) cultured in vitro was treated with different concentrations of TPL (0, 25, 50, and 100 nmol/L). The proliferation of cells was detected by MTT, the invasion ability of cells by Transwell, and the apoptosis level by flow cytometry. The protein expression levels of nuclear factor-erythroid 2-related factor 2 (Nrf2), matrix metalloproteinase (MMP)-2, and MMP-9 were detected by western blotting. After transfection with sh-Nrf2, HT29 cells were divided into NC group, NC + TPL group and sh-Nrf2 + TPL group, and the above assays were repeated for each group. TPL significantly inhibited the proliferation and invasion ability of HT29 cells and promoted apoptosis (p < .05). Notably, its inhibitory or promotional effects were concentration-dependent, which were enhanced with increasing drug concentration (p < .05). After silencing Nrf2 expression, the proliferation, and invasion ability of HT29 cells were further significantly inhibited while cells apoptosis was further promoted (p < .05). Besides, the decreased Nrf2 expression reduced the protein expression levels of MMP-2 and MMP-9 (p < .05). TPL can effectively inhibit the proliferation and invasion while promoting apoptosis of HT29 cells. And its mechanism of action may be related to the inhibition of Nrf2 signaling expression.

BCL-2 family protein BOK is a positive regulator of uridine metabolism in mammals

It is believed that the Bcl-2 family protein Bok has a redundant role similar to Bax and Bak in regulating apoptosis. We report that this protein interacts with the key enzyme involved in uridine biosynthesis, uridine monophosphate synthetase, and positively regulates uridine biosynthesis and chemoconversion of 5-fluorouracil (5-FU). Bok-deficient cell lines are resistant to 5-FU. Bok down-regulation is a key feature of cell lines and primary colorectal tumor tissues that are resistant to 5-FU. Our data also show that through its impact on nucleotide metabolism, Bok regulates p53 level and cellular proliferation. Our results have implications for developing Bok as a biomarker for 5-FU resistance and for the development of BOK mimetics for sensitizing 5-FU-resistant cancers.

BCL-2 family proteins regulate the mitochondrial apoptotic pathway. BOK, a multidomain BCL-2 family protein, is generally believed to be an adaptor protein similar to BAK and BAX, regulating the mitochondrial permeability transition during apoptosis. Here we report that BOK is a positive regulator of a key enzyme involved in uridine biosynthesis; namely, uridine monophosphate synthetase (UMPS). Our data suggest that BOK expression enhances UMPS activity, cell proliferation, and chemosensitivity. Genetic deletion of Bok results in chemoresistance to 5-fluorouracil (5-FU) in different cell lines and in mice. Conversely, cancer cells and primary tissues that acquire resistance to 5-FU down-regulate BOK expression. Furthermore, we also provide evidence for a role for BOK in nucleotide metabolism and cell cycle regulation. Our results have implications in developing BOK as a biomarker for 5-FU resistance and have the potential for the development of BOK-mimetics for sensitizing 5-FU-resistant cancers.

Inhibition of RNA polymerase III transcription by Triptolide attenuates colorectal tumorigenesis

Background

Upregulation of RNA polymerase (Pol) III products, including tRNAs and 5S rRNA, in tumor cells leads to enhanced protein synthesis and tumor formation, making it a potential target for cancer treatment. In this study, we evaluated the inhibition of Pol III transcription by triptolide and the anti-cancer effect of this drug in colorectal tumorigenesis.

Methods

The effect of triptolide on colorectal cancer development was assessed in colorectal cancer mouse models, 3D organoids, and cultured cells. Colorectal cancer cells were treated with triptolide. Pol III transcription was measured by real-time quantitative polymerase chain reaction (PCR). The formation of TFIIIB, a multi-subunit transcription factor for Pol III, was determined by chromatin immunoprecipitation (ChIP), co-immunoprecipitation (Co-IP), and fluorescence resonance energy transfer (FRET).

Results

Triptolide reduced both tumor number and tumor size in adenomatous polyposis coli (Apc) mutated (Apc^Min/+) mice as well as AOM/DSS-induced mice. Moreover, triptolide effectively inhibited colorectal cancer cell proliferation, colony formation, and organoid growth in vitro, which was associated with decreased Pol III target genes. Mechanistically, triptolide treatment blocked TBP/Brf1interaction, leading to the reduced formation of TFIIIB at the promoters of tRNAs and 5S rRNA.

Conclusions

Together, our data suggest that inhibition of Pol III transcription with existing drugs such as triptolide provides a new avenue for developing novel therapies for colorectal cancer.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1232-x) contains supplementary material, which is available to authorized users.

Biodistribution and radiation dosimetry of [¹⁸F]-5-fluorouracil

PURPOSE

To estimate the radiation dose and biodistribution of (18)F-5-fluorouracil ([(18)F]-5-FU) from positron emission tomography/computed tomography (PET/CT) data, and to extrapolate mouse data to human data in order to evaluate cross-species consistency.

METHODS

Fifteen cancer patients (head and neck cancer (n=11), colon cancer (n=4)) were enrolled. Sequential PET/CT images were acquired for 2h after intravenous administration of [(18)F]-5-FU, and the percent of the injected dose delivered to each organ was derived. For comparison, [(18)F]-5-FU was administered to female BALB/cAJcl-nu/nu nude mice (n=19), and the percent of the injected dose delivered to mouse organs was extrapolated to the human model. Absorbed radiation dose was calculated using OLINDA/EXM 1.0 software.

RESULTS

In human subjects, high [(18)F]-5-FU uptake was seen in the liver, gallbladder and kidneys. The absorbed dose was highest in the gallbladder wall. In mice, the biodistribution of [(18)F]-5-FU corresponded to that of humans. Estimated absorbed radiation doses for all organs were moderately correlated, and doses to organs (except the gallbladder and urinary bladder) were significantly correlated between mice and humans. The mean effective [(18)F]-5-FU dose was higher in humans (0.0124mSv/MBq) than in mice (0.0058mSv/MBq).

CONCLUSION

Biodistribution and radiation dosimetry of [(18)F]-5-FU were compared between humans and mice: biodistribution in mice and humans was similar. Data from mice underestimated the effective dose in humans, suggesting that clinical measurements are needed for more detailed dose estimation in order to ensure radiation safety. The observed effective doses suggest the feasibility of [(18)F]-5-FU PET/CT for human studies.

Triplet chemotherapy in patients with metastatic colorectal cancer: toward the best way to safely administer a highly active regimen in clinical practice

A major problem concerning the addition of more drugs in a chemotherapy combination is designing a proper schedule assuring the balance between dose intensity of each drug, efficacy of the combination, and tolerability lessening the burden of drug toxicity. We evaluated triplet chemotherapy-based intensive regimens proposed as first-line treatment in patients with metastatic colorectal cancer. Using a FOLFOXIRI (5-fluorouracil [5-FU], irinotecan, and oxaliplatin) combination regimen, patients with metastatic colorectal cancer now have the possibility of longer survival, but disappointingly, with increased toxicities. Triplet chemotherapy regimen according to 5-fluorouracil, irinotecan /5-fluorouracil, oxaliplatin, characterized by timed flat-infusion 5-FU administration, without leucovorin, obtained efficacy equivalent to other reported similar combination regimens (5-FU, irinotecan, and oxaliplatin), with increased received 5-FU dose intensity and lower grade 3 to 4 neutropenia. To guarantee the proper balance between dose intensities, efficacy, and toxicity, triplet chemotherapy schedules could be further improved by abrogation of folinic acid and bolus 5-FU, a new and easy modality of 5-FU administration, such as timed flat-infusion 5-FU, associated with alternating irinotecan and oxaliplatin; this could favor diffusion of this intensive treatment in clinical practice.

GUCY2C molecular staging personalizes colorectal cancer patient management

While the most significant prognostic and predictive marker in the management of colorectal cancer patients is cancer cells in regional lymph nodes, approximately 30% of patients whose lymph nodes are ostensibly free of tumor cells by histopathology ultimately develop recurrent disease reflecting occult metastases. Molecular techniques utilizing highly specific markers and ultra-sensitive detection technologies have emerged as powerful staging platforms to establish prognosis and predict responsiveness to chemotherapy in colorectal cancer patients. This review describes the evolution of the tumor suppressor GUCY2C as a prognostic and predictive molecular biomarker that quantifies occult tumor burden in regional lymph nodes for staging patients with colorectal cancer.

Molecular staging individualizing cancer management

Although the most important prognostic and predictive marker in colorectal cancer is tumor cells in lymph nodes, approximately 30% of patients who are node-negative die from occult metastases. Molecular staging employing specific markers and sensitive detection technologies has emerged as a powerful platform to assess prognosis in node-negative colon cancer. Integrating molecular staging into algorithms that individualize patient management will require validation and the definition of relationships between occult tumor cells, prognosis, and responses to chemotherapy.

Can colorectal cancer be prevented or treated by oral hormone replacement therapy?

Guanylyl cyclase C (GCC) is the receptor specifically expressed by intestinal cells for the paracrine hormones guanylin and uroguanylin and diarrheagenic bacterial heat-stable enterotoxins. This tissue-specific receptor coordinates lineage-dependent regulation of epithelial homeostasis, and its disruption contributes to intestinal tumorigenesis. It coordinates regenerative and metabolic circuits by restricting the cell cycle and proliferation and programming metabolic transitions central to organizing the dynamic crypt-surface axis. Further, mice deficient in GCC signaling are more susceptible to colon cancer induced by Apc mutations or the carcinogen azoxymethane. Moreover, guanylin and uroguanylin are gene products most commonly lost, early, in colon cancer in animals and humans. The role of GCC as a tumor suppressing receptor regulating proliferation and metabolism, together with the universal loss of guanylin and uroguanylin in tumorigenesis, suggests a model in which colorectal cancer is a paracrine hormone deficiency syndrome. In that context, activation of GCC reverses the tumorigenic phenotype by limiting growth of colorectal cancer cells by restricting progression through the G1/S transition and reprogramming metabolic circuits from glycolysis to oxidative phosphorylation, limiting bioenergetic support for rapid proliferation. These observations suggest a pathophysiological hypothesis in which GCC is a lineage-dependent tumor suppressing receptor coordinating proliferative homeostasis whose dysregulation through hormone loss contributes to neoplasia. The correlative therapeutic hypothesis suggests that colorectal cancer is a disease of hormone insufficiency that can be prevented or treated by oral supplementation with GCC ligands.

Overexpression of matrix metalloproteinase 9 in tumor epithelial cells correlates with colorectal cancer metastasis

Colorectal cancer mortality largely reflects metastasis, the spread of the disease to distant organs. Matrix metalloproteinase 9 (MMP-9) is a key regulator of metastasis and a target for anticancer strategies in colon cancer. Here, the overexpression of MMP-9 in pure tumor epithelial, but nor stromal, cell populations was associated with metastatic progression of colorectal cancer, as defined by reverse transcriptase-polymerase chain reaction (qRT-PCR) and confirmed by immunostaining. Thus, cancer cell MMP-9 represents a novel, selective prognostic and predictive factor that may be exploited for more effective disease stage stratification and therapeutic regimen selection in patients with colorectal cancer.

Covering the colon anastomoses with amniotic membrane prevents the negative effects of early intraperitoneal 5-FU administration on anastomotic healing

PURPOSE

This study investigated whether covering the colonic anastomoses with amniotic membrane (AM) protects the anastomotic healing from the adverse effects of immediate 5-fluorouracil (5-FU) administration.

METHODS

One hundred twenty wistar albino rats were randomized to one of four groups (I-IV, 30 rats in each) and underwent a standardized left colon resection and anastomoses. The anastomoses of the rats in groups II (AM) and IV (5-FU + AM) were covered with AM. Saline solution (2 ml/day; groups I (control) and II) or 5-FU (20 mg/kg/day; groups III (5-FU) and IV) was administered to the rats intraperitoneally once daily from the day of operation until sacrificed. Half of each group was sacrificed on the postoperative day 4 (IA, IIA, IIIA, and IVA) and other half on the postoperative day 8 (IB, IIB, IIIB, and IVB), and their anastomoses were evaluated when sacrificed.

RESULTS

The dehiscence rate of anastomotic dehiscence and adhesion formation were significantly higher in groups IIIA and IIIB compared with groups IVA and IVB, respectively. Bursting pressure was significantly higher in the 5-FU + AM groups than in the 5-FU groups. The inflammatory cell infiltration was significantly lower in groups IIIA and IVA compared with group IA, in groups IIIB and IVB compared with group IB, and in group IVA compared with group IIIA. Neoangiogenesis, fibroblast activity, collagen deposition, and hydroxyproline levels were significantly higher in the 5FU + AM groups compared with control and 5-FU groups. Malondialdehyde levels were significantly higher in the 5-FU groups than in the 5-FU + AM groups.

CONCLUSION

Covering colon anastomoses with AM protects them, preventing leakage and reversing the negative effects of 5-FU administration.

Molecular staging estimates occult tumor burden in colorectal cancer

Tumor cells in regional lymph nodes are a key prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colorectal cancer. However, clinicopathologic techniques to detect lymph node metastases remain imperfect, and approximately 30% of patients with lymph nodes negative by histology (pN0) develop recurrent disease, reflecting occult metastases that escape detection. These observations underscore an unmet clinical need for accurate approaches to identify occult nodal metastases in colorectal cancer patients. GUCY2C is a receptor whose expression normally is restricted to intestinal epithelial cells, but is universally overexpressed by colorectal cancer cells. A prospective, multicenter, blinded clinical trial established the prognostic utility of GUCY2C qRT-PCR to detect occult nodal metastases in pN0 colorectal cancer patients. Molecular staging revealed that approximately 13% of pN0 patients were free of cancer cells, while approximately 87% had GUCY2C results that suggested occult metastases. The presence of occult nodal metastases was the most powerful independent predictor of time to recurrence and disease-free survival. These observations establish the utility of molecular detection of occult nodal metastases for assessing prognostic risk in pN0 colorectal cancer patients. Advancing GUCY2C into staging paradigms in clinical laboratories will require validation in independent patient populations, definition of the relationship between the quantity of occult tumor metastases and risk, and determination of the utility of GUCY2C qRT-PCR to identify pN0 patients who might benefit from adjuvant chemotherapy.

GCC signaling in colorectal cancer: Is colorectal cancer a paracrine deficiency syndrome?

Guanylyl cyclase C (GCC) is the receptor expressed by intestinal cells for the paracrine hormones guanylin and uroguanylin that coordinate mucosal homeostasis and its silencing contributes to intestinal transformation. It orchestrates proliferative and metabolic circuits by limiting the cell cycle and programming metabolic transitions central to regeneration along the crypt-villus axis. Mice deficient in GCC are more susceptible to colon cancer induced by germline mutations or carcinogens. Moreover, guanylin and uroguanylin are the most commonly lost gene products in colon cancer. The role of GCC as a tumor suppressor and the universal loss of its hormones in transformation suggest a paradigm in which colorectal cancer is a disease of paracrine hormone insufficiency. Indeed, GCC signaling reverses the tumorigenic phenotype of human colon cancer cells by regulating proliferation and metabolism. These data suggest a pathophysiological hypothesis in which GCC is a tumor suppressor coordinating proliferative homeostasis whose silencing through hormone loss initiates transformation. The correlative therapeutic hypothesis suggests that colorectal cancer is a disease of hormone insufficiency that can be prevented or treated by oral hormone replacement therapy employing GCC ligands.

GUCY2C reverse transcriptase PCR to stage pN0 colorectal cancer patients

The most important prognostic marker of survival and predictive marker of response to adjuvant chemotherapy in colon cancer patients is tumor cells in regional lymph nodes. Despite their importance, standard techniques to assess nodal metastases remain imperfect, as approximately 30% of patients with histology-negative lymph nodes (pN0) die of recurrent disease, reflecting occult metastases that escape detection. These observations highlight the clinical need for novel, accurate approaches to detect occult lymph node metastases in patients with colon cancer. GUCY2C is a biomarker whose expression normally is restricted to intestinal cells, but is near universally overexpressed by colorectal cancer cells. Recently, a prospective, multicenter, blinded clinical trial demonstrated for the first time that the prognostic utility of GUCY2C quantitative reverse transcriptase (qRT)-PCR to detect occult lymph node metastases in pN0 colorectal cancer patients. Molecular staging revealed that approximately 13% of pN0 patients were free of tumor cells, while approximately 87% had GUCY2C results that suggested occult metastases. The presence of occult lymph node metastases was the strongest independent predictor of time to recurrence and disease-free survival. These observations establish the utility of molecular detection of occult lymph node metastases for estimating prognostic risk in pN0 colorectal cancer patients. Advancing this molecular diagnostic into staging paradigms in clinical laboratories will require validation in independent patient populations, definition of the relationship between the quantity of occult tumor metastases and risk, and determination of the utility of GUCY2C qRT-PCR to identify pN0 patients who might benefit from adjuvant chemotherapy.

Guanylyl cyclase C prevents colon cancer metastasis by regulating tumor epithelial cell matrix metalloproteinase-9

Matrix metalloproteinase-9 (MMP-9) produced by colorectal cancer cells is a critical determinant of metastatic disease progression and an attractive target for antimetastatic strategies to reduce colon cancer mortality. Cellular signaling by cyclic GMP (cGMP) regulates MMP-9 dynamics in various cell systems, and the bacterial enterotoxin receptor guanylyl cyclase C (GCC), the principle source of cGMP in colonocytes, which is overexpressed in colorectal cancers, inhibits tumor initiation and progression in the intestine. Here, we show that ligand-dependent GCC signaling through cGMP induces functional remodeling of cancer cell MMP-9 reflected by a compartmental redistribution of this gelatinase, in which intracellular retention resulted in reciprocal extracellular depletion. Functional remodeling of MMP-9 by GCC signaling reduced the ability of colon cancer cells to degrade matrix components, organize the actin cytoskeleton to form locomotory organelles and spread, and hematogenously seed distant organs. Of significance, GCC effects on cancer cell MMP-9 prevented establishment of metastatic colonies by colorectal cancer cells in the mouse peritoneum in vivo. Because endogenous hormones for GCC are uniformly deficient in intestinal tumors, reactivation of dormant GCC signaling with exogenous administration of GCC agonists may represent a specific intervention to target MMP-9 functions in colon cancer cells. The notion that GCC-mediated regulation of cancer cell MMP-9 disrupts metastasis, in turn, underscores the unexplored utility of GCC hormone replacement therapy in the chemoprevention of colorectal cancer progression.

Effects of oxaliplatin and 5-fluorouracil on the healing of colon anastomoses

PURPOSE

Oxaliplatin (OX) and 5-fluorouracil (5-FU) are the most widely used chemotherapeutic agents in the adjuvant treatment of colon cancer. Although the early initiation of adjuvant chemotherapy can improve the outcome of surgery, it carries potentially fatal risks. This experimental study investigates the effects of 5-FU and OX on colon anastomoses.

METHODS

We used 60 rats, divided into six groups. After being subjected to bowel resection and anastomosis, the rats were given 5-FU on days 1-3, or OX 130 mg/m(2) on days 1 or 5, or 5% dextrose as a control. The bursting pressures and hydroxyproline content of the anastomoses were measured, and complications and adhesions were recorded.

RESULTS

There were no major complications in the treatment groups. The bursting pressures of the 5-FU group were significantly lower than those of the control and OX groups. The bursting pressures of the OX groups were not significantly different from those of the control groups. The hydroxyproline levels of the rats treated with OX on day 1 were significantly lower than those of the rats treated with OX on day 5 and the 5-FU groups.

CONCLUSION

Oxaliplatin and 5-FU did not compromise wound healing of the colon significantly. Our results indicate that OX is less detrimental to the healing of colonic anastomoses, when administered on days 1 and 5 after resection, than 5-FU.

Resveratrol induces apoptosis in chemoresistant cancer cells via modulation of AMPK signaling pathway

Resveratrol has been reported to possess therapeutic effects for various cancers including colon cancers. In this article, the molecular basis of resveratrol with emphasis on its ability to control intracellular signaling cascades of adenosine monophosphate (AMP)-activated protein kinase (AMPK) responsible for inducing apoptosis in drug-resistant cancer cells was investigated. Recently, the evolutionarily conserved serine/threonine kinase, AMPK, emerges as a possible target molecule of cancer control. We have investigated the effects of resveratrol on apoptosis in relation to AMPK in HT-29 cells shown chemoresistant to a cancer chemotherapeutic drug, etoposide. Resveratrol exhibited a variety of molecular events in etoposide-based combination therapy in HT-29 colon cancer cells including the AMPK activation, inhibition of cell growth, induction of apoptosis, and reactive oxygen species (ROS) generation. The involvement of AMPK signaling cascade in resveratrol-based cancer therapy was clearly shown by comparing the conditions of AMPK activated states and inactivated states. We have identified ROS as an upstream regulator of AMPK. Further investigation warrants to elucidate the mechanism by which resveratrol generates ROS and AMPK activation.

Mitomycin C and Etoposide in Advanced Colorectal Carcinoma

BACKGROUND

Aim of this study was to evaluate the activity of a combination regimen of chemotherapy containing mitomycin C (MMC) and etoposide (ETO) in advanced colorectal carcinoma.

METHODS

Fourteen pretreated patients received MMC 2 mg/m2 and ETO 60 mg/m2, days 1-5 every 28 days. The clinical study was interrupted since no clinical response was observed in 14 patients following four courses of chemotherapy. An in vitro study was then performed on HTC-8 cell line. The cytotoxic activity of the MMC/ETO combination was tested by sulforhodamine B assay and the type of drug interaction was assessed using the method of Chou and Talalay. Cell cycle perturbations and apoptosis were evaluated by flow cytometry.

RESULTS

While MMC and ETO were singularly active, the simultaneous exposure of cells to both drugs and the sequence MMC-->ETO ensued in antagonistic interaction at all levels of killed cell fraction. Conversely, the sequence ETO-->MMC produced a synergistic interaction.

CONCLUSIONS

These results suggest that the activity of the MMC/ETO combination is highly schedule-dependent and that the experimental drug associations should be based on a preclinical rationale before clinical trials are designed.

Effect of gastrectomy on the pharmacokinetics of S-1, an oral fluoropyrimidine, in resectable gastric cancer patients

PURPOSE

The effect of gastrectomy on pharmacokinetics after S-1 administration was investigated.

PATIENTS AND METHODS

A dose of 40 mg/m(2) of S-1 was administered orally twice daily for 7 days (80 mg/m(2)/day) preoperatively in ten patients with resectable gastric cancer, and the same dose of S-1 was administered for 28 consecutive days after gastrectomy. Plasma concentrations of tegafur, gimeracil, and oteracil potassium, all the components of S-1, and 5-FU were measured on pre- and postoperative days. Concentrations of 5-FU in tumor and normal tissues were also determined.

RESULTS

At day 4 from the initial preoperative administration of S-1, the AUC of 5-FU was 1,055 +/- 304 ng h/ml. At day 18, day 28, and day 42 after gastrectomy, it was 1,012 +/- 331, 1,070 +/- 403, and 946 +/- 226 ng h/ml, respectively. No significant differences for plasma 5-FU were observed between pre- and postoperative days. In the resected tumor tissues, concentrations of 5-FU were 242 +/- 83 ng/g around 4.5 h and 91.7 +/- 37.0 ng/g around 20 h after the final administration, respectively.

CONCLUSION

Gastrectomy does not affect on pharmacokinetics of 5-FU derived from S-1 regardless of partial or total gastrectomy, indicating that S-1 can be a useful drug in postoperative adjuvant chemotherapy for gastric cancer.

Mechanisms of acquired chemoresistance to 5-fluorouracil and tomudex: thymidylate synthase dependent and independent networks

PURPOSE

Thymidylate synthase (TS) over-expression is widely accepted as a major molecular mechanism responsible for 5-fluorouracil (5-FU) and tomudex (TDX) resistance. In this study, the importance of TS in 5-FU and TDX resistance was evaluated.

METHODS

The sensitivity of TS-over-expressing 5-FU (3) and TDX (3) resistant cell lines to 5-FU and TDX was analysed. The cross-resistance between 5-FU and TDX resistant cell lines was determined. The relationship between p53 and NF-kappaB status and the sensitivity to 5-FU and TDX was evaluated.

RESULTS

Compared to relevant parental sensitive cell lines, the 5-FU resistant cell lines were highly cross-resistant to TDX (over 20,000-fold). In contrast, over-expression of TS did not significantly confer 5-FU resistance on the TDX resistant cell lines (0.8- to 1.3-fold). Thymidine (20 microM) rescue induced TDX resistance in TDX sensitive cell lines (over 10,000-fold) but only moderately influenced 5-FU sensitivity in 5-FU sensitive cell lines (1.1- to 2.4-fold). Uridine moderately protected one cancer cell line (RKO) from 5-FU-induced, but not TDX-induced, cytotoxicity. NF-kappaB transfected MCF-7 and p53 knockout HCT116 cells were resistant to 5-FU (4.4- and 2.4-fold, respectively) but not to TDX. TS protein expression in NF-kappaB transfected and p53 knockout cell lines was comparable to the relevant parental cell lines.

CONCLUSION

In some cancer cell lines, TS-independent molecular events may play a key role in 5-FU resistance. Loss of p53 function and NF-kappaB over-expression may be involved in TS-independent 5-FU chemoresistance in some cancer cell lines.

Biweekly oxaliplatin plus irinotecan and folinic acid-modulated 5-fluorouracil: a phase II study in pretreated patients with metastatic colorectal cancer

Oxaliplatin (OXA) and irinotecan (IRI) are active drugs for metastatic colorectal cancer, their toxicity profiles are not overlapping, and both drugs have shown at least additivity with folinic acid-modulated 5-fluorouracil (5FU). We carried out this phase II study to assess the activity and toxicity of a biweekly regimen including OXA plus IRI on day 1, and levo-folinic acid (LFA) plus 5FU on day 2 (OXIRIFAFU) in pretreated patients with metastatic colorectal cancer. Forty-one patients, all previously treated with adjuvant and/or palliative 5FU-based chemotherapy (16 of them already exposed to IRI, OXA or both), were enrolled into this trial. On the basis of sensitivity to previous treatment, 19 patients were considered as chemo-resistant and 14 patients as chemo-refractory. OXA 110 mg/m (over 2 h) and IRI 175 mg/m (over 1 h) were delivered on day 1, followed by LFA 250 mg/m (2-h infusion) plus 5FU 800 mg/m as intravenous bolus on day 2. Cycles were repeated every 2 weeks. A total of 348 cycles were delivered, with a median of nine cycles per patient (range, 1-12 cycles per patient). Five complete and 13 partial responses were reported on 40 assessable patients, giving a response rate of 45% [95% confidence interval (CI), 29-62%]; eight of 19 (42%) resistant patients and five of 14 (36%) refractory patients achieved a major response, which was also obtained in four of eight (50%) patients pretreated with IRI and in three of eight (38%) patients pretreated with OXA. Grade 3 or higher neutropenia occurred in 68% of patients, but febrile neutropenia or infections affected only seven (17%) patients. No episodes of grade 3 or higher thrombocytopenia or anemia were recorded. Occurrence of severe non-hematologic toxicities by patients were: diarrhea, 34%; vomiting, 17%; peripheral cumulative neuropathy, 15%; stomatitis, 10%; acute cholinergic syndrome, 7%. Actually delivered dose intensities of all three drugs resulted in about two-thirds of the planned ones. After a follow-up of 39 months, median progression-free survival was 7.5 months. Median overall survival was 14.4 (95% CI, 10.4-18.4) months from the start of OXIRIFAFU and 25.3 (95% CI, 18.1-32.5) months from the diagnosis of metastatic disease. This OXIRIFAFU triplet regimen was highly effective in resistant/refractory colorectal cancer patients. A slight dose reduction of all cytotoxic drugs could be advisable in order to improve the tolerability of this regimen without jeopardizing its activity.

Apoptotic effect of EGCG in HT-29 colon cancer cells via AMPK signal pathway

EGCG [(-)epigallocatechin-3-gallate], a green tea-derived polyphenol, has been shown to suppress cancer cell proliferation, and interfere with the several signaling pathways and induce apoptosis. Practically, there is emerging evidence that EGCG has a potential to increase the efficacy of chemotherapy in patients. We hypothesized that EGCG may exert cell cytotoxicity through modulating AMPK (AMP-activated protein kinase) followed by the decrease in COX-2 expression. EGCG treatment to colon cancer cells resulted in a strong activation of AMPK and an inhibition of COX-2 expression. The decreased COX-2 expression as well as prostaglandin E(2) secretion by EGCG was completely abolished by inhibiting AMPK by an AMPK inhibitor, Compound C. Also, the activation of AMPK was accompanied with the reduction of VEGF (vascular endothelial growth factor) and glucose transporter, Glut-1 in EGCG-treated cancer cells. These findings support the regulatory role of AMPK in COX-2 expression in EGCG-treated cancer cells. Furthermore, we have found that reactive oxygen species (ROS) is an upstream signal of AMPK, and the combined treatment of EGCG and chemotherapeutic agents, 5-FU or Etoposide, exert a novel therapeutic effect on chemo-resistant colon cancer cells. AMPK, a molecule of newly defined cancer target, was shown to control COX-2 in EGCG-treated colon cancer cells.

Brachytherapy technique for abdominal wall metastases of colorectal cancer: ultrasound-guided insertion of applicator needle and a skin preservation method

PURPOSE

To report a technique of interstitial brachytherapy for the treatment of subcutaneous metastatic abdominal wall tumors.

MATERIAL AND METHODS

We developed a brachytherapy technique consisting of ultrasound-guided insertion of applicator needles to avoid the organs at risk, such as intestines, and saline injection into the subcutaneous tissue between the tumor and the skin to decrease the skin dose. We encountered three patients with painful metastases from rectal carcinoma in the abdominal wall refractory to external radiotherapy. They were subjected to this brachytherapy with a single dose of 20 Gy.

RESULTS

The procedure was safely achieved in all three patients. Long-lasting pain reduction and tumor shrinkage was obtained without early or late complications.

CONCLUSION

This interstitial brachytherapy technique seems to be feasible in the treatment of metastatic abdominal wall tumors.

Available options in chemotherapy for advanced gastric cancer: the current developments in Japan

Although techniques for early diagnosis and treatment of gastric cancer have been established, standard treatment for advanced gastric cancer has not. 5-Flourouracil (5-FU) plus cisplatin containing regimens, including 5-FU plus cisplatin, epirubicin plus cisplatin and 5-FU, and docetaxel plus cisplatin and 5-FU, are considered to be the most effective regimens for advanced gastric cancer in US, Europe and Korea. In Japan, oral fluoropyrimidine S-1 is currently considered to be the first-line treatment for advanced gastric cancer. S-1-based combination therapies with other promising drugs, including cis-platin, irinotecan and taxanes, are expected to yield good results. Above all, S-1 plus cisplatin therapy showed high efficacy and expected to be a standard therapy for advanced gastric cancer. Further evaluation by well-controlled clinical trials is still required.

Intensive systemic chemotherapy combined with surgery for metastatic colorectal cancer: results of a phase II study

PURPOSE

To evaluate the efficacy and tolerability of the metastatic irinotecan plus oxaliplatin (MIROX) strategy (adjuvant FOLFOX-7 followed by FOLFIRI), in patients with resectable metastatic colorectal cancer.

PATIENTS AND METHODS

Forty-seven patients with resectable metastases of colorectal cancer were prospectively enrolled onto this study. Treatment consisted of six cycles of leucovorin 400 mg/m(2), oxaliplatin 130 mg/m(2) in a 120-minute infusion, and fluorouracil (FU) 2,400 mg/m(2) in a 46-hour infusion, every 2 weeks (FOLFOX-7), followed by six cycles of leucovorin 400 mg/m(2), irinotecan 180 mg/m(2) in a 90-minute infusion, bolus FU 400 mg/m(2), and FU 2,400 mg/m(2) as a 46-hour infusion, every 2 weeks (FOLFIRI). Surgery was performed before chemotherapy in 25 patients and after six cycles of FOLFOX-7 in 22 patients (six cycles of FOLFIRI were administered after surgery).

RESULTS

All but one of the patients underwent curative surgery. Two patients refused postoperative chemotherapy. Tolerability was generally good. The main toxicities were grade 3 to 4 neutropenia (13%) and thrombocytopenia (11%); no febrile neutropenia or bleeding occurred, and there were no deaths caused by toxicity. Two pathologically confirmed complete responses and 15 partial responses were obtained with FOLFOX-7 in the 22 patients who received this regimen before surgery (overall response rate, 77%; 95% CI, 68 to 86). The median disease-free survival time was 21 months; the median overall survival has not yet been reached. The 2-year overall and disease-free survival rates were 89% and 47%, respectively.

CONCLUSION

The MIROX strategy is feasible and well tolerated by patients with resectable metastatic colorectal cancer. Progression-free and overall survival rates are promising, with a median of 38 months of follow-up. This strategy currently is being compared with the leucovorin and FU regimen in a phase III trial.

Mechanistic and predictive profiling of 5-Fluorouracil resistance in human cancer cells

Gene expression was analyzed in five pairs of 5-fluorouracil (5-FU) resistant and parental cancer cell lines on DNA microarrays. In unsupervised analysis, a prediction rule was built from the expression profiles of 29 genes, and 5-FU sensitivity class was predicted with 100% accuracy and high predictive strength. In supervised analysis of key 5-FU pathways, expression of 91 genes was associated with 5-FU sensitivity phenotype and segregated samples accordingly in hierarchical analysis. Key genes involved in 5-FU activation were significantly down-regulated (thymidine kinase, 2.9-fold; orotate phosphoribosyltransferase, 2.3-fold; uridine monophosphate kinase, 3.2-fold; pyrimidine nucleoside phosphorylase 3.6-fold) in resistant cells. Overexpression of thymidylate synthase and its adjacent gene, c-Yes, was detected in the resistant cell lines. The mRNA and protein overexpression of nuclear factor kappaB (NFkappaB) p65 and related antiapoptotic c-Flip gene was detected in resistant cells. The 5-FU-resistant cell lines also showed high NFkappaB DNA-binding activity. Cotransfection of NFkappaB p50 and p65 cDNA induced 5-FU resistance in MCF-7 cells. Both NFkappaB- and 5-FU-induced resistant cell lines manifested reduced expression of genes governing G(1)-S and S-phase transition. Expression of genes involved in DNA replication was also down-regulated in resistant cell lines. These findings were highly consistent with the slower growth rate, higher proportion of G(1), and lower proportion of S-phase cells in the resistant cell lines. This phenotype may protect resistant cells from cell death induced by incorporation of 5-FU into DNA chains, by allowing time to repair 5-FU-induced damage. Our findings may provide novel targets for tackling 5-FU resistance.

New chemotherapeutic strategies in colorectal cancer

Since colorectal cancer is the second most prevalent cancer worldwide, its treatment remains a major challenge for researchers, gastroenterologists and oncologists. Despite curative resections, half of all patients diagnosed with colorectal cancer die because of their underlying disease. Integral chemotherapeutic components of standard regimens are 5-fluorouracil (5-FU), its modulation by folinic acid and irinotecan or oxaliplatin. All these drugs sequentially given have results in terms of median overall survival of more than 20 months in the palliative treatment of advanced colorectal cancer. Oral fluoropyrimidines, currently under clinical investigation, are likely to substitute continuous 5-FU. Inhibitors of growth factor receptors or their signaling may further prolong disease-free and overall survival rates. Preliminary evidence exists that improved adjuvant and neoadjuvant chemotherapy strategies may further improve the prognosis, mainly because more patients are able to go for primary or secondary surgery with curative intent.

Hepatic arterial chemotherapy for colorectal cancer liver metastases: a review of advances in 2003

PURPOSE OF REVIEW

During 2003, two new randomized trials comparing fluoropyrimidine-based hepatic arterial chemotherapy (HAC) with systemic chemotherapy were published. These new data will be reviewed in the context of previous trials and new observations of novel approaches involving HAC.

RECENT FINDINGS

The large Medical Research Council (MRC)/European Organization for the Research and Treatment of Cancer (EORTC) and the smaller Cancer and Leukaemia Group B (CALGB) trials reported conflicting conclusions. Lack of difference in response rates and survival outcomes was noted by the European trial groups whereas the contrary was reported by the US investigators, with statistically significant difference in response rates of 48% and 25% and median survival of 22.7 months and 19.8 months, respectively, being observed, favoring HAC. Early studies testing incorporation of irinotecan or oxaliplatin into HAC, either as additional systemic chemotherapy or as integral components of the HAC infusional regimen, confirmed feasibility, safety, and efficacy, with response rates between 30% and 60% being reported in some series. Other studies showed that combination with internal irradiation with lipiodol I-131 and biologic agents, eg, replication-selective adenovirus and cytokines, could be achieved with tolerable toxicity. Molecular prognostic factors that may help tailor treatment for individual patients were being investigated and low expression of thymidylate synthase (TS) and p21 was shown to correlate with better outcome, whereas patients with positive TS seemed to derive more benefit from HAC plus systemic chemotherapy than systemic chemotherapy alone.

SUMMARY

These studies confirmed that fluoropyrimidine-based HAC cannot be recommended routinely outside clinical trial as yet, but this treatment has its own merits and will continue to evolve with the availability of novel chemotherapeutic and biologic agents. Further studies into molecular prognostic factors will eventually define the role of HAC by selecting the right drug and the best route of administration for an individual patient.

Double modulation of 5-fluorouracil by trimetrexate and leucovorin in patients with advanced colorectal carcinoma

The purpose of this report is to evaluate the efficacy and toxicity (Tx) of a double modulation of 5-fluorouracil (5-FU) by trimetrexate (TMTX) and leucovorin (LV) in patients with advanced recurrent (inoperable) or metastatic colorectal cancer (ACC). Between December 1997 and August 2000, 36 patients were entered in this phase II study. Median age was 61 years, and 18 patients (50%) were female. Median performance status was 0 (range: 0-1), whereas primary tumor location was colon in 21 patients (58%) and rectum in 15 patients (42%). The number of metastatic sites was 1:29 patients (81%); 2:6 patients (17%) and 3:1 patient (3%). Hepatic involvement was observed in 33 patients (92%). Treatment consisted of TMTX 110 mg/m2 IV over 1 hour at hour (H) 0; LV 50 mg/m2 IV over 2 hours IV infusion starting at H 18; and 5-FU 900 mg/m2 IV bolus at H 20. LV (rescue) 15 mg/m2 orally was administered every 6 hours (total 6 doses) beginning at H 24. Cycles were repeated every 2 weeks until progressive disease (PD) or severe Tx. Thirty-four patients are assessable for response (R) (two patients refused further treatment after the first course of therapy), whereas all patients were assessable for Tx. Complete response: 1 patient (3%); partial response: 4 patients (12%), with an overall objective response rate of 15% (95% CI, 1%-25%); no change: 12 patients (35%); and progressive disease: 17 patients (50%). The median time to treatment failure was 4 months and median survival was 11 months. Tx was within acceptable limits. The dose-limiting side effect was mucositis. Eight episodes of grade II or III stomatitis were observed and were responsible for dosage modifications of TMTX and 5-FU. Leukopenia was observed in 16 patients (44%); neutropenia was registered in 19 patients (53%); anemia was seen in 18 patients (50%); emesis in 22 patients (61%); and dermatitis in 3 patients (8%). There were no therapy-related deaths. The double modulation of 5-FU by TMTX and LV showed modest antitumoral activity with mild to moderate Tx.

Enhanced sensitivity to irinotecan by Cdk1 inhibition in the p53-deficient HT29 human colon cancer cell line

Mutations in the tumor-suppressor gene p53 have been associated with advanced colorectal cancer (CRC). Irinotecan (CPT-11), a DNA topoisomerase 1 inhibitor, has been recently incorporated to the adjuvant therapy. Since the DNA-damage checkpoint depends on p53 activation, the status of p53 might critically influence the response to CPT-11. We analysed the sensitivity to CPT-11 in the human colon cancer cell line HT29 (mut p53) and its wild-type (wt)-p53 stably transfected subclone HT29-A4. Cell-cycle analysis in synchronised cells demonstrated the activation of transfected wt-p53 and a p21(WAF1/CIP1)-dependent cell-cycle blockage in the S phase. Activated wt-p53 increased apoptosis and enhanced sensitivity to CPT-11. In p53-deficient cells, cDNA-macroarray analysis and western blotting showed an accumulation of the cyclin-dependent kinase (cdk)1/cyclin B complex. Subsequent p53-independent activation of the cdk-inhibitor (cdk-I) p21(WAF1/CIP1) prevented cell-cycle progression. Cdk1 induction was exploited in vivo to improve the sensitivity to CPT-11 by additional treatment with the cdk-I CYC-202. We demonstrate a gain of sensitivity to CPT-11 in a p53-mutated colon cancer model either by restoring wild-type p53 function or by sequential treatment with cdk-Is. Considering that mutations in p53 are among the most common genetic alterations in CRC, a therapeutic approach specifically targeting p53-deficient tumors could greatly improve the treatment outcomes.

Glucuronidation as a mechanism of intrinsic drug resistance in colon cancer cells: contribution of drug transport proteins

We have recently shown that drug conjugation catalysed by UDP-glucuronosyltransferases (UGTs) functions as an intrinsic mechanism of resistance to the topoisomerase I inhibitors 7-ethyl-10-hydroxycamptothecin and NU/ICRF 505 in human colon cancer cells and now report on the role of drug transport in this mechanism. The ability of transport proteins to recognise NU/ICRF 505 as a substrate was evaluated in model systems either transfected with breast cancer-resistance protein 1 (Bcrp1), multidrug-resistance protein 2 (Mrp2) or Mrp3, or overexpressing MRP1 or P-170 glycoprotein. Results from chemosensitivity assays suggested that NU/ICRF 505 was not a substrate for any of the above proteins. In drug accumulation studies in human colon cancer cell lines NU/ICRF 505 was taken up avidly and retained in cells lacking UGTs (HCT116), whereas, following equally rapid uptake, it was cleared rapidly from cells displaying UGT activity (HT29) as glucuronide metabolites. HT29 cells were shown to express MRP1 and 3, but not P-170 glycoprotein, MRP2 or breast cancer-resistance protein. The major glucuronide of NU/ICRF 505 inhibited ATP-dependent transport of estradiol 17-beta-glucuronide in Sf9 insect cell membrane vesicles containing MRP1 or MRP3, while co-incubation of HT29 cells with the MRP antagonist, MK571, significantly restored intracellular concentrations of NU/ICRF 505. These data lead us to conclude that the presence of a glucuronide transporter is essential for glucuronidation to represent a major de novo resistance mechanism and that UGTs will contribute more as a primary resistance mechanism when the parent drug (e.g. NU/ICRF 505) is not itself recognised by transport proteins.

A Multicenter Phase II Study of Irinotecan in Patients with Advanced Colorectal Cancer Previously Treated with 5-Fluorouracil

This multicenter, open-label, phase II study was performed to assess the efficacy and toxicity of irinotecan 350 mg/m2 intravenously every 3 weeks in patients with advanced colorectal cancer (CRC) previously treated with 5-fluorouracil (5-FU). The study enrolled 115 patients and a total of 558 cycles (median, 6 per patient) were administered. The overall objective response rate on an intent-to-treat basis was 18% (with 1 complete response and 20 partial responses), whereas 42 patients (37%) showed stable disease. Median time to progression was 4.8 months and median survival was 13.6 months. Grade 3/4 toxicities included delayed diarrhea (19.1%), nausea/vomiting (10.4%), and neutropenia (8.7%). There were 2 toxic deaths, 1 from delayed diarrhea and 1 from hemorrhage and grade 4 mucositis. In conclusion, the present study confirms the antitumor efficacy of irinotecan monotherapy in patients with CRC pretreated with 5-FU.

S-1 in gastric cancer: a comprehensive review

The current basic and clinical studies of S-1 (TS-1) were reviewed. S-1 is a novel oral dihydropyrimidine dehydrogenase (DPD) inhibitory fluoropyrimidine (DIF) based on a biochemical modulation of 5-fluorouracil (5-FU); S-1 contains tegafur (FF) and two types of enzyme inhibitor, 5-chloro-2,4-dihydroxypyridine (CDHP) and potassium oxonate (Oxo) in a molar ratio of 1:0.4:1. In pharmacokinetic studies, S-1 showed high 5-FU concentration in blood for long periods of time. In a combined analysis of two pivotal late phase II studies in gastric cancer, the overall response rate was 44.6% (45/101), and median survival time and 1-year survival rate were 244 days and 37%, respectively. A postmarketing survey was conducted, and in the interim analysis, tolerability and safety profiles were shown in 3294 patients with gastric cancer. The oral dose form and low incidence of adverse reactions permit treatment on an outpatient basis. To evaluate the survival benefit of S-1 in advanced gastric cancer, a phase III study of S-1 vs 5-FU vs cisplatin (CDDP) plus irinotecan (CPT-11) has been conducted. The effect of S-1 in adjuvant chemotherapy is also promising. Currently, a phase III study of surgery alone vs S-1 in patients with curative resection of gastric cancer is in progress. Further therapeutic benefits are expected to be gained by combining S-1 with other chemotherapeutic agents. Several preliminary results of combination phase I/II studies of S-1 with CDDP or CPT-11 have recently been obtained, and phase II studies are in progress. Thus, S-1 is currently the first candidate as the standard anticancer drug for gastric cancer. Further evaluations by well-controlled clinical trials are still needed.

Nonsteroidal anti-inflammatory drugs in colorectal cancer: from prevention to therapy

In this review, we discuss the available experimental evidences supporting the chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) on colorectal cancer and the biological basis for their possible role as anticancer agents. Although the comprehension of the mechanisms underlying the effects of these drugs on colon cancer cells is incomplete, research efforts in identifying the biochemical pathway by which NSAIDs exert their chemopreventive effect have provided a rationale for the potential use of NSAIDs alone or in combination with conventional and experimental anticancer agents in the treatment of colorectal cancer. In this paper, we review three main issues: (i) the role of COX-2 in colon cancer; (ii) the common death pathways between NSAIDs and anticancer drugs; and (iii) the biological basis for the combination therapy with COX-2 selective inhibitors and new selective inhibitors of growth factor signal transduction pathways.

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.

Oxaliplatin plus irinotecan and leucovorin-modulated 5-fluorouracil triplet regimen every other week: a dose-finding study in patients with advanced gastrointestinal malignancies

BACKGROUND

Oxaliplatin (OXA) and irinotecan (IRI) are active drugs in first-line as well as second-line treatment of advanced colorectal cancer patients, their toxicity profiles are not overlapping, and both drugs have shown synergism with folinic acid-modulated 5-fluorouracil (5-FU). We planned this phase I study to define the dose-limiting toxicities (DLTs), the maximum tolerated doses (MTDs), and the recommended doses (RDs) for a triplet regimen including OXA plus IRI on day 1, and 6S-folinic acid (LFA) plus 5-FU on day 2, every 2 weeks.

PATIENTS AND METHODS

At least three patients had to be treated at each dose level, and the trial proceeded if no more than 33% of patients showed a DLT after the first cycle. Starting from OXA 85 mg/m(2) (over 2 h) and IRI 150 mg/m(2) (over 1 h), an alternated escalation was planned up to 110 mg/m(2) and 200 mg/m(2), respectively. Thereafter, a fixed dose of LFA, 250 mg/m(2) (as 2-h infusion), plus an escalating dose of 5-FU (from 650 to 800 mg/m(2) as an intravenous bolus) was added on day 2 to the previous dose level of OXA and IRI.

RESULTS

Forty-six patients, all but four affected by advanced colorectal primaries, entered this study. The MTDs for OXA and IRI given on the same day were 110 and 200 mg/m(2): these doses caused a DLT in three of six patients. The previous dose level (110 and 175 mg/m(2), respectively) on day 1 was safely followed on day 2 by LFA plus 5-FU up to 800 mg/m(2). Indeed, only one of three patients treated at this last level had a DLT. This cohort was then expanded including a total of 14 patients, and on the whole series five cases of DLT occurred: WHO grade 4 neutropenia (two patients), grade 3 or 4 diarrhoea (three patients). Cumulative toxicity was analysed in 43 patients for a total of 347 cycles: grade 4 neutropenia was detected in 13 patients (30%); it was not dose-related, nor was it exacerbated by the addition of modulated 5-FU. Febrile neutropenia occurred in four patients. Grade 3 or 4 diarrhoea was suffered by nine (21%) and five (12%) patients, respectively. Two complete and nine partial responses were reported on 40 evaluable patients (six patients were disease-free at study entry), giving a response rate of 27.5% (95% confidence interval 15% to 44%); nine of 18 (50%) assessable patients of the two last cohorts treated with the triplet regimen achieved a complete response (two patients) or a partial response (seven patients).

CONCLUSIONS

The RDs for this biweekly regimen were: OXA 110 mg/m(2) plus IRI 175 mg/m(2) on day 1, and LFA 250 mg/m(2) plus 5-FU 800 mg/m(2) on day 2. This regimen appeared active in pretreated gastrointestinal malignancies, and it is worthy of being evaluated in advanced colorectal carcinoma after failure of 5-FU-based adjuvant or palliative treatment.

Biweekly chemotherapy with oxaliplatin, irinotecan, infusional Fluorouracil, and leucovorin: a pilot study in patients with metastatic colorectal cancer

PURPOSE

To determine the feasibility, recommended doses, plasma pharmacokinetics, and antitumor activity of a biweekly chemotherapy regimen with oxaliplatin (L-OHP), irinotecan (CPT-11), infusional fluorouracil (5-FU), and leucovorin (LV) in metastatic colorectal cancer patients.

PATIENTS AND METHODS

Patients received CPT-11 followed by L-OHP and LV 200 mg/m(2) and followed by 5-FU 3,800 mg/m(2) as a 48-hour infusion, repeated every 2 weeks. In the first part of the study, an escalation of CPT-11 dose and/or a decrease of the L-OHP dose were planned. Once the recommended doses of CPT-11 and L-OHP were determined, all subsequent patients were treated at the recommended doses.

RESULTS

Forty-two patients entered the study. CPT-11 175 mg/m(2) and L-OHP 100 mg/m(2) in combination with LV 200 mg/m(2) and 5-FU 3,800 mg/m(2) could be administered with acceptable toxicities; 39 patients were treated at these dose levels. The pharmacokinetics parameters of the agents used and their metabolites did not seem to be influenced by the concomitant use of the other drugs. The most relevant toxicities were diarrhea and neutropenia, with 14% of patients experiencing one episode of febrile neutropenia. In five patients (11.9%) a complete and in 25 (59.5%) a partial response was demonstrated, for an objective response rate of 71.4% (95% confidence interval, 47% to 83%). In 11 patients (26%), a surgical resection of residual disease could be performed. Median progression-free and overall survival times were 10.4 and 26.5 months, respectively.

CONCLUSION

This biweekly regimen is feasible and has acceptable and manageable toxicities and no apparent relevant pharmacokinetics interactions. This combination is associated with a promising antitumor activity, time to progression, and survival. A phase III randomized trial in Italy planned by the Gruppo Oncologico Nord Ovest has just started.

Ketoconazole potentiates the antitumor effects of nocodazole: In vivo therapy for human tumor xenografts in nude mice

Our previous studies demonstrated that the oral antifungal agent ketoconazole (KT) induces apoptosis and G0/G1 phase cell cycle arrest in human cancer cell lines. In this study, we first demonstrated that KT (1 microM) potentiated the apoptotic effects of nocodazole (ND, 1 nM) in COLO 205 cancer cells. We further demonstrated the therapeutic efficacy of a combined treatment of KT (50 mg/kg/three times per week) and ND (5 mg/kg/three times per week) in vivo by treating athymic mice bearing COLO 205 tumor xenografts. The antitumor effects of ND were significantly potentiated by KT in mice after 6 wk of treatment. No gross signs of toxicity were observed in mice receiving these treatment regimens. The apoptotic cells were detected in a microscopic view of the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and by observation of DNA fragmentation in KT + ND-treated tumor tissues. The levels of cell cycle regulatory proteins were determined by Western blot analysis. Treatment with KT inhibits tumor growth through elevation of p53, p21/CIP1, and p27/KIP1 as well as inhibition of cyclin D3 and cyclin-dependent kinase 4 protein expression. Immunohistochemical staining analysis showed that p53, p21/CIP1, and p27/KIP1 immunoreactivity were induced in the tumor tissues. To clarify the roles of the p21/CIP1 and p27/KIP1 protein expression involved in G(0)/G(1) arrest and/or apoptosis induced by a combined treatment with KT and ND, antisense oligodeoxynucleotides (ODNs) specific to p21/CIP1 and p27/KIP1 were used. Our results demonstrated that apoptotic phenomena, including BAX induction and cytochrome C released from mitochondria induced by KT + ND, were significantly attenuated by pretreatment the cells with the p27/KIP1-specific antisense ODNs. These results indicate that p27/KIP1 protein does indeed play a critical role in the KT + ND-induced apoptosis. Our study revealed the molecular mechanism of KT + ND in regression of the tumor growth. The apoptotic effects of KT in a great variety of cancer cells make it a very attractive agent for cancer chemotherapy.

RPR-115135, a farnesyltransferase inhibitor, increases 5-FU- cytotoxicity in ten human colon cancer cell lines: role of p53

A new non peptidic farnesyltransferase inhibitor, RPR-115135, in combination with 5-FU was studied in 10 human colon cancer cell lines (HCT-116, RKO, DLD-1, Colo-320, LoVo, SW-620, HT-29, HCT-15, Colo-205 and KM-12) carrying several mutations but well characterized for p53 and Ras status. We found that there was a slight tendency (not statistically significant) for the p53 inactivated cells to be less sensitive to 5-FU after 6 days continuous treatment. Simultaneous administration of RPR-115135 and 5-FU, at subtoxic concentrations, resulted in a synergistic enhancement of 5-FU cytotoxicity in the p53 wildtype cells (HCT-116, RKO, DLD-1, Colo-320, LoVo). In the p53 mutated cells (SW-620, HT-29, HCT-15, Colo-205, KM-12) the effect was very complicated. In HCT-15 the combination resulted in antagonism, in KM-12 in antagonism or in synergy (at different concentrations) and in SW-620, HT-29 and Colo-205 cells in synergy but only when 5-FU was administered at high concentrations. Growth inhibition could be accounted for on the basis of a specific cell cycle arrest phenotype (G2-M arrest), as assayed by flow cytometry, only in the p53 functioning cell lines. The combination RPR-115135 + 5-FU increases apoptotic events only in these cell lines. In the mutated cell lines no major alterations on cell cycle arrest phenotype and no induction of apoptosis was observed. Although RPR-115135 can potentiate the effect of 5-FU in cells in which p53 function is disrupted, these data suggest strongly that RPR-115135 significantly enhances the efficacy of 5-FU only when p53 is functioning.

Addition of either irinotecan or methotrexate to bolus 5-fluorouracil and high-dose folinic acid every 2 weeks in advanced colorectal carcinoma: a randomised study by the Southern Italy Cooperative Oncology Group

PURPOSE

The purpose of this study was to compare the activity and toxicity of the combination of irinotecan (IRI) plus folinic acid (FA)-modulated 5-fluorouracil (5-FU) i.v. bolus with a regimen of double modulation of 5-FU with methotrexate (MTX) and FA in patients with advanced colorectal carcinoma.

PATIENTS AND METHODS

Two-hundred and thirty-four patients were enrolled: 118 patients received IRI 200 mg/m2 (90-min i.v. infusion) on day 1, followed by levo-FA 250 mg/m2 (2-h i.v. infusion) and 5-FU 850 mg/m2 (i.v. bolus) on day 2 (IRIFAFU), and 116 patients received MTX 750 mg/m2 (2-h i.v. infusion) on day 1, followed by levo-FA 250 mg/m2 (2-h i.v. infusion) and FU 800 mg/m2 (i.v. bolus) on day 2 (MTXFAFU). Both cycles were repeated every 2 weeks until progression or to a maximum of 16 cycles. Response rate (RR) was the main end point of the study; responses were assessed every four cycles and confirmed after 2 additional months of treatment.

RESULTS

RR was significantly greater with IRIFAFU (36%) than with MTXFAFU (20%) (P <0.001). Multivariate analysis showed that IRIFAFU was significantly associated with a greater activity (P = 0.028). Median progression-free survival was longer with IRIFAFU than with MTXFAFU (7.2 months compared with 4.8 months; P = 0.048). Median survival time (MST) did not differ between the two arms (14.7 months compared with 14.8 months, respectively). Patients not receiving second-line chemotherapy, however, lived longer when treated in the first-line with IRIFAFU (MST 11.9 months compared with 6.4 months; P = 0.038). IRIFAFU caused a significantly greater occurrence of grade 3 or 4 neutropenia (40% compared with 9%; P = 0.001) and diarrhoea (13% compared with 4%; P = 0.024), but a significantly lower incidence of stomatitis (3% compared with 12%; P = 0.007), than the comparative regimen.

CONCLUSIONS

IRIFAFU appeared comparable in terms of activity and toxicity with other weekly or biweekly bolus or infusional combination regimens. IRIFAFU, however, seems easier to administer, because it does not require infusional catheter or pump devices, and it is less expensive. It may represent a new option for treating advanced colorectal carcinoma.

Differential expression of cell cycle and apoptosis related proteins in colorectal mucosa, primary colon tumours, and liver metastases

AIMS

Tumour cell growth results from a disturbance in the balance between the rate of proliferation and cell death. In this study, proteins involved in the regulation of cell cycle arrest and apoptosis were studied as possible factors responsible for uncontrolled cell growth in colorectal cancer.

METHODS

The expression of proteins involved in these processes was investigated in 48 metastases from patients with colorectal cancer and compared with eight normal colon mucosa samples and 14 primary tumours. Both primary tumours and metastases were obtained from eight patients. The expression of thymidylate synthase (TS), p53, retinoblastoma protein (Rb), Fas receptor, Fas ligand, bcl-2, mcl-1, bax, and bcl-x was measured using immunohistochemistry. Proliferation was determined by Ki67 staining, whereas apoptosis was assessed by M30 immunostaining, which recognises cleaved cytokeratin 18.

RESULTS

In the limited number of cases in which paired comparisons were possible, the expression of TS and Ki67 was significantly higher in metastases than in the matched primary tumour samples (p = 0.014 and 0.016, respectively), whereas Rb expression was lower in metastases than in primary tumours (p = 0.024). Fas receptor expression was high in normal mucosa but absent in primary tumours and metastases, whereas the opposite was seen for p53. The expression of bax, mcl-1, and bcl-x in normal mucosa was more apical than that seen in malignant cells, where a more diffuse expression pattern was seen (p < 0.04). Apoptosis was more abundant in primary tumours than in metastases.

CONCLUSIONS

These results demonstrate that proliferation and apoptosis are disturbed during colorectal cancer progression, and this is accompanied by loss of Rb and Fas expression, the accumulation of p53 and TS, and changes in the expression patterns of bax, mcl-1, and bcl-xl.

Enhanced clearance of topoisomerase I inhibitors from human colon cancer cells by glucuronidation

As part of a program to identify novel mechanisms of resistance to topoisomerase I (topo I) inhibitors, the cellular pharmacology of 7-ethyl-10-hydroxycamptothecin (SN-38), the active metabolite of clinically used irinotecan (CPT-11) and NU/ICRF 505, an anthraquinone-tyrosine conjugate, has been investigated in two human colorectal cancer (CRC) cell lines. Two novel metabolites of NU/ICRF 505 (M1 and M2) and a single metabolite of SN-38 (M1) were detected by high performance liquid chromatography in the culture medium of HT29 cells but were absent in HCT116 cells. Identities of all three metabolites were established by a combination of biochemical and physicochemical techniques. M1 of SN-38 was the C10-(beta)-glucuronide of the parent lactone while M1 of NU/ICRF 505 was the C4-O-glucuronide and M2 the tyrosine-O-glucuronide, both of the parent compound. Drug transport studies revealed that by 24hr HT29 cells had effectively cleared 82.5% of NU/ICRF 505 (10 microM) into the culture medium as the two glucuronides. In contrast, intracellular concentrations of NU/ICRF 505 were maintained in HCT116 cells in the absence of glucuronidation at a level 550 times greater than in HT29 cells. HT29 cells cleared 40.9% of SN-38 (1 microM) as the glucuronide to the culture medium, while the parent drug was maintained at a level 2-fold greater in HCT116 cells. Enhanced drug clearance due to glucuronidation may contribute to intrinsic drug resistance of human CRC.