Review of the role of CPT-11 in the treatment of colorectal cancer

Enzyme and Reactive Oxygen Species-Responsive Dual-Drug Delivery Nanocomplex for Tumor Chemo-Photodynamic Therapy

Introduction

Combination therapy is a promising approach to promote the efficacy and reduce the systemic toxicity of cancer therapy. Herein, we examined the potency of a combined chemo-phototherapy approach by constructing a hyaluronidase- and reactive oxygen species-responsive hyaluronic acid nanoparticle carrying a chemotherapy drug and a photosensitizer in a tumor-bearing mouse model. We hypothesized that following decomposition, the drugs inside the nanocomplex will be released in the tumors to provide effective tumor treatment. We aimed to design a smart drug delivery system that can improve traditional chemotherapy drug delivery and enhance the therapeutic efficacy in combination with photodynamic therapy.

Methods

Hydrophilic hyaluronic acid (HA) was covalently modified with a hydrophobic 5β-cholanic acid (CA) via an ROS-cleavable thioketal (tk) linker for a targeted co-deliver of 10-Hydroxy camptothecin (HCPT) and Chlorin e6 (Ce6) into tumors to improve the efficiency of combined chemo-photodynamic therapy.

Results

The obtained HA-tk-CA nanoparticle carrying HCPT and Ce6, named HTCC, accumulated in the tumor through the enhanced permeable response (EPR) effect and HA-mediated CD44 targeting after intravenous administration. Upon laser irradiation and hyaluronidase degradation, HTCC was disrupted to release HCPT and Ce6 into the tumors. Compared to the monotherapy approach, HTCC demonstrated enhanced tumor growth inhibition and minimized systemic toxicity in a tumor-bearing mouse model.

Conclusion

Our results suggested that controlled dual-drug release not only improved tumor drug delivery efficacy, but also reduced systemic side effects. In addition to HCPT and Ce6 delivery, the HA-tk-CA nanocomplex can be used to deliver other drugs in synergistic cancer therapy. Since most current combined therapy uses free drugs with distinct spatiotemporal distributions, the simultaneous co-delivery of dual drugs with a remote on-demand drug delivery nanosystem provides an alternative strategy for drug delivery design.

Drug Resistance of CPT-11 in Human DLD-1 Colorectal Cancer Cells through MutS Homolog 2 Upregulation

Colorectal cancers (CRCs) is the most commonly diagnosed and deadly cancer types in the world. Despite advances in chemotherapy for CRCs, drug resistance remains a major challenge to high incurable and eventually deadly rates for patients. CPT-11 is one of the current chemotherapy agents for CRC patients and the CPT-11 resistance development of CRCs is also inevitable. Recently, accumulating data has suggested that DNA repair system might be an inducer of chemotherapy resistance in cancer cells. Thus, this study was aimed to examine whether MutS homolog (MSH) 2, one member of DNA repair system, plays a role to affect the cytotoxicity of CPT-11 to CRCs. Human DLD-1 CRC cells were used in this study. It was shown that MSH2 gene and protein expression could be upregulated in DLD-1 cells under CPT-11 treatment and this upregulation subsequently attenuates the sensitivity of DLD-1 cells to CPT-11. Moreover, ERK1/2 and Akt signaling and AP-1 transcription factor have been found to modulate these effects. These results elucidate the drug resistance role of MSH2 upregulation in the CPT-11-treated DLD-1 CRC cells. Our findings may provide a useful thought for new adjuvant drug development by controlling the DNA repair system.

Phase III study of weekly high-dose infusional fluorouracil plus folinic acid with or without irinotecan in patients with metastatic colorectal cancer: European Organisation for Research and Treatment of Cancer Gastrointestinal Group Study 40986

PURPOSE

To demonstrate that adding irinotecan to a standard weekly schedule of high-dose, infusional fluorouracil (FU) and leucovorin (folinic acid [FA]) can prolong progression-free survival (PFS).

PATIENTS AND METHODS

Four hundred thirty patients with measurable or assessable metastatic colorectal cancer were randomly assigned to receive either FA 500 mg/m(2) as a 2-hour infusion and FU 2.6 g/m(2) by intravenous 24-hour infusion, both administered weekly for 6 weeks, followed by a 2-week rest (Arbeitsgemeinschaft für Internistische Onkologie [AIO] arm, n = 216), or a similar schedule but with FU 2.3 or 2.0 g/m(2) preceded by irinotecan 80 mg/m(2) administered over 30 minutes (experimental group, n = 214).

RESULTS

The median PFS time in the experimental group was 8.5 months (95% CI, 7.6 to 9.9 months) compared with 6.4 months (95% CI, 5.3 to 7.2 months) in the AIO arm (P < .0001). The median overall survival time was increased from 16.9 to 20.1 months (P = .2779). The objective response rate was 62.2% (95% CI, 55.0% to 69.5%) in the experimental group and 34.4% (95% CI, 27.5% to 41.3%) in the AIO arm (P < .0001).

CONCLUSION

The addition of irinotecan to the standard AIO FU/FA regimen was associated with a highly significant improvement in PFS and response rate and was well tolerated. The results of this study confirm that irinotecan in combination with high-dose infusional FU/FA is a reference first-line treatment.

Outcome of colorectal carcinoma in patients under 40 years of age

AIMS

Colorectal carcinoma in patients under 40 years of age usually has a poor prognosis. Controversies still exist regarding the features and the prognosis of colorectal cancer in young patients.

METHODS

The records of 45 patients with histologically confirmed colorectal carcinoma treated between 1992 and 2002 at the Division of Oncology at Taipei Veterans General Hospital were reviewed. The relevance of sex, duration of symptoms, tumor site, histological type, lymph node involvement, Karnofsky performance status (KPS), carcinoembryonic antigen (CEA) and lactate dehydrogenase (LDH) levels at the diagnosis and tumor stage to overall survival (OS) were determined by univariate analysis, and their independent significance were tested by multivariate analysis.

RESULTS

Most patients presented with an advanced tumor stage (24% Dukes' C and 66% Dukes' D). Colon carcinoma constituted 76% of the colorectal tumors. Family history was present in two patients and did not affect the OS. Two patients were found to have colon carcinoma during pregnancy. The 5-year survival rate in patients with Stage B, C, and D were 25, 16 and 0%, respectively. With aggressive treatment, patients with early stage carcinoma achieved longer survival. Eleven patients received resection of metastatic carcinoma of the liver, lung and ovary. Adjuvant chemotherapy with irinotecan/5-fluorouracil-based chemotherapy seemed to improve the OS in such patients, though the OS was still poorer than in patients with early stage tumors. In univariate analysis, KPS (P = 0.0001), lymph node involvement (P = 0.0024), CEA (P = 0.0423) and LDH levels (P = 0.0126) at the diagnosis and tumor stage (P = 0.0122) proved to be significant predictors of overall survival. Multivariate analyses revealed that KPS > or =70% (P = 0.007) and normal LDH levels at diagnosis (P = 0.004) were predictive of overall survival in this population.

CONCLUSIONS

The present study shows that performance status and preoperative LDH levels were the major determinants for survival in patients with colorectal carcinoma under 40 years of age and the present series also suggests that surgical resection of metastatic colorectal carcinoma followed by adjuvant chemotherapy might be beneficial in certain patients. The data also suggests that current treatment modalities for young patients with advanced colorectal cancer might not be effective and more effective therapeutic regimens might be needed. Thus, it is important for surgeons to recognize the potential for colorectal cancer in young patients and to take an aggressive approach to the diagnosis and early treatment of the disease.

The irinotecan/5-fluorouracil combination induces apoptosis and enhances manganese superoxide dismutase activity in HT-29 human colon carcinoma cells

BACKGROUND

We examined whether induction of apoptosis and Mn-superoxide dismutase (Mn-SOD) and Cu,Zn-superoxide dismutase (Cu,Zn-SOD) activities were involved in the greater cytotoxicity of the irinotecan (CPT-11)/5-fluorouracil (5-FU) combination for human colon cancer cells when compared to both drugs alone.

METHODS

HT-29 and SNU-C4 human colon carcinoma cell lines were treated with 5-FU and CPT-11, then apoptosis was evaluated by flow cytometry and SOD activities were determined by polyacrylamide gel electrophoresis.

RESULTS

Enhanced apoptosis of HT-29 cells was observed with all treatments containing 5-FU in SNU-C4 cells; however, in HT-29 cells, apoptosis was enhanced only with the CPT-11/5-FU combination. In the SNU-C4 cell line, none of the treatments exerted a significant effect on Cu,Zn-SOD or Mn-SOD activity. However, in HT-29 cells, the CPT-11/5-FU combination enhanced Mn-SOD activity when compared to cells treated with CPT-11 alone. Nevertheless, the combined treatment did not interfere with Cu,Zn-SOD activity.

CONCLUSION

Treatment with the CPT-11/5-FU combination may promote in HT-29 cell apoptosis by enhancing Mn-SOD activity.

Small-cell carcinoma of the gastrointestinal tract: a retrospective study of 64 cases

Small-cell carcinoma (SmCC) of the gastrointestinal tract is a very rare and aggressive malignancy. To better define its clinicopathological features, the records of all patients with this disease seen at Memorial Sloan Kettering Cancer Center between 1980 and 2002 (n=64) were reviewed. The most common primary tumour locations were in the large bowel and oesophagus. Predisposing medical conditions for non-small-cell cancers, positive family cancer history, and metachronous tumours were common. In all, 37% had mixed tumour histology and 48% presented with extensive disease, according to the Veterans' Administration Lung Study group (VALSG) staging system used for small-cell lung cancer. Treatment outcome in limited disease (LD) suggested a role for surgery and chemotherapy. Platinum-based regimens resulted in a 50% response rate. The 2-year survival was 23% and two prognostic factors were identified, the extent of disease according to the VALSG system (P<0.01) and TNM stage (P=0.03). Anatomic location had no clinical impact. In conclusion, SmCC from various gastrointestinal sites can be viewed as one clinical entity. Mixed tumour histology is common and may affect therapy. Surgery, combined with chemotherapy, should be considered for LD. The value of the VALSG system was implied and possible differences from small-cell lung cancer were noted.

A novel mouse model of rectal cancer established by orthotopic implantation of colon cancer cells

A novel intraluminal colon tumor model was established in mice by intrarectal instillation of colon cancer cells followed by short-term induction of colitis by an irritant agent. Male BALB/c mice were fed a diet containing 3% (w/w) dextran sulfate sodium (DSS) for 7 days to induce colitis, and colon 26 cells (1-2 x 10(6) cells/mouse) were infused intrarectally after the mice had been deprived of food for the last 18 h of DSS treatment. The tumor incidence (%) and size (mean volume +/- SD, mm(3)) at the rectal mucosa were 35% (2 +/- 3), 95% (96 +/- 79), 95% (141 +/- 137) and 94% (325 +/- 270) at 1, 2, 3 and 4 weeks after instillation of tumor cells, respectively. Histopathological analyses revealed that a solid tumor was formed initially at the rectal mucosa at 1 week after instillation, then became invasive into the submucosal and muscular tissues at 3 weeks after implantation. Intrarectal instillation of human colon cancer cells, LS174T (1 x 10(7) cells/mouse), mixed with "Matrigel" (0.5 mg/mouse), an extracellular matrix solution, in SCID mice led to formation of rectal tumors at 4 weeks after instillation, and immunohistochemical analysis revealed that the tumor cells expressed human carcinoembryonic antigen, suggesting that the tumor nodule was derived from the instilled LS174T cells. Oral or intravenous administration of a camptothecin (CPT) derivative, CPT-11, resulted in a significant reduction in tumor incidence and tumor volume in the colon 26-intraluminal implantation system. In conclusion, it was suggested that the present intraluminal colon tumor model is useful for examination of chemotherapeutic agents and also intraluminal factors (dietary compounds, intestinal microflora, etc.) that might function to suppress or enhance the growth of colorectal cancer in situ.

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.