Treatment of Advanced Colorectal Cancer

Dynamic observation of 5-fluorouracil-induced myocardial injury and mitochondrial autophagy in aging rats

Patients treated with 5-fluorouracil (5-FU) can develop rare but potentially severe cardiac effects, including cardiomyopathy, angina pectoris, heart failure and cardiogenic shock. The specific pathologies and underlying mechanisms are yet to be fully understood. The results of previous studies have indicated that mitochondrial autophagy is widely detected in many angiocardiopathies. In the present study, the dynamic changes in the homeostasis of mitochondrial injury and autophagy were observed in rats treated with 5-FU for different durations. A corresponding control group and a 5-FU model group were established in groups of Sprague-Dawley rats aged 2 and 18 months, and the myocardial enzyme levels were determined at different time points. At 2 weeks post-model establishment, cardiac ultrasound and myocardial histological staining were performed, cardiomyocyte apoptosis and myocardial mitochondrial function were assessed, and mitochondrial ultrastructure was examined. In addition, the expression levels of autophagy-related proteins were evaluated in the 18-month-old rats on days 7 and 14 of 5-FU administration. The experimental results demonstrated that 5-FU induced an elevation in the levels of myocardial enzymes, as well as changes in the cardiac structure and function, and that these changes were more prominent over longer drug durations. In addition, 5-FU decreased the levels of myocardial mitochondrial ATP and mitochondrial membrane potential, and aggravated myocardial fibrosis and cardiomyocyte apoptosis compared with those observed in the untreated control group, treated with the same volume of saline as 5-FU in the 5-FU group. These injuries were particularly evident in aging rats. Notably, 5-FU increased the expression levels of myocardial mitochondrial autophagy-related proteins, and electron microscopy revealed a more severe autophagic state in the model groups compared with that in the control groups. In conclusion, 5-FU induced myocardial mitochondrial damage, the degree of which was more severe in aging rats compared with that in young rats. The mitochondrial autophagy induced by 5-FU was excessive, and the degree of autophagy was aggravated with increased 5-FU administration time.

Association between SNPs and hepatotoxicity in patients with primary central nervous system lymphoma on high-dose methotrexate therapy

OBJECTIVES

This study aims to evaluate the association between polymorphisms of methotrexate pathway genes and high-dose methotrexate-related hepatotoxicity in Chinese patients with primary central nervous system lymphoma.

METHODS

Sixty-five patients in 411 treatment courses were enrolled and their toxicities were evaluated. The association between 30 candidate SNPs from 20 methotrexate pathway genes and high-dose methotrexate-related hepatotoxicity was analysed by PLINK and logistic regression.

KEY FINDINGS

TYMS 6 bp DI + II (rs151264360; OR, 0.41; 95% CI, 0.25-0.66; P = 0.00029), MTHFD1 1958 GA + AA (rs2236225; OR, 0.55; 95% CI, 0.33-0.91; P = 0.020) and CCND1 870 GA + GG (rs9344; OR, 0.42; 95% CI, 0.24-0.73; P = 0.0024) had less risk of hepatotoxicity compared with their homozygotes (DD, GG and AA, respectively), while ABCC2 intron 29 GA + GG (rs3740065; OR, 3.14; 95% CI, 1.89-5.20; P = 0.00001) was more prevalent in patients with hepatotoxicity than TT.

CONCLUSIONS

TYMS 6 bp DI + II, MTHFD1 1958 GA + AA, CCND1 870 GA + GG genotypes were associated with a lower probability of hepatotoxicity in patients with primary central nervous system lymphoma on high-dose methotrexate therapy, and ABCC2 intron 29 GA + GG was correlated with increased risk of hepatotoxicity.

Combined antitumor effects of an adenoviral cytosine deaminase/thymidine kinase fusion gene in rat C6 glioma

OBJECTIVE

In this study, we investigated the feasibility of a double-suicide gene/prodrug therapy, involving direct introduction of the herpes simplex virus Type 1 thymidine kinase (TK) gene and the Escherichia coli cytosine deaminase (CD) gene, via a recombinant adenoviral vector, and ganciclovir (GCV) and/or 5-fluorocytosine (5-FC) treatment, in a rat C6 glioma model.

METHODS

Efficient gene transfer and transduction of C6 glioma cells via a recombinant adenovirus were evaluated by infecting cells with adenovirus bearing the beta-galactosidase gene and then staining cells with X-5-bromo-4-chloro-3-indolyl-13-D-galactoside. CD/TK expression in cells infected with adenovirus bearing the CD/TK gene (ad-CD/TK) was examined by immunoblotting analysis. For in vitro cytotoxicity experiments, the cells were infected with ad-CD/TK or ad-deltaE1 (as a control). After the addition of a variety of concentrations of GCV and 5-FC, either separately or in combination, cell viability was determined by staining the cells with crystal violet solution 6 days after infection. For in vivo antitumor experiments, 1x10(5) cells were stereotactically injected into the right caudate-putamen of female Wistar rat brains. At 3 days after implantation, 1x10(8) plaque-forming units of ad-CD/TK or ad-deltaE1 (as a control) were stereotactically injected into the tumors and GCV (25 mg/kg) and 5-FC (250 mg/kg), alone or in combination, were intraperitoneally administered. Animals were then killed, and tumor volumes were measured by determining the tumor area in every fifth section, using a light microscope.

RESULTS

C6 glioma cells were efficiently transduced with recombinant adenoviral vector at multiplicities of infection of 200 or more. In vitro cytotoxicity of GCV and/or 5-FC, either alone or in combination, was exclusively observed in the cells transduced with ad-CD/TK. Obvious cytotoxicity (>50% inhibition) was observed in the presence of 5-FC at concentrations greater than 30 microg/ml or GCV at concentrations greater than 0.3 microg/ml at a multiplicity of infection of 100. Additionally, cytotoxicity in the presence of both GCV and 5-FC was greater than that after single-prodrug treatments, indicating additive effects of the prodrug treatments. In in vivo experiments, the tumor volumes of the rats treated with GCV or 5-FC alone after ad-CD/TK injection (59.1+/-4.6 and 57.4+/-7.1 mm3, respectively) were significantly smaller than that of the control rats (157+/-8.9 mm3, P<0.05). Furthermore, the tumor volume of the rats treated with GCV and 5-FC in combination was 14.7+/-1.8 mm3.

CONCLUSION

These results demonstrated the efficient transduction of C6 glioma cells with a recombinant adenovirus and the additive effects of CD/TK fusion gene/GCV/5-FC treatment, compared with single-gene therapy with the TK or CD gene. Therefore, our data suggest that the direct administration of a double-suicide gene/prodrug therapy has great potential in the treatment of brain tumors.

Glioma cells transduced with an Escherichia coli CD/HSV-1 TK fusion gene exhibit enhanced metabolic suicide and radiosensitivity

To ascertain whether concomitant expression of Escherichia coli deaminase (CD) and herpes simplex virus type-1 thymidine kinase (HSV-1 TK) could mediate greater levels of cytotoxicity beyond that observed with either suicide gene alone, 9L gliosarcoma cells were transduced with a retrovirus encoding a CD/HSV-1 TK fusion gene. The resultant CD/HSV-1 TK fusion protein (CDglyTK) was found to be bifunctional via CD and HSV-1 TK enzymatic assays, and conferred upon cells prodrug sensitivities equivalent to or better than that observed for each enzyme independently (ganciclovir [GCV] and bromovinyldeoxyuridine [BVdU] for HSV-1 TK and 5-fluorocytosine [5-FC] for CD). Simultaneous treatment of CDglyTK-expressing cells with prodrugs specific for HSV-1 TK and CD (GCV/5-FC or BVdU/5-FC) resulted in slight synergistic toxicity, two- to three-fold greater than that expected if the cytotoxic effects of each prodrug were purely additive. More importantly, co-treatment with HSV-1 TK- and CD-specific prodrugs was found to increase greatly the radiosensitivity of CDglyTK-expressing cells. Sensitivity enhancement ratios of 2.44 (GCV/5-FC) and 3.90 (BVdU/5-FC) were achieved. The results suggest that double suicide gene therapy, using a bifunctional CD/HSV-1 TK fusion gene, coupled with radiotherapy may provide a highly efficient means of selectively treating cancer.

Transcriptional regulatory sequences of carcinoembryonic antigen: identification and use with cytosine deaminase for tumor-specific gene therapy

The 5' sequences from the human carcinoembryonic antigen gene (CEA) were analyzed using luciferase reporter gene assays. This analysis identified important cis-acting sequences needed for selective expression in CEA-positive cells. Over 50 CEA/luciferase reporter clones were constructed and analyzed in two CEA-positive and two CEA-negative cell lines. The CEA sequences analyzed extended from the translational start to 14.5 kb 5' of the CEA gene. A 408-bp region from the CEA 3' untranslated region was also examined for its effect on reporter gene activity. The CEA promoter was located between bases -90 and +69 of the transcriptional start site. Sequences between -41 and -18 were essential for expression from the CEA promoter. Multimerization of sequences between -89 and -40 resulted in copy number-related increases in both expression level and selectivity for CEA-positive cells. Two upstream regions of CEA, -13.6 to -10.7 kb or -6.1 to -4.0 kb, when linked to the multimerized promoter led to high-level, selective expression in CEA-positive cell lines. Several CEA/luciferase constructs demonstrated 80- to 120-fold higher expression in CEA-positive cell lines compared to expression in CEA-negative Hep3B cells. The expression from these constructs was quite strong in CEA-positive cells, being two- to four-fold higher than an SV40 enhancer/promoter construct. The most promising CEA transcriptional regulatory sequences were used to regulate the expression of cytosine deaminase (CD) in stable cell lines. The expression of CD was assessed directly by an enzymatic assay and indirectly by determining the in vitro IC50 to 5-fluorocytosine (5FC). The chimeric gene pCEA/CD-145 displayed the desired expression spectrum--high-level expression in the CEA-positive cells and low-level expression in CEA-negative cells. CD expression from this chimera correlated well with the expression of the endogenous CEA gene. Treatment of mice bearing NCI H508 pCEA/CD-145 tumor xenografts with 5FC lead to significant antitumor effects in vivo. The CEA/CD chimeric gene should be useful for tumor-specific suicide gene therapy of CEA-positive tumors.

Role of the lung in accumulation and metabolism of xenobiotic compounds--implications for chemically induced toxicity

The mammalian lung is exposed to and affected by many airborne and bloodborne foreign compounds. This review summarizes the role of lung in accumulation and metabolism of xenobiotics, some of which are spontaneously reactive or are metabolically activated to toxic intermediates. The specific architectural arrangement of mammalian lung favors that so-called pneumophilic drugs are filtered out of the blood and are retained within the tissue as shown in particular for amphetamine, chlorphentermine, amiodarone, imipramine, chlorpromazine, propranolol, local anaesthetics, and some miscellaneous therapeutics. There is strong evidence that intrapulmonary distribution activity and regulation of drug-metabolizing enzymes in lung is distinct from liver. This review focuses on the metabolic rate of selected compounds in lung such as 5-fluoro-2'-deoxyuridine, local anesthetics, nicotine, benzo(alpha)pyrene, ipomeanol, 4-methylnitrosamino-1-(3-pyridyl)-1-butanone. It is widely accepted that the formation of radical species is a key event in the pneumotoxic mechanisms induced by bleomycin, paraquat, 3-methylindole, butylhydroxytoluene, or nitrofurantoin. Finally, methodological approaches to assess the capacity of lung to eliminate foreign compounds as well as biochemical features of the pulmonary tissue are evaluated briefly.

Inhibition of fluorouracil catabolism in cancer patients by the antiviral agent (E)-5-(2-bromovinyl)-2'-deoxyuridine

The thymidine analogue (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVdUrd), which is an antiviral agent effective against herpes simplex virus type 1 and varicella zoster virus, has also proved to be a potent inhibitor of dihydrouracil dehydrogenase, the major degrading enzyme of the anticancer drug fluorouracil (FUra). To evaluate the effect of BVdUrd on the pharmacokinetics of FUra in cancer patients, BVdUrd was administered orally at a daily dose of 250 mg (five patients) or 3 x 250 mg (five patients). FUra was infused at doses of 110-400 mg over 10 min. Blood and urine samples were collected regularly during a period of up to 50 h. BVdUrd was rapidly absorbed, peak plasma levels of 0.6-7.1 micrograms/ml being achieved after 1-2 h. Following a rapid decline, plasma BVdUrd levels remained higher than 10 ng/ml for up to 2 days after BVdUrd administration. The total body clearance of FUra was approximately 61/h and t1/2 markedly increased to 4-7 h. The mean urinary excretion of FUra was 50%. No differences in FUra kinetics were observed between patients receiving one or three oral doses of BVdUrd. We conclude that the concomitant use and subsequent interaction of FUra and the antiviral agent BVdUrd resulted in an impressive inhibition of FUra breakdown and marked increase of renal clearance. The findings indicate that the simultaneous use of FUra and drugs resembling this antiviral agent in patients may result in unexpected toxicity. Further experience with BVdUrd and new analogues might enable the development of new FUra treatment schedules and treatment designs e.g. combinations with leucovorin.

Management of advanced rectal cancer

If possible, palliative resection should be undertaken for advanced rectal cancer as it provides good relief of local symptoms; there is, however, little evidence that it prolongs survival. If palliative excision is not possible, endoscopic transanal resection may be used for obstructing lesions at or below the peritoneal reflection. Laser therapy is an alternative in the frail. Both procedures allow quick and effective relief of symptoms. These methods and other options for treating advanced rectal cancer are described in this review.

Nonsurgical management of recurrent colorectal cancer

Most patients with colorectal carcinoma undergo attempts at curative surgery. However, some present with metastatic disease and many others ultimately relapse. Most recurrences of colorectal cancer are not resectable and require nonsurgical approaches such as chemotherapy and radiation therapy directed against local recurrences, hepatic metastases, and widely disseminated disease. Nonsurgical therapy for locoregional recurrence of rectal cancer can offer significant palliation. Intraarterial chemotherapy for liver metastases increases the likelihood of response compared to systemic treatments, but has little effect on survival. Extrahepatic progression and hepatic toxicity are important limitations to this regional therapy. 5-fluorouracil (5-FU) is the mainstay of systemic chemotherapy, and efforts to modulate biochemically the cytotoxic effects of 5-FU with folinic acid, phosphonacetyl-L-aspartate, interferon, and other agents have resulted in promising response rates. The different approaches to biochemical modulation are being studied in ongoing cooperative group trials. Novel approaches, including monoclonal antibody therapy, biologic modifier therapy, and gene therapy, are under investigation.

The therapeutic use of the unconjugated monoclonal antibodies (MAb) 17-1A in combination with GM-CSF in the treatment of colorectal carcinoma (CRC)

Unconjugated monoclonal antibodies (MAb) and granulocyte macrophage-colony stimulating factor (GM-CSF) may induce tumor regression in patients. Antibody-dependent cellular cytotoxicity (ADCC) is considered to be one of the effector functions of MAb. Human peripheral blood mononuclear cells (PBMC) preincubated with GM-CSF and used as effector cells in an 18h ADCC assay with SW948 (human colorectal carcinoma cell line) as target cells and MAb 17-1A induced significant increase in the lytic capacity of the effector cells. Based on these findings the therapeutic effect of the combination of mouse MAb 17-1A (IgG2a) against colorectal carcinoma (CRC) cells and GM-CSF was evaluated in 20 patients with metastatic CRC. The patients received GM-CSF (250 micrograms/m2/day s.c.) for 10 days and a single i.v. infusion of MAb 17-1A (400 mg) at day 3 of the cycle. The cycles were repeated with an interval of one month. Four cycles were given. ADCC as well as Fc-receptor bearing mononuclear cells increased significantly during therapy. Two patients achieved CR (10%). One patient had an MR (5%) and a further three patients were considered to have SD > 3 months (15%). The two CR patients are still in CR, 35+ and 30+ months respectively after initiation of therapy. Patients with an ADCC activity at start of therapy above the median value of the total patient material survived significantly longer than those patients with an ADCC reactivity below this value (p = 0.002).

Phase II evaluation of recombinant alpha-2a-interferon and continuous infusion fluorouracil in previously untreated metastatic colorectal adenocarcinoma

BACKGROUND

Thirty-nine patients with advanced measurable metastatic colorectal carcinoma were entered in a clinical trial of recombinant alpha-2a-interferon (r alpha-2a-IFN) and continuous-infusion 5-fluorouracil (5-FU). Patients had not been treated previously with chemotherapy and had bidimensionally measurable disease.

METHODS

A course of therapy consisted of a 5-day continuous infusion of 5-FU, 750 mg/m2/day, with r alpha-2a-IFN, 9 x 10(6) IU, subcutaneously, on days 1, 3 and 5 of the 5-FU infusion. A course of therapy was repeated every 15 days, and patients were examined for response after receiving four courses of therapy.

RESULTS

One patient had a complete response, and 11 patients experienced partial responses, for an overall response rate of 31% (95% confidence interval [CI], 17-48%). The median duration of response was 7.5 months (range, 2-13 months). Fifty-two percent of the patients entered in this trial are alive at time of this writing, with a median follow-up duration of 12.2 months (range, 6-24 months). Grade 3-4 toxicities included mucositis (nine patients), diarrhea (two patients), granulocytopenia (two patients), and fatigue (three patients).

CONCLUSION

This regimen of 5-FU with r alpha-2a-IFN administration does not appear to be superior to previously published schedules of 5-FU with r alpha-2a-IFN or to other methods that modulate 5-FU.

Phase II study of gemcitabine in advanced colorectal adenocarcinoma

A phase II trial of gemcitabine (difluorodeoxycytidine) was conducted in 14 patients with advanced colorectal adenocarcinoma. Gemcitabine was administered intravenously over 30 minutes at weekly intervals for 3 consecutive weeks each month. The starting dose was 800 mg/m2, with dose escalation as tolerated. No complete or partial response were observed. Ten patients experienced progressive disease while on therapy. Toxic effects were primarily hematologic in nature. Grade 3 toxicities included leukopenia (one patient at 1000 mg/m2), granulocytopenia (two patients at 800 mg/m2), anemia (two patients at 800 mg/m2), and myalgia (one patient at 800 mg/m2). No grade 4 toxic effects or treatment-associated deaths were observed. Gemcitabine, at the doses and schedule used in this study, did not demonstrate activity against advanced colorectal adenocarcinoma.

Antineoplastic activity of three ruthenium derivatives against chemically induced colorectal carcinoma in rats

The antineoplastic activity of the ruthenium complexes trans-imidazolium[tetracholorobisimidazole-ruthenate(III)], HIm(RuIm2Cl4), trans-indazolium-[tetrachlorobis(1H-indazole)ruthenate (III, N2)], HInd [RuInd2Cl4(N2)], and trans-indazolium[tetrachloro-bis(2H-indazole)ruthenate(III,N 1)], HInd[RuInd2Cl4-(N1)] was assessed in acetoxymethylmethylnitrosamine-induced autochthonous colorectal carcinomas of Sprague-Dawley rats. The model is not sensitive to clinically established antineoplastic agents, including cisplatin. An exception is the combination therapy with 5-fluorouracil/leucovorin, which shows moderate activity against the tumour model. In contrast to this general trend, the new substances were all active against this tumour. HIm(RuIm2Cl4) was very effective at all dosages applied (7.5 mg/kg, 5.3 mg/kg, and 3.8 mg/kg), as indicated by percentage treated/control (T/C values of 23%, 34.5%, and 44%. Toxicity was considerable as shown by a body weight change of -30%, -19%, and -9%. Nevertheless, the medium dose seems to be the optimum in terms of mortality (0% vs 15% in the control group), whereas at the highest dose, mortality increased as a result of substance toxicity, and at the lowest dose mortality increased through tumor growth combined with substance toxicity. HInd[RuInd2Cl4(N2)] showed high efficacy at the highest dosage of 13 mg/kg, reaching a T/C value of 27% combined with 0% mortality versus 15% in the control group. In equimolar dosages (10 mg/kg, 7.1 mg/kg and 5.1 mg/kg), the compound is not as active as HIm-(RuIm2Cl4), as indicated by T/C values of 50.2%, 45.7%, and 38.6%. HInd[RuInd2Cl4(N1)] was slightly but not significantly better than HInd[RuInd2Cl4(N2)] at a dosage of 7.1 mg/kg and is advantageous over combination therapy with 5-fluorouracil and leucovorin (20/20 mg/kg) in terms of efficacy (T/C = 37.6% versus 44.7%) and mortality (6% versus 33.3%).

Resident research award: tumor necrosis factor alpha selectively enhances growth and cytotoxic activity of tumor infiltrating lymphocytes from human colorectal cancer

Adoptive immunotherapy with tumor-infiltrating lymphocytes (TIL) and interleukin-2 (IL2) can induce regression of tumor metastases in animal models and in human metastatic malignant melanoma. We investigated the potential of colorectal cancer TIL as a source of killer cells and the effect of tumor necrosis factor alpha (TNF alpha) in combination with IL2 on their cytotoxic activity. Tumor-infiltrating lymphocytes were isolated from surgical specimens using a mechanical and enzymatic dissociation process. Autologous lamina propria mononuclear cells (LPMC) were used as control. Tumor-infiltrating lymphocytes and LPMC were cultured in the presence of IL2 with/without TNF alpha (1000 U/ml each) for 5 to 8 weeks. Cytotoxicity (% lysis) was tested against Daudi target cells in a 4-hr 51Cr-release assay. The combination of IL2 and TNF alpha resulted in a significantly greater-fold expansion of TIL than IL2 alone (P less than 0.01). Lamina propria mononuclear cells expanded less than TIL, and TNF alpha had an inhibitory effect on their growth (P less than 0.05). Tumor-infiltrating lymphocytes and LPMC showed comparable cytotoxicity when cultured with IL2 alone. However, the addition of TNF alpha augmented the killer activity of TIL while inhibiting that of LPMC (P = 0.035). These results indicate that TNF alpha selectively increases the IL2-induced growth and cytotoxic function of colorectal cancer TIL, but not those of gut mucosal lymphoid cells, suggesting that TIL and LMPC differ in their response to TNF alpha. Therefore, this combination of cytokines may hold more promise than single agents for the immunotherapy of colorectal cancers with TIL.

Is colonoscopic screening appropriate in asymptomatic patients with family history of colon cancer?

Colonoscopy has been advocated by some investigators as the most appropriate means of screening asymptomatic patients with a positive family history of colorectal cancer. However, results of such screening have been widely disparate. The purpose of this study was to evaluate the yield of colonoscopy in a cohort of completely asymptomatic individuals with one or two first-degree relatives with a history of colorectal cancer and to compare this yield with that of colonoscopy in a group of patients with apparent anal bleeding. Patients with possible genetic disorders, such as familial polyposis, were excluded. A total of 160 asymptomatic patients and a comparison group of 137 patients with nonacute anorectal bleeding underwent colonoscopy. Colonoscopy was completed in 143 of the 160 study patients (89 percent) and in all of the comparison patients and did not result in any complications. Twenty-two adenomas were found in 17 study patients (10.6 percent); 16 of the 22 adenomas were less than 1 cm in size. In the comparison group, eight adenomas were identified (5.8 percent of patients). No cancers were identified. The difference in polyp frequency between groups was not significant. The relatively low yield of colorectal neoplasms discovered at colonoscopy in this study may in part be due to the small sample size or to the strict criteria used to define these asymptomatic patients but does not lend strong support to the notion that colonoscopy is an appropriate first step in screening the asymptomatic patient with one or two first-degree relatives with colon cancer.

Clinical relevance of biochemical modulation of 5-fluorouracil

Biochemical modulation is a special type of combination chemotherapy which aims to selectively improve the therapeutic index by increasing the antitumor effect and protecting against toxic side effects. Biochemical modulation seems to be an attractive way to circumvent quantitative and qualitative heterogeneity of tumors. In the past decade a number of biochemical modulation approaches have been tested to improve the activity of 5-fluorouracil (5FU). 5FU itself has only modest anticancer activity but has been shown to be a very attractive target for biochemical modulation. A number of the combinations have been ineffective in the clinic despite extensive testing in a number of schedules. Some other combinations were initially tested in an inappropriate schedule, but were active when applied in another schedule. The latter was made possible by a systematic preclinical development of combinations with a proper translation to the clinic accompanied by pharmacodynamic evaluation. This review describes a number of biochemical modulation combinations, both inactive and active. The main conclusion is that properly applied biochemical modulation schedules may lead to successful use in the clinic.