Search

Historically, locally advanced rectal cancer is known for its dismal prognosis. The treatment of locally advanced rectal cancer is subject to continuous change due to development of new and better diagnostic tools, radiotherapeutic techniques, chemotherapeutic agents and understanding of the subject. It is clear, that a multimodality approach is the only way to achieve satisfactory local recurrence and survival rates in this type of cancer. However, which multimodality strategy is to be used still remains a point of controversy. This review summarises recent developments in imaging, (neo-) adjuvant therapy and surgical techniques in the treatment of primary locally advanced rectal cancer.

Patients with a germline mutation leading to a deficiency of the dihydropyrimidine dehydrogenase (DPD) enzyme are at risk from developing severe toxicity on the administration of 5FU-containing chemotherapy. We report on the implications of this inborn genetic error in two patients who received 5FU and oxaliplatin. A possible co-medication effect of oxaliplatin is considered, as are the consequences of screening for DPD deficiency.

Purpose: The aim of this study was to determine the relationship between survival and value of molecular markers in the primary tumour in a group of patients with irresectable rectal cancer, treated with preoperative chemo-radiotherapy., Materials and Methods: Immunohistochemistry for p53, p21, bcl-2 and Ki-67 was performed on pre-treatment biopsy specimens of 34 patients with irresectable rectal cancer. Preoperative treatment consisted of pelvic irradiation of 45-56 Gy, combined with 5FU and leucovorin (350/20 mg/m2 x 5 d; in weeks 1 and 5 during radiotherapy). The median follow-up was 38 months. Endpoints were pathological T-stage and survival after surgery., Results: Expression of p21 correlated significantly with survival (p=0.005). Survival and p21 expression also correlated significantly, when adjusted for tumour response (p=0.005, RR=4.8 (1.6-14.7))., Conclusion: Expression of p21 predicts a worse survival in irresectable rectal cancer treated with preoperative chemo-radiotherapy. No relationship was found between tumour response in chemo-radiotherapy and p53, bcl-2 or Ki-67.

An improved understanding of the pathogenesis of inflammatory bowel disease (IBD) has led to the development of new drugs such as infliximab and insights into the modes of action of commonly used drugs such as azathioprine and methotrexate. These drugs act, at least in part, by inducing apoptosis of activated T-cells, which are an important phenomenon in the aberrant mucosal immune response in Crohn's disease. Gene therapy directed towards delivering anti-inflammatory proteins such as interleukin 10 (IL-10) to the inflamed mucosa is another new means of correcting the balance between the proinflammatory and anti-inflammatory cytokines in IBD. Gene-therapeutic manipulation of T-cells or bacteria to make them selectively deliver IL-10 to the gut mucosa has been successfully described in experimental models of IBD. Although interleukin-10-based gene therapy for Crohn's disease is an attractive option, safety aspects concerning the gene transfection method and questions about the efficacy of interleukin-10 in Crohn's disease in particular, prevent its application in the near future.

In rats, the relationship between [(18)F]FHPG accumulation and HSVtk expression was studied with PET and autoradiography. [(18)F]FHPG distribution closely corresponded with HSVtk immunohistochemical staining. ROI analysis of tracer uptake 2 hours p.i. and Patlak graphical analysis were applied to quantify the PET data. For both analysis methods, the [(18)F]FHPG PET signal correlated well with the fraction of HSVtk expressing cells implanted, but showed a plateau when plotted against HSVtk protein levels. This might be due to rate limiting [(18)F]FHPG membrane transport.

Background: Cornea-derived transcript 6 (CDT6, also known as AngX) has been described to inhibit tumour growth in a human melanoma growing in nude mice. In another report, however, enhancement of tumour growth in comparable circumstances occurred. We therefore studied the effect of the same gene in different circumstances, using an immune competent mouse model., Materials and Methods: In this report we describe the generation of a stably CDT6-expressing clone of the murine melanoma cell line B16-F10. These cells were implanted in female C57/B16 mice with empty vector transfected cells as control., Results: We found no significant inhibition or stimulation of either lag-time or doubling-time of the tumours. In addition no effect of the CDT6 gene product was found on proliferation of endothelial cells in vitro., Conclusion: In contrast to an immune deficient mouse model, no anti-tumour effect could be detected with the CDT6 gene product in an immune competent mouse model.

To improve current angiogenic gene therapy with a vascular endothelial growth factor (VEGF)-encoding plasmid (Baumgartner et al. Circulation 1998; 97: 1114-23 [1]; Kusumanto et al. Fifth Annual Meeting of the American Society of Gene Therapy, Boston, 2002, Abstr. 621 [2]), we have generated a combination plasmid, encoding the VEGF gene and the thymidine phosphorylase (TP, also known as platelet-derived endothelial growth factor (PD-ECGF) or gliostatin (GLS)) gene: phVEGF165-TP.MB. Upon transfection in COS-7 cells both gene products were expressed and functional as shown by Western blots, ELISAs and bioassays. Culture supernatants of COS-7 cells transfected with this plasmid were able to induce endothelial proliferation. In an in vitro angiogenesis assay with recombinant proteins, TP was able to increase VEGF-induced tube formation. The phVEGF165-TP.MB plasmid is therefore a promising candidate for in vivo angiogenesis studies.

Background: Cornea-derived transcript 6 (CDT6 = AngX) has been shown to have an anti-tumor effect., Materials and Methods: We transfected the murine melanoma cell line B16-F10 with the CDT6 gene and compared the sensitivity to cytostatic drugs of the resulting cell line, B16-CDT6, to that of the empty vector-transfected control cell line B16-CMV., Results: The B16-CDT6 line showed a significantly increased sensitivity to doxorubicin as well as a tendency towards a decreased sensitivity to cisplatin. To further resolve the mechanism of the increase in sensitivity to doxorubicin, we also tested the cytotoxic agents vincristine, etoposide and taxol. However no difference in sensitivity for these drugs was found between the B16-CDT6 and the control cell line., Conclusion: CDT6 increased the sensitivity to doxorubicin in a mechanism probably not related to interference with the efflux pumps MRP, Pgp or the DNA-associated target enzyme topoisomerase II. Altered gene expression induced by gene therapy might influence tumor sensitivity to chemotherapy.

Therapeutic angiogenesis constitutes an alternative treatment for patients with extensive tissue ischaemia in whom primary vascular reconstruction procedures are not feasible or have previously failed. At present vascular endothelial growth factor (VEGF) has been the most widely used angiogenic factor in experimental and human clinical trials. Early clinical data provide evidence that gene transfer of the VEGF gene can achieve beneficial angiogenesis, with minimal side-effects. Ongoing phase III clinical studies will reveal definitive efficacy.

Initial treatments of locally advanced rectal cancers focus on local control, as local relapse of a rectal cancer is correlated with a high morbidity and mortality. We studied the effect of neoadjuvant radiochemotherapy on advanced rectal cancer patients in relation to downstaging, local relapse and survival. Post-treatment pathological staging, local relapse and survival were analysed in 66 patients from a single institution. 43 patients had irresectable cancer as determined by laparatomy (n=42) or rectal examination (n=1). These 43 patients received 45-56 Gy preoperatively with 5-fluorouracil (5-FU) and leucovorin (350/20 mg/m(2)x5 day (d)) in weeks 1 and 5 during the radiation therapy. 23 patients had primary resectable tumours with a T1-2 stage. Of the initially irresectable tumours 79% became macroscopically resectable, in 74% a R0 resection was performed. In 6 of 34 (18%) surgical specimens, no tumour was found (pT0), 7 patients had small tumour remnants (pT1-2). In these pT0-2 tumours, no local relapses occurred (observation period of median 4.5 years, range 18-87 months). In the 21 patients with pT3-4 tumours 3 local relapses were seen. In the 23 patients with primary resectable T1-2 tumours the relapse rate was 4%. Downstaging of an initially irresectable rectal tumour to pT2 or less results in a local relapse rate and overall survival that correspond with the rates in primary resectable cancer with the same T classification.

The measurement of circulating vascular endothelial growth factor (VEGF) levels as a prognostic factor will gain increasing relevance in the diagnosis and evaluation of treatment in cancer patients. Angiogenesis is an absolute requirement in tumour growth and metastatic disease. In the present study data are presented which indicate that circulating VEGF mainly resides in peripheral blood cells. In 15 healthy volunteers we demonstrated that approximately 34% of the circulating VEGF resides in platelets and approximately 11% in patients with cancer ( n = 4). An important part namely 58% in healthy volunteers and 69% in patients with cancer of the total circulating VEGF is contained in granulocytes, particular in the neutrophils, as confirmed by fluorescence-activated cell sorting (FACS). Also an increased VEGF level per granulocyte is found in patients with cancer (77 microg VEGF/l) compared with the healthy volunteers (164 microg VEGF/l). In contrast only 2% was present in plasma. The biological significance of platelet- or granulocyte-derived VEGF is not yet known. Liberation of VEGF from these compartments could well be of importance for tumour angiogenesis. Therefore, future studies on the clinical value of circulating VEGF as a prognostic factor in cancer patients should include measurements of VEGF in peripheral blood cells.

We investigated if dendritic cells (DCs) were able to present intracellularly located antigens derived from apoptotic cells to T cells, thereby inducing a CD4+ and a CD8+ response. A transfected cell line with the cytomegalovirus-derived protein pp65 was triggered to go into apoptosis by ultraviolet B (UVB) irradiation, and after the uptake of apoptotic cells by DC, the activation and proliferation of T cells were determined. We found that DC efficiently phagocytosed apoptotic cells and induced a CD4+ and a CD8+ T-cell response specific for the viral protein pp65. This mechanism can be useful for vaccination studies to induce an antiviral immune response.

Despite the development of new therapeutic strategies, cancer remains incurable in most patients with advanced disease. A recent potential improvement in therapeutic strategies is the concept of suicide gene therapy. After transfection with a suicide gene, cells can convert a harmless prodrug into its toxic metabolite, resulting in selective elimination of these cells. One of the most frequently studied therapeutic strategies is based on transfection with the herpes simplex virus thymidine kinase gene (HSV-tk), followed by ganciclovir administration. Despite promising results in vitro and in vivo, the antitumor effect in clinical trials remains poor, due to very low transfection efficiency. However, high percentages of transfected cells are not mandatory for complete eradication of a tumor in vivo. Transfected tumor cells appear to be capable of inducing the death of neighboring untransfected cells. This cell kill is called the "bystander effect". Various attempts have been made to increase this effect. A substantial bystander effect could overcome the limitations of low transfection efficiency and result in an enhanced and possibly clinically worthwhile antitumor effect in patients. This review is focused on the HSV-tk/GCV system and gives an overview of current knowledge on the bystander effect in vitro and in vivo. In addition, theories concerning its mechanisms and possible approaches to augment this effect are discussed. Finally, we give an overview of clinical trials using suicide gene therapy.

Although there has been considerable experience with interferons in the treatment of malignancy and viral illnesses, acute renal failure as a side-effect of interferon treatment has rarely been reported. We present the case of a patient who developed acute on chronic renal failure 16 months after the initiation of interferon alpha 2b for a metastatic carcinoid tumor.

The evolution of molecular biology has enabled the exploration of novel sophisticated gene-directed treating modalities for cancer. Suicide gene therapy - i.e. transfection of a so-called suicide gene that sensitizes target cells towards a prodrug - may offer an attractive approach to treat malignant tumors. For the development of effective clinical suicide gene therapy protocols, a non-invasive method to assay the extent, the kinetics and the spatial distribution of transgene expression is essential. This would allow investigators and physicians to assess the efficiency of experimental and therapeutic gene transfection protocols and would enable early prognosis of therapy outcome. Radionuclide imaging techniques like single photon emission computed tomography (SPECT) and positron emission tomography (PET), which can non-invasively visualize and quantify metabolic processes in vivo, are being evaluated for repetitive monitoring of transgene expression in living animals and humans. Transgene expression can be monitored directly by imaging the expression of the therapeutic gene itself, or indirectly using a reporter gene that is coupled to the therapeutic gene. Various radiopharmaceuticals have been developed and are now being evaluated for imaging of transgene expression. This review surveys the progress that has been made in the field of non-invasive nuclear imaging of transgene expression and focuses on the herpes simplex virus type 1 thymidine kinase (HSVtk) gene therapy approaches.

This paper describes the production of recombinant Semliki Forest virus encoding murine or human granulocyte-macrophage colony-stimulating factor (GM-CSF) and the capacity of these vectors to transduce murine and human tumor cells ex vivo. High-titer stocks (up to 3 x 10(9) particles/ml) of conditionally infective, replication-defective, recombinant SFV particles were generated using the SFV Helper-2 system. It is shown that the recombinant SFV/GM-CSF virus, as well as recombinant SFV carrying the beta-galactosidase reporter gene, efficiently transduce both murine tumor cell lines as well as primary human renal carcinoma cells. Using ELISA's specific for GM-CSF, levels of GM-CSF production by the cells were determined. Levels of murine GM-CSF (mGM-CSF) produced by SFV/mGM-CSF transduced renal cell cancer cultures were equal to or higher than corresponding levels reported in the literature after transduction of similar renal carcinoma cell cultures using a retroviral vector system. The biological activity of GM-CSF was demonstrated by using cells which are dependent on GM-CSF for growth and by using primary bone marrow cells. All the transduced cell cultures (including the human renal cell carcinoma samples) produced GM-CSF for up to at least 4 days after transduction. The results imply that the recombinant SFV system can be used for rapid and facile preparation of autologous cancer cell vaccines.

A 55-year-old man receiving alpha-interferon and interleukin-2 therapy for renal cell carcinoma presented with seizures and delirium. A CT-scan of the cerebrum did not reveal any disorder. Both alpha-interferon and interleukin-2 were stopped. Treatment with steroids led to complete regression of central nervous system symptomatology. We emphasize the importance of ruling out iatrogenesis in patients treated with alpha-interferon and/or interleukin-2 who display neuropsychiatric symptoms.

Occasionally long-term survival in disseminated melanoma can be obtained through chemotherapy. We treated 22 patients with disseminated melanoma with an outpatient regimen consisting of dacarbazine (DTIC) and carboplatin. Three patients had a complete response lasting 4+, 9 and 9 months (survival 4+, 10 and 16 months), respectively; 3 patients had a partial response lasting 4, 6 and 8 months (survival 6+, 11+ and 14 months), respectively. Overall response was 27% (95% confidence interval 11-50%). Toxicity was relatively mild and mainly due to nausea. In 3 patients the dose of carboplatin was reduced because of grade 4 haematological toxicity. This described easy outpatient regimen shows comparable results as other polychemotherapeutic regimens in disseminated melanoma, but with a relatively mild toxicity profile.

long-term peripheral blood counts and factors influencing long-term trilineage haematological recovery of consecutive patients in a single institution treated with high-dose chemotherapy (hdc) and abmt or psct for solid tumours were examined. patients with a relapse-free survival of >1 year were included in the analysis (n = 131). Peripheral blood counts were examined 6 months and yearly following transplantation. Median follow-up was 4.1 years (range 1-10+ years). Three years after transplantation 91% of patients had normal white blood counts (WBC), 94% normal haemoglobin (Hb) and 75% normal platelets. Trilineage recovery was complete in 70% (n = 83) at 3 years and 85% (n = 50) at 5 years. Recovery of Hb occurred before WBC and platelet recovery. Approximately 25% of patients displayed an elevated MCV throughout the follow-up period. These long-term results were independent of age, high-dose regimen, number of reinfused stem cells and stem cell source. Double (n = 12) vs single (n = 119) transplantations showed significantly slower trilineage recovery and higher MCV. No secondary graft failure, myelodysplasia or leukaemia was encountered. In conclusion, complete trilineage recovery after HDC followed by ABMT or PSCT occurs slowly. PSCT and ABMT are capable of maintaining long-term haematopoiesis. Slower recovery is seen after double transplantations. The results suggest lasting implications for bone marrow function after autologous transplantation.

Endothelial cells (EC) are currently used as in vitro model systems for various physiological and pathological processes, especially in angiogenesis research. Primary EC have a limited lifespan and display characteristics that differ from batch to batch due to their multidonor origin. In recent years many groups have established EC lines. This Review gives an overview of the advantages and disadvantages of currently available vascular EC lines. Its aim is to help the investigator to decide which cell line matches his or her research goal best. Truly immortalized cell lines are generally better characterized and more stable in their endothelial traits than EC that were given an extended life span. Presently the best characterized macro- and micro-vascular EC lines are EA.hy926 and HMEC-1, respectively.

The reverse transcriptase polymerase chain reaction (RT-PCR) can be of clinical relevance in identifying malignant melanoma cells in blood or tissues of patients at risk for disseminated melanoma. The diagnostic value of this marker however, is still controversial. The objective of this study was to compare and quantify the difference in sensitivity of the nested RT-PCR for tyrosinase, with respect to the method utilized to produce the template c-DNA. We found a difference of a factor 10 in favor of a specific priming versus a random one. We concluded that this difference can be exploited in the analysis of blood samples. However, in the analysis of lymph node specimens, where the chance of positivity due to tyrosinase positive non-melanoma cells is much higher, the choice of a highly sensitive assay should be made with caution.

Cytotoxic T cells can specifically kill target cells that express antigens recognized by the T-cell receptor. These are membrane-bound proteins that are not ubiquitous and thus are difficult to purify and study at the protein level. The advent of recombinant DNA technology has facilitated these objectives, thereby enabling researchers to gain valuable information about major T-cell receptor characteristics. Genetic manipulation of T-cell receptors has also been used to exploit specificity of killing by cytotoxic T lymphocytes, which represents an attractive feature for therapeutic purposes. The objective of this review was to provide an overview of the major strategies adopted to genetically manipulate T-cell receptors.

The specificity and sensitivity of the nested reverse transcriptase polymerase chain reaction (RT-PCR) on tyrosinase was studied, for the detection of micrometastases of malignant melanoma. The specificity was assessed in the blood of six healthy donors, four patients with non-melanoma cancers of which one patient was treated with granulocyte-colony stimulating factor. Lymph nodes of nine patients without malignant melanoma were tested and four cell lines of various other tumours. Six of the nine non-melanoma lymph nodes were positive in this assay. The sensitivity was tested in a spike experiment in vitro, using a melanoma cell line. The detection limit was ten melanoma cells per 10(7) peripheral blood lymphocytes.

Background: The T cell receptor (TCR) is an heterodimeric protein on the cell membrane of cytotoxic T cells (CTLs). In CTLs TCRs mediate the recognition of target cells through interaction with specific, MHC class I presented peptides., Materials and Methods: As a model system to show proof of principle we chose the Jurkat/MA cell line and the HLA-A2.1 binding MAGE-3 derived peptide 271-279, as target specificity., Results: We show that this cell line can be successfully transduced with the dicistronic retroviral vector (LZRS) containing cDNAs encoding for the complete alpha and beta chains of the selected TCR. Following retroviral transduction, Jurkat/MA cells do express the anti-MAGE-3 TCR on their membrane. The transduced TCR is functional as travoductants are successfully triggered, upon stimulation with T2 cells or MAGE-3+ melanoma cells loaded with the MAGE-3 peptide., Conclusion: We conclude that TCR gene transfer is possible and it represents a powerful therapeutic tool for the genetical modification of T calls of patients sullering from cancer.

9-[(1-[18F]Fluoro-3-hydroxy-2-propoxy)methyl]guanine ([18F]FHPG) was evaluated as a tracer for noninvasive positron emission tomography (PET) imaging of herpes simplex virus type 1 thymidine kinase (HSV-tk) gene expression. C6 rat glioma cells with and without the HSV-tk gene were incubated with [18F]FHPG for 2 h. The in vitro tracer uptake in HSV-tk-containing C6tk cells was 35 +/- 5 times higher than that in control cells. In nude rats carrying both a C6 and a C6tk tumor, the average ratio of tracer accumulation between the tumors was 15 +/- 5 at 2 h postinjection. The tracer is rapidly cleared from nontarget tissue into the urine because only the HSV-tk-expressing tumor, kidneys, and bladder remained visible on the late PET images. HPLC analysis revealed that three metabolites, tentatively assigned as FHPG mono-, di-, and triphosphate, were formed in the C6tk tumors only. In conclusion, we have demonstrated that [18F]FHPG is a promising tracer for monitoring HSV-tk enzyme activity in vivo with PET.

[(11)C]-2'-Fluoro-5-methyl-1-beta-D-arabinofuranosyluracil ([(11)C]FMAU) and [(18)F]-9-[(3-fluoro-1-hydroxy-2-propoxy)methyl]guanine ([(18)F]FHPG), radiolabeled representatives of two classes of antiviral agents, were evaluated as tracers for measuring herpes simplex virus thymidine kinase (HSV-tk) enzyme activity after gene transfer and as tracers for localization of active human cytomegalovirus (HCMV) infections. In vitro accumulation experiments revealed that both [(11)C]FMAU and [(18)F]FHPG accumulated significantly more in HSV-tk expressing cells than they did in control cells. [(18)F]FHPG uptake in HSV-tk expressing cells, however, was found to depend strongly on the cell line used, which might be due to cell type dependent membrane transport or cell type dependent substrate specific susceptibility of the enzyme. In vitro, both tracers exhibited a good selectivity for accumulation in HCMV-infected human umbilical vein endothelial cells over uninfected cells. In contrast to [(18)F]FHPG, [(11)C]FMAU uptake in control cells was relatively high due to phosphorylation of the tracer by host kinases. Therefore, [(18)F]FHPG appears to be the more selective tracer not only to predict HSV-tk gene therapy outcome, but also to localize active HCMV infections with PET.

Drug resistance is a major cause of chemotherapy failure in cancer treatment. One reason is the overexpression of the drug efflux pump P-glycoprotein (P-gp), involved in multidrug resistance (MDR). In vivo pharmacokinetic analysis of P-gp transport might identify the capacity of modulation by P-gp substrate modulators, such as cyclosporin A. Therefore, P-gp function was measured in vivo with positron emission tomography (PET) and [11C]verapamil as radiolabeled P-gp substrate. Studies were performed in rats bearing tumors bilaterally, a P-gp-negative small cell lung carcinoma (GLC4) and its P-gp-overexpressing subline (GLC4/P-gp). For validation, in vitro and biodistribution studies with [11C]daunorubicin and [11C]verapamil were performed. [11C]Daunorubicin and [11C]verapamil accumulation were higher in GLC4 than in GLC4/P-gp cells. These levels were increased after modulation with cyclosporin A in GLC4/P-gp. Biodistribution studies showed 159% and 185% higher levels of [11C]daunorubicin and [11C]verapamil, respectively, in GLC4 than in GLC4/P-gp tumors. After cyclosporin A, [11C]daunorubicin and [11C]verapamil content in the GLC4/P-gp tumor was raised to the level of GLC4 tumors. PET measurements demonstrated a lower [11C]verapamil content in GLC4/P-gp tumors compared with GLC4 tumors. Pretreatment with cyclosporin A increased [11C]verapamil levels in GLC4/P-gp tumors (184%) and in brains (1280%). This pharmacokinetic effect was clearly visualized with PET. These results show the feasibility of in vivo P-gp function measurement under basal conditions and after modulation in solid tumors and in the brain. Therefore, PET and radiolabeled P-gp substrates may be useful as a clinical tool to select patients who might benefit from the addition of a P-gp modulator to MDR drugs.

In a prospective randomized trial, 40 stage IV breast cancer patients undergoing intermediate high-dose chemotherapy (cyclophosphamide, 5-fluorouracil plus epirubicin or methotrexate), received either recombinant human G-CSF (rhG-CSF, group I) or ciprofloxacin and amphotericin B (CAB, group II) for prevention of febrile leucopenia (FL). In group I, seven of 18 patients developed FL (after 10/108 courses); in group II, seven of 22 patients (7/98 courses) (P = NS). Median hospitalization duration and costs were not different. RhG-CSF was 6.6 times more expensive per course than CAB. In conclusion, prophylactic CAB has similar efficacy to rhG-CSF in this setting, and is more cost-effective.

Radio- and chemotherapy for the treatment of malignancies are often associated with significant toxicity. One approach to reduce the toxicity is the concomitant treatment with chemoprotective agents. This article reviews two sulfhydryl compounds, namely the agent WR-2721 (amifostine), a compound recently registered for use in human in many countries, and the natural occurring compound glutathione (GSH). GSH is not registered as a chemoprotective agent. WR-2721 is an aminothiol prodrug and has to be converted to the active compound WR-1065 by membrane-bound alkaline phosphatase. WR-1065 and GSH both act as naturally occurring thiols. No protective effect on the tumour has been found when these compounds are administered intravenously. There is even in vitro evidence for an increased anti-tumour effect with mafosfamide after pretreatment with WR-2721, and in vivo after treatment with carboplatin and paclitaxel. Randomized clinical studies have shown that WR-2721 and GSH decrease cisplatin-induced nephrotoxicity and that WR-2721 reduces radiation radiotherapy-induced toxicity. Side-effects associated with WR-2721 are nausea, vomiting and hypotension, GSH has no side-effects. An exact role of WR-2721 and GSH as chemoprotectors is not yet completely clear. Future studies should examine the protective effect of these drugs on mucositis, cardiac toxicity, neuro- and ototoxicity, the development of secondary neoplasms and their effect on quality of life.

Specific inhibition of mammalian genes is possible through the use of antisense oligonucleotides (AS ODNs) or ribozymes. These strategies have led to a better understanding of several cellular and molecular mechanisms, among which cancer development. Recently, these strategies have been applied also for therapeutical purposes in diseases such as AIDS and cancer. In some of these therapeutical trials the antisense strategy is combined with gene transfer technology: the AS ODN or the ribozyme are expressed within the cell by the use of adenoviral or retroviral vectors. However, many difficulties have still to be overcome before ODNs and ribozymes can be used routinely in the clinic.

Twenty-nine patients with metastatic or T4 breast cancer who were in pathologically proven complete remission after induction chemotherapy, received intensification chemotherapy with autologous bone marrow support. Twelve patients had T4 breast cancer, 17 had metastatic disease. The median age was 42 years (27-52). Intensification consisted of cyclophosphamide 7 g/m2 i.v. and etoposide 1.5 g/m2 i.v. in 24 patients, or thiotepa 800 mg/m2 i.v. and mitoxantrone 50-75 mg/m2 i.v. in 5 patients. The median observation is 7 years. Median survival is 36 months. Ten year relapse-free survival is 20%. For patients with metastatic disease median survival is 34 months, time to relapse 18 months; two patients (12%) have survived disease-free for more than 6 years. The patients with T4 cancer have a median survival of 80 months and a median time to relapse of 53 months; four patients (33%) have survived more than 5 years disease-free.

This article describes the use of granulocyte macrophage colony stimulating factor and granulocyte colony stimulating factor in two patients with drug induced granulocytopenia. A granulocyte count > 1 x 10(9)/l was obtained after 7 days' treatment. These results suggest that the haematopoietic growth factors shortened the period of agranulocytosis and subsequently may improve the survival of these patients.

Dengue haemorrhagic fever in two female tourists to Thailand (1990) and Indonesia (1989) respectively, is reported for the first time in the Netherlands. The main symptoms directly after return were high fever, haemorrhagic exanthema, thrombocytopenia and in one patient signs of haemoconcentration. Initially both patients were treated with antibiotics. They recovered after intravenous fluid therapy; one of them received a thrombocyte transfusion. Increasing travel to Asia and South America will result in more tourists returning with this potentially serious arboviral disease (dengue haemorrhagic shock).

The cisplatin(CDDP)-resistant cell line GLC4-CDDP shows a variety of differences from the parent line GLC4. The aim of this study was to determine which of the observed changes correlated with the degree of resistance and was therefore relevant to the phenomenon of CDDP resistance. For these experiments we used cells of the sensitive hSCLC cell line GLC4 and the in vitro-acquired CDDP-resistant sublines GLC4-CDDP3 and GLC4-CDDP11, with a resistance factor (RF) of 3 and 11 respectively for CDDP and of 1.8 and 7.4 respectively for carboplatin. Carboplatin was used, in addition to CDDP in seeking relevant mechanisms. No consistency was found between the RF and the growth pattern or antigen expression, cellular volume, doubling time, cellular or nuclear platinum (Pt) content or the level of Pt-non-histone chromatin protein (NHCP) binding. A correlation was found between the RF and the level of glutathione (GSH), and a trend was found for the level of Pt-DNA binding, Pt-GG adduct content and the amount of interstrand cross-links (ISC). These changes might therefore be relevant for the development of resistance. These findings are compatible with a GSH-induced reduction of the amount of reactive Pt in the resistant cell, resulting in a lower net platination and toxic Pt-DNA adduct formation.

The role of glutathione (GSH) in resistance to cisplatin (CDDP) was studied in a human small cell lung carcinoma cell line (GLC4) and a CDDP-resistant subline (GLC4-CDDP). In addition to studying the steady state of GSH, the kinetics of this defence system were also studied via the monitoring of the GSH status of the cells under continuous pressure of CDDP. GLC4-CDDP maintained its elevated GSH level whereas GLC4 (under pressure of CDDP) quickly synthesised GSH to about twice its initial level, corresponding with 80% of the GSH level of GLC4-CDDP. D,L-buthionine-S,R-sulphoximine (BSO) was used to analyse the role of GSH in resistance to CDDP. Pretreatment with BSO (48 h, 50 microM, GSH not detectable) increased the CDDP-induced cytotoxicity 2.8-fold in GLC4-CDDP and 1.7-fold in GLC4. In GLC4 no changes in the amount of platinum (Pt) bound to DNA could be observed after GSH depletion. Changes in formation of interstrand cross-links or the main Pt-containing intrastrand cross-link in digested DNA, the Pt-GG adduct, were also not observed. In GSH depleted GLC4-CDDP cells, an increase in the amount of Pt bound to DNA and in the Pt-GG adduct was observed. Pretreatment with BSO substantially reduced the repair of Pt bound to DNA in both cell lines. We conclude that an increased GSH level and GSH synthesis capacity were demonstrated in CDDP resistant cells. The observations after BSO treatment suggest two roles for GSH in CDDP resistance, namely that of a cytosolic elimination resulting in less DNA platination and a nuclear effect on the formation and repair of DNA platinum adducts.

In DNA digested samples of CDDP sensitive (GLC4) and an 11-fold resistant (GLC4-CDDP) hSCLC line, the CDDP induced DNA adducts Pt-GG (Pt-(NH3)2d (pGpG], Pt-AG (Pt-(NH3)2d (pApG], G-Pt-G (Pt-(NH3)2d (GMP)2) and Pt-GMP (Pt-(NH3)3d GMP), were measured with polyclonal antibodies. The total amount of platinum (Pt) bound to DNA was also measured but with the help of atomic absorption spectroscopy (AAS). An increased net formation in GLC4 compared with GLC4-CDDP is found for the total Pt bound to DNA, Pt-GG and Pt-AG adducts after a 2 h 100 microM CDDP treatment. No significant difference is detected in the net formation of the Pt-GMP and G-Pt-G adducts. A slow Pt-AG adduct formation, with a maximum reached 10 h after CDDP composition, is found for both cell lines. In the 22 h period after the 2 h 100 microM CDDP treatment, a significant removal in GLC4 is measured for the Pt-GG, Pt-AG and the Pt-GMP adducts. For GLC4-CDDP a significant removal is detected in the total Pt bound to DNA, the Pt-AG and the Pt-GMP adducts. The removal of the total Pt bound to DNA in GLC4-CDDP cannot be explained by an adduct measured with the immunochemical method. In conclusion, no evidence is found that CDDP resistance is based upon the repair of the Pt-GG, Pt-AG, G-Pt-G and Pt-GMP adducts.

Treatment of cancer patients often fails because of the resistance in the tumor to chemotherapeutic drugs. A better understanding of mechanisms which are active in resistant cells might lead to measures to circumvent the resistance. This review deals with the mechanisms of action of cisplatin (CDDP) and the various causes for CDDP resistance in the tumor cells. Also, possibilities to circumvent CDDP resistance in vitro and in vivo are presented.

In a sensitive, human, small cell lung carcinoma cell line (GLC4) and a cisplatin (CP)-resistant subline (GLC4-CP), the effect of co-culturing with docosahexaenoic acid (DCHA) on CP cytotoxicity was studied. Cells were cultured for 4 days, with 32 microM of DCHA added on days 1 and 3. Incorporation of DCHA into the cellular phospholipids was demonstrated by fatty acid analysis. Supplementation with DCHA led to almost a threefold decrease of resistance in GLC4-CP and had no influence on CP cytotoxicity in GLC4. After culturing with DCHA, cellular platinum (Pt); total Pt bound to DNA; and Pt-GG, Pt-AG, G-Pt-G, and Pt-GMP adduct contents increased in both lines, whereas interstrand cross-link formation was elevated only in GLC4-CP. These experiments demonstrate that DCHA reduces CP resistance. Although an effect on cellular membranes resulting in an increased CP uptake apparently was present, this mechanism does not seem to be responsible for resistance modulation. Rather, an effect on nuclear, probably DNA-related, structures is likely and leads to an increased formation of interstrand cross-links in GLC4-CP.

A 6.4-fold cis-diamminedichloroplatinum(II) (CDDP) resistant human small cell lung carcinoma cell line (GLC4-CDDP) was developed to study acquired CDDP resistance in vitro. Compared to the sensitive cell line (GLC4), the GLC4-CDDP showed an increase in doubling time and a decrease in cloning efficiency, cellular size, double minutes per cell, cellular protein, and nuclear protein content. While a complete cross-resistance for tetraplatin and a partial cross-resistance for doxorubicin, melphalan, cadmium chloride, carboplatin, and cis-dichloro-trans-dihydroxo-cis-bis(isoprolylamine)platinum (IV) (resistance factor, respectively,4.0,5.8,2.1,1.5,2.9) was found, no cross-resistance for vincristine was found. In the GLC4-CDDP line in comparison to the GLC4 line, glutathione and total amount of sulfhydryl compounds was significantly increased, while glutathione S-transferase and glutathione reductase was the same. The platinum content in cells and nuclei was lower in the resistant line, but after correction for cellular protein or volume no difference was found. The amount of platinum bound to DNA was significantly lower in the GLC4-CDDP line. After a 1-h incubation with CDDP, the amount of Pt-GG adducts was the same and the amount of interstrand cross-links was reduced in the GLC4-CDDP line as compared to GLC4. In conclusion, in the GLC4-CDDP line the phenotype and genotype are changed and various mechanisms, such as decreased Pt-DNA binding, elevated glutathione, and reduced interstrand cross-links, play a role in the development of the CDDP resistance.