New approaches to treatment of metastatic bladder cancer

The adeno-associated virus-mediated HSV-TK/GCV suicide system: a potential strategy for the treatment of bladder carcinoma

Novel treatment strategies such as gene therapy are warranted in view of the failure of current treatment approaches to cure a high percentage of patients with advanced bladder cancers. The emergence of cancer gene therapy potentially offers a number of exciting treatments. The majority of approaches involve strategies to suppress the function of activated oncogenes to restore the expression of functional tumour suppressor genes or to initiate tumour self-destruction. One gene therapy approach against tumours that holds great promise is suicide gene therapy. Herpes simplex virus thymidine kinase (HSV-TK) phosphorylates ganciclovir (GCV), which in turn interacts with cellular DNA polymerase and interferes with DNA synthesis to cause death of rapidly dividing cells. The development of an effective delivery system is absolutely critical to the usefulness and safety of gene therapy. At present, the adeno-associated virus (AAV) vector has the most promising potential in view of its non-pathogenicity, wide tropisms and long-term transgene expression in vivo. Gene therapy studies using different serotypes of recombinant AAV (rAAV) as delivery vehicles have proved rAAVs to be an effective modality of cancer gene therapy. In the present study, we investigated the suppression effect of AAV-mediated HSV-TK/GCV system on the bladder cancer cells and in mice xenograft models of bladder cancer. Our data demonstrate that rAAV-HSV-TK system controlled tumour cell growth and achieves strong antitumour efficacy in vivo. These findings provide a foundation for the development of potential targeted clinical therapies for bladder cancer in humans.

Suppression of bladder cancer growth in mice by adeno-associated virus vector-mediated endostatin expression

Novel treatment strategies such as gene therapy are warranted in view of the failure of current treatment approaches to cure a high percentage of patients with advanced bladder cancers. Testing of the hypothesis that blocking the angiogenic switch may keep tumour growth in check has been facilitated by the discovery of endogenous inhibitors of angiogenesis and has also added another research dimension to the field of cancer gene therapy. Consequently, the concept of targeting the tumour vasculature with anti-angiogenic agents has emerged as an attractive new strategy in the treatment of cancer. Targeted biological therapies that selectively interfere with tumour angiogenesis could improve survival among patients with bladder cancer. Endostatin is a tumour-derived angiogenesis inhibitor and is the first endogenous inhibitor of angiogenesis to be indentified in a matrix protein. Gene therapy represents an attractive approach to treat cancers and other chronic diseases. The development of an effective delivery system is absolutely critical to the usefulness and safety of gene therapy. At present, the adeno-associated virus (AAV) vector has the most promising potential in view of its non-pathogenicity, wide tropisms and long-term transgene expression in vivo. Gene therapy studies using different serotypes of recombinant AAV (rAAV) as delivery vehicles have proved rAAVs to be an effective modality of cancer gene therapy. In the present study, an IgG fragment was inserted at the start of the sequence coding for endostatin with the aim of enabling continuous secretion of endostatin the serum. We also investigated the suppression effect of AAV-mediated endostatin expression on endothelial cells and in mice xenograft models of bladder cancer. Our data demonstrates that rAAV-endostatin controlled tumour cell growth and achieves strong anti-tumour efficacy in vivo.

Sequential gemcitabine and cisplatin followed by docetaxel as first-line treatment of advanced urothelial carcinoma: a multicenter phase II study of the Hellenic Oncology Research Group

BACKGROUND

The purpose of this study was to investigate the toxicity and efficacy of the sequential administration of gemcitabine (GMB) in combination with cisplatin (CDDP) followed by docetaxel (Taxotere) as first-line treatment of advanced urothelial carcinoma.

PATIENTS AND METHODS

Patients [aged </=70 years and performance status (PS) (Eastern Cooperative Oncology Group) 0-2] with previously untreated locally advanced/recurrent or metastatic urothelial carcinoma were eligible. Study treatment consisted of GMB (1000 mg/m(2), days 1 and 8) and CDDP (70 mg/m(2), day 1) (GP regimen), every 21 days for a total of four cycles followed by docetaxel (D; 100 mg/m(2), day 1) every 21 days for four cycles.

RESULTS

Thirty-eight patients with a median age of 67 years were enrolled; 67% of them had PS 0 and 87% stage IV disease. Patients received a median of four GP and four D cycles per patient. Grade 3-4 neutropenia occurred in 27% and 63% patients with GP and D, respectively. Grade 3-4 thrombocytopenia occurred in 11% of patients, only with the GP regimen. Other toxic effects were mild. There was no toxic death. The objective response rate was 55.2% [95% CI: 39.45%-71.07%]. Five patients had complete response (13.15%) and 16 patients had partial response (42.1%), while nine patients had disease stabilization (23.7%) (intention-to-treat analysis). After a median follow-up period of 13 months (range 1.5-40.5 months), the median time to progression was 6.8 months (range 1-40.5 months), the median overall survival 13 months (range 1.5-40.5 months), and the 1-year survival rate 55.3%.

CONCLUSION

The sequential administration of GP followed by D is active and well tolerated as first-line treatment of advanced urothelial carcinoma and merits to be further evaluated.

Combination of adenovirus-mediated thymidine kinase gene therapy with cytotoxic chemotherapy in bladder cancer in vitro

We evaluated efficacy, toxicity and potential synergism of adenoviral-mediated thymidine kinase (tk)- ganciclovir (GCV) gene therapy in combination with 4 cytotoxic chemotherapeutic agents (doxorubicin, cisplatin, mitomycin C, and methotrexate) in 3 human bladder cancer cell lines. Cell lines were exposed to (1) 10 different concentrations of adenovirus expressing tk plus GCV; (2) 8 different concentrations of either doxorubicin, methotrexate, mitomycin C or cisplatin; or (3) combination treatment consisting of either low-, medium- or high-dose tk-GCV gene therapy plus 8 different concentrations of a single chemotherapeutic agent. Cell survival was determined using a MTT-based cell proliferation-assay. For most combinations, adding chemotherapy to tk-GCV gene therapy did not result in any therapeutic benefit. In some scenarios, we observed modest improvement with combinations of high-dose tk-GCV gene therapy and high-dose standard chemotherapy over tk-GCV monotherapy. Low concentrations of methotrexate enhanced the antitumor effects of low- and medium-dose tk-GCV gene therapy. Low level negative interference between tk-GCV gene therapy and chemotherapy occurred in some combinations but was overall negligible. In general, adding chemotherapy to tk-GCV gene therapy did not demonstrate significant therapeutic benefit in vitro. High doses of chemotherapeutic agents should be used in combination with tk-GCV gene therapy in order to take advantage of the occasional instance where modest improvement occurred with combination therapy. Additional studies exploring the role of methotrexate in enhancing the tk-GCV system are required. Investigation of other, potentially more synergistic chemotherapeutic agents in combination with tk-GCV is warranted.