Intravesical suramin: A novel agent for the treatment of superficial transitional-cell carcinoma of the bladder

Patients with recurrent or high-grade superficial transitional-cell carcinoma of the bladder that has recurred after intravesical chemotherapy are at increased risk for tumor invasion and metastases. Intravesical chemotherapy is a minimally invasive technique that allows high doses of therapeutic agents to be delivered directly to the malignancy, doses that would not be tolerated systemically. In vitro studies demonstrate suramin's significant efficacy against transitional-cell carcinoma cell lines at relatively low doses. Humans treated with similar doses delivered in a systemic fashion have experienced no bladder toxicity. Suramin has been shown to block the binding of epidermal growth factor (EGF) to its receptors, which are found in large amounts in bladder cancers. Because a significant association has been found between the number of EGF receptors on a bladder-cancer cell and its sensitivity to suramin, transitional-cell carcinoma could potentially be very responsive to such therapy. On the basis of these findings, a phase I escalating-suramin-dose study is currently being conducted.