A Phase I Study of Intravesical Suramin for the Treatment of Superficial Transitional Cell Carcinoma of the Bladder

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Abstract
Suramin is a polysulfonated naphthylurea that inhibits proliferation and DNA synthesis of transitional cell carcinoma cell lines. Its large molecular size and negative charge inhibit bladder absorption, making suramin an excellent candidate for intravesical chemotherapy. Intravesical suramin was evaluated in a phase I study to define dose limiting toxicity and systemic absorption, determine a starting dose and regimen for phase II studies and provide a preliminary assessment of in vivo antitumor activity. Intravesical suramin treatment was administered in 9 patients with histologically identified transitional cell carcinoma (Tcis, Ta or T1) in whom at least 1 course of standard intravesical chemotherapy (bacillus Calmette-Guerin, thiotepa or mitomycin C) had failed. Suramin was administered once weekly for 6 weeks. Patients were treated in groups of 3 using a 60 cc volume and intrapatient dose escalation schedule. Suramin doses of 0.3 to 614.4 mg./ml. were administered intravesically. The last group was treated with the same weekly dose for 6 weeks. The 9 patients underwent 54 treatments with suramin. Plasma suramin concentration after treatment was 1.9 to 38.0 μg./ml. and was not related to treatment dose. The dose escalation phase was limited by the solubility of suramin in solution. Complications included self-limited bladder spasms (less than 24 hours) in 4 of 54 treatments (7%) and new or worsening vesicoureteral reflux in 3 ureters (17%). Another patient who was treated after the Foley balloon was inflated in the urethra experienced bladder spasms, skin flushing and fever (39C). Mean bladder capacity before and after treatment was 600 and 540 ml., respectively. At followup 7 patients had stage Ta tumors and 2 had carcinoma in situ. An intravesical suramin dose of 153 mg./ml was defined as a safe treatment parameter with acceptable plasma concentrations and minimal side effects. Phase II studies are needed to assess the antitumor activity of suramin in patients with transitional cell carcinoma of the bladder.