Single Photodynamic Therapy Research Articles

Sequential whole bladder photodynamic therapy treatments: A preclinical study

We postulated that sequential whole bladder photodynamic therapy (WBPDT) treatments with a low WBPDT dose would result in improved safety profile and good local tumor control. However, the drawback with such a proposal is the potential cumulative effect of sequential WBPDT treatments on bladder function. We designed this preclinical study to determine the safety of sequential WBPDT treatments. Six female dogs underwent a single WBPDT treatment comprising 1.5 mg/kg of Photofrin® and 15 J/cm 2 of light. Four dogs received a second treatment; and three dogs received three treatments. Pre- and post-WBPDT evaluations included cystoscopy and saline cystometry at baseline, 1 week, and 12 weeks. Gross and histopathologic analysis of cystectomy specimens occurred at 1 and 12 weeks. A single photodynamic therapy (PDT) treatment induced average bladder capacity losses of 11% (0–33) and 0% at post-WBPDT weeks 1 and 12, respectively. A second sequential WBPDT treatment caused average bladder capacity losses of 36% (0–57%) and 17% (2–24%) at weeks 1 and 12, respectively. Three sequential WBPDT treatments induced average bladder capacity losses of 22% (0–42) and 0% at weeks 1 and 12, respectively. Full recovery in bladder capacity occurred in all cases except after the second sequential treatment, which induced a persistent bladder capacity loss of 17% at 12 weeks. Histopathologic analysis of cystectomy specimens revealed a focal discernible injury to the superficial muscle in only one of the dogs that received three treatments. We conclude that sequential WBPDT treatments using low dose PDT Photofrin® (1.5 mg/kg and light ≤15 J/cm 2) is safe, and we recommend using this low WBPDT dose in clinical investigation.

Photodynamic Therapy in the Management of Bladder Cancer

Photodynamic therapy (PDT) is primarily suggested for the therapy of papillary transitional cell carcinoma (TCC) and refractory carcinoma in situ (CIS), and prophylaxis of recurrent superficial TCC in those patients who have failed intravesical chemotherapy or immunotherapy. We reviewed our 13-year experience to assess the long-term role of PDT in the management of superficial bladder cancer, and propose a standard protocol. Fifty eight patients underwent a single PDT treatment with 1.5-2.0 mg/kg of Photofrin and 10-25 J/cm2 of light (630 nm). This single PDT treatment produced overall response rates of 84.2% in 19 patients with recurrent superficial papillary TCC, 80% in 20 patients with refractory CIS, and 89.5% in 19 patients receiving prophylaxis. The PDT dose of 2.0 mg/kg and 15-25 J/cm2 produced the most durable tumor response at the expense of severe local morbidity. However, the PDT dose of 1.5 mg/kg and 10-15 J/cm2 yielded variable tumor responses, with minimal local morbidity. Overall our data confirm that PDT is an effective therapy for superficial bladder cancer. We recommend PDT as a second line or immediate therapy for BCG or chemotherapy failures using a standard PDT dose of 1.5 mg/kg of Photofrin and 15 J/cm2 (630 nm) and a scheduled repeat treatment with 1.5 mg/kg and 10 J/cm2 at 6 and 12 months.