A phase I trial of intravesical nanoparticle albumin-bound paclitaxel in the treatment of bacillus Calmette-Guérin refractory nonmuscle invasive bladder cancer.

PURPOSE: Up to 50% of patients treated with intravesical agents for high grade nonmuscle invasive bladder cancer will have disease recurrence. Response rates to current second line intravesical therapies are low and for these high risk patients novel agents are necessary. Our previously completed phase I trial showed docetaxel was a safe agent for intravesical use. Nanoparticle albumin-bound paclitaxel (Abraxane®, ABI-007) has been shown to have increased solubility and lower toxicity compared to docetaxel in systemic therapy. Thus, we assessed the dose limiting toxicity and maximum deliverable dose of intravesical nanoparticle albumin-bound paclitaxel.
MATERIALS AND METHODS: Inclusion criteria for this institutional review board approved phase I trial were recurrent high grade Ta, T1 and Tis transitional cell carcinoma of the bladder for which at least 1 prior standard intravesical regimen failed. Six weekly instillations of nanoparticle albumin-bound paclitaxel were administered with a modified Fibonacci dose escalation model used until the maximum deliverable dose was achieved. The primary end point was dose limiting toxicity and the secondary end point was response rate.
RESULTS: A total of 18 patients were enrolled in the study. One patient demonstrated measurable systemic absorption after 1 infusion. Grade 1 local toxicities were experienced by 10 (56%) patients with dysuria being the most common, and no grade 2, 3 or 4 drug related local toxicities were encountered. Of the 18 patients 5 (28%) had no evidence of disease at posttreatment evaluation.
CONCLUSIONS: Intravesical nanoparticle albumin-bound paclitaxel exhibited minimal toxicity and systemic absorption in the first human intravesical phase I trial to our knowledge. A larger phase II study has begun to formally evaluate the activity of this regimen.