AUA 2021: Updated Treatment Results from a Phase I study of WST11 Phototherapy (VTP) for Upper Tract Urothelial Carcinoma

(UroToday.com) Upper tract urothelial carcinoma (UTUC) is a relatively rare malignancy, comprising a small subset of urothelial disease. Compared to bladder cancer, endoscopic management of UTUC and intraluminal therapy is substantially more difficult. As a result, organ-preserving treatments are technically difficult. Thus, these approaches are often reserved for easily accessible, small, low-grade tumors. However, novel approaches are being evaluated to expand the population of patients who may receive nephron-sparing treatments. Vascular-targeted photodynamic therapy (VTP) using intravascular photosensitizing agent padeliporfin (WST11) has demonstrated preclinical efficacy in preclinical animal models and provides an alternative to extirpative surgery in patients unable or unwilling to undergo extirpative surgery.


In a podium presentation at the American Urologic Association Annual Meeting, Dr. Lucas Nogueira and colleagues presented results from a phase 1 dose-finding study of WST11-VTP of the upper tract.

The authors enrolled 18 patients with recurrent UTUC. To be eligible patients must have had residual or recurrent urothelial carcinoma of the ureter or renal pelvis failing prior endoscopic treatment and be unable or unwilling to undergo surgical management by resection of the involved ureter or kidney. Enrolled patients were treated with up to 2 sessions of endoscopic WST11-VTP. A light dose escalation model was employed with increasing light fluence from 100mW/cm up to a maximally tolerated dose of 200mW/cm. The primary endpoint was the determination of maximally tolerated laser light fluence rate, with the secondary objective to evaluate treatment efficacy defined by absence of visible tumor and negative urine cytology following treatment.

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Among enrolled patients, the complete response (CR) and tumor recurrence rates at 30 days after treatment were 64% and 29%, respectively. A second VTP treatment was performed in 6 patients, with a 67% CR rate following the second treatment. The efficacy rates were comparable among patients who received the intermediate and highest light fluence and between the first and second treatment.

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In terms of toxicity, there were no grade 5 events and only a single grade 4 event (fever). No ureteral strictures were identified with the procedure. No evidence of increased toxicity was identified among patients who received a second VTP treatment.

In conclusion, Dr. Nogueira suggested that WST11-VTP shows promising efficacy in the treatment of patients with low- and high-grade upper tract urothelial tumors with limited treatment-related toxicity. These data support a larger, multicenter trial which is planned.

Presented by: Lucas Nogueira, MD, Visiting Investigator - MSKCC; Scientific Director - Brazilian Society of Urology



Written by: Christopher J.D. Wallis, University of Toronto Twitter: @WallisCJD during the 2021 American Urological Association, (AUA) Annual Meeting, Fri, Sep 10, 2021 – Mon, Sep 13, 2021.

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