Effect of extending the period from oral administration of 5-aminolevulinic acid hydrochloride to photodynamic diagnosis during transurethral resection for non-muscle invasive bladder cancer on diagnostic accuracy and safety: a single-arm multicenter phase III trial

Background: In Japan, the authorized period (2-4 h) between oral administration of 5-aminolevulinic acid hydrochloride (5-ALA) and transurethral resection for non-muscle invasive bladder cancer (NMIBC) may restrict photodynamic diagnosis (PDD) usage. Therefore, this prospective, single-arm, phase III study aimed to evaluate the diagnostic accuracy and safety of PDD at an extended administration period (4-8 h).

Methods: From January 2022 to May 2023, 161 patients with NMIBC were enrolled from eight hospitals. The primary endpoint was the blue light (BL) sensitivity of pathologically positive biopsies. The secondary endpoints were a comparison of the specificity and positive and negative prediction rates under BL and white light (WL) conditions.

Results: A total of 1242 specimens comprising 337 histological NMIBC specimens were analyzed. BL-sensitivity was 95.3%. Its lower limit of 95% confidence interval (92.4-97.3%) exceeded the threshold (70%) of non-inferiority to authorized usage. Sensitivity and specificity were significantly higher and lower for BL than those for WL (95.3% vs. 61.1%, P < 0.001; 52.7% vs. 95.2%, P < 0.001), respectively. The positive and negative predictive rates were significantly lower and higher for BL than those for WL (42.9% vs. 82.7%, P < 0.001; 96.8% vs. 86.8%, P < 0.001), respectively. Of the 145 patients receiving 5-ALA, 136 (93.8%) and 75 (51.7%) experienced 377 adverse events and 95 adverse reactions, respectively, most of which were grade 1 or 2.

Conclusion: For extended period, the efficacy of PDD for NMIBC was similar to that of authorized period, in terms of higher sensitivity and lower specificity compared with WL, and the safety was acceptable.