Ryan Flannigan, MD, highlights phase 2 data on ST-01 for chronic scrotal content pain

In this video, Ryan K. Flannigan, MD, FRCSC discusses phase 2 data evaluating ST-01, a sustained-release polymer formulation of lidocaine, for men with chronic scrotal content pain (CSCP).¹ These findings were presented at the 2026 American Urological Association Annual Meeting in Washington, DC. Flannigan is an assistant professor in the department of urologic sciences at the University of British Columbia and a senior research scientist at the Vancouver Prostate Centre.

In the randomized, multicenter trial (NCT05707208), 54 evaluable men received standard-of-care 5 mL 1% lidocaine hydrochloride plus either 3 mL ST-01 70 mg/mL, 3 mL ST-01 140 mg/mL, or additional 3 mL 1% lidocaine as a control, with repeat injections planned approximately every 28 days. Clinical response, defined as at least a 2-point reduction in cycle average pain scores, occurred in 15 of 17 patients (88%) receiving ST-01 70 mg/mL, compared with 9 of 18 (50%) receiving the 140 mg/mL dose and 7 of 19 (37%) in the control group. The 70 mg/mL dose was significantly improved vs control (P = .002), whereas the 140 mg/mL dose was not (P = .515). Flannigan noted that the lower concentration may have produced greater therapeutic exposure because the higher concentration may have precipitated within the polymer vehicle, potentially limiting lidocaine release.

According to Flannigan, the findings could provide an additional nonsurgical option for men with CSCP, for whom existing treatments can include short-acting local anesthetic injections, systemic medications, and surgical interventions such as microsurgical denervation. After crossover to ST-01, 60% and 63% of patients in the 70 mg/mL and 140 mg/mL groups, respectively, reported at least a 2-point pain reduction. Overall, 47 of 54 men reported at least 1 adverse event, most of which were mild or moderate and involved bruising, swelling, or injection-site pain; 3 serious adverse events occurred. The investigators concluded that the findings support further evaluation of ST-01 in phase 3 studies for CSCP.

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