Ryan K. Flannigan, MD, discusses sustained-release lidocaine for chronic scrotal content pain

In this video, Ryan K. Flannigan, MD, FRCSC, highlights a phase 2 study (NCT05707208) evaluating ST-01, a sustained-release lidocaine formulation, as a potential nonsurgical treatment option for men with chronic scrotal content pain (CSCP). Data from the study were presented at the 2026 American Urological Association Annual Meeting in Washington, DC.¹

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.

Flannigan explained that CSCP is a common yet difficult condition to manage because many patients lack an identifiable or reversible cause of pain. As a result, treatment often focuses on symptom management, but nonsurgical options are limited. ST-01 was developed to provide a longer-lasting therapeutic alternative by delivering lidocaine in a sustained-release polymer formulation, with the goal of offering more durable pain relief than conventional spermatic cord blocks.

The prospective, randomized, multicenter, single-blind phase 2 trial enrolled 63 men with CSCP across 8 Canadian sites, with efficacy results reported for the first 54 evaluable participants. Patients were randomly assigned to receive standard-of-care lidocaine injections alone or ST-01 at either 70 mg/mL or 140 mg/mL, with repeat dosing approximately every 28 days. Patients in the control arm had the option to cross over to ST-01 after 2 treatment cycles and reaching 28 days after the second injection. Flannigan noted that the study built upon previously published phase 1 safety data and was designed to evaluate both repeated-dose safety and efficacy.

The 70 mg/mL ST-01 dose demonstrated significantly higher response rates than standard of care, with 71% of patients achieving at least a 2-point reduction in pain compared with 32% in the control arm (P = .044). The response rate was 33% in the 140 mg/mL arm (140 mg/mL vs control, P = 1). Clinical response rates based on cycle-average pain scores were also significantly higher with the 70 mg/mL dose (88% vs 37%; P = .002), and crossover responses further supported a treatment effect.

Regarding safety, Flannigan said most participants (47 of 54) experienced at least 1 adverse event (AE), although these were predominantly mild or moderate injection-related events, including bruising, swelling, and pain at the injection site. Three serious AEs occurred, including 2 hospitalizations for management of suspected infection and 1 hospitalization for pain management, but all resolved without persistent complications by the end of the study. He noted that transient injection-site AEs are expected with spermatic cord injections.

REFERENCE

1. Brink SM, Giddens J, Patel P, et al. PD26-15: A RANDOMIZED PHASE II STUDY OF REPEAT DOSE ST-01 (LIDOCAINE POLYMER SOLUTION) VS LIDOCAINE FOR SPERMATIC CORD BLOCK IN MEN WITH CHRONIC SCROTAL CONTENT PAIN. J Urol. 2026;215(5S):e1460. doi:10.1097/01.JU.0001191720.97092.ae.15