Non-Opioid ST-01 Provides Sustained Pain Relief in Chronic Scrotal Pain

ST-01, a non-opioid treatment for pain, showed promise in a new phase 2 trial, Sustained Therapeutics announced on January 8, 2026.1

Chronic scrotal pain (CSP) impacts over 5 million men in the United States, with around 700,000 new cases each year. Treatment options are often limited and produce inconsistent results, from simple pain relievers such as ibuprofen to more invasive surgical procedures. Only about 15% of patients undergo surgery.

Urologists in a recent survey reported that ST-01 addresses a significant unmet clinical need and has the potential to improve patient care and simplify administration, as it requires no specialized training.

In this phase 2, randomized, single-blind, 3-arm, active-controlled study, investigators evaluated the safety and efficacy of repeat dosing of ST-01, a sustained-release lidocaine, every 28 days plus standard of care, compared with standard of care plus 1% lidocaine HCl for chronic scrotal pain. The primary outcome was the change from baseline in Pain Scores on the Numerical Rating Scale (NRS) at 56 days.2

The study included 63 male patients aged ≥ 19 years who had been experiencing unilateral or bilateral chronic scrotal pain for > 3 months and had an average daily maximum scrotal pain score over 7 days ≥ 6 on the 0 – 10 NRS. Eligibility criteria also included a positive response to test spermatic cord block with 1% lidocaine, defined as a decrease in pain score of ≥ 2 within 1 hour of reaction.2

Participants were randomized into 1 of the 3 groups: ST-01 70 mg/mL, ST-01 140 mg/mL, or 1% lidocaine HCL.1 Throughout the trial, participants could receive up to 4 injections; after completing 2 study treatments, they could join an SPT-01 arm. The research was conducted across 8 clinical sites in Canada, with 2 in British Columbia (Vancouver Prostate Centre [lead investigator: Ryan Flannigan, MD] and the Kelowna General Hospital Clinical Research Department [Jennifer Locke, MD]); 3 in Ontario (the Mt. Sinai Hospital – Men’s Health Institute [Keith Jarvi, MD], the Jonathan Giddens Medicine Professional Corporation [Jonathan Giddens, MD], and the Fe/Male Health Centre [Richard W. Casey, MD], and the rest in Alberta (Prostate Cancer Center [Geoffrey Gotto, MD]), Manitoba (Men’s Health Clinic Manitoba [Premal Patel, MD]), and Quebec (THEO Medical center [Jean -Baptiste Lattouf, MD).3

The trial met both its primary and secondary endpoints, ultimately showing that repeat injections of ST-101 were safe and effective, providing clinically meaningful sustained reductions in pain.1

“Many men suffering from chronic scrotal pain are in the prime of their lives and experience persistent, often debilitating pain that significantly impacts their quality of life," said Martin Gleave, co-founder and Chief Medical Officer of Sustained Therapeutics, in a statement.1 "The exciting Phase 2 results reinforce our belief that ST-01 has the potential to reduce or even resolve pain over time with repeat treatment, offering patients a meaningful alternative to existing therapies."

Sustained Therapeutics plans to conduct phase 3 trials in Canada and the United States. The company also plans on conducting the ST-01 trial in other chronic pain indications with high unmet needs, such as chronic pelvic pain.1

“The opioid epidemic continues to be one of the most pressing public health crises across North America, and far too often patients with long-term chronic pain have few non-opioid options," said William Annett, CEO of Sustained Therapeutics, in a statement.1 "There is an urgent need for effective, non-opioid alternatives that provide sustained pain relief without contributing to dependency."

References

1. Sustained Therapeutics Reports Positive Phase 2 Results for Its Long-Acting Non-Opioid Medication for Chronic Pain. PR Newswire. Published on January 8, 2026. Accessed January 9, 2026. https://www.prnewswire.com/news-releases/sustained-therapeutics-reports-positive-phase-2-results-for-its-long-acting-non-opioid-medication-for-chronic-pain-302656100.html.

2. A Randomized, Controlled Study of Repeat Dose Sustained Release Lidocaine for Treatment of Chronic Scrotal Pain. ClinicalTrials.gov. Accessed January 9, 2025. https://clinicaltrials.gov/study/NCT05707208.

3. ST-CP-202 - A Randomized, Controlled Study of Repeat Dose Sustained Release Lidocaine for Treatment of Chronic Scrotal Pain. Sustained Therapeutics. Accessed January 9, 2026. https://sustainedtherapeutics.com/chronic-scrotal-pain-clinical-trial/.