Akyso Therapeutics announced two significant milestones in advancing long-acting treatments for opioid use disorder (OUD): the successful completion of its first-in-human Phase 1a clinical trial of iSTEP-N® and the receipt of $15 million in federal funding to develop a complementary buprenorphine-based implant.
The privately held biotechnology company's iSTEP-N® represents a bioabsorbable extended-release naltrexone implant engineered to deliver naltrexone for 12 months following a single, simple, in-office treatment. The Phase 1a trial demonstrated that the implant was well-tolerated with no serious adverse events or implant-related complications.
Phase 1a Trial Results Show Promise
The Phase 1a study revealed sustained therapeutic plasma levels of naltrexone for three months following a single implant. Importantly, residual naltrexone content of the implant after three months suggests potential for the targeted 12-month efficacy. The iSTEP® platform utilizes a proprietary, fully bioabsorbable polymer system that does not require surgical removal, addressing a key limitation of existing implant technologies.
"We are thrilled to share not only the success of our Phase 1a iSTEP-N® trial, but also the launch of our buprenorphine implant program with support from NIDA," said Steven Cohen, MD, FACS, co-founder and co-CEO of Akyso Therapeutics. "This expanded funding and validation from the NIH will allow us to pursue our dual-track approach to transforming OUD treatment with both naltrexone and buprenorphine."
Expanding Pipeline with NIDA Support
The National Institute on Drug Abuse (NIDA) awarded Akyso Therapeutics $15 million in federal funding to develop iSTEP-B®, a 6-12-month extended-release buprenorphine implant. The new buprenorphine implant project builds directly upon Akyso's iSTEP® platform, using the same bioabsorbable, subcutaneous delivery system as iSTEP-N®, with the goal of delivering therapeutic buprenorphine levels continuously for more than six months.
The company plans to follow a similar clinical development pathway for iSTEP-B®, including formulation, CMC analytics, GLP toxicology, and human trials. A Phase 1b study in patients with OUD is planned for early 2026 and will include a comparison to Vivitrol®.
Addressing Market Need
Naltrexone and buprenorphine formulations represent over 90 percent of treatment options for OUD in the United States. The iSTEP products represent disruptive ultra long-acting formulations of both naltrexone and buprenorphine, positioning Akyso Therapeutics to capture a large portion of the $3 billion OUD treatment market in the US.
"Our goal is to offer patients long-acting, discreet treatments that reduce relapse risk during the most vulnerable stages of recovery," said Jeffrey Benner, MD, co-founder and co-CEO. "With iSTEP-N® entering patient trials and iSTEP-B® now funded for development, we are well-positioned to provide scalable, very long acting, implantable therapies for both opioid and alcohol use disorders."
The iSTEP-N® program is supported in part by NIDA under grant UH3DA048338, with the Phase 1a trial registered on ClinicalTrials.gov under identifier NCT06053197. The new iSTEP-B® buprenorphine program is supported by a separate $15 million federal grant covering the period from 2025 to 2029.
