SiteOne Therapeutics, a pain biotech, secures $100M in partnership with Vertex

SiteOne Therapeutics, a biotechnology firm located in South San Francisco, has successfully secured a substantial $100 million in Series C funding. This new infusion of capital marks a significant step for the company, which is focused on developing non-opioid treatments for both acute and chronic pain. This funding round places SiteOne among the 92 biotech companies that have achieved a private megaround this year, as reported by Endpoints News.

The growing interest in non-addictive pain management solutions is partly attributed to the pioneering work of Vertex Pharmaceuticals. In early 2022, Vertex formed a partnership with SiteOne to investigate NaV1.7, a sodium ion channel that is crucial for pain management. While details of this partnership remain undisclosed, the collaboration, alongside federal grants, has been vital in sustaining SiteOne's operations after the termination of its partnership with Amgen in 2019.

Vertex is a notable ally in the non-opioid treatment landscape. The biopharmaceutical company is developing an experimental oral medication named suzetrigine, aimed at inhibiting NaV1.8, another sodium ion channel. The U.S. Food and Drug Administration (FDA) is expected to make a decision on the drug's approval by January 30.

SiteOne is also concentrating on NaV1.8 with its lead internal program, STC-004. Currently in Phase 1, SiteOne anticipates releasing data from this study in the first quarter of 2025. CEO John Mulcahy expressed optimism, highlighting the opportunity to advance non-opioid pain treatments and rectify past industry missteps related to opioid prescription practices.

Founded in 2010 by Mulcahy and three professors from Stanford University, SiteOne initially focused on natural toxins targeting sodium channels. Although the company previously conducted clinical trials for a NaV1.7 program named ST-2427, it has shifted its focus to a different NaV1.7 program in collaboration with Vertex.

Mulcahy emphasized the exciting developments within the field, noting the challenges in achieving adequate selectivity for specific ion channels over off-target ones. This challenge has been a significant hurdle in the development of effective treatments.

In parallel, another biotech company, Latigo Biotherapeutics, has also entered the non-opioid treatment arena with a $135 million funding round. Similar to SiteOne, Latigo is testing a NaV1.8 inhibitor targeting the peripheral nervous system. The startup, based near Los Angeles, has already completed Phase 1 trials for its lead program and recently appointed former Horizon Therapeutics CEO Tim Walbert as its board chair. Similarly, SiteOne announced the appointment of Praveen Tipirneni, former CEO of Morphic Therapeutic, as its board chair.

SiteOne, currently operating with 16 employees, intends to advance STC-004 to Phase 2 trials in the United States by the latter half of 2025. The development process for acute pain treatments is relatively straightforward, involving clinical trials in models such as bunionectomy and abdominoplasty. However, the path for chronic pain treatments is more complicated, with the company still deciding which specific indications to pursue.

Beyond pain management, SiteOne is exploring potential applications in other sensory hyperexcitability disorders, such as chronic cough, due to the similar physiological mechanisms involved.

The Series C funding was led by Novo Holdings, with additional investments from OrbiMed, Wellington Management, Mission BioCapital, BSQUARED Capital, and others. This financial boost is expected to accelerate SiteOne's efforts in pioneering non-opioid pain treatments, potentially transforming the landscape of pain management.