Lilly acquires SiteOne in US$ 1B non-opioid pain drug deal

USA – Eli Lilly is stepping into the non-opioid pain treatment space with a significant acquisition. On Tuesday, Lilly announced that it will buy SiteOne Therapeutics in a deal worth up to US$ 1 billion, including potential milestone payments.

This move adds SiteOne’s promising sodium channel blocker, STC-004, to Lilly’s pipeline.

SiteOne’s lead drug, STC-004, targets the NaV1.8 sodium channel, a key player in pain signaling. In early trials, STC-004 demonstrated safety, well-tolerability, and rapid absorption, making it suitable for once-daily oral administration. A Phase II trial is expected to begin soon.

The deal follows significant progress in the field of non-opioid pain relief. Vertex Pharmaceuticals recently received FDA approval for its NaV1.8 inhibitor Journavx (suzetrigine) – the first such approval in over 20 years.

Meanwhile, SiteOne raised US$ 100 million in Series C funding late last year, demonstrating strong investor confidence.

SiteOne is also advancing other pain programs, including NaV1.7 inhibitors (in partnership with Vertex) and a topical treatment for eye pain.

With the growing demand for safer pain relief options, sodium channel blockers like STC-004 are attracting significant investments from major pharmaceutical companies.

Eli Lilly currently has several pain treatments in development, but none targeting sodium channels—until now. The company has three mid-stage candidates:

• LY3848575, a monoclonal antibody targeting epiregulin
• Mazisotine (LY3556050), a small molecule modulating somatostatin signaling
• LY3857210, an oral P2X7 antagonist for chronic pain

“An effective non-opioid treatment remains elusive,” said Mark Mintun, Lilly’s head of neuroscience R&D. “Lilly is eager to move STC-004 forward.”

With the SiteOne buyout, Lilly adds cutting-edge innovation to its pipeline and strengthens its push into safer, non-addictive pain relief.

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