Eli Lilly has agreed to acquire privately held biopharma company SiteOne Therapeutics, adding a non-opioid-based pain treatment to the big pharma’s pipeline.
The sale agreement will see Eli Lilly pay up to $1bn to buy SiteOne, which includes an upfront payment and further regulatory and commercial-based milestone payments.
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Shares in Eli Lilly rose 0.46% to a price of $717.03 at market open following the announcement. The company has a market cap of $648.5bn.
US-headquartered SiteOne has not disclosed its full pipeline, though the biopharma says it is “developing selective ion channel modulators for the treatment of pain, cough, and other conditions involving hyperexcitability of the peripheral nervous system”.
The only publicly known candidate in SiteOne’s portfolio is an oral pain treatment asset dubbed STC-004.
STC-004 works by blocking the Nav1.8 sodium channel, a voltage-gated channel primarily found in pain-sensing neurons. The asset could have a lucrative market potential, given that it is not opioid-based, unlike many currently approved pain treatments. The acquisition adds to Eli Lilly’s pain pipeline, which includes four candidates.
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By GlobalDataA Phase I trial (ACTRN12624000642583) evaluating the drug for the treatment of pain demonstrated rapid absorption with a half-life appropriate for once-daily oral dosing. STC-004 was well-tolerated at all doses tested, SiteOne previously reported.
Eli Lilly stated STC-004 is “Phase II ready” and “may represent a next-generation, non-opioid treatment for patients suffering from chronic pain”.
Commonly prescribed pain treatments include hydrocodone and oxycodone, both known under various brand names. Other common opioid treatments include morphine, codeine, and fentanyl. Whilst effective medicines for pain relief, they are highly addictive, and overdoses are common. Their use has fuelled opioid epidemics around the world, one of the most famous being in the US.
This has forced pharmaceutical companies to develop alternatives to the opioid receptor mechanism of action for pain treatments. The US Food and Drug Administration (FDA) approved the first non-opioid pain medication in January 2025 in the form of Vertex Pharmaceuticals’s Journavx (suzetrigine). Similar to STC-004, Journavx acts via blockage of NaV1.8 sodium channels. Eyes will be on STC-004’s mid-stage trial after Journavx produced mixed responses in a Phase II trial (NCT06176196), despite meeting its primary endpoint.
If Journavx is anything to go by, Eli Lilly has a fruitful future with STC-004. Analysis by GlobalData’s Pharma Intelligence Center forecasts that Journavx will generate sales of $2.7bn by 2031, with the drug expected to hit blockbuster status in 2028, just three years after approval by the FDA.
GlobalData is the parent company of Pharmaceutical Technology.
Eli Lilly’s neuroscience research and development group vice-president Mark Mintun said: “The global burden of chronic pain continues to increase, and an effective non-opioid treatment remains elusive.
“Lilly is eager to continue the development of STC-004 with the outstanding SiteOne team as part of our efforts to advance novel, addiction-free pain therapies. Innovation in pain management is critical to address the unmet needs of millions of patients around the world.”
