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Eli Lilly to buy SiteOne for $1 billion with eye on non-opioid pain drug

Published by Global Banking & Finance Review

Posted on May 27, 2025

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· Last updated: January 23, 2026

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Eli Lilly to buy SiteOne for $1 billion with eye on non-opioid pain drug
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(Reuters) -Eli Lilly will acquire privately held SiteOne Therapeutics, the companies said on Tuesday, giving the drugmaker access to an experimental non-opioid pain drug. (Reporting by Sriparna Roy in

Eli Lilly Acquires SiteOne for Up to $1 Billion to Enhance Pain Drug Pipeline

By Sriparna Roy

(Reuters) -Eli Lilly will buy privately held SiteOne Therapeutics in a deal worth as much as $1 billion, the companies said on Tuesday, giving the drugmaker access to an experimental non-opioid pain medicine.

SiteOne's STC-004 will help Lilly expand its pipeline of drugs for chronic pain conditions such as migraine, as the pharma giant strives to get ahead in the race for alternatives to addictive opioid painkillers.

STC-004 belongs to a class of drugs known as Nav1.8 inhibitors that targets the channels involved in transmitting pain signals. Opioids, on the other hand, trigger the brain's reward centers as they travel through the blood and then attach to neural receptors, leading to addiction and abuse.

Vertex Pharmaceuticals' recently approved non-opioid painkiller Journavx is also a Nav1.8 inhibitor.

Lilly's wider pain profile includes experimental drugs for diabetic peripheral neuropathic pain and to treat nerve pain that begins in the feet and moves up the leg to just below the knee.

The SiteOne deal extends Lilly's trend of diversification beyond its recent success in obesity into therapeutic areas that the company knows well, said BMO Capital Markets analyst Evan Seigerman.

Under the deal terms, SiteOne shareholders could get up to $1 billion in cash, including an upfront sum and subsequent payments when certain regulatory and commercial milestones are met.

SiteOne is also studying other experimental drugs to treat conditions including pain and cough.

For years, drugmakers have been trying and failing to bring new alternatives to opioid painkillers that have fueled a national addiction crisis in the U.S.

Lilly and partner Pfizer discontinued the development of another non-opioid experimental drug, tanezumab, in 2021 after regulatory setbacks.

In 2023, Lilly signed a deal with Confo Therapeutics to license its experimental non-opioid drug for neuropathic pain, a condition caused by damage to the nerves outside the brain and spinal cord.

(Reporting by Sriparna Roy in Bengaluru; Editing by Devika Syamnath)

Key Takeaways

  • Eli Lilly acquires SiteOne Therapeutics for up to $1 billion.
  • The acquisition focuses on non-opioid pain drug STC-004.
  • STC-004 targets Nav1.8 channels to manage pain.
  • Lilly aims to diversify beyond obesity into pain management.
  • The deal includes milestones-based payments to SiteOne.

Frequently Asked Questions

What is the value of Eli Lilly's acquisition of SiteOne?
Eli Lilly will buy SiteOne Therapeutics in a deal worth as much as $1 billion, which includes an upfront sum and subsequent payments based on milestones.
What is the purpose of SiteOne's STC-004 drug?
SiteOne's STC-004 is an experimental non-opioid pain drug aimed at treating chronic pain conditions such as migraines.
What class of drugs does STC-004 belong to?
STC-004 belongs to a class of drugs known as Nav1.8 inhibitors, which target the channels involved in transmitting pain signals.
What challenges have drugmakers faced in developing alternatives to opioids?
For years, drugmakers have been trying and failing to bring new alternatives to opioid painkillers, which have contributed to a national addiction crisis in the U.S.
What recent deal did Eli Lilly sign related to non-opioid drugs?
In 2023, Lilly signed a deal with Confo Therapeutics to license its experimental non-opioid drug for neuropathic pain.

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