Novo Holdings leads $100m round for novel painkiller biotech

SiteOne Therapeutics has completed a $100 million third-round financing that will support clinical trials of new pain drugs that work in a different way to opioid analgesics.

The Series C – which was led by Novo Nordisk's parent company Novo Holdings – follows a $15 million second round for the South San Francisco-based company in 2017 and a $15 million Series A in 2014.

SiteOne is focused on the development of selective, small-molecule ion channel modulators, including inhibitors of sodium channels NaV1.7 and NaV1.8.

The biotech's lead candidate targets NaV1.8, putting it in the same area as Vertex Pharma, whose NaV1.8 inhibitor suzetrigine (formerly VX-548) has already been filed for approval in the US or moderate-to-severe acute pain with an FDA decision due by 30th January after a priority review.

NaV1.8 sodium channels are thought to play a role in relaying pain signals to the spinal cord from peripheral nerves, and suzetrigine has shown efficacy in providing rapid acute pain relief in patients undergoing abdominoplasty and bunionectomy surgery in phase 3 trials.

The hope is that the drug class could be a major step forward in the bid to find effective pain relief free of the side effects and risk of dependency that accompanies the use of opioids and has fuelled an epidemic of overdose deaths in the US and other countries around the world.

SiteOne's chief executive, John Mulcahy, said the company is "committed to developing non-opioid treatments for conditions that involve hyperexcitability of the peripheral nervous system, such as pain and cough."

He added that its NaV1.8 inhibitor has the potential to provide meaningful analgesia with a reduced side effect profile and risk of abuse compared to current care.

"This funding will enable human proof of concept studies on our isoform-selective sodium channel inhibitors and development of other ion channel modulators," said Mulcahy.

Earlier efforts to develop non-opioid painkillers for acute pain applications have revolved mainly around nerve growth factor inhibitors, but the two leaders in the category, Eli Lilly and Regeneron, have both pulled the plug on their programmes in this area in the last few years.

OrbiMed, Wellington Management, Mission BioCapital, BSQUARED Capital, and existing investors also participated in the Series C.

Novo's Ken Harrison, OrbiMed's Mona Ashiya, Mission'a Zach Collins have joined SiteOne's board, while former Morphic Therapeutics CEO Praveen Tipirnen has been named executive chairman and life science advisor Martin Edwards has become an independent board member.