Scoop: As Sio closes, former CEO from ‘vant exit finds himself at helm of Irv Weissman stealth biotech

Stanford stem cell luminary Irv Weissman is building a new biotech around the ‘don’t eat me’ signal CD47 — but instead of cancer, the new biotech is developing anti-CD47 therapies for heart disease.

Nicholas Leeper

Bitterroot Bio, named after the Bitterroot river in Weissman’s home state of Montana, “likely will unveil our intentions early in 2023,” co-founder Nicholas Leeper told Endpoints News in an email, though he declined to say more. Bitterroot is going after “atherosclerosis from the anti-CD47 angle,” according to Weissman’s disclosures in a Nature Cancer paper published in November.

And as of March, Pavan Cheruvu, former CEO of Axovant-turned-Sio Gene Therapies, has been CEO of the stealth company. In moving to Bitterroot, Cheruvu is returning to his cardiologist roots. Cheruvu did not respond to requests for comment.

Cheruvu orchestrated Axovant’s separation from the Roivant web and its rebranding as Sio in 2020, as the biotech pivoted away from Alzheimer’s to gene therapies. At the time, he declared, “We’re not a vant any longer.”

In January, Cheruvu left Sio after it ditched its lead Parkinson’s disease gene therapy and pivoted to its two remaining programs for GM1 and GM2 gangliosidosis. But just a few months later, the biotech laid off most of its employees and cut its last two programs. Yesterday, Sio said it will shut its doors after it had been unable to find a buyer for the past year.

In going after CD47, Bitterroot will be pursuing the same signal as Weissman’s last biotech Forty Seven, which was bought by Gilead in 2020 for $4.9 billion. But the centerpiece of that buyout, magrolimab, ran into clinical holds from the FDA at the start of this year, some of which were lifted three months later, and all of which were lifted in June. Gilead said it plans to read out the first interim analysis of its pivotal Phase III study in myelodysplastic syndrome in the first half of next year.

Weissman and Leeper have published a number of papers linking CD47 blockage and improved outcomes in heart disease, including a study in Nature in 2016 and a retrospective analysis on heart inflammation in a magrolimab trial in a brief NEJM piece from 2021.

Others in the anti-CD47 cancer space have retreated. AbbVie terminated its study of I-Mab’s anti-CD47 antibody, and soon after, Zai Lab said it was shelving its program as well.

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