With the ink barely dry on an antibody-drug conjugate-style deal with Regeneron, Parabilis Medicines has now turned its attention to the public markets.
The Massachusetts biotech, formerly known as FogPharma, has yet to set out how many shares it will offer—or at what price—but Parabilis made clear in its Securities and Exchange Commission filing May 19 that top of the list of spending priorities will be funding the launch of a phase 3 study of its Wnt/β-catenin pathway inhibitor zolucatetide for desmoid tumors.
Desmoid tumors are rare noncancerous growths that form in connective tissue. Zolucatetide snagged a fast-track designation from the FDA for the indication in November 2025.
Part of the IPO proceeds will also be used to continue the phase 1 trials of zolucatetide in the rare genetic condition familial adenomatous polyposis, the liver cancer hepatocellular carcinoma, and other solid tumors that harbor Wnt pathway-activating mutations.
Zolucatetide targets beta-catenin, an intracellular protein that is implicated in a large swath of cancer types and has long been a Holy Grail for the industry. Scientists have tried to create drugs attacking beta-catenin since its discovery in the early 1990s.
Zolucatetide is one example of Parabilis’ helicon peptides, which are engineered to attach to flat surfaces that would otherwise make traditional small-molecule binding difficult.
The helicon platform caught the eye of Regeneron, which earlier this week agreed to pay $50 million upfront and make a $75 million equity investment in Parabilis as part of a deal that would see Regeneron not only explore the use of helicons as standalone therapies but also conjugate them with the U.S. pharma’s own antibodies.
Beyond its helicons, Parabilis said in Tuesday’s SEC filing that some of the IPO cash would be used to advance its other assets into the clinic, including ERG, AR, and ß-catenin degraders.
Parabilis is hardly short of money. Even before the Regeneron payment, the biotech was sitting on around $329 million in cash and equivalents, following on from a $107 million series C back in 2021, a $178 million D round in 2022, a $145 million series E in 2024 and a $305 million series F to kick off this year.
The company, which oversees 145 full-time employees along with 31 full-time consultants, is led by CEO Mathai Mammen, M.D., Ph.D., former global head of R&D at Johnson & Johnson. Mammen told Fierce Biotech in an interview back in January that his vision is to grow Parabilis into a “big, important company.”
“I want to be a company that does research, development, manufactures and commercializes product,” the CEO said at the time.
Starting by evaluating zolucatetide in smaller patient populations, which are easier to commercialize in, is part of this strategy. Mammen also confided that pharma partnerships were required to help finance this dream, but the gameplan has now clearly expanded to include access to the public markets.
If the IPO goes ahead, Parabilis will be joining a growing influx of new biotech entrants to the Nasdaq this year like Seaport Therapeutics, Hemab Therapeutics, Odyssey Therapeutics and Generate:Biomedicines. Last month, obesity biotech Kailera Therapeutics made history with an upsized $625 million offering that served as welcome sign that the IPO window remains open.
