Parabilis Files for IPO After $75 M Regeneron Deal and 100% Tumor Shrinkage Claim

Parabilis, a biotech focused on stabilized helical peptides called Helicons™, announced its intention to list on Nasdaq under the ticker PBLS. The filing follows a strategic research collaboration with Regeneron Pharmaceuticals that could exceed $2.3 billion in total value. As part of the deal, Regeneron will purchase roughly $75 million of Parabilis common stock in a concurrent private placement, pricing the shares at 90 % of the anticipated IPO price.

The company’s registration statement lists a placeholder $100 million IPO size, which would raise its cash balance by about 30 % to roughly $329 million. The exact amount to be raised remains undefined, as the S‑1 filing does not disclose the number of shares to be offered.

Parabilis highlighted clinical data for its lead candidate zolucatetide, a direct inhibitor of the β‑catenin:TCF interaction, a target long considered undruggable. In desmoid‑tumor patients, the drug achieved tumor shrinkage in 100 % of cases, with a 74 % objective response rate—meaning that patients with at least two follow‑up scans saw measurable tumor reduction.

The firm plans to use IPO proceeds to advance zolucatetide into a Phase III registrational trial for desmoid tumors, expand trials in familial adenomatous polyposis, hepatocellular carcinoma, and other rare cancers, and fund development of additional pipeline programs such as an ERG protein degrader and an allosteric androgen‑receptor candidate.

Regeneron’s involvement adds both capital and validation to Parabilis’s Helicon platform, which blends artificial‑intelligence modeling, physics‑based calculations, and high‑throughput peptide synthesis to design molecules that can disrupt protein‑protein interactions or trigger targeted protein degradation.

If the IPO proceeds as outlined, Parabilis will have a stronger balance sheet to support its ambitious clinical agenda and to scale the Helicon discovery engine. The market will watch the pricing of the offering, the final amount raised, and the company’s ability to translate its early tumor‑shrinkage data into regulatory approval.

What to watch next: the final IPO pricing, the allocation of raised funds to Phase III trials, and any updates on the Regeneron collaboration’s pipeline milestones.