Parabilis Medicines (Nasdaq: PBLS), a clinical-stage biopharmaceutical company whose lead oncology asset has generated a 74% objective response rate in desmoid tumor patients, filed an S-1 registration statement with the SEC seeking to list on the Nasdaq Global Market. Regeneron Pharmaceuticals has agreed to purchase approximately USD 75 million of shares in a concurrent private placement at 90% of the IPO price, in connection with their recently announced USD 2.3 billion research collaboration for antibody-helicon conjugates.
As per the S-1 filing, details of share pricing and timing have yet to be finalized. Parabilis has applied for listing under the ticker PBLS.
Parabilis has raised over USD 800 million in pre-IPO financing from a syndicate that includes ARCH Venture Partners, Cormorant Asset Management, Fidelity Investments, GV, RA Capital Management, and venBio, according to the filing.
Company background
Parabilis was founded in 2015 based on technology in-licensed from the laboratory of Greg Verdine, Ph.D., at Harvard University. The company describes its core modality, Helicons, as stabilized helical peptides engineered to penetrate cells and engage intracellular protein targets that have historically been inaccessible to both small molecules and biologics.
The company is led by Mathai Mammen, M.D., Ph.D., who previously served as Global Head of R&D at Johnson & Johnson, where his team secured approvals for nine medicines across oncology, immunology, and neuroscience. The filing also names Fawzi Benzaghou, M.D., as Chief Medical Officer, previously Senior Vice President and Global Head of Oncology R&D at Ipsen.
The lead asset, zolucatetide (FOG-001), is described as the first investigational therapy to directly inhibit the interaction between beta-catenin and the T-cell factor family of transcription factors, the central downstream node of the Wnt/beta-catenin signaling pathway. Activating mutations in this pathway are present in over 10% of all cancers. The company states that direct drugging of this node eluded three decades of industry effort prior to zolucatetide's development.
In the company's ongoing Phase I/II trial in desmoid tumors, as of February 16, 2026, 38 patients had been enrolled and treated, of whom 25 had sufficient follow-up to be response-evaluable. All 25 showed tumor reductions, representing a 100% disease control rate, and 74% of the 19 patients with at least two post-baseline scans achieved an objective response per RECIST 1.1 criteria, the filing states. The FDA has granted zolucatetide both Orphan Drug and Fast Track designations for desmoid tumors. The company plans to initiate a global registrational Phase III trial in desmoid tumors in the first half of 2027.
Beyond desmoid tumors, the filing describes zolucatetide's evaluation across familial adenomatous polyposis, hepatocellular carcinoma, colorectal cancer, and additional rare Wnt/beta-catenin-driven tumor types including adamantinomatous craniopharyngioma, solid pseudopapillary neoplasm, salivary gland tumors, and ameloblastoma. In a heavily pre-treated patient with CTNNB1-mutant hepatocellular carcinoma, the company reported a confirmed partial response lasting nine months. In two familial adenomatous polyposis patients with associated desmoid tumors, the filing states that administration of zolucatetide demonstrated improvement in duodenal polyposis burden at 10 and 60 weeks following treatment initiation.
The preclinical pipeline includes an ERG degrader targeting a transcription factor present in approximately 40% to 50% of prostate cancer patients, and an allosteric androgen receptor degrader designed to bind a co-activator protein binding site distinct from the ligand binding pocket targeted by all approved androgen receptor antagonists. The filing states the ERG program is advancing toward IND-enabling studies, while the androgen receptor program is in late lead optimization. The company is also developing beta-catenin degraders as a follow-on to zolucatetide's foundational biology.
The Regeneron collaboration, disclosed separately in connection with this voting common stock offering, focuses on Antibody-Helicon Conjugates, a format that would combine antibody targeting with Helicon payloads designed to modulate intracellular proteins. The filing describes this as a capital-efficient approach to evaluating the broader applicability of the Helicon platform alongside a strategic partner.
This article was generated with AI assistance and reviewed and edited by the AllSci editorial team
Explore more at AllSci News: https://allsci.com/news/
Spot something wrong? Report an issue with this article