CAMBRIDGE, Mass. — Parabilis Medicines, a clinical-stage biopharmaceutical company developing novel treatments for cancer, announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to FOG-001 for the treatment of desmoid tumors. FOG-001 is the first and only direct inhibitor of the β-catenin:TCF interaction, a target previously considered “undruggable.”
The designation recognizes both the significant unmet need in desmoid tumors and the potential of FOG-001 to transform care for patients with this rare disease. Fast Track status facilitates closer collaboration with the FDA and allows for accelerated review options, including Rolling Review and potential Priority Review, to help bring promising therapies to patients sooner.
“Obtaining Fast Track designation for FOG-001 reinforces our confidence in its potential to offer meaningful clinical benefit to patients with desmoid tumors, who today have no therapies that directly address the underlying disease biology,” said Fawzi Benzaghou, M.D., Chief Medical Officer of Parabilis Medicines. “More than half of patients do not respond to current treatments, which are also associated with high toxicities. By inhibiting the β-catenin:TCF interaction, FOG-001 has the potential to intervene at the source of disease and represents a major step forward in our mission to drug the undruggable.”
The FDA milestone follows compelling preliminary clinical data presented at the ESMO Congress and the Connective Tissue Oncology Society (CTOS) 2025 Annual Meeting, demonstrating clinically meaningful anti-tumor activity in desmoid tumors. In the company’s ongoing Phase 1/2 study, as of mid-August 2025, 12 patients with desmoid tumors had been treated with FOG-001. Tumor reductions were observed in all evaluable patients (n=10), with an 80 percent objective response rate (ORR) among patients with multiple post-baseline scans (n=5), per RECIST 1.1 criteria. Responses occurred regardless of prior treatment with gamma secretase inhibitors, tumor location, or CTNNB1/APC mutation status.
FOG-001 also showed an acceptable safety and tolerability profile, with no Grade 4 or 5 treatment-related adverse events or discontinuations, and no high-grade gastrointestinal or skin toxicities.
“The Wnt/β-catenin pathway is implicated in millions of cancer cases each year, yet remains unaddressed by any approved therapies despite decades of effort,” said Mathai Mammen, M.D., Ph.D., Chairman and CEO of Parabilis Medicines. “FOG-001 demonstrates that our Helicon peptides can unlock disease biology once considered inaccessible—opening new pathways to drug targets long thought out of reach and offering the potential to fundamentally transform outcomes for patients.”
Beyond desmoid tumors, FOG-001 is being studied across a range of rare and common Wnt/β-catenin-driven cancers. Data presented at the AACR-NCI-EORTC 2025 meeting showed single-agent activity in several tumor types, including adamantinomatous craniopharyngioma (ACP), ameloblastoma, salivary gland cancer, and solid pseudopapillary neoplasm (SPN), with strong rationale for combination therapy in more complex cancers such as microsatellite-stable colorectal cancer (MSS CRC).
