Ipafricept

Summary

Ipafricept (OMP‑54F28) is an investigational recombinant fusion protein that acts as a decoy receptor for Wnt ligands. By binding extracellular Wnt proteins, it blocks activation of the Wnt/β‑catenin signaling pathway, a driver of cancer stem‑cell traits and tumor dedifferentiation. Early‑phase clinical trials have explored its use in solid tumours such as desmoid tumours, germ‑cell cancers, hepatocellular carcinoma, ovarian cancer and pancreatic adenocarcinoma, primarily as a monotherapy or in combination with standard chemotherapy.

Mechanism of Action

Ipafricept consists of the extracellular domain of human Frizzled‑8 fused to an IgG1 Fc fragment. The Frizzled‑8 segment binds a broad range of Wnt ligands, preventing them from engaging native Frizzled receptors on cell surfaces. This sequestration blocks downstream β‑catenin accumulation and transcription of Wnt‑responsive genes that support stem‑cell maintenance, proliferation and survival in tumours. The Fc portion prolongs plasma half‑life and may engage immune effector mechanisms, although its primary effect is ligand neutralisation.

What the Research Shows

A first‑in‑human Phase I study enrolled 26 patients with advanced solid tumours, delivering ipafricept intravenously every three weeks. Dose escalation identified a recommended Phase II dose of 15 mg/kg; pharmacodynamic changes in hair‑follicle Wnt‑target genes were seen at ≥2.5 mg/kg. Two desmoid‑tumour patients and one germ‑cell cancer patient achieved disease stability beyond six months. In a Phase Ib trial combining ipafricept (3–5 mg/kg) with gemcitabine and nab‑paclitaxel in metastatic pancreatic cancer, 34.6% of 26 patients had partial responses and 46.2% stable disease, yielding an 81% clinical‑benefit rate, though the program was later halted due to bone‑related toxicity concerns. Review articles note that upstream Wnt inhibitors, including ipafricept, frequently cause skeletal adverse effects such as fragility fractures, prompting suggestions of bisphosphonate co‑administration.

Reported Benefits

Early clinical data suggest ipafricept can induce disease stabilization in Wnt‑driven tumours, exemplified by prolonged stable disease in desmoid and germ‑cell cancers. In combination with gemcitabine and nab‑paclitaxel, it produced partial responses in roughly one‑third of pancreatic cancer patients and achieved a high overall clinical‑benefit rate. These findings support the concept that Wnt pathway blockade may enhance chemotherapy efficacy and target cancer stem‑cell populations, though benefits remain limited to small, early‑phase cohorts.

Limitations of the Evidence

Evidence for ipafricept is confined to Phase I and Phase Ib trials with modest patient numbers, leaving efficacy uncertain across tumour types. Bone toxicity, including fragility fractures and biochemical markers of bone turnover, has limited dose escalation and contributed to program termination. No regulatory approval exists, and long‑term outcomes, optimal dosing schedules, and predictive biomarkers have not been established. The drug’s activity appears modest when used alone, requiring combination strategies that further complicate safety assessments.

Safety Considerations

The most frequent treatment‑related adverse events (≥20% of patients) were dysgeusia, decreased appetite, fatigue and muscle spasms, typically grade 1–2. Grade 3 events included hypophosphatemia, weight loss, elevated liver enzymes, nausea, rash and leukopenia. High doses (20 mg/kg) were associated with fragility fractures, while lower doses still caused elevations in bone‑resorption markers (β‑CTX). Immunogenicity was low, with anti‑drug antibodies detected in about 8% of subjects without affecting exposure. Close monitoring of bone health and supportive measures such as bisphosphonates are advised in clinical studies.

How It Is Administered

Ipafricept is administered as an intravenous infusion, usually every three weeks in monotherapy studies. In combination protocols with gemcitabine and nab‑paclitaxel, dosing has been given on day 1 (and sometimes day 15) of a 21‑day cycle, with sequential or concurrent schedules explored. The drug is supplied as a recombinant protein formulated for IV infusion.

Routes of Administration

Goals & Uses

• Ovarian cancer treatmentOncologyLow
• Pancreatic cancer treatmentOncologyLow
• Cancer stem cell targetingOncologyModerate
• Pancreatic cancerOncologyModerate
• Hepatocellular carcinoma treatmentOncologyLow
• Colorectal cancerOncologyModerate

Contraindications

• Active pregnancyReproductive SafetyHigh
• Severe hepatic impairmentOrganModerateLiver function concerns
• PregnancyPopulationHighPotential fetal risk or insufficient safety data
• Severe uncontrolled infectionInfectionModerate

Adverse Effects

• DysgeusiaNeurologicalUncommon
• Bone fracturesMusculoskeletalRare
• Infusion‑related reactionsGeneralCommon
• NauseaGastrointestinalCommonFeeling of sickness or urge to vomit
• FatigueGeneralCommonLow energy or tiredness
• Muscle-related toxicity (myalgia, muscle weakness)MusculoskeletalCommon
• Decreased appetiteMetabolicCommonReduced desire to eat
• DiarrheaGastrointestinalUncommonLoose or frequent stools
• Bone density loss / skeletal effectsMusculoskeletalUncommon

Drug Interactions

• Cytotoxic chemotherapy agentsModerate
• Paclitaxel / CarboplatinModerate
• Nab-paclitaxel / GemcitabineModerate
• SorafenibModerate

Population Constraints

• Patients with pre-existing bone diseaseMusculoskeletalRelative
• Pediatric patientsAgeRelative
• Pregnant womenReproductiveAbsolute

Regulatory Status

• European UnionInvestigationalClinical trial authorization granted for selected centers.
• United StatesInvestigationalIND in place for Phase I/II oncology trials.
• United KingdomInvestigationalUnder MHRA clinical trial approval.

Investigational biologic under clinical development; not approved by FDA, EMA, or MHRA. Used only within registered clinical trial protocols.

Evidence & Sources

• A First-in-Human Phase I Study of the Anticancer Stem Cell Agent Ipafricept (OMP-54F28), a Decoy Receptor for Wnt Ligands, in Patients with Advanced Solid Tumors
  Journal ArticleModerateJimeno A, et al.2017-01-01T00:00:00.000000Z
• Beyond the target: implications of Wnt pathway inhibitors on bone health
  Journal ArticleModerateNachef C, et al.2026-01-01T00:00:00.000000Z
• Hepatocellular Carcinoma: Etiology and Current and Future Drugs
  Journal ArticleModerateJindal A, Thadi A, Shailubhai K2019-01-01T00:00:00.000000Z
• Phase Ib Study of Wnt Inhibitor Ipafricept with Gemcitabine and nab-paclitaxel in Patients with Previously Untreated Stage IV Pancreatic Cancer
  Journal ArticleModerateDotan E, et al.2020-01-01T00:00:00.000000Z
• Regulatory Signaling Pathways in Ovarian Cancer Stem Cells: Their Role in Tumor Progression and Therapeutic Strategies
  Journal ArticleModerateAmalia D, Febriani F, Arfianti A2025-01-01T00:00:00.000000Z
• Multi‑layered prevention and treatment of chronic inflammation, organ fibrosis and cancer associated with canonical WNT/β‑catenin signaling activation (Review)
  Journal ArticleModerateKatoh M2018-01-01T00:00:00.000000Z

Frequently Asked Questions