Filgotinib
| Evidence Level: L5 | Predicted Indications: 10 |
Table of Contents
Filgotinib: From Its Marketed Use (JAK1 Inhibition) to HER2-Positive Breast Carcinoma
One-Sentence Summary
Filgotinib is a selective JAK1 inhibitor marketed in Singapore as Jyseleca. It has been developed for inflammatory diseases such as rheumatoid arthritis and ulcerative colitis, although the registered indication text is not available in the data compiled for this report. The TxGNN model predicts it may be effective for HER2-positive breast carcinoma, but there are currently 0 clinical trials and 0 publications supporting this direction. This prediction rests on the model score alone.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not stated in the Singapore licence data (the licences carry no indication text) |
| Predicted New Indication | HER2-positive breast carcinoma |
| TxGNN Prediction Score | 98.88% |
| Evidence Level | L5 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 2 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Filgotinib is a selective JAK1 inhibitor. It also shows pharmacological activity on JAK2, JAK3 and TYK2. Detailed mechanism-of-action text is not available in the data compiled for this report, but the target profile is known.
The JAK/STAT pathway, particularly STAT3, has been implicated in breast cancer biology. This offers a loose theoretical rationale for the prediction. However, no trial or publication links filgotinib to HER2-positive disease. The high score (0.989) is a model output only and is not backed by clinical or preclinical evidence.
Other top-ranked predictions show similar weakness. Several are thrombocytopenia-related conditions, and the only literature found for "thrombocytopenia" includes a 2026 case report of immune-mediated thrombocytopenia arising after filgotinib was started in an ulcerative colitis patient. That is a safety signal rather than support for repurposing.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
Currently no related literature available for HER2-positive breast carcinoma.
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN16980P | JYSELECA FILM-COATED TABLET 100MG | Tablet, film coated | Not listed in licence data |
| SIN16981P | JYSELECA FILM-COATED TABLET 200MG | Tablet, film coated | Not listed in licence data |
Safety Considerations
- Drug Interactions: The interaction screen was completed. It returned four pharmacological target entries rather than drug-drug interactions: JAK1, JAK2, JAK3 and TYK2.
- Other Safety Signals: A 2026 case report describes immune-mediated thrombocytopenia after filgotinib initiation in an ulcerative colitis patient, and the authors advise close platelet monitoring. Causality is uncertain.
- Regulatory Note: Public reports state the FDA issued a complete response letter in 2020 because of concerns about the effect of the 200 mg dose on sperm concentration. The EMA and Japan's PMDA approved filgotinib for rheumatoid arthritis.
Please refer to the package insert for full warnings and contraindications.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction is supported only by the model score. There are no clinical trials or publications for HER2-positive breast carcinoma. The mechanistic link is speculative, and the safety package insert data are missing.
To proceed, the following is needed:
- Preclinical evidence (cell line or in vivo) of filgotinib activity in HER2-positive breast cancer
- Detailed mechanism-of-action data and analysis of how JAK1 inhibition would apply to this tumour type
- The Singapore package insert (warnings, contraindications, approved indications) for safety screening
- A review of the JAK inhibitor class safety profile, including thrombocytopenia, infection, thrombosis and lipid effects, in the context of cancer patients
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.