Siltuximab
| Evidence Level: L5 | Predicted Indications: 8 |
Table of Contents
Siltuximab: From Castleman Disease to Extracutaneous Mastocytoma
One-Sentence Summary
Siltuximab is an anti-IL-6 monoclonal antibody, originally used to treat Castleman disease (a rare lymphoproliferative disorder). The TxGNN model predicts it may be effective for extracutaneous mastocytoma, but this is a model prediction only, with 0 clinical trials and 0 publications currently supporting this direction.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Castleman disease (the US license indication text is blank, so this comes from the knowledge graph indication data) |
| Predicted New Indication | Extracutaneous mastocytoma |
| TxGNN Prediction Score | 99.64% |
| Evidence Level | L5 |
| US Market Status | Cancelled only |
| Number of NDAs | 1 (BLA125496) |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in the data compiled for this report. Based on general knowledge, siltuximab is an anti-IL-6 monoclonal antibody, and its efficacy in Castleman disease is linked to IL-6 driven lymphoproliferation and inflammation.
A possible rationale for extracutaneous mastocytoma is that IL-6 may play a role in mast cell proliferation and inflammatory signaling. However, no supporting trial or publication was found, so this link is speculative. The prediction should be regarded as a hypothesis generated by the model, not as an evidence-based indication.
Other predicted indications were also reviewed. All remain at the model-prediction stage (L5), except Kaposi’s sarcoma (L4), which has an indirect link through HHV-8-associated Castleman disease (see the note in the conclusion).
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
Currently no related literature available for extracutaneous mastocytoma.
US Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| BLA125496 (cancelled) | Sylvant (Recordati Rare Diseases, Inc.) | Injection, powder, for solution | Not listed in the data compiled for this report |
Cytotoxicity
| Item | Content |
|---|---|
| Cytotoxicity Classification | Targeted therapy (monoclonal antibody, not a conventional cytotoxic agent) |
| Myelosuppression Risk | Please refer to the package insert warnings and precautions |
| Emetogenicity Classification | Please refer to the package insert warnings and precautions |
| Monitoring Items | Please refer to the package insert warnings and precautions |
| Handling Protection | Please refer to the package insert warnings and precautions |
Safety Considerations
- Drug Interactions: The interaction screen returned 100 potential interactions. Of the 20 listed in the data compiled for this report, the main ones are:
- Major: Deferiprone
- Moderate: Simvastatin, warfarin, apixaban, rivaroxaban, dicoumarol, tacrolimus, theophylline, aminophylline, oxtriphylline, roflumilast, lidocaine, fentanyl, hydrocodone, nifedipine, tetanus toxoid vaccine
- Minor: Zinc salts (sulfate, acetate, gluconate, chloride)
Many of these are drugs with a narrow therapeutic index that are metabolised by CYP enzymes (warfarin, tacrolimus, theophylline, simvastatin). IL-6 blockade can normalise suppressed CYP activity, so drug levels should be monitored when treatment starts or stops.
For other safety information, such as warnings and contraindications, please refer to the package insert.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction rests only on a model score (99.64%), with no clinical trials or publications for extracutaneous mastocytoma. The mechanistic link is speculative, mastocytosis-type diseases are driven mainly by KIT signaling, and the only US license has been cancelled.
To proceed, the following is needed:
- Mechanism of action data and a review of IL-6 involvement in mast cell disease
- Preclinical or literature evidence for IL-6 blockade in mastocytoma
- FDA package insert warnings and contraindications, which are required before safety screening
- A decision on product availability, since the Sylvant license is cancelled
Note on other predictions: Kaposi’s sarcoma is the most promising alternative (L4, “Research Question”). It shares pathogenic features with HHV-8-associated Castleman disease, including viral and human IL-6 dysregulation. The only publication retrieved (PMID 39970477, a 2024 review in AIDS Reviews on Castleman disease) is indirect and does not study siltuximab in Kaposi’s sarcoma. The remaining predictions (hepatic infarction, hepatic veno-occlusive disease, peliosis hepatis, familial Mediterranean fever, aggressive systemic mastocytosis, autosomal dominant familial periodic fever) have no supporting evidence and remain on Hold.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.