Fostamatinib

證據等級: L5

預測適應症: 10 個

Fostamatinib: From Immune Thrombocytopenia (ITP) to Autosomal Thrombocytopenia with Normal Platelets

One-Sentence Summary

Fostamatinib (brand name: Tavalisse/Tavlesse) is an oral spleen tyrosine kinase (SYK) inhibitor approved for the treatment of chronic immune thrombocytopenia (ITP) in adults who have had an insufficient response to a previous therapy. The TxGNN model predicts it may be effective for Autosomal Thrombocytopenia with Normal Platelets — a rare inherited platelet disorder — with a prediction confidence of 99.45%. However, no clinical trials and no disease-specific publications currently support this repurposing direction; the prediction reflects knowledge graph clustering of thrombocytopenia-related disease nodes rather than direct mechanistic evidence.

Quick Overview

Item	Content
Original Indication	Chronic immune thrombocytopenia (ITP) in adults
Predicted New Indication	Autosomal Thrombocytopenia with Normal Platelets
TxGNN Prediction Score	99.45%
Evidence Level	L4
Denmark Market Status	Not marketed
Number of Marketing Authorisations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Detailed mechanism of action data is not available in the current evidence pack. Based on known pharmacology, Fostamatinib is a selective inhibitor of spleen tyrosine kinase (SYK). In chronic immune thrombocytopenia (ITP), activated SYK mediates Fcγ receptor (FcγR)-driven macrophage destruction of antibody-coated platelets. By inhibiting SYK, Fostamatinib reduces this immune-mediated clearance and thereby raises circulating platelet counts. This mechanism has been clinically validated across multiple Phase 3 trials leading to FDA (2018) and EMA approval.

Autosomal Thrombocytopenia with Normal Platelets (OMIM reference) is a genetically inherited condition caused by germline mutations affecting platelet production or survival — not by autoantibody-mediated platelet destruction. Because the underlying aetiology is fundamentally different from ITP, the SYK-FcγR inhibition mechanism has limited direct applicability to this inherited disorder.

That said, SYK signalling is known to participate in megakaryocyte differentiation and platelet biogenesis pathways. This opens a theoretical — but currently unproven — hypothesis that SYK modulation could influence platelet production in genetic thrombocytopenias. The TxGNN high score (99.45%) most plausibly reflects the model’s knowledge graph clustering effect among thrombocytopenia-related disease nodes, and should be interpreted as a hypothesis-generating signal requiring preclinical validation before any clinical consideration.

Clinical Trial Evidence

Currently no related clinical trials registered for Fostamatinib in Autosomal Thrombocytopenia with Normal Platelets.

Literature Evidence

Currently no related literature available for Fostamatinib in Autosomal Thrombocytopenia with Normal Platelets.

Denmark Market Information

Fostamatinib is currently not marketed in Denmark and holds no marketing authorisations from the Danish Medicines Agency (Laegemiddelstyrelsen). No centralised European Marketing Authorisation (EMA) procedure listing is present in the evidence pack.

Note for prescribers: Fostamatinib is approved in the EU as Tavlesse (R-Pharm) for chronic ITP in adult patients. The EMA-approved Summary of Product Characteristics (SmPC) is available via the EMA product database and constitutes the authoritative reference for dosing, contraindications, and safety in any potential named-patient or compassionate use context in Denmark.

Safety Considerations

Please refer to the approved Summary of Product Characteristics (SmPC) for Tavlesse (EMA) for complete safety information, including warnings, contraindications, and drug interactions.

Conclusion and Next Steps

Decision: Hold

Rationale: Autosomal Thrombocytopenia with Normal Platelets is a genetically inherited platelet disorder with a pathophysiology distinct from the immune-mediated ITP for which Fostamatinib is approved; there is no clinical trial evidence, no disease-specific literature, and no confirmed mechanistic link to support advancing this repurposing candidate at this stage.

To proceed, the following is needed:

Preclinical evidence: Establish whether SYK pathway dysregulation is present in the specific genetic variant(s) underlying this condition (e.g., in vitro megakaryocyte differentiation assays or patient-derived iPSC models)
Mechanistic data (MOA): Retrieve full Fostamatinib pharmacology from DrugBank API (currently flagged as Data Gap DG002) to refine mechanistic plausibility assessment
Safety profile review: Obtain and review the Tavlesse SmPC from EMA (Data Gap DG001 equivalent) — particularly hepatotoxicity, hypertension, and neutropenia signals relevant to any investigational use
Genetic subtype mapping: Define the specific OMIM mutation(s) and determine whether any involve SYK-related signalling cascades before framing a research hypothesis
Orphan disease pathway assessment: If preclinical data are supportive, evaluate eligibility for EU orphan designation prior to any clinical development planning
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.