Lapatinib
| Evidence Level: L5 | Predicted Indications: 10 |
Table of Contents
Lapatinib: From HER2-Positive Breast Cancer to Dermatofibrosarcoma Protuberans
One-Sentence Summary
Lapatinib was originally used to treat HER2-positive breast cancer. The TxGNN model predicts it may be effective for dermatofibrosarcoma protuberans (DFSP), but no clinical trials and no publications in the data compiled for this report support this direction, so it is a model prediction only.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | HER2-positive breast carcinoma (from the knowledge graph; the Singapore licence record contains no indication text) |
| Predicted New Indication | Dermatofibrosarcoma protuberans |
| TxGNN Prediction Score | 99.30% |
| Evidence Level | L5 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 1 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism-of-action data is not currently available. Lapatinib is generally known as an oral dual EGFR/HER2 tyrosine kinase inhibitor. Its efficacy in HER2-positive breast cancer is established, but that mechanism does not obviously transfer to DFSP.
DFSP is driven mainly by the COL1A1-PDGFB fusion and PDGFRB signalling, which is not a recognised lapatinib target. The high score (0.993) most likely reflects proximity in the knowledge graph (for example, to other fibroblastic and sarcoma-type tumours) rather than a specific pharmacological rationale. The data compiled for this report do not support a mechanistic link.
Other predictions in the list are similarly unsupported: fibroblastic neoplasm, conventional fibrosarcoma, kidney fibrosarcoma, heart fibrosarcoma, low-grade fibromyxoid sarcoma, cysticercosis, coenurosis and lymphangiomyoma. The one exception is Plasmodium falciparum malaria (rank 8), which has preclinical evidence. It showed that lapatinib inhibits haemozoin formation (PMID 32235391), which makes it a research question rather than a clinical candidate.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
Currently no related literature available for dermatofibrosarcoma protuberans.
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN13366P | Tykerb tablet 250mg | Film-coated tablet (oral) | Indication text not available in the registration record |
Cytotoxicity
| Item | Content |
|---|---|
| Cytotoxicity Classification | Targeted therapy (small-molecule EGFR/HER2 tyrosine kinase inhibitor) |
| Myelosuppression Risk | Please refer to the package insert warnings and precautions |
| Emetogenicity Classification | Please refer to the package insert warnings and precautions |
| Monitoring Items | Liver function, cardiac function (including QT interval and left ventricular function), electrolytes (e.g. potassium), and respiratory symptoms, based on the knowledge-graph contraindication signals below |
| Handling Protection | Please refer to the package insert warnings and precautions |
Safety Considerations
- Knowledge-graph contraindication signals (not label text): long QT syndrome, familial long QT syndrome, torsades de pointes, liver failure, potassium deficiency, interstitial lung disease, drug-induced liver injury, heart failure.
- Drug Interactions: 100 interactions were recorded. The main ones are:
- Major: loperamide and clarithromycin.
- Moderate (examples):
- acid-suppressing drugs (omeprazole, rabeprazole, dexlansoprazole, famotidine, ranitidine, cimetidine)
- corticosteroids (dexamethasone, hydrocortisone, betamethasone, budesonide, triamcinolone)
- aprepitant, pioglitazone, saxagliptin, and several laxatives or bowel-preparation agents
Package-insert warnings and contraindications were not available, so please refer to the package insert for the full safety information.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction score is very high, but it is not backed by any clinical trial or publication. The proposed mechanism (DFSP driven by PDGFB/PDGFRB signalling) does not match lapatinib's EGFR/HER2 targets. The safety profile also raises concerns, including QT prolongation, hepatotoxicity, and major drug interactions.
To proceed, the following is needed:
- Mechanism-of-action data for lapatinib, and a biological rationale linking it to DFSP (for example, preclinical models)
- Package-insert warnings and contraindications from HSA, which are needed before safety screening
- Systematic literature and trial searches specific to DFSP and fibrosarcoma
- If the malaria lead is pursued, in vitro potency and exposure compared with existing antimalarials, plus a safety assessment (hepatotoxicity, QT prolongation)
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.