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EGFR inhibitor
Are EGFR Inhibitors the Same as Tyrosine Kinase Inhibitors (TKIs)?
Not exactly. All EGFR tyrosine kinase inhibitors are EGFR inhibitors, but not all EGFR inhibitors are tyrosine kinase inhibitors (TKIs).
EGFR Inhibitors
EGFR inhibitors refer to any drug that blocks the activity of the epidermal growth factor receptor (EGFR). There are two main types:
- Monoclonal Antibodies (mAbs):
- Target the extracellular domain of EGFR
- Block ligand binding (e.g., EGF, amphiregulin) and prevent receptor dimerization
- Examples:
- Cetuximab
- Panitumumab
- Tyrosine Kinase Inhibitors (TKIs):
- Target the intracellular kinase domain of EGFR
- Compete with ATP to block autophosphorylation and downstream signaling
- Examples:
- Erlotinib
- Gefitinib
- Afatinib
- Osimertinib
Tyrosine Kinase Inhibitors (TKIs)
TKIs are a broader class of drugs that inhibit the kinase activity of various receptor tyrosine kinases, not just EGFR. Examples include:
- EGFR-TKIs: Erlotinib, Gefitinib
- VEGFR-TKIs: Sunitinib, Sorafenib
- MET-TKIs: Crizotinib
- ABL-TKIs: Imatinib (for BCR-ABL in CML)
Comparison Table
| Feature | EGFR Inhibitor | Tyrosine Kinase Inhibitor (TKI) |
|---|---|---|
| Target | EGFR | Kinase domains (multiple receptors) |
| Includes | mAbs + TKIs | TKIs only |
| Example (mAb) | Cetuximab | ✘ |
| Example (EGFR-TKI) | Erlotinib | ✔ |
| Broader category | No | Yes |
Summary
- EGFR inhibitors = monoclonal antibodies and EGFR-TKIs
- TKIs = small molecules targeting various kinase domains, including EGFR