KRAS G12C Mutation
The KRAS G12C mutation is a specific alteration in the KRAS gene that results in uncontrolled cell growth and cancer development. It is now a target for precision therapies.
🔬 What is KRAS?
KRAS is part of the RAS family of oncogenes and encodes a small GTPase involved in:
- Cell proliferation
- Cell differentiation
- Cell survival
It cycles between active (GTP-bound) and inactive (GDP-bound) states. Mutations lock it in the active state.
🧬 The G12C Mutation
- Mutation: Glycine (G) → Cysteine (C) at codon 12
- Mechanism: Point mutation (GGT → TGT)
- Effect: Constitutive activation of KRAS protein
[folded|Click to expand: Cancer types with KRAS G12C]
- Non-Small Cell Lung Cancer (NSCLC): ~13%
- Colorectal Cancer: ~3–4%
- Pancreatic Cancer: <1%
- Other: rare cases (endometrial, ovarian, etc.)
[/folded]
💊 Targeted Therapies
KRAS G12C is targetable with covalent inhibitors:
- Adagrasib (Krazati)
- Sotorasib (Lumakras)
These drugs bind KRAS G12C in its inactive (GDP-bound) form, blocking downstream signaling.
🔄 Resistance & Combinations
Mechanisms of resistance:
- Secondary KRAS mutations
- Reactivation via bypass pathways (e.g., EGFR, MET)
Current strategies:
- KRAS inhibitors + checkpoint inhibitors (PD-1/PD-L1)
- KRAS inhibitors + EGFR inhibitors (e.g., cetuximab)
- KRAS inhibitors + SHP2/MEK inhibitors