Mechanism of Dacomitinib: How can irreversible pan HER inhibitors target lung cancer?
Dacomitinib, as a second-generation irreversible pan HER inhibitor, inhibits tumor growth by covalently binding to the tyrosine kinase domain of the HER family receptor, persistently blocking downstream signaling pathways. Its unique mechanism of action enables it to demonstrate significant efficacy in the treatment of EGFR mutation positive non-small cell lung cancer (NSCLC).
1、 Mechanism of action
1. Targeting HER family receptors
Dakatinib selectively inhibits HER1 (EGFR), HER2, and HER4 receptors, forming covalent bonds with ATP binding sites to achieve irreversible binding. This characteristic allows it to remain active against traditional reversible inhibitor resistant mutations (such as T790M).
2. Blocking signal transduction pathways
(1) Inhibition of receptor autophosphorylation: Blocking the dimerization and autophosphorylation of HER family receptors, reducing downstream signal activation.
(2) Interference with the PI3K AKT mTOR pathway: reduces the survival and proliferation ability of tumor cells.
(3) Inhibition of MAPK pathway: reduces the expression of cell cycle progression related proteins.
3. Overcoming resistance mechanisms
Compared with the first generation EGFR-TKI, dacotinib has a stronger inhibitory effect on resistance caused by T790M mutation. Its broad-spectrum HER inhibitory properties can delay secondary drug resistance caused by bypass activation.
2、 Drug interactions
1. CYP2D6 substrate drugs
Dakatinib may inhibit CYP2D6 activity. When used in combination with drugs metabolized by this enzyme, such as fluoxetine and metoprolol, it is necessary to monitor the substrate drug concentration and consider reducing the dosage to prevent an increase in adverse reactions.
2. Gastric acid regulator
(1) Proton pump inhibitors (such as omeprazole): may reduce the absorption of dacotinib, it is recommended to administer them intermittently or switch to H2 receptor antagonists.
(2) Antacids: They should be taken at least 2 hours apart from Dakatinib to avoid affecting drug solubility and bioavailability.
3. CYP3A4 influencing agent
Strong CYP3A4 inducers (such as rifampicin) may reduce the blood concentration of Dakatinib and should be avoided in combination; Medium efficacy inducers need to be closely monitored for efficacy. Strong inhibitors (such as ketoconazole) may increase exposure and toxicity risks need to be evaluated.
4. HER targeted drugs
Combined use with other EGFR/HER2 inhibitors may increase skin toxicity, diarrhea, and other adverse reactions, and is usually avoided in clinical practice.
5. Specific food interactions
Grapefruits and their products may increase the concentration of dacotinib by inhibiting CYP3A4, and should be avoided during treatment. A high-fat diet may delay absorption, and it is recommended to take medication on an empty stomach.
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