Crizotinib – ALK and ROS1 Inhibitor Therapy
Crizotinib is a highly selective oral receptor tyrosine kinase inhibitor that represents a breakthrough in personalized oncology. The drug belongs to the category of targeted therapies and is specifically designed to treat tumors whose growth is driven by specific genetic alterations. Crizotinib blocks signaling pathways within cancer cells, inhibiting their division and inducing cell death.
The mechanism of action of crizotinib involves the inhibition of anaplastic lymphoma kinase (ALK), proto-oncogene ROS1, and hepatocyte growth factor receptor (HGFR, c-Met). In ALK-positive patients, a genetic rearrangement occurs, leading to the fusion of the ALK gene with the EML4 gene, creating an abnormal protein that constantly stimulates tumor growth. Crizotinib selectively binds to the ATP-binding pocket of these enzymes, effectively "switching off" the molecular growth switch. This leads to a significant reduction in tumor mass and disease stabilization, even in advanced stages where traditional chemotherapy proves ineffective.
The drug is available in oral capsule form, allowing patients to undergo treatment in an outpatient setting under the regular supervision of a physician.
Indications
Crizotinib is indicated for the treatment of adult patients with advanced or metastatic cancers harboring a specific biomarker:
- ALK-positive NSCLC: first-line therapy or subsequent treatment of non-small cell lung cancer with a confirmed ALK gene translocation.
- ROS1-positive NSCLC: treatment of metastatic non-small cell lung cancer in patients whose tumors harbor a ROS1 gene rearrangement.
- Genetic Testing: the drug should only be prescribed after mandatory confirmation of these genetic abnormalities using certified diagnostic methods (FISH or IHC).
Dosage and administration
The dosing regimen for crizotinib is standardized but may be adjusted based on the patient's individual tolerance to the medication.
- Standard Dose: the recommended dose is 250 mg twice daily (total daily dose of 500 mg).
- Administration Method: capsules should be swallowed whole, with or without food. Do not crush, dissolve, or open the capsules.
- Missed Dose: if the next dose is due in less than 6 hours, the missed dose should be skipped.
- Dose Adjustment: in case of severe adverse reactions, the dose may be tapered to 200 mg twice daily, and then to 250 mg once daily.
- Monitoring: regular monitoring of complete blood counts, liver enzyme levels, and ECG monitoring of the QT interval is required during therapy.
