Is imatinib (Gleevec) a chemotherapy drug or a targeted drug and analysis of its mechanism of action

Imatinib is not a chemotherapy drug in the traditional sense, but a targeted therapy drug. Traditional chemotherapy drugs inhibit tumor growth by killing rapidly dividing cells, but this mechanism of action often lacks selectivity and damages normal cells at the same time, resulting in serious side effects. Imatinib is a first-generation small molecule targeted tyrosine kinase inhibitor (TKI) that can accurately target signaling pathways driven by abnormal genes. Therefore, its therapeutic effect is more concentrated and its side effects are milder. It has triggered a revolutionary change in efficacy in diseases such as chronic myelogenous leukemia (CML).

In terms of mechanism of action, imatinib mainly targets the tyrosine kinase activity of BCR-ABL fusion protein. CML Patients have Philadelphia chromosome abnormalities, which lead to the emergence of the BCR-ABL fusion gene, which generates a continuously activated tyrosine kinase signal and promotes the unlimited proliferation of leukemia cells. Imatinib competitively binds to the ATP binding site of BCR-ABL , thereby blocking downstream signaling pathways, inhibiting abnormal proliferation of tumor cells and inducing apoptosis. This method of precisely blocking abnormal proteins is the core feature of targeted therapy.

In addition to acting on BCR-ABL , imatinib also inhibits other tyrosine kinase targets, such as KIT and PDGFR. Because of this, the drug is not only suitable for the treatment of CML but is also widely used for gastrointestinal stromal tumors (GIST), Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL), certain rare eosinophilia, etc. Compared with traditional chemotherapy, imatinib's treatment method is more targeted, which not only improves the efficacy, but also significantly reduces the damage to normal tissues.

In general, imatinib is a targeted drug, not a chemotherapy drug. It controls tumor progression by precisely inhibiting abnormal kinase activity, changing the treatment landscape of hematologic malignancies such as CML and is hailed as a milestone drug that "opens a new era of targeted therapy." For patients, a correct understanding of the properties and mechanism of action of imatinib will help them understand its therapeutic advantages and apply it rationally in clinical practice to achieve long-term and stable efficacy.

Reference materials:https://www.drugs.com/