Which drug is primarily used as targeted therapy for gastrointestinal stromal tumors (GIST)?

Imatinib, also known by its brand name Gleevec, is primarily used as targeted therapy for gastrointestinal stromal tumors (GIST) due to its ability to inhibit specific tyrosine kinases, particularly the mutated form of the KIT protein that is often involved in the development of GISTs. This mechanism of action allows Imatinib to effectively block the signals that promote tumor growth and proliferation in these types of cancers.

In comparison, the other drugs listed are traditional chemotherapy agents that are not specific to the molecular targets present in GIST. Cisplatin, for instance, is a platinum-based compound typically used for a range of solid tumors but lacks the specificity for targeting abnormalities in GIST. Likewise, Paclitaxel is a taxane used in various solid tumors and works by disrupting cell division but does not directly target the signaling pathways involved in GIST. Vincristine, an alkaloid chemotherapy drug, interferes with microtubule formation in cancer cells, again without the targeted approach seen with Imatinib.

Thus, Imatinib stands out as the primary choice for targeted therapy in patients with GIST, thanks to its mechanism that directly impacts the underlying causes of the tumor’s growth.