Does the use of larotinib/larlotinib require genetic testing?

Larotrectinib is a targeted therapy drug mainly used to treat tumors carrying neurotrophic tyrosine receptor kinase (NTRK) fusion genes. As a selective TRK inhibitor, larotrectinib has been approved for the treatment of patients with a variety of solid tumors, including patients with locally advanced, metastatic disease, especially those with unresectable tumors. The key feature of the drug is that it targets cancers driven by specific gene fusions, specifically those harboring NTRK gene fusions. Given the targeting mechanism and efficacy of larotrectinib, its use must rely on accurate genetic testing.

Genetic testing is necessary before using larotrectinib because the drug's efficacy is only significant in patients with tumors carryingNTRK gene fusions. NTRK gene fusion is a mutation caused by the fusion of the neurotrophic factor receptor kinase gene with other genes. It appears in a variety of tumors, such as neuroblastoma, non-small cell lung cancer, gastrointestinal stromal tumors (GIST), etc. The presence of NTRK fusion genes can lead to excessive activation of TRK receptors, thereby promoting the growth and spread of tumor cells. Larotrectinib achieves anti-tumor effects by inhibiting this overactivated signaling pathway. Therefore, larotrectinib can have the expected therapeutic effect only after it is confirmed that the tumor carries the NTRK fusion gene.

Genetic testing is not only used to confirm the presence of NTRK fusion genes, but also to rule out other possible gene mutations or drug resistance mechanisms. NTRK gene fusions can be accurately detected through genome sequencing or PCR-based detection methods. This type of genetic testing can often be performed on tumor biopsy samples (such as circulating tumor DNA (ctDNA) in tissue sections or blood). Advances in modern molecular diagnostics have made these tests more precise and efficient, providing patients with rapid and accurate diagnoses.

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