Firmonertinib Combined With Intrathecal Injection for the Treatment of EGFR Mutant NSCLC With Leptomeningeal Metastases

Leptomeningeal metastases (LM) are a relatively rare site of metastasis in advanced non-small cell lung cancer (NSCLC), and LM patients have a poor prognosis. Numerous retrospective studies have reported that high-dose Firmonertinib can also effectively increase patient prognosis and have tolerable side effects, but there is a lack of prospective studies to confirm this. In addition, there are currently no good biomarkers for monitoring the efficacy of LM treatment. cfDNA testing can be used for early cancer screening, monitoring tumor progression, evaluating treatment response, and discovering drug resistance mechanisms. Due to the influence of the blood-brain barrier, the level of cfDNA in the plasma of LM patients is often very low, and the detection of cfDNA in cerebrospinal fluid (CSF) is more advantageous. Therefore, exploring the dynamic monitoring of LM treatment efficacy using CSF cfDNA is of great significance for improving patient prognosis. Based on this, the applicant intends to conduct a prospective, multicenter, single-arm, post-market exploratory clinical trial on the treatment methods and efficacy monitoring of NSCLC-LM patients. The aim was to explore whether cfDNA has the potential to become a biomarker for LM efficacy monitoring and to validate the efficacy and safety of high-dose fumatinib combined with intrathecal injection in the treatment of NSCLC-LM patients.