Efficacy of nano‐particulated, water‐soluble erlotinib against intracranial metastases of EGFR‐mutant lung cancer

Central nervous system (CNS) metastasis is one of the serious complications of epidermal growth factor receptor (EGFR)‐mutant lung cancer, which arises due to poor penetration of the brain–blood barrier by EGFR‐tyrosine kinase inhibitors (EGFR‐TKIs). Although osimertinib, a third‐generation EGFR‐TKI, has efficacy against CNS metastases, further treatment modalities are still needed as some of these lesions do not respond to osimertinib, or undergo progression after an initial response to this drug if radiotherapy has already been conducted. Here, we investigated the efficacy of water‐soluble erlotinib (NUFS‐sErt) against these metastases. This agent was synthesized using a nano‐particulation platform technology utilizing fat and supercritical fluid (NUFS™) to resolve the low solubility problem that typically prevents the creation of injectable forms of EGFR‐TKIs. The average NUFS‐sErt particle size was 236.4 nm, and it showed time‐dependent dissolution in culture media. The effects of NUFS‐sErt were similar to those of conventional erlotinib in terms of inhibiting the proliferation of EGFR‐mutant lung cancer cells and suppressing EGFR signaling. In an intraperitoneal xenograft model of HCC827 cells, intraperitoneal administration of NUFS‐sErt produced a dose‐dependent inhibition of tumor growth and enhanced survival rate. Notably, the injection of NUFS‐sErt into the brain ventricle caused significant tumor growth inhibition in an intracranial xenograft model. Hence, our current findings indicate that NUFS‐sErt is a novel, water‐soluble form of erlotinib that can be administered using intraventricular or intrathecal injections. The target cases would be patients with a progressive CNS metastasis and no other therapeutic options. This drug could also be given intravenously to patients with swallowing difficulties or an inability to ingest due to a medical condition.