Rescue of Suprasellar Metastasis of EGFR -mutant NSCLC by Daily Osimertinib Re-escalation With Filgrastim Support

BACKGROUND/AIM: )-mutated non-small-cell lung cancer can be challenging if dose-limiting toxicities prevent adequate drug exposure. CASE REPORT: We report the case of a 70-year-old woman with a suprasellar metastasis abutting the optic chiasm for whom radiotherapy was contraindicated. Although treatment with 80 mg osimertinib once daily was begun, recurrent grade 3 neutropenia required a dose reduction to 40 mg every other day. During alternate-day dosing, the suprasellar lesion progressed despite continued control of extracranial disease, threatening the patient's vision. To enhance exposure of the CNS to osimertinib, its dosage was escalated to 40 mg once daily supported by granulocyte colony-stimulating factor (filgrastim). This strategy successfully led to tumor regression and maintained disease control without unmanageable toxicity. CONCLUSION: This case suggests that dose reduction can weaken the effect of osimertinib on the CNS and that maintaining dose intensity using granulocyte colony-stimulating factor support is a viable and effective strategy for controlling CNS lesions in eloquent areas when local therapy is contraindicated.