INNV-10. Extended Survival In A Patient With Leptomeningeal Disease Related To EGFR Exon 19 Deletion Metastatic Non-small Cell Lung Cancer: A Case Report

INTRODUCTION Leptomeningeal disease (LMD) represents a serious neurological complication of systemic malignancies. Once diagnosed, LMD has been associated with limited life-expectancy. Herein, we report a patient with non-small cell lung cancer (NSCLC) with LMD who achieved almost 7-year overall survival (OS) from her LMD diagnosis. CASE REPORT A 60-year-old female developed worsening dry cough at age of 52. A 3-cm FDG-avid right lower lobe lung mass was found. Biopsy revealed NSCLC with EGFR exon 19 deletion. Surveillance imaging was implemented given early-stage disease. Two years later, she was found to have focal LMD along with parenchymal brain metastases. She underwent surgical resection with concomitant placement of Ommaya Reservoir. She was initiated on Osimertinib. This resulted in improvement of her focal LMD, and control of extracranial disease for 33 months when neuroimaging revealed evidence of recurrent LMD over right lateral temporal lobe. Osimertinib dose was then increased from 80 mg to 160 mg daily. At 42 months, she developed LMD progression. Despite treatment with stereotactic radiosurgery, she had further LMD progression, and another surgical resection was performed at 55 months, yet LMD recurred at 62 months, and she was enrolled in phase-2 WSD0922 clinical trial utilizing an oral brain-penetrant non-competitive reversible EGFR inhibitor with complete radiological resolution of LMD. At 73 months, she had LMD relapse and was initiated on intrathecal pemetrexed and intravenous amivantamab, and has thus far received 11 doses of intrathecal pemetrexed and amivantamab every two weeks with complete radiological response. At last follow-up, the patient is alive 82 months from her LMD diagnosis with excellent functional status. DISCUSSION our case highlights that leveraging different mechanisms of action to target EGFR mutation in sequential fashion along with consideration of intrathecal chemotherapy in patients with LMD related to metastatic EGFR-mutated NSCLC can potentially help control LMD and prolong OS.