Systemic Treatment Patterns and Outcomes in Patients With EGFR Mutated Non-small Cell Lung Cancer and Leptomeningeal Disease

Introduction Leptomeningeal (LM) disease occurs in 9% to 10% of EGFR mutated non-small cell lung cancer (NSCLC) cases. The natural history and optimal systemic treatment strategies for this disease are not well-characterized, particularly in the era of osimertinib. Materials and Methods We identified 54 patients with EGFR mutated NSCLC and LM disease diagnosed between January 3, 2000 to March 31, 2020 and treated at an academic oncology practice in Seattle, Washington. We abstracted demographic, tumor, treatment, and outcome data from the electronic medical record. Univariate Cox models were run to evaluate the association between post-LM disease systemic therapy and overall survival. Differences in LM disease natural history and healthcare utilization between groups were assessed using Student's t test or a chi-squared test. Results Patients that received osimertinib prior to LM disease had a longer median time to LM disease diagnosis and trended toward better performance status than those that did not. Patients that received any post-LM disease systemic therapy had a lower risk of death relative to those that did not (HR 0.17, P < .001), with a suggestion that osimertinib-containing regimens result in longer median overall survival. Emergency department, hospital and hospice utilization were not associated with receipt of post-LM disease systemic therapy. Conclusion Prior exposure to osimertinib appears to favorably influence the natural history of LM disease. Any systemic therapy after LM disease diagnosis is associated with longer survival and does not increase healthcare utilization. Additional research is needed to assess whether an osimertinib-containing regimen confers a survival benefit after LM disease diagnosis among patients who received prior osimertinib.