CNS Outcomes of Osimertinib Plus Chemotherapy in Patients With EGFR Mutation Positive Lung Cancer Beyond Osimertinib Progression.

BACKGROUND: Central nervous system (CNS) metastases are common among patients with epidermal growth factor receptor (EGFR) mutation positive non-small cell lung cancer (NSCLC). Osimertinib in combination with chemotherapy beyond osimertinib progression may minimize CNS progression.

METHOD: In this retrospective analysis, patients with advanced EGFR mutation positive NSCLC and brain metastases who received platinum-based chemotherapy (PbChT) after disease progression on osimertinib were enrolled. The primary endpoint was real-world CNS progression-free survival (rwCNS-PFS) between patients who received PbChT with and without osimertinib continuation. Secondary endpoints included competing risk analysis of CNS progression and incidence of salvage radiotherapy to brain.

RESULTS: A total of 101 patients were analyzed, out of which, 39 (39%) continued osimertinib with chemotherapy (OSI+ cohort) and 62 (61%) received chemotherapy alone (OSI- cohort). Median rwCNS-PFS was significantly longer in the OSI+ cohort (9.0 months, 95% CI 6.6-11.4) than the OSI- cohort (5.7 months, 95% CI 4.6-6.9) (HR 0.37, 95% CI 0.18-0.76, P = .007). This remained significant after adjustment for EGFR mutation, line of osimertinib treatment, prior radiotherapy to brain, and CNS progression on osimertinib monotherapy. Estimated probability of CNS progression at 6 months was 5.6% in OSI+ cohort versus 20.9% in OSI- cohort. Incidence of salvage radiotherapy to brain was lower in the OSI+ cohort (15%) compared to OSI- cohort (24%).

CONCLUSION: In patients with EGFR mutation positive NSCLC and brain metastases, continuing osimertinib with chemotherapy after progression on osimertinib significantly reduced risk of CNS progression. Prospective studies are warranted to define the optimal treatment strategy for this patient population.