Therapeutic effect of osimertinib plus cranial radiotherapy compared to osimertinib alone in NSCLC patients with EGFR-activating mutations and brain metastases: a retrospective study.

Background: The study aimed to compare the efficacy of osimertinib plus cranial radiotherapy (RT) with osimertinib alone in advanced non-small-cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor (EGFR) mutations and brain metastases (BMs).

Methods: The clinical data of advanced NSCLC patients with BMs who received osimertinib were retrospectively collected. The patients were assigned to one of the two groups according to the therapeutic modality used: the osimertinib monotherapy group or the osimertinib plus RT group.

Results: This was a retrospective study and 61 patients were included from December 2015 to August 2020. Forty patients received osimertinib monotherapy, and twenty-one patients received osimertinib plus RT. Radiotherapy included whole-brain radiation therapy (WBRT, n = 14), WBRT with simultaneous integrated boost (WBRT-SIB, n = 5) and stereotactic radiosurgery (SRS, n = 2). The median number of prior systemic therapies in the two groups was one. Intracranial and systemic ORR and DCR were not significantly different between the two groups. No difference in iPFS was observed between the two groups (median iPFS: 16.67 vs. 13.50 months, P = 0.836). The median OS was 29.20 months in the osimertinib plus RT group compared with 26.13 months in the osimertinib group (HR = 0.895, P = 0.826). In the L858R mutational subgroup of 31 patients, the osimertinib plus RT group had a longer OS (P = 0.046). In the exon 19 deletion mutational subgroup of 30 patients, OS in the osimertinib alone group was longer than that in the osimertinib plus RT group (P = 0.011). The incidence of any-grade adverse events was not significantly different between the osimertinib plus RT group and the osimertinib alone group (47.6% vs. 32.5%, P = 0.762). However, six patients (28.5%) experienced leukoencephalopathy in the osimertinib plus RT group, and 50% (3/6) of the leukoencephalopathy was greater than or equal to grade 3.

Conclusion: The therapeutic effect of osimertinib with RT was similar to that of osimertinib alone in EGFR-positive NSCLC patients with BM. However, for patients with the L858R mutation, osimertinib plus RT could provide more benefit than osimertinib alone.