Intracranial Disease Control and Survival among Patients with KRAS-mutant Lung Adenocarcinoma and Brain Metastases Treated with Stereotactic Radiosurgery.

PURPOSE: Precision medicine according to molecularly defined subgroups offers great potential to improve outcomes for patients with metastatic lung adenocarcinoma. This study describes clinical outcomes and the impact of co-occurring genetic alterations on outcomes following stereotactic radiosurgery (SRS) among patients with Kirsten rat sarcoma viral oncogene homolog (KRAS)-mutant lung adenocarcinoma.

METHODS AND MATERIALS: A total of 195 patients with KRAS-mutant lung adenocarcinoma were treated with SRS for brain metastases (BMs) between 2014 and 2018 with follow-up until 2022 or death. Coprimary outcomes were median overall survival (OS) and intracranial progression-free survival (iPFS); univariable and multivariable Cox regression models and Kaplan-Meier survival analysis were used.

RESULTS

Median follow-up from the date of BM diagnosis was 11 months. Median OS and iPFS for the cohort were 27.7 months (95% CI, 19.7-36.8) and 22.1 months (95% CI, 16.8-48.9), respectively. Lesion-level local control at 12 and 24 months was 89.9% and 87.5%, respectively. In a multivariable Cox regression model, inferior OS was associated with coalterations in KEAP1 and STK11 (hazard ratio [HR], 1.94; 95% CI, 1.04-3.62; q = 0.087), progressive (HR, 3.41; 95% CI, 1.38-8.39; q = 0.087), and mixed response (HR, 3.52; 95% CI, 1.2-10.3; q = 0.092) extracranial disease, and 6 or more BMs at time of diagnosis (HR, 2.58; 95% CI, 1.22-6.63; q = 0.087). Positive programmed death ligand 1 status was associated with improved OS (HR, 0.57; 95% CI, 0.37-0.87; P = .01). Inferior iPFS was associated with chemotherapy before SRS (HR, 2.69; 95% CI, 1.42-5.09; q = 0.04) and age >65 years (HR, 2.21; 95% CI, 1.25-3.93; q = 0.055). KRAS G12C was not associated with differences in iPFS, OS, or type of intracranial progression event following SRS.

CONCLUSIONS

Coalteration of KRAS and KEAP1/STK11 was associated with inferior OS, but not iPFS. Similar outcomes were found in patients harboring KRAS G12C and non-G12C mutant non-small cell lung cancer BMs. Further understanding of molecularly characterized subgroups will be critical in driving personalized radiation therapy for patients with lung cancer BMs.