De novo brain metastases occur frequently in NSCLC. Untreated brain metastases are an exclusion criteria for most clinical trials whilst local therapies administered at the time of diagnosis may confound radiological response assessment. The intracranial activity of first line chemoimmunotherapy in this setting is uncertain, therefore further data on optimal treatment sequencing are needed.

KRAS is a common molecular driver in lung adenocarcinoma. KRAS subtypes can be grouped into transversion mutations (exchange of a purine for a pyrimidine bases or vice versa) such as KRAS G12C/G12V and transition mutations (interchange of a purine for another purine or interchange of a pyrimidine for another pyrimidine) such as KRAS G12D. This study assessed the efficacy of treatment and CNS prevalence across different subtypes of KRAS mutant NSCLC.