Osimertinib is effective for relapsed T790M-positive patients with brain metastases. The high brain permeability suggests that also such patients without T790M could benefit. Therefore, we evaluated the effect of osimertinib on brain metastases in both T790M-positive and -negative patients. The TREM-study was an investigator-initiated phase II, single-arm, multi-institutional clinical trial conducted in Northern Europe. Patients with resistance to prior EGFR-TKIs received osimertinib until radiological progression, unacceptable toxicity or death. Baseline brain scans were performed in...