Delayed or Upfront Brain RAdiotherapy in Treatment naïve Lung Cancer Patients With Asymptomatic or Minimally Symptomatic Brain Metastases and ALK rEarrangements

This study will consist of a Phase 1b and Phase 2 portion. The Phase 1b portion will enroll first followed by the Phase 2 portion. Each cycle of treatment = 28 days. Subjects will receive alectinib twice daily. Those in the Phase 1b portion will receive alectinib alone. Those in Phase 2 Arm A will receive alectinib alone. Those in Phase 2, Arm B will receive SRS + alectinib. A maximum of 25 cycles (2 years) of alectinib may be administered on study.