A Study Evaluating the Safety, Pharmacokinetics, and Efficacy of Alectinib in Pediatric Participants With ALK Fusion-Positive Solid or CNS Tumors

Inclusion Criteria * Histologically confirmed diagnosis of CNS or solid tumors with documented evidence of ALK gene fusions as assessed centrally through the use of the investigational F1CDx assay or based on pre-existing NGS test results * Disease status: prior treatment proven to be ineffective (i.e. relapsed or refractory), or for whom there is no satisfactory standard treatment available. Disease should be measurable and evaluable as defined by Response Evaluation Criteria in Solid Tumors (RECIST) v 1.1, or Response Assessment in Neuro-oncology criteria (RANO) +/- bone marrow criteria for primary CNS tumors or International Neuroblastoma Response Criteria (INRC) * Available tumor tissue for submission to the Sponsor from active disease, obtained subsequent to last anti-cancer therapy regimen administered and obtained prior to study enrollment (preferred option), or archival tumor tissue from original diagnosis, or willingness to undergo a core or excisional biopsy sample collection prior to enrollment * For participants \< 16 years old, Lansky Performance Status \>/= 50% * For participants \>/= 16 years old, Karnofsky Performance Status \>/= 50% * Adequate bone marrow function as defined by the protocol within at least 28 days prior to initiation of study drug * Participant and/or caregiver willingness and ability to complete clinical outcome assessments throughout the study using either electronic, paper, or interviewer methods * For females of childbearing potential: a…