Hovedinklusionskriterier: 1. Dokumenteret genetisk ændring i ROS1-punktmutation, -fusion eller -amplifikation eller NTRK1-3-fusion som identificeret ved lokal testning i et hospitalslaboratorie eller tilsvarende akkrediteret diagnostisk laboratorium uden for USA er påkrævet. 2. Fase 1: Alder <12 years; Phase 2: Age 12- 25 years 3. Prior cytotoxic chemotherapy is allowed. 4. Prior immunotherapy is allowed. 5. Resolution of all acute toxic effects (excluding alopecia) of any prior anti-cancer therapy to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) Version 4.03 Grade less than or equal to 1. 6. All subjects must have measurable disease by RECIST v1.1 or Response Assessment in Neuro-Oncology (RANO) criteria at time of enrollment. 7. Subjects with a primary CNS tumor or CNS metastases must be neurologically stable on a stable or decreasing dose of steroids for at least 7 days prior to enrollment. 8. Subjects must have a Lansky (< 16 years) or Karnofsky (≥ 16 years) score of at least 50. 9. Life expectancy greater than or equal to 12 weeks, in the investigator's opinion. 10. Adequate hematologic, renal and hepatic function. Phase 2 Inclusion Criteria: 1. Cohort Specific Inclusion Criteria: - Cohort 1: Subjects with NTRK fusion gene positive (NTRK+) advanced solid tumors (including primary CNS tumors), that are tropomyosin receptor kinase (TRK) TKI naïve; - Cohort 2: subjects with NTRK+ advanced solid tumors (including primary CNS tumors), that are TRK TKI pre-treated; - Cohort 3: subjects with advanced solid tumors with ROS1 gene fusions or other ROS1 aberrations (including amplifications and point mutations) with measurable disease. 2. Subjects in Cohorts 1 and 2 must have prospectively confirmed measurable disease by BICR prior to enrollment. Key Exclusion Criteria (Phase 1 and Phase 2): 1. Subjects with neuroblastoma with only bone marrow disease evaluable by bone marrow aspiration only. 2. Major surgery within 14 days (2 weeks) of start of repotrectinib treatment. Central venous access (Broviac, Mediport, etc.) placement does not meet criteria for major surgery. 3. Known active infections requiring ongoing treatment (bacterial, fungal, viral including HIV positivity). 4. Gastrointestinal disease (e.g., Crohn's disease, ulcerative colitis, or short gut syndrome) or other malabsorption syndromes that would impact drug absorption. 5. Any of the following cardiac criteria: - Mean resting corrected QT interval (ECG interval measured from the onset of the QRS complex to the end of the T wave) for heart rate (QTc)> Gennemsnitligt hvilekorrigeret QT-interval >480 msek, opnået fra tre på hinanden følgende EKG'er, ved brug af QTc-værdien fra screeningsklinikkens EKG–maskine - Alle klinisk vigtige abnormiteter i rytme, ledning, eller morfologi af hvile-EKG (f.eks. komplet venstre grenblok, tredjegrads hjerteblok, andengrads hjerteblok, PR-interval > 250 msek.) - Eventuelle faktorer, der øger risikoen for QTc-forlængelse eller risiko for arytmiske hændelser såsom hjertesvigt, medfødt langt QT-syndrom, slægtsanamnese med langt QT-syndrom eller eventuel samtidig medicin, der vides at forlænge QT-intervallet 6. Perifer neuropati af CTCAE ≥ grad 2. 7. Forsøgspersoner, der behandles med eller forventer et behov for behandling med stærke CYP3A4 -hæmmere eller induktorer 8. Eventuelle potentielle allergier over for repotrectinib og/eller dettes hjælpestoffer.