Criterios de inclusión clave: 1. Se requiere una alteración genética documentada de ALK, ROS1 o NTRK1-3 (mutación puntual, fusión, amplificación) según lo identificado por las pruebas locales en un laboratorio acreditado en virtud de las Enmiendas para la Mejora de los Laboratorios Clínicos (CLIA) en los EE. UU. o laboratorio de diagnóstico con una acreditación equivalente fuera de los Estados Unidos (EE. UU.). 2. Fase 1: Edad <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 Criteria (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 14 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. 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 tumors or ALCL characterized by other ALK/ROS1/NTRK alterations or NTRK fusions without centrally confirmed measurable disease or not otherwise eligible for Cohort 1 or 2. 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 (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)> 480 ms obtenido de tres ECG, usando el valor del QTc derivado de la máquina de ECG de la clínica de selección. - Cualquier anomalía clínicamente importante en el ritmo, la conducción o la morfología del ECG en reposo (p. ej., bloqueo completo de rama izquierda, bloqueo cardíaco de tercer grado, bloqueo cardíaco de segundo grado, intervalo PR >250 ms). - Cualquier factor que aumente el riesgo de prolongación del intervalo QTc o el riesgo de eventos arrítmicos, como insuficiencia cardíaca, síndrome congénito de prolongación del intervalo QT, antecedentes familiares de síndrome de prolongación del intervalo QT, o cualquier medicamento concomitante que se sepa que prolonga el intervalo QT. 6. Neuropatía periférica de grado ≥2 según los CTCAE. 7. Sujetos que reciben tratamiento con inhibidores o inductores potentes de CYP3A4 o que prevén la necesidad de dicho tratamiento.