Substudy 01A: Zilovertamab Vedotin in Pediatric and Young Adult Participants With Hematologic Malignancies or Solid Tumors (MK-9999-01A/LIGHTBEAM-U01)

Children's Hospital Los Angeles ( Site 1006), Los Angeles, California, United States

Children's Hospital Colorado-Center for Cancer and Blood Disorders ( Site 1016), Aurora, Colorado, United States

Yale New Haven Hospital ( Site 1012), New Haven, Connecticut, United States

Johns Hopkins All Children's Hospital ( Site 1025), St. Petersburg, Florida, United States

University of Iowa-Holden Comprehensive Cancer Center ( Site 1017), Iowa City, Iowa, United States

Dana-Farber Cancer Institute ( Site 1013), Boston, Massachusetts, United States

Corewell Health ( Site 1001), Grand Rapids, Michigan, United States

Children's Mercy Hospital ( Site 1024), Kansas City, Missouri, United States

Rutgers Cancer Institute of New Jersey ( Site 1008), New Brunswick, New Jersey, United States

Memorial Sloan Kettering Cancer Center ( Site 1010), New York, New York, United States

New York Medical College ( Site 1023), Valhalla, New York, United States

Sanford Fargo Medical Center-Roger Maris Cancer Center ( Site 1003), Fargo, North Dakota, United States

Oregon Health and Science University ( Site 1004), Portland, Oregon, United States

Children's Hospital of Philadelphia (CHOP) ( Site 1021), Philadelphia, Pennsylvania, United States

Sanford Children's Hospital-Sanford Children's Specialty Clinic ( Site 1015), Sioux Falls, South Dakota, United States

University of Texas MD Anderson Cancer Center ( Site 1007), Houston, Texas, United States

Intermountain - Primary Children's Hospital ( Site 1014), Salt Lake City, Utah, United States

Sydney Children's Hospital ( Site 1997), Randwick, New South Wales, Australia

Queensland Children's Hospital-Oncology & Haematology ( Site 1996), Brisbane, Queensland, Australia

Royal Children's Hospital-Children's Cancer Centre ( Site 1994), Melbourne, Victoria, Australia

UZ Gent ( Site 1428), Ghent, Oost-Vlaanderen, Belgium

Hospital Erasto Gaertner-CEPEP - Pesquisa Clínica ( Site 1268), Curitiba, Paraná, Brazil

Hospital de Clinicas de Porto Alegre ( Site 1265), Porto Alegre, Rio Grande do Sul, Brazil

Fundação Pio XII - Hospital de Câncer de Barretos ( Site 1264), Barretos, São Paulo, Brazil

Fundação Faculdade Regional de Medicina de São José do Rio Preto-Centro Integrado de Pesquisa ( Site 1267), São José do Rio Preto, São Paulo, Brazil

The Hospital for Sick Children ( Site 1225), Toronto, Ontario, Canada

McGill University Health Centre-Pediatric HematologyOncology ( Site 1223), Montreal, Quebec, Canada

Hospital Clínico Regional Dr. Guillermo Grant Benavente ( Site 1881), Concepción, Biobio, Chile

Hospital Luis Calvo Mackenna ( Site 1879), Santiago, Region M. de Santiago, Chile

Hospital Carlos Van Buren ( Site 1880), Valparaíso, Valparaiso, Chile

Hospital Pablo Tobon Uribe ( Site 1923), Medellín, Antioquia, Colombia

Clinica de la Costa S.A.S.-Clinical Research Oncology & Hematology -Pediatric ( Site 1924), Barranquilla, Atlántico, Colombia

IMAT S.A.S ( Site 1921), Montería, Departamento de Córdoba, Colombia

Detska nemocnice FN Brno ( Site 1388), Brno, Brno-mesto, Czechia

Fakultni nemocnice v Motole-Klinika detske hematologie a onkologie ( Site 1387), Prague, Praha 5, Czechia

Rigshospitalet-Department of paediatrics and adolescent medicine, Section of Paed haem-onc ( Site 1467), Copenhagen, Capital Region, Denmark

CHU de Bordeaux. Hopital Pellegrin ( Site 1105), Bordeaux, Aquitaine, France

CENTRE LEON BERARD-IHOPE (pediatrric oncology) ( Site 1100), Lyon, Auvergne-Rhône-Alpes, France

Centre Hospitalier Universitaire de Nantes - Hôpital Femme-Enfant-Adolescent Chu De Nantes ( Site 1104), Nantes, Loire-Atlantique, France

Assistance Publique Hôpitaux de Marseille - Hôpital de la Timone ( Site 1102), Marseille, Provence-Alpes-Côte d'Azur Region, France

Gustave Roussy ( Site 1103), Villejuif, Île-de-France Region, France

Universitaetsklinikum Tuebingen ( Site 1142), Tübingen, Baden-Wurttemberg, Germany

Universitaetsklinikum Koeln. Klinik und Poliklinik ( Site 1145), Cologne, North Rhine-Westphalia, Germany

Universitätsklinikum Münster - Albert Schweitzer Campus-Pädiatrische Hämatologie und Onkologie ( Site 1141), Münster, North Rhine-Westphalia, Germany

Charité Campus Virchow-Klinikum-Klinik für Pädiatrie mit Schwerpunkt Hämatologie und Onkologie ( Site 1143), Berlin, Germany

Aghia Sophia Children's Hospital-First Department of Pediatrics, National and Kapodistrian Universi ( Site 1797), Athens, Attica, Greece

Semmelweis Egyetem ( Site 1838), Budapest, Hungary

Rambam Health Care Campus-Pediatric Hemato-Oncology ( Site 1674), Haifa, Israel

Sheba Medical Center ( Site 1675), Ramat Gan, Israel

Fondazione IRCCS Istituto Nazionale dei Tumori-Pediatric Oncology ( Site 1552), Milan, Lombardy, Italy

Ospedale Pediatrico Bambino Gesù IRCCS-Dipartimento di Onco-Ematologia e Terapia Cellulare e Genica ( Site 1553), Rome, Roma, Italy

Ospedale Infantile Regina Margherita-S.C. Oncoematologia Pediatrica ( Site 1551), Torino, Italy

Prinses Maxima Centrum voor Kinderoncologie ( Site 1510), Utrecht, Netherlands

Narodny ustav detskych chorob ( Site 1592), Bratislava, Bratislava Region, Slovakia

Seoul National University Hospital-Pediatrics ( Site 1972), Seoul, South Korea

Asan Medical Center-Pediatrics - Pedicatric Oncology ( Site 1973), Seoul, South Korea

Hospital Sant Joan de Déu-Pediatric Oncology Department ( Site 1717), Esplugas de Llobregat, Barcelona, Spain

Hospital Infantil Universitario Niño Jesús-Servicio de Onco-Hematología Pediátrica ( Site 1715), Madrid, Madrid, Comunidad de, Spain

Hospital Universitari Vall d'Hebron-Servei de Hematologia i Oncologia Pediatrica ( Site 1716), Barcelona, Spain

Sahlgrenska Universitetssjukhuset ( Site 1634), Gothenburg, Västra Götaland County, Sweden

National Taiwan University Hospital ( Site 1983), Taipei, Taiwan

Ege Universitesi Hastanesi ( Site 1963), Bornova, İzmir, Turkey (Türkiye)

Hacettepe Universite Hastaneleri ( Site 1961), Ankara, Turkey (Türkiye)

Ankara Bilkent Şehir Hastanesi ( Site 1962), Ankara, Turkey (Türkiye)

Birmingham Children's Hospital-Oncology/Haematology ( Site 1349), Birmingham, England, United Kingdom

Royal Victoria Infirmary-Great North Children's Hospital ( Site 1348), Newcastle upon Tyne, England, United Kingdom

University College London Hospital ( Site 1350), London, London, City of, United Kingdom

Royal Marsden Hospital (Sutton)-Drug Development Unit ( Site 1347), Sutton, Surrey, United Kingdom

University Hospital of Wales ( Site 1346), Cardiff, United Kingdom