Substudy 01A: Zilovertamab Vedotin in Pediatric and Young Adult Participants With Hematologic Malignancies or Solid Tumors (MK-9999-01A/LIGHTBEAM-U01) — Stella
Phase 1 — Early testing in a small group of people (usually 20–80) to evaluate safety, determine safe dosage, and identify side effects.
(67 sites) United States
Children's Hospital Los Angeles ( Site 1006), Los Angeles, California Children's Hospital Colorado-Center for Cancer and Blood Disorders ( Site 1016), Aurora, Colorado Yale New Haven Hospital ( Site 1012), New Haven, Connecticut Johns Hopkins All Children's Hospital ( Site 1025), St. Petersburg, Florida University of Iowa-Holden Comprehensive Cancer Center ( Site 1017), Iowa City, Iowa Dana-Farber Cancer Institute ( Site 1013), Boston, Massachusetts Corewell Health ( Site 1001), Grand Rapids, Michigan Children's Mercy Hospital ( Site 1024), Kansas City, Missouri Rutgers Cancer Institute of New Jersey ( Site 1008), New Brunswick, New Jersey Memorial Sloan Kettering Cancer Center ( Site 1010), New York, New York New York Medical College ( Site 1023), Valhalla, New York Sanford Fargo Medical Center-Roger Maris Cancer Center ( Site 1003), Fargo, North Dakota Australia
Sydney Children's Hospital ( Site 1997), Randwick, New South Wales Queensland Children's Hospital-Oncology & Haematology ( Site 1996), Brisbane, Queensland Belgium
UZ Gent ( Site 1428), Ghent, Oost-Vlaanderen Brazil
Hospital Erasto Gaertner-CEPEP - Pesquisa Clínica ( Site 1268), Curitiba, Paraná Hospital de Clinicas de Porto Alegre ( Site 1265), Porto Alegre, Rio Grande do Sul Fundação Pio XII - Hospital de Câncer de Barretos ( Site 1264), Barretos, São Paulo Fundação Faculdade Regional de Medicina de São José do Rio Preto-Centro Integrado de Pesquisa ( Site 1267), São José do Rio Preto, São Paulo Canada
McGill University Health Centre-Pediatric HematologyOncology ( Site 1223), Montreal, Quebec Chile
Hospital Luis Calvo Mackenna ( Site 1879), Santiago, Region M. de Santiago Hospital Carlos Van Buren ( Site 1880), Valparaíso, Región de Valparaíso Hospital Clínico Regional Dr. Guillermo Grant Benavente ( Site 1881), Concepción, Región del Biobío Colombia
Hospital Pablo Tobon Uribe ( Site 1923), Medellín, Antioquia Clinica de la Costa S.A.S.-Clinical Research Oncology & Hematology -Pediatric ( Site 1924), Barranquilla, Atlántico IMAT S.A.S ( Site 1921), Montería, Departamento de Córdoba Czechia
Detska nemocnice FN Brno ( Site 1388), Brno, Brno-mesto Fakultni nemocnice v Motole-Klinika detske hematologie a onkologie ( Site 1387), Prague, Praha 5 Denmark
Rigshospitalet-Department of paediatrics and adolescent medicine, Section of Paed haem-onc ( Site 1467), Copenhagen, Capital Region France
CHU de Bordeaux. Hopital Pellegrin ( Site 1105), Bordeaux, Aquitaine CENTRE LEON BERARD-IHOPE (pediatrric oncology) ( Site 1100), Lyon, Auvergne-Rhône-Alpes Centre Hospitalier Universitaire de Nantes - Hôpital Femme-Enfant-Adolescent Chu De Nantes ( Site 1104), Nantes, Loire-Atlantique Assistance Publique Hôpitaux de Marseille - Hôpital de la Timone ( Site 1102), Marseille, Provence-Alpes-Côte d'Azur Region Gustave Roussy ( Site 1103), Villejuif, Île-de-France Region Germany
Universitaetsklinikum Tuebingen ( Site 1142), Tübingen, Baden-Wurttemberg Universitaetsklinikum Koeln. Klinik und Poliklinik ( Site 1145), Cologne, North Rhine-Westphalia Universitätsklinikum Münster - Albert Schweitzer Campus-Pädiatrische Hämatologie und Onkologie ( Site 1141), Münster, North Rhine-Westphalia Charité Campus Virchow-Klinikum-Klinik für Pädiatrie mit Schwerpunkt Hämatologie und Onkologie ( Site 1143), Berlin Greece
Aghia Sophia Children's Hospital-First Department of Pediatrics, National and Kapodistrian Universi ( Site 1797), Athens, Attica Hungary
Semmelweis Egyetem ( Site 1838), Budapest Israel
Rambam Health Care Campus-Pediatric Hemato-Oncology ( Site 1674), Haifa Sheba Medical Center ( Site 1675), Ramat Gan Italy
Fondazione IRCCS Istituto Nazionale dei Tumori-Pediatric Oncology ( Site 1552), Milan, Lombardy Ospedale Pediatrico Bambino Gesù IRCCS-Dipartimento di Onco-Ematologia e Terapia Cellulare e Genica ( Site 1553), Rome, Roma Ospedale Infantile Regina Margherita-S.C. Oncoematologia Pediatrica ( Site 1551), Torino Netherlands
Prinses Maxima Centrum voor Kinderoncologie ( Site 1510), Utrecht Slovakia
Narodny ustav detskych chorob ( Site 1592), Bratislava, Bratislava Region South Korea
Seoul National University Hospital-Pediatrics ( Site 1972), Seoul Asan Medical Center-Pediatrics - Pedicatric Oncology ( Site 1973), Seoul Spain
Hospital Sant Joan de Déu-Pediatric Oncology Department ( Site 1717), Esplugas de Llobregat, Barcelona Hospital Infantil Universitario Niño Jesús-Servicio de Onco-Hematología Pediátrica ( Site 1715), Madrid, Madrid, Comunidad de Hospital Universitari Vall d'Hebron-Servei de Hematologia i Oncologia Pediatrica ( Site 1716), Barcelona Sweden
Sahlgrenska Universitetssjukhuset ( Site 1634), Gothenburg, Västra Götaland County Taiwan
National Taiwan University Hospital ( Site 1983), Taipei Turkey (Türkiye)
Ege Universitesi Hastanesi ( Site 1963), Bornova, İzmir Hacettepe Universite Hastaneleri ( Site 1961), Ankara Ankara Bilkent Şehir Hastanesi ( Site 1962), Ankara United Kingdom
Birmingham Children's Hospital-Oncology/Haematology ( Site 1349), Birmingham, England Royal Victoria Infirmary-Great North Children's Hospital ( Site 1348), Newcastle upon Tyne, England University College London Hospital ( Site 1350), London, London, City of Royal Marsden Hospital (Sutton)-Drug Development Unit ( Site 1347), Sutton, Surrey University Hospital of Wales ( Site 1346), Cardiff
Key details Phase
Early testing / Safety & dosing
Sponsor
Merck Sharp & Dohme LLC
Enrollment target
~90 participants
Primary completion
March 2029
Age range
6 Months – 25 Years
Last updated April 2026
Interested in joining? Oregon Health and Science University ( Site 1004), Portland, Oregon
Children's Hospital of Philadelphia (CHOP) ( Site 1021), Philadelphia, Pennsylvania Sanford Children's Hospital-Sanford Children's Specialty Clinic ( Site 1015), Sioux Falls, South Dakota University of Texas MD Anderson Cancer Center ( Site 1007), Houston, Texas Intermountain - Primary Children's Hospital ( Site 1014), Salt Lake City, Utah