A Study of Patritumab Deruxtecan in Pediatric Participants With Relapsed or Refractory Solid Tumors (MK-9999-01C/LIGHTBEAM-U01)

NCT06941272 | Recruiting Phase 1 DMC FDA Drug

• 5 other identifiers: 9999-01CMK-9999-01CLIGHTBEAM-U01U1111-1314-18662024-518771-66-00
• Study Type: interventional
• Target: 50
• Locations: 23 countries
• Sites: 60

Brief Summary

Researchers are looking for new ways to treat children with hepatoblastoma or rhabdomyosarcoma (RMS) that has relapsed or is refractory:

• Hepatoblastoma is a common liver cancer in babies and very young children
• RMS is a cancer that starts in muscle cells, often in a child's head and neck, bladder, arms, or legs
• Relapsed means the cancer came back after treatment
• Refractory means the cancer did not respond (get smaller or go away) to treatment The study treatment HER3-DXd (also known as MK-1022 or patritumab deruxtecan) is an antibody-drug conjugate (ADC). An ADC attaches to a protein on cancer cells and delivers treatment to destroy those cells. The goals of this study are to learn:
• About the safety of HER3-DXd in children and if they tolerate it
• What happens to HER3-DXd in children's bodies over time
• If children who receive HER3-DXd have the cancer get smaller or go away

Conditions

Malignant Neoplasm

Outcome Measures

Primary Outcomes (13)

• Part 1: Percentage of Participants Who Experience Dose-limiting Toxicities (DLTs)

  A DLT is any of a prespecified list of adverse events (AEs) that occur during Cycle 1 (up to 21 days) if attributed to the study treatment and not attributed to any other clearly identifiable cause. The percentage of participants who experience DLTs will be reported. Each cycle is 21 days.

  Cycle 1 (up to approximately 21 days); each cycle is 21 days

• Part 1: Percentage of Participants Who Experience an Adverse Event (AE)

  An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The percentage of participants who experience AEs will be reported.

  Up to approximately 5 years

• Part 1: Percentage of Participants Who Discontinue Study Treatment Due to an AE

  An AE is any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. An AE can therefore be any unfavorable and unintended sign (including an abnormal laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use of a study intervention. The percentage of participants who discontinue study treatment due to an AE will be reported.

  Up to approximately 5 years

• Part 1: Area Under the Curve (AUC) of total anti-HER3 antibody liquid chromatography-mass spectrometry (LC-MS) in plasma

  Blood samples will be collected at specified intervals for the determination of AUC.

  At designated timepoints (up to approximately 5 years)

• Part 1: AUC of anti-HER3 antibody-conjugated DXd (anti-HER3-ac-DXd) in plasma

  Blood samples will be collected at specified intervals for the determination of AUC.

  At designated timepoints (up to approximately 5 years)

• Part 1: AUC of DXd in plasma

  Blood samples will be collected at specified intervals for the determination of AUC.

  At designated timepoints (up to approximately 5 years)

• Part 1: Maximum Concentration (Cmax) of anti-HER3 antibody LC-MS in plasma

  Blood samples will be collected at specified intervals for the determination of Cmax.

  At designated timepoints (up to approximately 5 years)

• Part 1: Cmax of anti-HER3-ac-DXd in plasma

  Blood samples will be collected at specified intervals for the determination of Cmax.

  At designated timepoints (up to approximately 5 years)

• Part 1: Cmax of DXd in plasma

  Blood samples will be collected at specified intervals for the determination of Cmax.

  At designated timepoints (up to approximately 5 years)

• Part 1: Concentration Immediately Before the Next Dose is Administered (Ctrough) of anti-HER3 antibody LC-MS in plasma

  Blood samples will be collected at specified intervals for the determination of Ctrough.

  At designated timepoints (up to approximately 5 years)

• Part 1: Ctrough of anti-HER3-ac-DXd

  Blood samples will be collected at specified intervals for the determination of Ctrough.

  At designated timepoints (up to approximately 5 years)

• Part 1: Ctrough of DXd in plasma

  Blood samples will be collected at specified intervals for the determination of Ctrough.

  At designated timepoints (up to approximately 5 years)

• Part 1 and Part 2: Objective Response Rate (ORR)

  ORR is defined as the percentage of participants with Complete Response (CR: disappearance of all target lesions) or Partial Response (PR: at least a 30% decrease in the sum of diameters of target lesions) per Response Evaluation Criteria In Solid Tumors Version 1.1 (RECIST 1.1). The percentage of participants who experience CR or PR as assessed by the investigator will be presented.

  Up to approximately 5 years

Secondary Outcomes (16)

• Part 2: Percentage of Participants Who Experience an AE

  Up to approximately 5 years

• Part 2: Percentage of Participants Who Discontinue Study Treatment Due to an AE

  Up to approximately 5 years

• Part 1 and Part 2: Disease Control Rate (DCR)

  Up to approximately 5 years

• Part 1 and Part 2: Time to Response (TTR)

  Up to approximately 5 years

• Part 1 and Part 2: Duration of Response (DOR)

  Up to approximately 5 years

Study Arms (1)

Patritumab Deruxtecan

EXPERIMENTAL

Participants receive patritumab deruxtecan via IV infusion on Day 1 of each 3-week cycle until discontinuation or progression.

Biological: Patritumab Deruxtecan

Interventions

Patritumab Deruxtecan BIOLOGICAL

IV Infusion

Also known as: MK-1022, HER3-DXd, U3-1402

Patritumab Deruxtecan

Eligibility Criteria

• Age: 1 Month - 17 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• Has one of the following histologically confirmed advanced or metastatic solid tumors: Rhabdomyosarcoma (RMS), or Hepatoblastoma
• Has progressed after at least 1 prior systemic treatment for RMS or hepatoblastoma and who has no satisfactory alternative treatment option (ie, is ineligible for other standard treatment regimens)
• Participants who have adverse events (AEs) due to previous anticancer therapies must have recovered to Grade ≤1 or baseline. Participants with endocrine-related AEs who are adequately treated with hormone replacement or participants who have Grade ≤2 neuropathy are eligible. Participants with Grade ≤2 alopecia are also eligible
• Hepatitis B surface antigen (HBsAg) positive participants are eligible if they have received hepatitis B virus (HBV) antiviral therapy and have undetectable HBV viral load
• Participants with a history of hepatitis C virus (HCV) infection are eligible if HCV viral load is undetectable

You may not qualify if:

• Has a history of (noninfectious) interstitial lung disease (ILD)/pneumonitis that required steroids or has current ILD/pneumonitis, and/or suspected ILD/pneumonitis that cannot be ruled out by standard diagnostic assessments
• Has clinically severe respiratory compromise resulting from intercurrent pulmonary illness
• Has a history of solid organ transplant
• Has a history of allogeneic stem cell transplant
• Has clinically significant corneal disease
• Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis/leptomeningeal disease; participants with previously treated brain metastases may participate provided they are radiologically stable (ie, without evidence of progression) for at least 4 weeks
• Has uncontrolled or significant cardiovascular disorder
• Has a history of clinically significant congenital cardiac syndrome
• Has a history of human immunodeficiency virus (HIV) infection
• Has a known additional malignancy that is progressing or has required active treatment within the past 1 year
• Has an active infection requiring systemic therapy
• Has concurrent active hepatitis B (HBsAg positive and/or detectable HBV deoxyribonucleic acid \[DNA\]) and HCV defined as anti-HCV antibody (Ab) positive and detectable HCV ribonucleic acid \[RNA\]) infection
• Has not adequately recovered from major surgery or have ongoing surgical complications

Sponsors & Collaborators

• Merck Sharp & Dohme LLC: lead
• Daiichi Sankyo: collaborator

Study Sites (60)

Childrens Hospital Los Angeles ( Site 3006)

Los Angeles, California, 90027, United States

RECRUITING

Children's Hospital Colorado-Center for Cancer and Blood Disorders ( Site 3016)

Aurora, Colorado, 80045, United States

RECRUITING

Yale New Haven Hospital ( Site 3012)

New Haven, Connecticut, 06510, United States

RECRUITING

Johns Hopkins All Children's Hospital ( Site 3025)

St. Petersburg, Florida, 33701, United States

RECRUITING

University of Iowa Health Care Holden Comprehensive Cancer Center ( Site 3017)

Iowa City, Iowa, 52242, United States

RECRUITING

Dana-Farber Cancer Institute ( Site 3013)

Boston, Massachusetts, 02215, United States

RECRUITING

Corewell Health ( Site 3001)

Grand Rapids, Michigan, 49503, United States

RECRUITING

Children's Mercy Hospital ( Site 3024)

Kansas City, Missouri, 64108, United States

RECRUITING

Rutgers Cancer Institute of New Jersey ( Site 3008)

New Brunswick, New Jersey, 08901, United States

RECRUITING

Memorial Sloan Kettering Cancer Center ( Site 3010)

New York, New York, 10065, United States

RECRUITING

New York Medical College ( Site 3023)

Valhalla, New York, 10595, United States

RECRUITING

Sanford Fargo Medical Center-Roger Maris Cancer Center ( Site 3003)

Fargo, North Dakota, 58102, United States

RECRUITING

Oregon Health and Science University ( Site 3004)

Portland, Oregon, 97239, United States

RECRUITING

Children's Hospital of Philadelphia (CHOP) ( Site 3021)

Philadelphia, Pennsylvania, 19104, United States

RECRUITING

Sanford Children's Hospital ( Site 3015)

Sioux Falls, South Dakota, 57117, United States

RECRUITING

University of Texas-MD Anderson Cancer Center ( Site 3007)

Houston, Texas, 77030, United States

RECRUITING

Intermountain - Primary Children's Hospital ( Site 3014)

Salt Lake City, Utah, 84113, United States

RECRUITING

Sydney Children's Hospital-Kids Cancer Centre ( Site 3997)

Sydney, New South Wales, 2031, Australia

RECRUITING

Queensland Children's Hospital ( Site 3996)

Brisbane, Queensland, 4101, Australia

RECRUITING

UZ Gent ( Site 3428)

Ghent, Oost-Vlaanderen, 9000, Belgium

RECRUITING

Hospital de Clinicas de Porto Alegre ( Site 3265)

Porto Alegre, Rio Grande do Sul, 90035-903, Brazil

RECRUITING

Fundação Pio XII - Hospital de Câncer de Barretos ( Site 3264)

Barretos, São Paulo, 14784-400, Brazil

RECRUITING

Fundação Faculdade Regional de Medicina de São José do Rio Preto ( Site 3267)

São José do Rio Preto, São Paulo, 15090-000, Brazil

RECRUITING

The Hospital for Sick Children ( Site 3225)

Toronto, Ontario, M5G 1X8, Canada

RECRUITING

Hospital Carlos Van Buren ( Site 3880)

Valparaíso, Valparaiso, 2341131, Chile

RECRUITING

Hospital Pablo Tobon Uribe ( Site 3923)

Medellín, Antioquia, 05034, Colombia

RECRUITING

Clinica de la Costa S.A.S. ( Site 3924)

Barranquilla, Atlántico, 080020, Colombia

RECRUITING

IMAT S.A.S ( Site 3921)

Montería, Departamento de Córdoba, 230002, Colombia

RECRUITING

Detska nemocnice FN Brno ( Site 3388)

Brno, Brno-mesto, 613 00, Czechia

RECRUITING

Fakultni nemocnice v Motole-Klinika detske hematologie a onkologie ( Site 3387)

Prague, Praha 5, 150 00, Czechia

RECRUITING

Rigshospitalet-Department of paediatrics and adolescent medicine, Section of Paed haem-onc ( Site 3467)

Copenhagen, Capital Region, DK-2100, Denmark

RECRUITING

Bordeaux University Hospital - Pellegrin ( Site 3105)

Bordeaux, Aquitaine, 33076, France

RECRUITING

Assistance Publique Hôpitaux de Marseille - Hôpital de la Timone ( Site 3102)

Marseille, Bouches-du-Rhone, 13005, France

RECRUITING

Centre Hospitalier Universitaire de Nantes - Hôpital Femme-Enfant-Adolescent Chu De Nantes ( Site 3104)

Nantes, Loire-Atlantique, 44093, France

RECRUITING

Centre Leon-Berard ( Site 3100)

Lyon, Rhone, 69373, France

RECRUITING

Institut Curie ( Site 3101)

Paris, Île-de-France Region, 75248, France

RECRUITING

Universitätsklinikum Münster - Albert Schweitzer Campus ( Site 3141)

Münster, North Rhine-Westphalia, 48149, Germany

RECRUITING

Aghia Sophia Children's Hospital-First Department of Pediatrics, National and Kapodistrian Universi ( Site 3797)

Athens, Attica, 11527, Greece

RECRUITING

Semmelweis University ( Site 3838)

Budapest, Pest County, 1094, Hungary

RECRUITING

Rambam Health Care Campus ( Site 3674)

Haifa, 3109601, Israel

RECRUITING

Sheba Medical Center ( Site 3675)

Ramat Gan, 5265601, Israel

RECRUITING

Fondazione IRCCS Istituto Nazionale dei Tumori ( Site 3552)

Milan, 20133, Italy

RECRUITING

Ospedale Pediatrico Bambino Gesù IRCCS ( Site 3553)

Roma, 00165, Italy

RECRUITING

Ospedale Infantile Regina Margherita ( Site 3551)

Torino, 10126, Italy

RECRUITING

Prinses Maxima Centrum voor Kinderoncologie ( Site 3510)

Utrecht, 3584 CS, Netherlands

RECRUITING

Narodny ustav detskych chorob ( Site 3592)

Bratislava, Bratislava Region, 831 01, Slovakia

RECRUITING

Seoul National University Hospital-Pediatrics ( Site 3972)

Seoul, 03080, South Korea

RECRUITING

Asan Medical Center-Pediatrics - Pedicatric Oncology ( Site 3973)

Seoul, 05505, South Korea

RECRUITING

Hospital Sant Joan de Déu ( Site 3717)

Esplugues de Llobregat, Barcelona, 08950, Spain

RECRUITING

Hospital Universitari Vall d''Hebron ( Site 3716)

Barcelona, 08035, Spain

RECRUITING

Hospital Infantil Universitario Nino Jesus ( Site 3715)

Madrid, 28009, Spain

RECRUITING

Sahlgrenska Universitetssjukhuset ( Site 3634)

Gothenburg, Västra Götaland County, 416 85, Sweden

RECRUITING

National Taiwan University Hospital ( Site 3983)

Taiwan, Taipei, 10002, Taiwan

RECRUITING

Hacettepe Universitesi Tip Fakultesi Hastanesi ( Site 3961)

Ankara, 06230, Turkey (Türkiye)

RECRUITING

Ankara Bilkent Şehir Hastanesi. ( Site 3962)

Ankara, 6800, Turkey (Türkiye)

RECRUITING

Ege Universitesi Hastanesi ( Site 3963)

Izmir, 35100, Turkey (Türkiye)

RECRUITING

Birmingham Children's Hospital ( Site 3349)

Birmingham, England, B4 6NH, United Kingdom

RECRUITING

Royal Victoria Infirmary ( Site 3348)

Newcastle upon Tyne, England, NE1 4PL, United Kingdom

RECRUITING

University Hospital of Wales ( Site 3346)

Cardiff, CF14 4XW, United Kingdom

RECRUITING

Royal Marsden Hospital ( Site 3347)

Sutton, SM2 5PT, United Kingdom

RECRUITING

Related Links

• Merck Clinical Trials Information
• Plain Language Summary

MeSH Terms

Conditions

Neoplasms

Interventions

patritumab deruxtecan

Study Officials

• Medical Director

  Merck Sharp & Dohme LLC

  STUDY DIRECTOR

Central Study Contacts

Toll Free Number

CONTACT

1-888-577-8839; Trialsites@msd.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 27, 2025
• First Posted: April 23, 2025
• Study Start: May 26, 2025
• Primary Completion (Estimated): December 30, 2030
• Study Completion (Estimated): December 30, 2030
• Last Updated: May 12, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share

Locations

DK (1); IL (2); CL (1); KR (2); AU (2); BE (1); CZ (2); GR (1); TU (3); GB (4); BR (3); CA (1); NL (1); CO (3); HU (1); IT (3); US (17); SL (1); ES (3); DE (1); TW (1); SE (1); FR (5)