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A Study of Patritumab Deruxtecan for Pediatric Solid Tumors

This study is looking for new ways to treat children aged 1 month to 17 years with rhabdomyosarcoma (RMS) or hepatoblastoma that has come back (relapsed) or didn't respond to previous treatment (refractory). Researchers are testing a treatment called Patritumab Deruxtecan, which is an antibody-drug conjugate (ADC). This means it's designed to attach to cancer cells and deliver medicine directly to them. The study aims to understand the safety of Patritumab Deruxtecan and how well it works. Success will be measured by looking at side effects and how many participants experience them. The study plans to enroll 50 participants, but its current status is unclear.

Study design
This is an interventional study with two parts: a safety lead-in followed by an evaluation of how well the treatment works. It plans to enroll 50 participants.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
Participants will be monitored for adverse events for up to approximately 5 years.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT06941272

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

Recruiting
PHASE1Ages 1–17InterventionalTreatment
Merck Sharp & Dohme LLC
~50 participants
Updated 2026-08-28 on ClinicalTrials.gov
What's tested:Patritumab Deruxtecan

At a glance

Recruiting sites
54 of 54 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Part 1: Percentage of Participants Who Experience Dose-limiting Toxicities (DLTs)
Measured over Cycle 1 (up to approximately 21 days); each cycle is 21 days
+12 more outcomes measured

Conditions

Malignant Neoplasm

Explore related trials

HepatoblastomaRhabdomyosarcomaSolid NeoplasmERBB3 wt Allele

Where it's being run

54 sites across 45 states
Italy3
New York2
Israel2
South Korea2
Spain2
Turkey (Türkiye)2
England2
United Kingdom2

Study leadership

  • Medical Director · STUDY_DIRECTOR · Merck Sharp & Dohme LLC

Who to contact

Toll Free Number
[email protected]
1-888-577-8839
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

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

Exclusion

Has a history of interstitial lung disease (ILD)/pneumonitis irrespective of steroid use, or current ILD/pneumonitis, or suspected ILD/pneumonitis, or ILD that cannot be ruled out by imaging
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

What this trial measures

  • Part 1: Percentage of Participants Who Experience Dose-limiting Toxicities (DLTs)Cycle 1 (up to approximately 21 days); each cycle is 21 days

    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.

  • Part 1: Percentage of Participants Who Experience an Adverse Event (AE)Up to approximately 5 years

    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.

  • Part 1: Percentage of Participants Who Discontinue Study Treatment Due to an AEUp to approximately 5 years

    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.

  • Part 1: Area Under the Curve (AUC) of total anti-HER3 antibody liquid chromatography-mass spectrometry (LC-MS) in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: AUC of anti-HER3 antibody-conjugated DXd (anti-HER3-ac-DXd) in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: AUC of DXd in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: Maximum Concentration (Cmax) of anti-HER3 antibody LC-MS in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: Cmax of anti-HER3-ac-DXd in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: Cmax of DXd in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: Concentration Immediately Before the Next Dose is Administered (Ctrough) of anti-HER3 antibody LC-MS in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1: Ctrough of anti-HER3-ac-DXdAt designated timepoints (up to approximately 5 years)

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

  • Part 1: Ctrough of DXd in plasmaAt designated timepoints (up to approximately 5 years)

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

  • Part 1 and Part 2: Objective Response Rate (ORR)Up to approximately 5 years

    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.