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Taking people in CanadaPhase 1/2

Tests patritumab deruxtecan in children with relapsed or refractory hepatoblastoma or rhabdomyosarcoma

Tests a targeted cancer drug in children with returned or unresponsive liver or muscle cancer.

Plain-language title generated from the registry record
Registry title: A Study of Patritumab Deruxtecan in Pediatric Participants With Relapsed or Refractory Solid Tumors (MK-9999-01C/LIGHTBEAM-U01)

Key facts

Where
Calgary and Toronto, CanadaSee the 2 sites
Phase
Phase 1/2

AI summary: who the study is looking for

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for children with hepatoblastoma or rhabdomyosarcoma that has come back or has not responded to treatment, and who have no satisfactory other treatment option.

Age
From 1 Month to 17 Years.
Sex
All sexes can join.
Disease stage
Advanced or metastatic rhabdomyosarcoma (RMS) or hepatoblastoma, confirmed by tissue examination.
Earlier treatment
The cancer must have got worse after at least 1 earlier systemic treatment. Side effects from earlier cancer treatment must have recovered to Grade ≤1 or baseline, with some exceptions.

Main reasons for not taking part

  • History of interstitial lung disease (ILD) or pneumonitis, or current or suspected ILD or pneumonitis
  • History of solid organ transplant or allogeneic stem cell transplant
  • History of human immunodeficiency virus (HIV) infection
  • Known active cancer in the brain or spinal fluid area (CNS metastases, leptomeningeal disease), unless previously treated and stable for at least 4 weeks
  • Clinically significant corneal disease

Read by machine on 9 November 2026.

Could this be for you?

Answer for yourself. This is not a decision: only the study team can say whether you can take part.

  • How old is the patient who may join a trial?
  • What type of cancer has the patient been diagnosed with?
  • Is this cancer newly diagnosed, or has it come back or not responded to treatment?

Source: NCT06941272, who can take part

Where in Canada

  • Alberta Children's Hospital (Site 3227)Calgary, CanadaTaking people
  • The Hospital for Sick Children (Site 3225)Toronto, CanadaTaking people

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Trial details

Who runs it
Merck Sharp & Dohme LLC
Trial code
NCT06941272EU 2024-518771-66-00
Record updated
6 October 2026
Original description
Researchers are looking for new ways to treat children with hepatoblastoma or rhabdomyosarcoma (RMS) that has relapsed or is refractory:Read full original descriptionShow less

LIGHTBEAM-U01 Substudy 01C: A Phase 1/2 Substudy to Evaluate the Safety and Efficacy of Patritumab Deruxtecan in Pediatric Participants With Relapsed or Refractory Solid Tumors

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

The main inclusion criteria include but are not limited to the following:; 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; The main exclusion criteria include but are not limited to the following:; 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.

ClinicalTrials.gov NCT06941272 · EU CTIS 2024-518771-66-00