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

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

PRODUCT

HER3-DXd

GENDER

ALL

AGE

1 Month to 17 Years

SPONSOR

Merck Sharp & Dohme LLC

COLLABORATOR

Daiichi Sankyo

TRIAL RUNS IN

25 Global Locations

Trial Summary

This study will have 2 parts: a safety lead-in to demonstrate a tolerable safety profile and confirm a preliminary recommended phase 2 dose (RP2D) (Part 1) followed by an efficacy evaluation (Part 2).

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

This was last updated on 2025-11-06 19:34:18.337.

The content contained is taken is taken directly from public registry ClinicalTrials.gov and has not been edited.

Information about pipeline compounds or investigational uses of compounds does not imply FDA approval for these compounds or uses, nor does it establish the safety or efficacy of these compounds or uses. There is no guarantee that the pipeline compounds or investigational uses will receive FDA approval. Daiichi Sankyo does not recommend or suggest use of its medicines in a manner inconsistent with FDA-approved labeling.