Not Yet RecruitingPhase 1/2

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

134 participantsStarted 2026-07-28

Plain-language summary

Researchers are looking for new ways to treat children with relapsed or refractory solid tumors: * Relapsed means the cancer came back after treatment * Refractory means the cancer did not respond (get smaller or go away) to treatment * Solid tumors are cancers mostly in body organs and tissues, not in the blood or other body liquids The study treatment I-DXd (also known as MK-2400 or ifinatamab 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 I-DXd and if children younger than 12 years old tolerate it * How many children who receive I-DXd have the cancer get smaller or go away

Who can participate

Age range

1 Month – 17 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

The main inclusion criteria include but are not limited to the following: * In Part 1, participant has recurrent or relapsed, refractory solid tumors (excluding primary central nervous system (CNS)); and in Part 2, participant has recurrent or relapsed, refractory and histologically confirmed diagnosis of osteosarcoma (OST), neuroblastoma (NBL), rhabdomyosarcoma (RMS), or Wilms tumor (WT). All participants must meet the following criteria: Has documented radiological disease progression after at least 1 line of prior therapy in the locally advanced/metastatic setting and who has no satisfactory alternative treatment option (ie, is ineligible for other standard treatment regimens). * Is an individual of any sex/gender, ≥1 month to \<12 years of age for Part 1 and ≥1 month to \<18 years for Part 2 at the time of providing the informed consent or assent, as applicable * Participants who have 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. The main exclusion criteria include but are not limited to the following: * Has clinically significant corneal disease * Has a history of cerebrovascular accident, transient ischemic attack, or another arterial thromboembolic event within 6 months before screening * Has uncontrolled or significant cardiovascular disease, including conduction abnormalities,…

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Part 1: Number of Participants From ≥1 Month to <12 Years Who Experience a Dose-limiting Toxicity (DLT)

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

Part 1: Number of Participants From ≥1 Month to <12 Years Who Experience One or More Adverse Events (AEs)

Timeframe: Up to approximately 5 years

Part 1: Number of Participants From ≥1 Month to <12 Years Who Discontinue Study Intervention Due to an AE

Timeframe: Up to approximately 5 years

Part 1: Number of Participants From ≥1 Month to <12 Years Who Receive Dose Modifications Due to AEs

Timeframe: Up to approximately 5 years

Part 1 and Part 2: Objective Response Rate (ORR) for Participants with neuroblastoma (NBL), rhabdomyosarcoma (RMS), and Wilms tumor (WT)

Timeframe: Up to approximately 5 years

Part 1 and Part 2: Disease Control Success at 4 Months (DCS-4) for Participants with osteosarcoma (OST)

Timeframe: Up to 4 Months

Trial details

NCT IDNCT07630974

SponsorMerck Sharp & Dohme LLC

Sponsor typeINDUSTRY

Study typeINTERVENTIONAL

Primary completion2031-08-17

View on ClinicalTrials.gov More Malignant Neoplasm trials

Plain-language summary

Who can participate

Age range

1 Month – 17 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

What they're measuring

Part 1: Number of Participants From ≥1 Month to <12 Years Who Experience a Dose-limiting Toxicity (DLT)

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

Part 1: Number of Participants From ≥1 Month to <12 Years Who Experience One or More Adverse Events (AEs)

Timeframe: Up to approximately 5 years

Part 1: Number of Participants From ≥1 Month to <12 Years Who Discontinue Study Intervention Due to an AE

Timeframe: Up to approximately 5 years

Part 1: Number of Participants From ≥1 Month to <12 Years Who Receive Dose Modifications Due to AEs

Timeframe: Up to approximately 5 years

Part 1 and Part 2: Objective Response Rate (ORR) for Participants with neuroblastoma (NBL), rhabdomyosarcoma (RMS), and Wilms tumor (WT)

Timeframe: Up to approximately 5 years

Part 1 and Part 2: Disease Control Success at 4 Months (DCS-4) for Participants with osteosarcoma (OST)

Timeframe: Up to 4 Months