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

Condition(s) studied

Investigational drug(s) / intervention(s)

Patritumab Deruxtecan: IV Infusion

Study 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

Eligibility

Primary outcome measure(s)

• 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 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 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 plasma — At 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 plasma — At 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 plasma — At 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 plasma — At 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 plasma — At 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 plasma — At 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 plasma — At 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-DXd — At 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 plasma — At 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.

Trial sites (64)

+ 24 more sites — see the full list on the official registry below.

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