a study of patritumab deruxtecan in pediatric participants with relapsed or refractory solid tumors (mk-9999-01c/lightbeam-u01)

Conditions: Malignant Neoplasm

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

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).

Eligibility criteria:
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 * 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 (noninfectious) interstitial lung disease (ild)/pneumonitis that required steroids or has current ild/pneumonitis, and/or suspected ild/pneumonitis that cannot be ruled out by standard diagnostic assessments * 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