LIGHTBEAM-U01 Substudy 01A: A Phase 1/2 Substudy to Evaluate the Safety and Efficacy of Zilovertamab Vedotin in Pediatric and Young Adult Participants With Hematologic Malignancies or Solid Tumors.

The main inclusion and exclusion criteria include but are not limited to the following: Inclusion Criteria: - For hematological malignancies: Confirmed diagnosis of B-precursor B-ALL or DLBCL/Burkitt lymphoma according to World Health Organization (WHO) classification of neoplasms of the lymphoid tissues. - For solid tumor malignancies: Histologically confirmed diagnosis of neuroblastoma or Ewing sarcoma. Exclusion Criteria: - History of solid organ transplant. - Clinically significant (ie, active) cardiovascular disease. - Known history of liver cirrhosis. - Ongoing Grade >1 peripheral neuropathy. - Demyelinating form of Charcot-Marie-Tooth disease. - Diagnosed with Down syndrome. - Ongoing graft-versus-host disease (GVHD) of any grade or receiving systemic GVHD treatment or prophylaxis. - History of human immunodeficiency virus (HIV) infection. - Contraindication or hypersensitivity to any of the study intervention components. - Received prior radiotherapy within 4 weeks of start of study intervention. Participants must have recovered from all radiation-related toxicities. - Ongoing, chronic corticosteroid therapy (exceeding 10 mg daily of prednisone equivalent). Prednisone equivalent dosing must have been stable for at least 4 weeks before Cycle 1 Day 1 (C1D1). - Received a strong cytochrome P450 3A4 (CYP3A4) inhibitor within 7 days or a strong CYP3A4 inducer within 14 days before the start of study intervention or expected requirement for chronic use of a strong CYP3A4 inhibitor or inducer during the study intervention period and for 30 days after the last dose of study intervention - Received prior systemic anticancer therapy including investigational agents within 4 weeks before the first dose of study intervention (except for prophylactic intrathecal chemotherapy and/or cytoreductive therapy with steroids/hydroxyurea. - Received a live or live-attenuated vaccine within 30 days before the first dose of study intervention. Administration of killed vaccines is allowed. - Has received an investigational agent or has used an investigational device within 4 weeks prior to study intervention administration. - Known additional malignancy that is progressing or has required active treatment within the past 1 year. - Active infection requiring systemic therapy. - Known history of Hepatitis B or known active Hepatitis C virus infection. - Participants who have not adequately recovered from major surgery or have ongoing surgical complications.