Study of Brentuximab Vedotin (SGN-35) in Pediatric Participants With Relapsed or Refractory (r/r) Systemic Anaplastic Large-Cell Lymphoma or Hodgkin Lymphoma

Inclusion Criteria:

* Male or female participants aged 2 to \<18 years (5 to \<18 years for Hodgkin lymphoma \[HL\])
* Diagnosis of systemic anaplastic large-cell lymphoma (sALCL), or HL for which standard, curative, life-prolonging, or palliative treatment does not exist or is no longer effective
* Participants with sALCL must have documented anaplastic lymphoma kinase (ALK) status and must be beyond first remission or refractory to front-line chemotherapy
* Participants diagnosed with any relapsed or refractory CD30+ hematologic malignancy (e.g., primary mediastinal B-cell lymphoma) may be included in phase 1 of the study
* Participants with HL must be in their second of later relapse, have failed systemic chemotherapy either as induction therapy for advanced stage disease or salvage therapy, and were ineligible for, refused, or previously received a stem cell transplant
* Performance score ≥ 60 from Lansky Play Performance Scale if ≤16 years
* Negative pregnancy test
* Fertile Participants must use 2 effective methods of contraception prior to and through 6 months after the last dose of the study drug

Exclusion Criteria:

* Current diagnosis of primary cutaneous ALCL (those with systemic ALCL are eligible)
* Received an allogeneic stem cell transplant \<3 months prior to the first dose of study medication, or presence of polymerase chain reaction (PCR)-detectable cytomegalovirus (CMV) in any post-allogeneic transplant participant
* Receiving immunosuppressive therapy
* Receiving systemic therapy for chronic graft-versus-host disease (topical therapy is allowed)
* Previous treatment with any anti-CD30 antibody
* Therapeutic monoclonal antibody use within the longer of 6 weeks or 5 plasma half-lives
* Systemic cardiac disease that would, in the opinion of the investigator or medical monitor, interfere with assessment of efficacy or safety of the drug
* History of another primary malignancy not in remission for at least 3 years (the following are exempt from the 3-year limit: nonmelanoma skin cancer and cervical carcinoma in situ on biopsy or a squamous intraepithelial lesion on Pap smear)
* Known active cerebral/meningeal disease, including signs or symptoms of progressive multifocal leukoencephalopathy (PML) or any history of PML
* History of cirrhosis
* Active systemic viral, bacterial, or fungal infection requiring antimicrobial, antiviral therapy or antifungal therapy within 2 weeks prior to the first dose of study drug (routine antimicrobial prophylaxis is acceptable)
* Concurrent therapy with other anti-neoplastic or experimental agents
* Systemic corticosteroid therapy \<7 days prior to first dose of the study medication
* Any serious underlying medical condition that, in the opinion of the investigator or medical monitor, would impair their ability to receive or tolerate the planned treatment
* Known hypersensitivity to recombinant proteins, murine proteins, or any excipient contained in the drug formulation
* Received nitrogen mustard agents, melphalan, or BCNU therapy within 6 weeks prior to the first study dose
* Prior autologous hematopoietic stem cell infusion \<4 weeks prior to first study dose
* Grade 2 or greater unresolved toxicity from prior antineoplastic therapy
* Grade 2 or greater peripheral neuropathy
* Female participants who are both lactating and breastfeeding, or have a positive serum pregnancy test during the screening period or a positive urine pregnancy test on Day 1 before the first dose of study drug
* Received local palliative radiation therapy \<14 days prior to the first dose of study medication
* Received radiation therapy to more than 25% of the bone marrow-containing spaces \< 84 days prior to first dose of study medication
* Received a strong or listed moderate inhibitor of CYP3A4 \<2 weeks prior to first study dose
* Participants must have fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study