 Study Population Eligible patients are those with relapsed or refractory primary mediastinal large B-cell lymphoma. Patients must also have histologically-confirmed CD30-positive disease, fluorodeoxyglucose FDG-avid and measurable disease of at least 1.5 cm, an Eastern Cooperative Oncology Group ECOG performance status of 0 or 1, and adequate hematologic, kidney, and liver function. 