Amendment 1: • The primary objective was revised to define ORR as lasting at least 4 months, and specify the study population. • The study population was modified to include only participants with a primary diagnosis of mycosis fungoides (MF) or primary cutaneous anaplastic large cell lymphoma (pcALCL). • The study population was revised to include participants who received at least 1 prior systemic therapy for their disease. • The protocol was revised to require confirmation of CD30 positivity, defined as membranous, cytoplasmic or golgi pattern of expression of the CD30 antigen by 10% or greater of either total lymphocytes or neoplastic cells at any intensity greater than zero on a scale of zero to 3+. • The protocol was revised to exclude patients with signs or symptoms of progressive multifocal leukoencephalopathy (PML) and contains instructions for the suggested management of suspected PML that include brentuximab vedotin discontinuation. • The schedule for modified severity weighted assessment tool (mSWAT) assessments was changed to include the following time points: before dose administration at Cycle 1, Day 1; at the end of every treatment cycle; within 30 days of the last dose of study drug; and at posttreatment follow-up visits. • The protocol was revised to exclude patients with known hepatitis B surface antigen-positive, or known or suspected active hepatitis C infection.

Amendment 2: • The protocol was revised to include information on the occurrence of pulmonary toxicity and specifies that the concomitant use of bleomycin with brentuximab vedotin is contraindicated. • Revised recommendations for subsequent treatment for patients who complete 48 weeks of treatment with reference therapy or 16 cycles of brentuximab vedotin. • The protocol was revised to remove plan to reallocate patients to low-enrolling treatment arms for strata analysis.

Amendment 3: • The protocol was revised to allow patients with stable disease (SD) to continue to receive study treatment up to the maximum treatment period (16 cycles of brentuximab vedotin or 48 weeks with methotrexate or bexarotene) at the discretion of the investigator. • The eligibility criteria was revised to allow for the enrollment of patients with pcALCL who have received prior radiation therapy or at least 1 prior systemic therapy for their disease. • A secondary objective was added to the protocol to assess duration of skin response with brentuximab vedotin. • The inclusion criterion requiring fasting serum triglycerides of <150 mg/dL before study entry was removed. • The timing of computed tomography (CT) scans was revised to align with current standard practice. • The planned analysis populations were revised to accommodate the change to the Ventana CD30 (Ber-H2) assay to determine CD30 expression for patient eligibility. • A real-time independent review performed at the time of anticipated treatment discontinuation for all patients, regardless of reason, was added. • References to ECGs were removed from the list of safety assessments in the protocol.

Amendment 4: • Reverted to the text that stated that the sponsor was to be notified in the event that a participant was withdrawn from study treatment or from the study. • Revised instructions for calculating body surface area (BSA) to determine the dose of bexarotene. • The protocol was revised to require all events of peripheral neuropathy to be followed for changes in severity until resolution to baseline or study closure, whichever occurred first. • The protocol was revised to remove requirement to end safety monitoring when a patient received subsequent anticancer therapy.

Amendment 5: • Updated safety information and revised the existing eligibility criteria regarding patients at risk for pancreatitis. • Language was added to the benefit and risk section summarizing the potential risk of pancreatitis in the population of patients at risk of pancreatitis and with cutaneous T-cell lymphoma (CTCL). • Eligibility criteria were updated to exclude patients with an elevated lipase value ≥3 times the upper limit of normal (ULN) with an amylase value > ULN. Allowed for Fludeoxyglucose-positron emission tomography (FDG-PET) scans and computed tomography (CT) taken within 8 weeks before signing the informed consent form (ICF) to be used as the subject FDG-PET scan, and CT scans taken within 4 weeks before signing the ICF to be used as the screening CT scan provided pre-specified conditions were met.