The purpose of this study is to assess safety and efficacy of brentuximab vedotin in combination with bendamustine in patients with relapsed or refractory Hodgkin lymphoma. It is an open-label, 2-stage study designed to determine the recommended dose level of bendamustine in combination with brentuximab vedotin. The study will assess the safety profile of the combination treatment and determine what proportion of patients achieve a complete remission.