Relapsed or Refractory Hodgkin's Lymphoma

The phase I part (safety assessment of the combination treatment) is aimed at determining the MTD of atezolizumab when combined with BEGEV schedule. 6-18 patients enrolled in this part will be treated with atezolizumab in combination with BEGEV regimen every 3 weeks for 4 cycles. Patients without a DLT in the first cycle and without disease progression after cycle 2, will undergo stem cell mobilization with 3-4 cycle of A-BEGEV + granulocyte colony-stimulating factor (G-CSF) and subsequently receive a myeloablative therapy followed by ASCT. The phase IIb part (expansion cohort) plans to randomize 122 patients in two arms (A and B, 61 per arm): 1. arm A will receive the BEGEV regimen followed by ASCT for patients achieving CR. 2. arm B will receive combination treatment with Atezolizumab and BEGEV regimen followed for patients reaching CR by ASCT plus a consolidation with 6 doses of atezolizumab at 1200 mg every 4 weeks. After the last treatment date of the last patient (LPLT), the phase IIb will be ended. A long term follow up will start, in order to better assess patients' prognosis. All evaluable patients from phase I and phase IIb study will enter in the long term follow up phase and will be followed for 18 months.