Study Of Nivolumab Alone, Or In Combination With Vinblastin In Patients With Classical Hodgkin Lymphoma

This study is a multicentric phase II open-label trial consisting of 6 cycles Nivolumab (2 weeks interval) followed by a PET-CT scan. The treatment will be allocated according to PET and CT scan responses. : * In case of CMR according to Lugano Classification (Cheson et al.2014, PET-CT based response), patients will receive 18 additional cycles of Nivolumab, according to CT-based response at Cycle 12. * In case of Partial Metabolic Response (PMR) or No Metabolic Response(NMR), according to Lugano Classification (Cheson et al.2014, PET-CT based response) patients will receive 12 to 18 cycles of Nivolumab combined with Vinblastin according to CT-based response at Cycle 12. * In case of progressive disease, according to Lugano Classification (Cheson et al.2014, PET-CT scan based response) patients will be considered in treatment failure.