Relapsed and refractory Hodgkin lymphoma: transplantation strategies and novel therapeutic options.

Many patients with Hodgkin lymphoma are cured with initial therapy, although a portion of patients will experience primary induction failure or disease relapse. Pathologic confirmation of refractory or relapsed Hodgkin lymphoma is important. Following two to four cycles of non-cross-resistant salvage chemotherapy, the standard of care is high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (HSCT), which is associated with long-term event-free survival rates of 45-68%. Of note, survival rates for studies integrating total lymphoid irradiation into the autologous HSCT-conditioning regimen are among the highest reported for relapsed/refractory Hodgkin lymphoma. Further treatment options are available for patients not fit to proceed to HSCT, for relapsed disease after autologous HSCT, and for 'high-risk' Hodgkin lymphoma including chemotherapy-resistant disease. Allogeneic HSCT is a valid treatment option, as a graft-vs.-Hodgkin-lymphoma effect has been demonstrated. In addition, novel targeted treatments are being investigated such as receptor-specific antibodies, radiolabeled antibodies, antiapoptotic agents including inhibitors of the nuclear factor-kappaB complex or X-linked inhibitor of apoptosis proteins, transcription pathway modulators such as histone deacetylase and mTOR inhibitors, and Epstein-Barr virus-directed therapy. Continued translational and collaborative prospective clinical research efforts are needed in order to continue to increase the survival rates for Hodgkin lymphoma and to lessen the toxicities associated with lymphoma-related therapy.