Abbreviations: ASCT, autologous stem cell transplantation; β₂-MG, β₂-microglobulin; CR, complete response; CSF, cerebrospinal fluid; ECOG PS, Eastern Cooperative Oncology Group Performance Status; LDH, lactate dehydrogenase; N/A, not applicable; NE, not evaluable; PD, progressive disease; PR, partial response; SD, stable disease.