Bortezomib before and after high-dose therapy in myeloma: long-term results from the phase III HOVON-65/GMMG-HD4 trial

The Dutch-Belgian Cooperative Trial Group for Hematology Oncology Group-65/German-speaking Myeloma Multicenter Group-HD4 (HOVON-65/GMMG-HD4) phase III trial compared bortezomib (BTZ) before and after high-dose melphalan and autologous stem cell transplantation (HDM, PAD arm) compared with classical cytotoxic agents prior and thalidomide after HDM (VAD arm) in multiple myeloma (MM) patients aged 18–65 years. Here, the long-term follow-up and data on second primary malignancies (SPM) are presented. After a median follow-up of 96 months, progression-free survival (censored at allogeneic transplantation, PFS) remained significantly prolonged in the PAD versus VAD arm (hazard ratio (HR)=0.76, 95% confidence interval (95% CI) of 0.65–0.89, P =0.001). Overall survival (OS) was similar in the PAD versus VAD arm (HR=0.89, 95% CI: 0.74–1.08, P =0.24). The incidence of SPM were similar between the two arms (7% each, P =0.73). The negative prognostic effects of the cytogenetic aberration deletion 17p13 (clone size ⩾10%) and renal impairment at baseline (serum creatinine >2 mg dl −1 ) on PFS and OS remained abrogated in the PAD but not VAD arm. OS from first relapse/progression was similar between the study arms (HR=1.02, P =0.85). In conclusion, the survival benefit with BTZ induction/maintenance compared with classical cytotoxic agents and thalidomide maintenance is maintained without an increased risk of SPM.