Significance of maintenance therapy after HDT/ASCT in symptomatic multiple myeloma: A multicenter retrospective analysis in Kansai Myeloma Forum.

A total of 129 symptomatic patients with multiple myeloma (MM) who underwent high-dose chemotherapy with autologous stem cell transplantation (HDT/ASCT) were analyzed. The 4-year overall survival (OS) of patients with maintenance ( n  = 82) was 80%, whereas that of patients without maintenance ( n  = 47) was 72% ( p  = 0.426). The 4-year progression-free survival (PFS) of patients with maintenance was 38%, whereas that of patients without maintenance was 27% ( p  = 0.088). Multivariate analysis revealed that an International Staging System score ≥2 was associated with worse PFS (hazard ratio 1.62, p  = 0.043). Among the 129 patients, two were excluded owing to early relapse, 50 patients achieved complete response (CR), and 77 patients failed to achieve CR. Patients who achieved CR showed better 4-year PFS than those who failed to achieve CR (41% vs. 30%, p  = 0.027); however, 4-year OS was not different (76% vs. 82%, p  = 0.971). In patients who achieved CR, 4-year OS with/without maintenance was 74%/81% ( p  = 0.357), 4-year PFS with/without maintenance was 42%/40% ( p  = 0.954). In patients who failed to achieve CR, the 4-year OS with/without maintenance was 97%/91% ( p  = 0.107), and 4-year PFS with/without maintenance was 36%/16% ( p  < 0.001). In patients who failed to achieve CR, maintenance significantly improved the PFS. Maintenance after HDT/ASCT can prolong PFS in patients who fail to achieve CR in real-world settings.