P-118: Relapse with plasmacytoma after upfront autologous stem cell transplantation in multiple myeloma

Abstract

<h3>Background</h3> Plasmacytoma has been reported to be associated with poor prognosis in patients with multiple myeloma (MM). In this study, we evaluated the incidence of plasmacytoma and survival outcomes in newly diagnosed MM who underwent upfront autologous stem cell transplantation (ASCT). <h3>Method</h3> This study retrospectively analyzed the data of 303 patients with MM who underwent upfront ASCT between April 2000 and April 2018 from 8 institutes in Korea. A total of 52 patients (17.1%) had plasmacytoma at relapse after upfront ASCT. Of them, 27 patients showed paramedullary plasmacytoma (PMD) and 25 patients showed extramedullary plasmacytoma (EMD). <h3>Results</h3> Patients with plasmacytoma at initial diagnosis had more plasmacytoma at relapse than those without plasmacytoma (37.1% vs. 11.2%). Over a median follow-up of 66.0 months, patients with plasmacytoma at relapse had significantly inferior overall survival (OS) than those without plasmacytoma (43.9months vs. 100.7 months, P <0.001), but the OS did not significantly differ between patients with EMD and those with PMD (56.6 months vs. 42.2 months, P=0.464). After relapse, all patients received salvage therapy with borteozmib or lenalidomide-based regimen, but progression free survival (PFS) after relapse was significantly shorter in patients with plasmacytoma than those with no plasmacytoma (6.4 months vs. 12.4 months, P <0.007). <h3>Conclusion</h3> This study showed that plasmacytoma was frequently developed at relapse after upfront ASCT in patients with plasmacytoma at initial diagnosis and plasmacytoma at relapse was significantly associated with poor prognosis.