P-218: Tandem autologous + non-myeloablative allogeneic stem cell transplantation in relapsed multiple myeloma: an Australian joint report from the Alfred and Myeloma and Related Diseases Registry

Background Graft-versus-myeloma (GvM) effect from allogeneic-SCT potentially affords long-term disease control in multiple myeloma (MM). A salvage program incorporating chemotherapy followed by tandem autologous + non-myeloablative allogeneic-SCT (TAA-SCT) may offer a survival advantage over chemotherapy alone (ChA) Method Consecutive patients with relapsed MM (R-MM) salvaged with chemotherapy followed by TAA-SCT at the Alfred between Jan-08 and Dec-19 were identified. A 2:1 comparator cohort salvaged with ChA (iMiD agent/PI available) matched for age/sex/ISS-stage, was extracted from the Myeloma and Related Diseases Registry (MRDR). All patients received autologous-SCT as part of their upfront treatment. Survival was assessed by Kaplan-Meier method and compared using log-rank test. Prognostic variables were adjusted using Cox-regression. Results 48 patients received TAA-SCT following salvage chemotherapy during the study period; 35% met criteria for high-risk myeloma at diagnosis (ISS-III and/or adverse CG/FISH) with a median age at salvage of 57 [range: 32-68] and 2 prior therapy lines [range: 1-7]. Preceding TAA-SCT, salvage chemotherapy yielded ≥ PR in ~95% of cases; iMiD® and/or PI were used in ~85%. 87 matched patients were identified from the MRDR as the ChA cohort. Baseline characteristics were comparable, except that the TAA-SCT cohort was more heavily pre-treated (p Conclusion In the iMiD® and PI era, TAA-SCT following chemotherapy remains an effective salvage strategy in selected patients with R-MM, providing an immunological platform for a GvM effect with OS and PFS advantage over chemotherapy alone.