Is there still a place for autologous salvage transplantation in relapsed/refractory multiple myeloma in the era of novel therapies?

For patients (pts) with relapsed or refractory multiple myeloma (RRMM) after previous autologous hematopoietic cell transplantation (AHCT), novel agents, cellular and immunotherapies are increasingly available. Options for second-line treatment mostly include triplet regimens based on proteasome inhibitors, immunomodulatory drugs and anti-CD38 monoclonal antibodies and since recently also CAR T cells. The importance of autologous salvage transplantation (retransplantation, Re-AHCT) has significantly decreased in recent years due to the availability of many new treatment options. Therefore, we performed a retrospective analysis of 171 pts cases with RRMM who received Re-AHCT between 2002 and 2021. With a median follow-up of 74.7 months, the 5-year rates of progression-free survival (PFS) and overall survival (OS) were 18% (median 20.6 months) and 57% (median 65.0 months), respectively, the 100-day mortality rate was 4%. Multivariate analysis identified R-ISS stage and duration of previous response (DoR) as independent prognostic factors for PFS and OS. While the revealed high-risk population (R-ISS stage II/III, DoR ≤ 24 months) was associated with a significantly worse PFS (HR 2.728) and OS (HR 3.129), the low-risk group (R-ISS I, DoR > 24 months) achieved a median PFS and OS of 45.0 months and 80.2 months, respectively. Therefore, Re-AHCT could remain an option in such prognostically favorable pts with RRMM even in the era of novel therapies especially when more potent treatment modalities are not available.