Second Autologous Stem Cell Transplant as Salvage in Multiple Myeloma – The Oregon Health and Science University Experience

Background: : Second autologous transplants (SAT) are routinely performed in the setting of myeloma relapse, though data on outcomes are lacking. We conducted a single-center review of all multiple myeloma patients at OHSU who received SAT (excluding tandems) with responses assessed by International Myeloma Working Group (IMWG) criteria. Results: : Sixty-eight patients received SAT between 1999 and 2019. Risk by IMWG was available for 50 patients (10 high-risk). Median age at SAT was 61 (45-74). Median time between 1st and 2nd Autologous stem cell transplantation (ASCT) was 5.5 years (1.1 - 15.2). Median progression-free survival (PFS) after 1st ASCT (available for 53 pts) was 2.5 years (0.3 - 10). The average # of lines of therapy prior to SAT was 2.8 (1-14). SAT prep regimens (available for 67 pts) were: Fifty-one (87%) melphalan 200 mg/m², 6 (9%) melphalan 140 mg/m², 1 (2%) BEAM, 1 (2%) melphalan 200 mg/m² and bortezomib. All used PBSC mobilization. Median overall survival (OS) after SAT was 4.68 years, and median PFS was 1.72 years. By treatment era (1999-2009 vs. 2010-2019), median OS was 1.97 vs. 5.52 years (P =.15). When analyzed by IMWG group (standard/low vs. high risk) median PFS and OS were not significantly different (1.87 vs. 1.61 years and 3.58 vs. 5.91 years, respectively). Treatment-Related Mortality (TRM) occurred in 1 patient (2%). Conclusion: : Our experience with SAT for multiple myeloma (MM) shows that it has low TRM and is effective, with median OS >4.5 years, though with a shorter PFS than after 1st ASCT.