P-195: Salvage autologous stem cells transplantation and maintenance therapy in relapsed refractory multiple myeloma

Background Multiple myeloma (MM) is an incurable hematological neoplasm. However, new therapies have improved overall survival (OS). In relapsed/refractory MM (RRMM) and a resource-limited environment, optimizing treatment options is essential. Autologous hematopoietic stem cell transplantation (ASCT) is an available strategy, frontline and at relapse Objective to analyze overall survival (OS2) and progression-free survival (PFS2) in RRMM patients comparing second-line consolidation strategies. Methods This retrospective survival analysis study, based on the Uruguayan Multiple Myeloma Registry, included all RRMM adult patients Results Fifty-nine patients were included, with a median age at diagnosis of 56 years (IQR 12), 49.1% were male, 70.10% IgG, 84.75% were Durie-Salmon stage (DS) III and 37.3% ISS-III, 27.1% ISS-II, and 30.5% ISS-I. Age, ISS, and DS were not statistically different between therapeutic groups. Most (69.5%) patients had received a first ASCT, and 35.6% received maintenance as first-line therapy. Maintenance therapy was lenalidomide in 20.3%, thalidomide in 6.8%, and 8.5% other options. Eleven patients (18.6%) received salvage ASCT and maintenance, 18.6% received only ASCT, 16.9% received only maintenance and 45.8% neither ASCT nor maintenance. The median OS2 was 34 months, and PFS2 was 26 months. The 3-year OS2 and 3-year PFS2 were 47.2% and 32.2% for the entire cohort, respectively. The combination of ASCT and maintenance achieved a 3-year OS2 of 75.0% whereas OS2 in the non-combined therapy (NCT)(ASCT or maintenance) was 50.7% (HR 0.1, CI95% 0.01 to 0.6, p=0.01). ASCT and maintenance achieved a 3-year PFS2 of 43.1% whereas PFS2 was 37.6% for the NCT (HR 0.2, CI95% 0.1 to 0.7, p=0.01). The 3-year OS2 was 50.7% for those who received ASCT or maintenance vs. 28.4% for those without second-line consolidation (HR 0.3, CI95% 0.2 to 0.9, p=0.02). The 3-year PFS2 was 37.6% for patients who received any of the consolidative strategies vs 19.1% (HR 0.4, CI95% 0.2 to 0.9, p=0.02) in those who did not receive salvage ASCT or maintenance Conclusion ASCT has been recommended for patients relapsing after primary therapy, including an ASCT with an initial remission duration of >18 months. The role of salvage ASCT in patients who received lenalidomide maintenance has not been determined. In our analysis, the combination of ASCT and maintenance improved the OS2 and PFS2 compared to those treated with only ASCT or maintenance. Not receiving second-line consolidation was associated with inferior PFS2 and OS2.