P-359: Survival of patients with multiple myeloma treated with bortezomib-based triplets and autologous hematopoietic stem cell transplant as frontline in Latin America.

Introduction: Anti-CD38 monoclonal antibodies have emerged as pivotal in newly diagnosed multiple myeloma (NDMM) management. However, in Latin America (LA) there is not widely access to them, and bortezomib-based triplets (BBT) followed by autologous stem cell transplant (ASCT) and post-ASCT maintenance with lenalidomide remains the best option.

The aim of this study was to assess the efficacy of BBT and ASCT consolidation in Latin American NDMM patients.

Methods: Retrospective international multicenter cohort study. Patients with NDMM who received BBT followed by ASCT as frontline, between 2010 and 2023 were analyzed.

Data were collected from clinical records in a standardized report form. Efficacy was evaluated in terms of post-induction response according to IMWG criteria, overall survival (OS) and progression free survival (PFS). Difference in outcomes were explored by risk-group stratification using the Kaplan-Meier method and the Log Rank test.

Results: A total of 534 patients from 7 Latin American countries with NDMM were included. Median age was 57 years (range 29-75) with a male predominance (59%). 54% were treated in private centers. 59% of MM were IgG subtype, 24% IgA and 16% light chain, and 64% and 77% were classified as stage II or III according to ISS and R-ISS, respectively. Bone disease was the most frequent myeloma-defining events (79%), followed by anemia (47%), renal failure (20%), and hypercalcemia (20%). 14% reported extramedular disease. FISH analysis was performed in 50% of patients (only 34% with sorting), del17p was the most frequent abnormality (14%), followed by t(4;14) (6%), and t(14;16) (3%).

The most frequently used BBT was cyclophosphamide-bortezomib-dexamethasone (CyBorD) (44%), followed by bortezomib-thalidomide-dexamethasone (VTD) (31%), and bortezomib-lenalidomide-dexamethasone (VRD) (25%). Very good partial remission (VGPR) or better was achieved in 80% for VRD, 78% for VTD, and 64% for CyBorD (p=0.008). Median time from diagnosis to ASCT was 273 days (range 94-1625). Maintenance treatment was administered to 85% of patients and was based on lenalidomide, thalidomide, and bortezomib in 72%, 9% and 7%, respectively.

With a median follow-up of 62 months, median PFS was not reached (NR) and the 3-year PFS was 76% (95% CI, 72-80%). Median OS of the whole cohort was NR, and the 3-year OS was 91% (95% CI, 89-94%). No significant difference between the 3 triplets was found.

In the multivariate analysis, hypercalcemia, extramedullary disease, and not receiving maintenance were independent risk factors for OS.

Conclusions: The use of BBT and ASCT as frontline is very effective approach for NDMM in LA, with long PFS and OS, and with similar results as internationally described. No differences between the 3 BBT were found in regard of survival. The major prognostic factors are hypercalcemia, extramedullary disease, and not receiving maintenance. In conclusion, this approach is effective and a good option for patients in LA.