P-366: Pre-Transplant Factors Predict Long-Term Outcomes in Newly Diagnosed Multiple Myeloma Patients Undergoing Autologous Stem Cell Transplantation in a Resource-Limited Setting

Introduction: In low- and middle-income countries, the management of multiple myeloma necessitates a tailored approach to maximize the utilization of scarce resources such as medications, transplant beds, and monitoring examinations. The objective of this research was to evaluate the potential impact of pre-transplant factors on the long-term response of individuals undergoing autologous stem cell transplantation for newly diagnosed multiple myeloma (NDMM) as a first-line therapy at a university-affiliated public cancer center.

Methods: Retrospective study of charts of patients with NDMM treated with ASCT from 2009 until 2019 at Instituto do Cancer do Estado de São Paulo (Brazil).

Results: In a cohort of 193 patients who underwent ASCT as their initial treatment for NDMM, the median age at diagnosis was 58 years (IQR 50-63). The majority of patients had the IgG subtype (62.2%) with kappa light chain (72.5%). The median hemoglobin level was 10.7 g/dL (IQR 8.5-12.6), and 92.2% of patients presented with bone disease. Median creatinine levels were 1.0 mg/dL (IQR 0.8-1.3). According to the International Staging System (ISS), 34.2% were at stage 1, 34.2% at stage 2, and 24.9% at stage 3, with 6.7% missing data. Most patients received a triple thalidomide-based regimen (89.1%), while a smaller proportion were treated with bortezomib (4.7%). The median number of induction cycles was 7 (IQR 5-8), and the median time to ASCT after diagnosis was 10.6 months (IQR 8.6-13.9). Complete hematological response was achieved by 27.5% of patients before ASCT and 56.5% after the procedure.

The median overall survival (OS) was 8.7 years (IQR 7-11.3). The median progression-free survival (PFS) after ASCT was 2.6 years (IQR 2.3-2.9). Patients with ISS stage 1 had better outcomes, including hematological response, PFS, and OS. Achieving complete response (CR) before ASCT was associated with improved OS (HR 0.57, CI 0.35-0.94, p = 0.021). Long-term survival was similar among patients who achieved CR only after ASCT and those with very good partial response (VGPR) or less during first-line therapy. A small percentage of patients received thalidomide as maintenance (11%), which did not improve PFS or OS, nor the time from diagnosis to ASCT.

By combining ISS at diagnosis and hematological response before ASCT, a subgroup of patients (12%) was identified with favorable long-term outcomes, showing a remarkable 79% OS rate after 10 years.

Conclusions: The study demonstrates that achieving complete response before ASCT and having an early-stage diagnosis (ISS stage 1) are significant predictors of long-term survival in NDMM patients. Despite the challenges in resource-limited settings, timely ASCT and effective pre-transplant management can lead to excellent long-term outcomes for a subset of patients.