P-061: Spinal involvement predicts for inferior overall survival (OS), progression free survival (PFS) and higher skeletal related events risk in Multiple Myeloma (MM) patients. A Single center experience.

Introduction: Skeletal related events (SRES) include pathological fractures, radiotherapy (XRT), spinal cord compression (SCC) and surgical interventions (SI) and represent frequent complications of MM osteolytic bone disease (MM OBD) with significant impact on patients’ survival. Data from previous studies indicate that spine is the most common site affected by OBD. The aim of this study was to explore the impact of OBD and spinal involvement on survival of MM patients.

Methods: We retrospectively evaluated the electronic records of 905 newly diagnosed MM (NDMM) patients followed up in a single center between 2018-2023.

Results: We identified 905 NDMM patients (541 (60%) males, 454 (68%) White, 102 (15%) Black, 61 (9%) Asian, and 43 (8%) of mixed or other ethnic origin. Myeloma subtype was IgG in 509 (78%), IgA in 138 (21%) and light chain in 199 patients . Among patients with known cytogenetics, 118/576 (20%) had high risk (HRC). At diagnosis 692/905 (75%) patients had OBD as per IMWG criteria.405 (45%) patients presented with at least one SRE at diagnosis, 258 with single (186 fractures, 6 SCC, 55 XRT, 11 surgery) and 147 with SREs combinations. Fractures distribution: C1-C7(15), T1-T6 (63), T7-T12 (180), lumbar (131), femora (4), clavicles (5), sacrum (3), pubic rami (4), sternum (9), humeri (8) and ribs (30). 396/905 (44%) patients with OBD, had spinal involvement (vertebral fractures, lytic lesions, and diffuse infiltration of the spinal column). The management of spinal involvement included radiotherapy (87), spinal bracing (157) and 74 surgical interventions (36 cement augmentation, 38 metal spinal operation). On univariable analysis, patients with OBD at diagnosis had significantly worse OS than those without (HR = 2.09, 95% CI 1.11-3.94, p=0.02). This remained significant after adjustment for age, sex, heavy and light chain type (HR 2.54, 95% CI 1.16-5.54, p=0.02). Spinal involvement at diagnosis had significantly worse OS (HR 2.95 95% CI 1.61-5.39 p < 0.001), PFS (HR 1.23 95% CI 1.00-1.52 p=0.05). and remained the only significant independent factor for increased SREs risk (HR 4.19 HR2.09-8.40 p< 0.001). Age (HR 1.04 95% CI 1.00-1.08 p=0.05), application of brace at diagnosis (HR 2.09 95% CI 1.01-4.35p=0.05) and the presence of HRC (HR 2.63 95% CI 1.29-5.38, p=0.008) remained independent prognostic factors on overall survival in multivariable analysis in patients with OBD at diagnosis.

Conclusions: The presence of OBD had a profound impact on OS in NDMM patients. Spinal involvement, that was identified in 44% of the patients, was found to be an independent significant prognostic factor for inferior PFS, OS and higher SREs risk. These findings, warrant focus on optimizing further early spinal disease management, to improve survival outcomes in this subgroup of MM patients.