A composite score of neutrophil gelatinase-associated lipocalin and fibroblast growth factor-23 is associated with survival in multiple myeloma: A retrospective study

Abstract

Multiple myeloma (MM) is frequently complicated by renal impairment, but traditional markers like the estimated glomerular filtration rate (eGFR) are inherently late indicators that fail to capture early structural damage. We aimed to evaluate the combined prognostic value of neutrophil gelatinase-associated lipocalin (NGAL), a marker of tubular injury, and fibroblast growth factor-23 (FGF-23), a reflection of bone-mineral dysregulation and tumor burden, independently of eGFR and disease stage.

Methods. This retrospective cohort study included 95 adult patients with a confirmed diagnosis of MM. Baseline serum NGAL and FGF-23 concentrations were quantified using enzyme-linked immunosorbent assays (ELISA). Optimal prognostic cutoffs were determined using maximally selected rank statistics. A composite risk score was constructed to compare patients with concurrent biomarker elevations (score 2) against those with zero or one elevated marker (score 0–1). Overall survival was assessed using Kaplan-Meier analysis and multivariable Cox proportional hazards regression models adjusted for eGFR and International Staging System (ISS) stage.

Results. The optimal prognostic cutoffs were identified as 153.8 ng/mL for NGAL and 36.4 pg/mL for FGF-23. Patients with a composite score of 2 experienced significantly lower overall survival probabilities (log-rank p = 0.0071). In multivariable analysis, the composite risk score remained a potential independent prognostic marker for mortality after adjustment for baseline eGFR (adjusted HR = 6.32, 95% CI: 1.25–31.88, p = 0.025) and ISS stage (p = 0.0057).

Conclusions. The combined assessment of serum NGAL and FGF-23 provides additional prognostic insight over standard eGFR evaluations. Due to the critically low number of events, these findings are strictly hypothesis-generating. This exploratory composite score may aid in identifying a highly vulnerable patient subgroup, independent of baseline filtration status and global tumor burden, but requires validation in larger cohorts.