Dynamic HALP Score as a Time-Dependent Prognostic Biomarker in Multiple Myeloma Patients Undergoing Autologous Stem Cell Transplantation

Background and Objectives: The hemoglobin, albumin, lymphocyte, and platelet (HALP) score is an immunonutritional biomarker reflecting systemic inflammation, nutritional status, and immune competence. Its dynamic behavior and prognostic relevance in multiple myeloma (MM) following autologous stem cell transplantation (ASCT) remain insufficiently characterized. Materials and Methods: In this retrospective cohort study, 95 MM patients undergoing ASCT were analyzed. HALP scores were calculated at diagnosis and at post-transplant day +100, and dynamic changes (ΔHALP) were assessed. Associations with overall survival (OS) and progression-free survival (PFS) were evaluated using Kaplan–Meier and multivariable Cox regression analyses, with maintenance therapy incorporated as a covariate. Results: During a median follow-up of 50 months (range: 11.0–144.0), 36.8% of patients progressed or relapsed, and 23.2% died. Baseline HALP was associated with both OS and PFS in unadjusted analyses; however, the inverse association at diagnosis was substantially attenuated after adjustment for maintenance therapy (HR: 0.71, 95% CI: 0.28–1.80; p = 0.466). HALP at day +100 showed a robust association with PFS that strengthened after adjustment (HR: 3.27, 95% CI: 1.45–7.38; p = 0.004). The discriminative performance for treatment response was limited, with 95% CIs encompassing AUC = 0.50. Conclusions: Post-transplant HALP at day +100 emerged as the most robust HALP-based prognostic indicator for PFS. Given the small sample size, limited OS events (n = 22), use of outcome-driven cut-offs, and absence of cytogenetic and minimal residual disease data, dynamic HALP assessment may provide exploratory prognostic information warranting validation in larger, prospective, multi-center cohorts.