Prognostic utility of baseline hypoalbuminemia vs. peripheral immune biomarkers in a real-world immunotherapy cohort.

Abstract

e23413 Background: Peripheral immune biomarkers absolute lymphocyte count (ALC), Neutrophil-to-Lymphocyte ratio (NLR) are established prognosticators in clinical trials of Immune checkpoint inhibitors (ICIs) in treatment of solid organ malignancies. However, their utility remains ill-defined in unselected community cohorts in which the populations often characterized by advanced age and multiple comorbidities. We hypothesized that host physiologic reserve (measured by serum albumin), which acts as a surrogate marker for metabolic fitness, can serve as an important predictor of Overall Survival (OS) than peripheral immune counts in a real world setting, predicting survival in the real world setting. Methods: We performed a retrospective study of 185 adult cancer patients with metastatic solid tumors treated with standard-of-care ICIs Immune Checkpoint Inhibitors (Excluding concurrent chemotherapy) at a single center from January 2017 to December 2025. Patients were stratified by baseline immune status (High: ALC < 1,000/µL or NLR > 5) and baseline metabolic status (Hypoalbuminemia: Albumin < 3.5 g/dL). The primary endpoint was Overall Survival (OS). Multivariate Cox models were utilized to identify the independent prognostic value of host frailty versus baseline immune status. Results: The cohort had a median age of 73 years, significantly older than typical trial populations. Baseline immune biomarkers failed to yield a prognostic signal in this setting. Kaplan-Meier analysis showed superimposable survival curves for High vs. Low Immune Risk groups (p = 0.97), confirming that baseline peripheral lymphocyte counts are not predictive of the survival outcome. In contrast, baseline hypoalbuminemia emerged as a powerful, independent predictor of mortality. Patients with low albumin had a 3-fold increased risk of death (HR 2.99; 95% CI 1.07–8.33; p = 0.036) , whereas standard demographic factors failed to reach statistical significance. Kaplan-Meier curves demonstrated early and sustained separation, highlighting the consistently inferior survival outcomes associated with baseline hypoalbuminemia. Conclusions: In this real-world cohort (median age 73), host physiologic reserve emerged as the dominant determinant of survival over peripheral immune biomarkers. This study demonstrates that serum albumin, an established marker of physiologic reserve, far outperforms ALC and NLR as a survival predictor in older patients. These findings suggest that metabolic optimization should be prioritized over isolated immune counts for prognostication in the general oncology population.