Serum Albumin: Early Prognostic Marker of Benefit for Immune Checkpoint Inhibitor Monotherapy But Not Chemoimmunotherapy

•Hypoalbuminemia has broadly been viewed as a marker for unfavorable treatment response in advanced cancers, and poor health condition such as cancer-associated cachexia. Decreases in albumin may also correspond to increases of ICI clearance, which has been demonstrated as a potential biomarker for ICI outcomes.•In this single-center retrospective study, we found that low pretreatment albumin, and an albumin decrease of more than 10% from pretreatment within the first or second cycle were strongly associated with short OS in patients with advanced NSCLC treated with ICI monotherapy, but not in patients treated with chemoimmunotherapy.•Our result also showed that such lack of association between albumin and OS in chemoimmunotherapy was even more pronounced among patients with ≥ 1% PD-L1 expression.•Eearly serum albumin change can be incorporated into a holistic model, along with other early biomarkers to better inform outcomes predictions, and early decision-making with ICI monotherapy.•Cancer cachexia may contribute to the association of albumin changes and ICI treatment outcome. However, the underlying mechanism of the observed association in ICI monotherapy but disconnected association in chemoimmunotherapy needs to be further investigated.