Prognostic value of baseline serum IgG in metastatic clear cell renal cell carcinoma treated with first-line IO–TKI therapy.

Abstract

563 Background: Serum immunoglobulins (IgG, IgA, and IgM) may reflect systemic immune status and potentially influence the efficacy of IO–TKI therapy. This study aimed to investigate the prognostic value of baseline serum immunoglobulin levels in patients with metastatic renal cell carcinoma (mRCC) receiving first-line IO–TKI therapy. Methods: A total of 121 mRCC patients treated with first-line IO–TKI therapy between August 2019 and April 2025 were retrospectively analyzed. Baseline serum IgG (8.6–17.4 g/L), IgA (1.0–4.2 g/L), and IgM (0.3–2.2 g/L) levels were categorized as “elevated” or “normal” based on the upper limit of the reference range. Kaplan–Meier analysis was used to assess associations with progression-free survival (PFS) and overall survival (OS). Spearman correlation was applied to evaluate the relationship between IgG and IMDC risk score. Results: The median follow-up was 31.0 months (95% CI, 26.0–41.0). The median PFS was 18.0 months (95% CI, 16.0–39.0), while the median OS was not reached (95% CI, 44.0–NA). Elevated baseline IgG levels were significantly associated with inferior OS (p = 0.037), whereas IgA and IgM showed no significant association with OS or PFS (all p > 0.05). No correlation was observed between IgG levels and IMDC score (ρ= 0.07, p = 0.44). Conclusions: Baseline serum IgG level was independent of IMDC risk classification and showed a significant association with overall survival in patients with metastatic clear cell renal cell carcinoma receiving first-line IO–TKI therapy. Elevated baseline IgG identified a subgroup with unfavorable prognosis and may serve as a readily accessible prognostic biomarker deserving validation in prospective studies.