Serum lactate dehydrogenase to alanine aminotransferase ratio as a prognostic factor in patients with head and neck squamous cell carcinoma treated with immune checkpoint inhibitors.

[BACKGROUND] Immune checkpoint inhibitors (ICIs) are standard treatments for recurrent/metastatic head and neck squamous cell carcinoma (HNSCC). Simple and reliable biomarkers are required to optimize patient selection.

[OBJECTIVES] To evaluate the prognostic significance of the pretreatment serum lactate dehydrogenase (LDH)/alanine aminotransferase (ALT) ratio in patients with HNSCC treated with ICIs.

[PATIENTS AND METHODS] We retrospectively analyzed 110 patients with HNSCC treated with nivolumab or pembrolizumab between 2017 and 2023. LDH and ALT were measured before ICI initiation. Survival rates were estimated using the Kaplan-Meier method. A Cox proportional hazards model was used to calculate hazard ratios (HRs). The effect on treatment response was assessed by a logistic regression model.

[RESULTS] Neither LDH nor ALT alone was associated with survival whereas the LDH/ALT ratio was. High LDH/ALT ratio was associated with worse disease control (odds ratio 0.16, 95% confidence interval (CI) 0.04-0.65). Patients in the high LDH/ALT group showed significantly worse overall survival (HR 2.75, 95% CI 1.37-5.50) and progression-free survival (HR 3.35, 95% CI 1.72-6.52) compared with the intermediate groups.

[CONCLUSIONS] The LDH/ALT ratio is an independent prognostic biomarker in HNSCC patients receiving ICIs.