The predictive role of hematological markers in patients with recurrent or metastatic squamous cell carcinoma of the head and neck (R/M SCCHN) treated with pembrolizumab remains unclear.

We conducted a multicenter retrospective cohort study to investigate the predictive impact of the pre-treatment hematological markers neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), CRP-albumin-lymphocyte (CALLY) index, and the modified Glasgow prognostic score (mGPS) on overall survival (OS) and progression-free survival (PFS) in patients with R/M SCCHN treated with pembrolizumab. From December 2019 to February 2022, 119 and 28 patients were treated with pembrolizumab alone and pembrolizumab plus chemotherapy, respectively. The optimal cut-off point of dichotomized hematological markers was calculated using the area under the receiver operating characteristic curve. Hazard ratios (HRs) and 95% confidence intervals (95%CIs) were estimated using Cox proportional hazard models with adjustment for potential confounders.

In the pembrolizumab monotherapy group, patients with higher NLR, PLR, and mGPS and a lower CALLY index showed significantly shorter OS after adjustment for potential confounders. In addition, all hematological markers examined in this study tended to be associated with clinical response, such as overall response rate or disease control rate (DCR); in particular, a lower CALLY index and higher mGPS were significantly associated with poor DCR. In the pembrolizumab with chemotherapy group, these hematological markers had a similar association with OS but not with clinical response.

Pre-treatment NLR, PLR, CALLY index, and mGPS might be predictive markers of survival in patients with R/M SCCHN treated with pembrolizumab.