High CD3 and ICOS and low TIM-3 expression predict favourable survival in resected oesophageal squamous cell carcinoma

With the increasing oncological potential of immunotherapy, several immune checkpoint modulators are being investigated. The value of immune markers, including programmed cell death ligand-1, programmed cell death-1 (PD-1), inducible co-stimulator (ICOS), lymphocyte activation gene-3, T-cell immunoglobulin, and mucin-dominant containing-3 (TIM-3), is not well known. Using tissue microarrays of 396 patients who underwent surgery for oesophageal squamous cell carcinoma (ESCC), infiltrated T-cell subsets (CD3, CD8, and Foxp3) and checkpoint protein expression were scored. With a median follow-up of 24.8 months, CD3⁺ TIL subsets (50.0%) had longer median recurrence-free survival (RFS, 55.0 vs 21.4 months) and overall survival (OS, 77.7 vs 35.8 months). Patients with high ICOS expression (46.5%) had longer median RFS (53.9 vs 25.3 months) and OS (88.8 vs 36.9 months). For PD-1, RFS (hazard ratio [HR] 0.67) and OS (HR 0.66) were significantly longer in the high-expression group (45.2%). In the multivariate analysis, high TIM-3 expression (50.8%) had a significant relationship with shorter RFS (HR = 1.52) and OS (HR = 1.60). High CD3⁺ TIL and T-cell ICOS expression were associated with favourable prognosis, whereas high TIM-3 expression suggested a poor prognosis. Our findings may confer new insights to improve ESCC outcomes beyond the application of PD-1 blockade.