RNASE1 and metastatic neoplasm: We subsequently investigated the potent prognostic value of RNase1 as a serum biomarker for ICI treatment because T‐cell dysfunction in the TME has been associated with ICI treatment failure.[4, 19] We collected serum samples from HNSC patients with recurrent or metastatic diseases undergoing ICI therapy and measured RNase1 concentrations by using ELISA assays.