Further corroborating the immunophenotyping and reduced primary tumor immunosuppression, immunohistochemical staining for CD163 as M2 TAM marker was significantly reduced in chitin- and chitin + anti-PD-1-treated primary tumors compared to untreated and anti-PD-1-treated primary tumors from both models (Additional file 11: Fig. S9A). Here, CD163 is linked to neoplasm.