Although axillary lymph nodes from untreated 66cl4 tumor-bearing mice already had a very high number/percentage of CD4+ and CD8α+ T-cells compared to the 4T1-based model, an additional significant increase in the number/percentage of CD8α+ T-cells and an increased—albeit not significantly—CD4+ T-cell number/percentage was also detected upon chitin + anti-PD-1 combination treatment (Fig. 7H, Additional file 14: Fig. S12F). The gene discussed is PDCD1; the disease is neoplasm.