A carbohyrate polymer in which galactose molecules are attached to the amino groups of the glucosamine polymer chitosan, with potential imunostimulating activity. After a tumor ablation and upon intratumoral injection directly into the location of the ablated tumor, N-dihydrogalactochitosan may trigger a tumor-specific systemic immune response when exposed to tumor-associated neoantigens that are liberated by tumor ablation. This may kill tumor cells.