The aim of our research was to examine the presence of MC4R in colorectal and thyroid cancer cells and to evaluate it as a novel target for anticancer therapy in vitro and in vivo by blocking its pathways using the selective antagonist ML in combination with vinorelbine in the case of anaplastic thyroid cancer, and with irinotecan in the case of colorectal adenocarcinoma. Here, MC4R is linked to thyroid cancer.