Drug resistance, which is often of a multiple type, can be defined as the ability of cancer cells to obtain resistance to both conventional and novel chemotherapy agents. It remains a major problem to solve in cancer therapy. The mechanisms of resistance are multifactorial, and in our cellular models of acute myeloid leukemia, hepatocellular carcinoma, and triple-negative breast cancer, it involves the NF-κB pathway. In our opinion, multitarget molecules can be considered as privileged compounds capable of attacking and reversing the resistant phenotype. In the phenomena of both innate and acquired drug resistance that we have been studying since 1998 to today and up to 2016 under the guidance of Professor Natale D’Alessandro, more strictly pharmacological factors are certainly involved. These factors include P-glycoprotein and biological factors such as inhibitory proteins; apoptosis; the Raf-1 kinase inhibitor protein, an important tumor suppressor and metastasis inhibitor, which enhances drug-induced apoptosis of cancer cells; and Yin Yang, a transcription factor involved in drug resistance.