Introduction to Drug Resistance in Cancer

Treating cancer has so many hurdles, and drug resistance is one of them. Treatment strategies are evolving for cancer due to innate and acquired resistance capacity in them. The mechanism behind the resistance is constantly evolving in response to new drug treatment strategies and is an outcome of the acquired or adaptive mutation expression in cancer cells. In a broader perspective, cancer drug resistance can be governed by genetic, epigenetic, proteomic, metabolic, or microenvironment cues that ultimately enable selected resistant cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance has been widely studied in cancer that progressively leads to the generation of new targets for novel anticancer drugs having better efficacy than previous ones. However, due to the high variability in resistance acquired by cancer cells toward existing drugs, novel strategic options with better efficacy need to be explored that overcome resistance. Combination therapy is a widely used alternative with a better success rate though the risk of amplified side effects is commonplace. However, recent groundbreaking immune therapy combination with the drugs is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent. However, more study is needed to be done at genetic, epigenetic, proteomic, and metabolic levels to identify targets of different cancers that can help to develop new therapies that are more effective to the existing challenge of cancer drug resistance. This chapter will focus on the recent challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level.