Question

Drug resistance is a big problem in treating cancers as well as many other diseases. Why is it so hard to find the perfect drug that cures the patients in cancer?

Answer 1

Initially all cancer tissue are susceptible to drug treatment. But gradually they develop resistance to certain drugs. Then it becomes difficult to treat and new methods of treatment of cancer needs to be developed.

It is hard to find a perfect drug to cancer treatment because the chemotherapeutic drugs develop resistance to the conventional therapies. This can happen by various methods. The DNA of the cancer cells may mutate,bringing certain metabolic changes which will promote drug degradation. Usage of drugs also can bring certain epigenetic changes which bring cancer drug resistance and also can activate the development of cancer progenitor cells that are not killed by conventional cancer therapies.

Drug resitance can also be due to drug target alterations, drug efflux, DNA damage repair of the cancer cells etc.

Cancer cells show lot of heterogenicity in the same tumor.The cancer cells collected from different regions of the same tumor are quiet different. This poses a big challenge to completely destroy cancer cells in a tumor by single drug treatment. Cancer cells divide very rapidly and produce huge number of cells. Every time a cell replicates DNA, some errors develop in new DNA which are repaired. But because of the rapidity with which cancer cells divide, some of the DNA damage remains as such and this adds up as the divisions increase. All this adds up to the differences in the cancer cells leading to heterogenicity. So, it is like the evolution happening with in the tumor. That is why it is hard to find a perfect drug for cancer.