Breast cancer patients who do not respond to targeted therapy show epigenetic differences, a new study has revealed. According to the study, presented at the Experimental Biology 2019, breast cancer patients who don't respond to targeted therapy have different patterns of epigenetic modifications than patients who do respond. Epigenetic modifications change gene expression without altering the DNA's genetic code, Targeted cancer therapies use drugs to block molecules in cells that cause them to grow out of control. The therapy specifically targets cancer cells, unlike chemotherapy, which kills all quickly growing cells whether they are cancerous or not. Although the development of targeted therapies has increased breast cancer survival, treatment failure is still an important problem.