“Good drugs often go to the wrong cells. The solution is to target the drug at the diseased cells and to prevent its uptake by normal cells,” said Philip S. Low of Purdue University, U.S., delivering a lecture at IIT-Madras.
Dr. Low has spent over 40 years exploring targeted therapeutic and imaging agents for diseases affecting people, including cancers, autoimmune disease, infectious diseases, and even fractures. His talk was part of the ‘India-Purdue Collaborative Lecture Series in honour of Professor C.N.R. Rao.’
In the context of cancer, targeted therapy is different from traditional methods such as chemotherapy. In this, the researchers develop what are known as molecular ligands that can actively seek out particular genes or proteins found in cells and bind to them. The trick is to attach the drug to the other end of the ligand so that when it enters the targeted cell, so, too, will the drug. Dr. Low explained that as cancer cells divide really fast, they show an increased appetite for the vitamin folic acid which is needed for DNA synthesis. Creating a ligand which can bind to folic acid will help target the drug specifically at the cancer cells which will absorb it along with the ‘Trojan horse’ folic acid.
This technique, called the Trojan Horse process, was discovered by Dr. Low and Christopher E. Leamon, and can also be used to illuminate cancers during surgery.
If the Trojan horse molecule is attached to a fluorescent dye of red or yellow colour, it will tend to be absorbed by the cancerous tissue. During surgery, the cancerous tissue glows in a different colour and the surgeon can avoid cutting out normal tissue. “Nearly 40% of cancers recur after surgery because a portion of the malignant tissue is left behind. This treatment vastly improves the situation,” said Dr. Low.
