Targeted Cancer Drugs

Even small doses of powerful cancer medicines cause fatigue, nausea, hair loss, anemia, numbness, and other symptoms. This is because they often attack both healthy and tumor cells. Biomedical engineers have sought to solve this problem with systems that target only tumors and leave healthy cells alone. 

It has proven a game of cat and mouse, with each advance uncovering new barriers to improving drug efficacy and reducing side-effects.

Decades ago, researchers began exploring ways to chemically link tumor‑targeting antibodies to cancer drugs, an idea that took many years of progress in antibody engineering to become practical. The concept was right, but no one could make enough antibodies and the chemical links often failed. 

It took 40 years of steady progress beforeone of the first widely used nanocarrier‑based targeted cancer medications, Doxil, received regulatory approval. It consists of a chemotherapy drug encapsulated in a lipid, a small bubble of fat. A coating hides the lipid from the immune system, allowing it to circulate in the blood stream and accumulate when it slipped through tumors' leaky blood vessels. Doxil improved safety and reduced hair loss and heart damage but did not always release its payload into the right cells. 

Researchers responded by decorating lipids with receptors designed to bond with molecules found in cancer cells. Once inside, though, the cancer cells quickly recognize the lipids as intruders and trapped them in lysosomes that break them apart. 

Biomedical engineers attacked the problem with molecules that help carriers escape from lysosomes so the drug can reach its target inside the cell. They also developed medicines that would seek out specific tumor targets, then activate when heated or lit up with UV radiation. 

Researchers also began to harness the inherent stability and targeting abilities of our body's own antibodies. In CAR-T cell therapy, technicians collect a patient’s T cells and insert genes that enable them to recognize cancer molecules. Then they grow millions of these modified CAR-T cells and inject them into the patient, where they attack the cancer.

Thanks to continuing advances in targeting, today's cancer patients live longer, healthier lives and suffer less pain from treatment.