Targeted therapy

What is targeted therapy?

St. Joseph's/Candler - Summit Cancer Care Medical Oncologist Dr. Drew White explains how advancements in medical oncology are leading to a new level of individualized treatment

Like any battle, the fight against cancer takes courage, resilience, and tirelessness. Physicians and caregivers hope to go into that battle with the latest, most advanced weapons.

For certain types of cancer, medical oncologists now have the equivalent of a guided missile in their arsenal. It’s an approach called targeted therapy.

“The field of medical oncology has an increasing arsenal of drugs that specifically target abnormal cancer gene expression,” explains Stephen “Drew” White, MD, of Summit Cancer Care. “They are designed to selectively act on tumor cells, and thereby avoid the toxicities to normal cells that can often accompany chemotherapy.”

The unprecedented precision of targeted therapy is delivered through a variety of drug types and is commonly used for cancers like breast, lung, colorectal, and certain types of leukemia. 

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A Range Of Possibilities

There are several types of targeted therapy, each with a unique mechanism for fighting cancer. These include:

Small-Molecule Inhibitors

A class of drugs called small-molecule inhibitors can slip inside cancer cells and dismantle their inner workings. Kinase Inhibitors target proteins called kinases, which act like internal switches that tell a cell to grow, divide, or survive. In cancer, these switches are often stuck in the ON position. The inhibitors physically fit into the active site of the kinase switch, preventing it from functioning. By blocking the signal, they force the cancer cell to stop growing and eventually die.

Proteasome inhibitors target a protein complex called the proteasome, which acts as a cell's garbage disposal.  Cancer cells are typically very busy, generating lots of faulty proteins that need to be broken down. By jamming the proteasome, these drugs cause the abnormal proteins to build up inside the cancer cell, eventually overwhelming and killing it.

Poly-ADP ribose polymerase, or PARP, is a family of proteins that is targeted by a class of drugs called PARP inhibitors. Cells use PARP to repair damaged DNA. The inhibitors block this last line of defense against DNA damage in cancer cells that are already genetically weak. Without this backup repair system, the cancer cell’s DNA damage becomes too extensive, and the cell self-destructs. They are used for some ovarian, breast, prostate, and pancreatic cancers.

Monoclonal Antibodies

Another targeted therapy approach uses large proteins made in a lab that act like natural antibodies in the immune system. These are called monoclonal antibodies.

Surface receptor blockers target specific receptors that sit on the surface of cancer cells. Cancer cells often have too many of these receptors, which constantly receive signals to grow. These antibodies physically attach to the receptor, blocking the growth signals from reaching the cell's interior.

Another type of monoclonal antibody is known as an anti-angiogenesis inhibitor. These drugs target a protein called Vascular Endothelial Growth Factor, or VEGF, which a tumor releases to build its own blood supply. Anti-angiogenesis inhibitors prevent new blood vessels from forming and may even damage existing ones. By starving the tumor of oxygen and nutrients, they slow or stop its growth.

More Options, Individualized

Small-molecule Inhibitors and monoclonal antibodies are just some of the many targeted therapy options available to certain cancer patients today. The arsenal is large and diverse in order to match the different mutations across various cancers. For Dr. White and his colleagues at the Nancy N. and J.C. Lewis Cancer & Research Pavilion, having these options is essential to delivering individualized treatment, with precision medicine as a guiding force.

“It is personally very gratifying to participate in the care of patients with targeted therapy,” Dr. White says.  He concedes that for some patients, conventional chemotherapy is still the most appropriate treatment. But every patient’s cancer journey is different, and treatment at the LCRP is tailored to each patient’s individual needs.

“Our patients in chemotherapy are monitored closely with laboratory testing and other means to adjust doses and treatment schedules,” Dr. White says. “Any physical or emotional challenges arising from chemotherapy are addressed collectively at the LCRP, not just through medical and radiation oncologists, but also surgeons, palliative care specialists, social workers, nutritionists and nurse navigators. We have an incredible team here.”