Why Personalized Cancer Treatment Doesn’t Always Work as Expected

Personalized cancer treatment aims to match patients with therapies based on specific features of their cancer, but tumors can adapt in ways that make this approach more complicated, according to Dr. Miguel Gonzales-Velez, a medical oncologist at John Theurer Cancer Center.

The goal of personalized, or individualized, medicine is to identify markers or proteins on cancer cells that can be targeted with a particular treatment, Gonzales-Velez explained. One way to think about this is that if a cancer has a "yellow" protein, a patient receives a medication designed to target that yellow protein. If it has a "red" protein, the treatment targets the red protein instead.

However, cancer can develop what are known as "escape mechanisms," he noted. Cancer cells may change how they grow or find ways to hide from the immune system, allowing the disease to continue growing despite treatment.

This is one reason cancer treatment may involve different approaches, including chemotherapy, immunotherapy, targeted therapy and cellular therapy. These treatments can work in different ways or combinations to target cancer and make it more difficult for the disease to evade treatment.

Another challenge is that cancer cells do not exist on their own, Gonzales-Velez added. They live within what is known as the tumor microenvironment, which includes the surrounding tissues, cells and components of the immune system.

The tumor microenvironment can be thought of as the cancer's "house" and surrounding neighborhood, he said. The normal tissue provides some of the structure, while components of the immune system function almost like the plumbing and electricity.

Because of this environment, effectively treating cancer may require more than targeting cancer cells directly, Gonzales-Velez concluded. Some approaches aim to activate the immune system or change the tumor microenvironment so that the body is better able to recognize and destroy cancer cells, with the ultimate goal of preventing the disease from continuing to grow or spread.

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