Directly Injecting a Tumor May Give It a Death Sentence

Some forms of cancer treatment have to attack the entire body to attack the cancer cells, chemotherapy, and immunotherapy, to name two. Radiation therapy is targeted, but it has serious side effects and risks.

What if you could simply inject a tumor with two special ingredients and it would disappear, along with others of the same type of tumors throughout the body?

That was the approach of a team from the Stanford University School of Medicine in Palo Alto, California. The study investigated the potential of injecting minute amounts of two agents that stimulate the body’s immune system directly into a solid malignant tumor.

The study’s senior author, Dr. Ronald Levy, explained the initial findings, “When we use these two agents together we see the elimination of tumors all over the body.”

The study was published at the end of January in the journal Science Translational Medicine.

Targeted immunotherapy

Dr. Levy comes from the world of immunotherapy, especially when used to fight lymphoma, cancer of the lymphatic system. In immunotherapy, the body’s immune response is enhanced to target cancer cells. There are several types of immunotherapy. Some boost the entire immune system of the body, while others are more targeted.

But they come with asterisks. Immunotherapy can have serious side effects, can typically be time-consuming (often not a luxury cancer patients have), and is often too costly to present a serious, widespread cancer treatment option. Plus, many types of cancer cells can evade detection in complex ways. Normally, a type of white blood cell called T cells would target and fight cancer tumors, but the cancer cells learn to “trick” them and escape the normal immune response attack.

The study

In this study, Dr. Levy and his team delivered micrograms of two specific agents into one hard tumor site in each of the affected mice. These were the two agents:

  • CpG oligonucleotide, a short stretch of DNA that boosts the immune cells’ ability to express a receptor called OX40, which is found on the surface of T cells
  • An antibody that binds to the receptor, activating the T cells

The researchers first injected the two agents together in mice with lymphoma. Of the 90 mice injected, 87 became cancer-free. In the other three mice, the tumors did recur, but when a second injection was given, they disappeared.

They then tested in mice with breast, color, and skin cancer. The rates of success were similar. This proved true, the study notes, even in mice that were genetically engineered to develop breast cancer spontaneously.

Only the type of cancer in the injected tumor

The team also investigated whether an animal with two types of cancer would benefit. The injections were given only into the tumor of one of the forms of cancer, not the other, in this case, lymphoma and colon cancer. When the lymphoma tumor was injected, the results were the same. Unfortunately, they didn’t affect the colon cancer tumor in the same way.

It appears the T cells learn to deal with the cancer cells in the immediate vicinity of the injection site. Dr. Levy explained, “This is a very targeted approach. Only the tumor that shares the protein targets displayed by the treated site is affected.”

Once the T cells were activated by the injection, however, some of them then migrated to other parts of the body, hunting down and destroying other tumors of the same makeup. The study said that this method could teach immune cells how to fight against that specific type of cancer, which then allows them to migrate and destroy all other existing tumors present in the body.

The study points to the value of the targeted approach. Dr. Levy said, “This approach bypasses the need to identify tumor-specific immune targets and doesn’t require wholesale activation of the immune system.”

With the success of these results, the same research team is preparing a clinical trial to test the effectiveness of this treatment in people with low-grade lymphoma. If this trial is successful, there is the reason to believe this therapy could be used to target virtually any kind of cancer tumor in humans.

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