Is Immunotherapy For Cancer All It Is Promised to Be?

At the 2016 meeting of the American Association for the Advancement of Science, immunotherapy researcher and oncologist Stanley Riddell of Seattle's Fred Hutchinson Cancer Research Center, announced an exciting new cancer treatment. "The early data are unprecedented," Dr. Ridell said. Adoptlive cell therapy could be the long-awaited breakthrough in the war of cancer.

What Is Adoptive Cell Therapy?

For about 100 years cancer specialists have been using radiation and chemotherapy to attack cancer cells directly. The problem with this approach has always been that any treatment that kills cancer cells also kills healthy cells. In recent decades, oncologists have been developing a different approach, recruiting the body's own immune defenses into the fight against cancer. Of course, any non-medical observer might ask why, if our immune systems can fight cancer, do we need treatment at all?

The reason our immune systems don't always defeat cancer (actually, they do more often than not, before cancer is ever symptomatic) is that some cancer cells have an ability to evade detection. They grow inside tumors that aren't connected with most of the body's blood vessels. White blood cells don't detect the cancer because they never come in contact with it. Or the white blood cells known as T cells simply don't have a targeting system for cancer. They don't have a way of attacking cancer without also attacking healthy cells.

It uses the patient's existing T cells. In an earlier version of this technique, the T cells are removed from the patient, grown in the lab, and given back to the patient in vastly increased numbers.  As many as 100 billion T cells may be grown in the lab and infused back into the patient's bloodstream. Sometimes this is enough to defeat a cancer.

In a more advanced version of this technique called adoptive cell therapy, a second set of laboratory techniques creates a "chimera" of the patient's native T cells with an antibody attached to what is called a chimeric antigen receptor of CAR, and then multiplies the result. Adding an antibody to the T cells turns them into what some researchers call an elite fighting force for the kind of cancer on which the antibody acts. This method hasn't been used with very many people, but in some studies, 90 percent of leukemia patients have had "complete responses," meaning they have gone into remission, with adoptive cell therapy. 

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This therapy is not yet FDA-approved, but it is being adapted to modifying other kinds of immune cells, such as natural killer (NK) cells, and to other kinds of cancer, such as non-small cell lung cancer, melanoma, certain kinds of of bone cancer, and multiple myeloma. Adoptive cell therapy boosts the immune system's first line of defense against cancer and gets results, unfortunately, not all of them are positive.

Downside to Adoptive Cell Therapy

Adoptive cell therapy, in one study, eliminated 94 percent of participants with acute lymphoblastic leukemia. This would seem to be a wonderful advance. Most of the time, it is, however, in that other 6 percent there were patients who had to be put in ICU and later died from side effects of the immunotherapy.

Other Approaches To Cancer Immunotherapy

Immunotherapy for cancer has been described as the next "moonshot" for cancer research, and since President Obama announced the awarding of $1 billion in government research funding, the various pharmaceutical companies that stand to make a profit have presented a united front to promote the possibilities of adoptive cell therapy. However, there are other techniques of cancer immunotherapy that have been around longer that also sometimes get good results.

Enzyme Therapy for Cancer

Dr. Nicholas Gonzalez, a New York City doctor who later had to relocate his practice to Mexico and who died in 2015 , believed that the immune system might be able to fight cancer on its own if it simply got some help with disposing all the waste products released when cancerous tumors died. To facilitate the breakdown of cancer cells so they could be removed from the body, he gave patients large doses of pancreatic enzymes, up to 180 enzyme capsules a day. In four cases of pancreatic cancer, patients of Dr. Gonzalez lived much longer than expected. In a clinical trial of a variety of types of cancer, his patients lived  only 1/3 as long as conventionally treated patients.

Fighting Cancer with Viruses

The improbably named Talimogene Laherparepvec is an oncolytic, or "cancer dissolving" virus developed by BioVex, Inc. for treating melanoma. It has been approved for use in both the United States and the European Union. This virus was genetically engineered from the herpes virus HSV-1, the kind of herpes that most commonly causes cold sores. The genetic engineers removed the virus's ability to cause the symptoms of herpes, made it more compatible with cancerous skin cells than healthy skin cells, and added genes that enabled it to secrete a substance called a cytokine, which initiates an immune response.

What this virus does is to give the immune system a target. White blood cells can't "find" melanoma, but they can find the virus, and it attacking the melanoma tumors that have been infected with the virus, they kill both the virus and the cancer. Shanghai Sunway Biotech, in China, has engineered a "colds" virus that has been modified to attack head and neck cancers. This treatment is available in China.

Vaccines Against Cancer

Personalized vaccines against cancer have been successful in a limited number of cases. These vaccines are not mass produced. Instead, they are made for a unique combination of markers from the patient's own cancer. Every cancerous tumor produces at least 100 different proteins that could be used by the immune system to locate and identify it, but the immune system tends to "forget" which markers are associated with the tumor. A vaccine "reminds" the immune system that it needs to attack the cancer by concentrating just a few of the markers to "teach" the immune to fight the cancer. At this time, vaccines are an addition to other treatments for cancer. They don't replace traditional treatments for cancer.

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And that may be the case with all kinds of immunotherapy for some years to come. Very few doctors believe that immunotherapy will provide a magic bullet for killing cancer any time soon. Immunotherapy combined with other treatments, however, may help many more people achieve remission and resume their lives.