Immunotherapy’s Rise Among Cancer Treatments

BY DEVORAH SAFFERN

Most cancer patients are treated with chemotherapy, radiation, and/or surgery, but recent promising research has given hope to another option: immunotherapy. This approach allows the immune system itself to fight the cancer. Tumorous cells often prevent the immune system from attacking, or even make themselves undetectable to the body’s white blood cells. Immunotherapy treatment types vary, solving all these sorts of issues. Treatments come in the form of drugs, vaccines, catheters, and even creams, sometimes combined with other cancer treatments. Researchers are currently studying various forms of immunotherapy, which have shown promising results. As studies are done and clinical trials run, the form of treatment is rapidly becoming more widely accepted. Just a few weeks ago, the FDA (U.S. Food and Drug Administration) approved Keytruda, a checkpoint inhibitor immunotherapy drug used to treat metastatic lung cancer, also known as the drug that cured former president Jimmy Carter from a deadly form of melanoma. Keytruda can now be used as a first step in treatment over chemotherapy, in certain cases. A number of other immunotherapy drugs have been approved in the past, including Provenge in 2010, a treatment for prostate cancer, and Imlygic in 2015, for metastatic melanoma. These recent advances indicate that immunotherapy will likely become more prevalent in treatments.

Following the new FDA approval and general successes in immunotherapy testing, the media has displayed this exciting ray of hope for cancer patients. Dr. Crystal Mackall of Stanford’s School of Medicine, who specializes in this type of treatment, told FOX news that the recent immunotherapy findings are “turning the practice of oncology on its head.” New York times writer Denis Grady wrote: “All this has brought new optimism to cancer doctors — a sense that they have begun tapping into a force of nature, the medical equivalent of splitting the atom.”

Keytruda, the new drug, is a checkpoint inhibitor. These inhibitors are the most common form of immunotherapy drugs, and are relevant in treating different types of melanoma, lymphoma, lung, kidney, and bladder cancers. Normally, T-cells (white blood cells that have the ability to kill cancer cells) can detect which harmful cell to attack through reception of the antigen on the cell’s surface. Some cancer cells, however, can activate an immune checkpoint “switch” on the T-cell during the process, and prevent the T-cell from carrying out its function. Checkpoint inhibitor drugs block the checkpoints of T-cells so that the cancer cell cannot “switch off” T-cells. A recent study published in the June 2016 edition of the Cancer Immunology, Immunotherapy journal discusses the increase in the number of T-cells and their functionality in eighteen glioblastoma patients who were treated with the inhibitor Axitinib. Many other significant studies on the treatment have been published in recent years. In an article from last May, an approach similar to the checkpoint inhibitor method is described. Scientists designed specific molecules to remove sugars from the coatings of tumor cells, preventing the tumor cells from deactivating T-cells via these sugars.

CAR (chimeric antigen receptor) T-cells are another of the more prevalent types of immunotherapy methods, frequently used in clinical trials. T-cells are removed from the patient’s bloodstream and mutated in the lab to produce the chimeric antigen receptors, which enables the cell to attach to the cancer cell antigens. The mutated cells are given back to the patient through an infusion. CAR T-cells are used to treat leukemia and lymphoma and have had positive effects. In a trial that took place in Children’s Hospital in Philadelphia, in which T-cells were used, twenty-seven out of the thirty patients achieved remission.  Other types of monoclonal antibody treatments are also being tested. Researchers are working to create more of these antibodies that attach to antigens of cancer cells, essentially “flagging” the cancer cells so that the immune system can sense and attack. The antibodies are also sometimes made to target and destroy the cancer cells on their own.

While there are still many unanswered questions regarding the efficacy and side affects of immunotherapy, studies demonstrate potential for further improved treatments. In future work, researchers will begin to examine surrounding tissue of the cancer cells to gain a better understanding of the paths of the T-cells. Another step to be taken is looking for undiscovered checkpoints to be blocked, as well as combining this inhibitor method with other treatments. Implementing inhibitors with other methods could be particularly useful, as remnants of destroyed cancer cells from the other treatments could trigger immune system responses that would be refined via these inhibitors. Like all cancer treatments, immunotherapy has side effects and risks associated. If those obstacles can be eliminated, though, immunotherapy could be highly effective, as the immune system is the body’s natural tool and would typically only target unhealthy cells, unlike chemotherapy and radiation therapies, posing less collateral damage to the patient. Future studies are expected to be done in this growing branch of cancer research, with the Fred Hutchinson Cancer Researcher Center, a new immunotherapy research clinic that will focus on treatment with T-CELLS, scheduled to open in Seattle this December. All of us hoping for new forms of effective cancer treatment can expect to see more of this exciting, growing field of immunotherapy.

Sources:

 

http://link.springer.com/article/10.1007/s00262-016-1836-3

http://www.pnas.org/content/113/37/10304.abstract

http://myfox8.com/2016/10/30/can-your-own-immune-system-kill-cancer/

https://www.washingtonpost.com/news/to-your-health/wp/2016/11/01/seattle-cancer-center-bets-big-on-t-cell-immunotherapy

http://www.nytimes.com/2016/07/31/health/harnessing-the-immune-system-to-fight-cancer.html?rref=collection%2Fseriescollection%2Fimmunotherapy&_r=0

 

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