Revving the Immune Engine
New therapies harness the body’s own horsepower to beat cancer.
In September 2011, Geraldine Howard underwent what she thought would be routine corrective surgery to improve her eyesight when one of her eyes did not seem to “set properly,” as she says. Instead, she was diagnosed with malignant choroidal melanoma, a form of cancer that begins underneath the retina. Although it is relatively uncommon in the broad scope of cancers, if left untreated, it often spreads rapidly to the liver and elsewhere. “I was given the option of radiotherapy,” says the London-based cofounder and president of Aromatherapy Associates, “but that would have involved sewing a metal plate into my eye, with some quite grim side effects, and they did not feel that the outcome would be as positive as surgery.” Howard’s doctors opted for the latter, and, to be certain they got the entire tumor, removed the whole eye. Even so, given choroidal melanoma’s 95 percent likelihood of spreading, the team recommended Howard undergo additional treatment. What that treatment might be was unclear, says Howard, since no preventive options existed. Instead, someone on the team suggested she look into immunotherapy trials then taking place at the Defence Against Cancer Foundation at Radboud University in the Netherlands.
Immunotherapy is not new. As far back as the 1850s, German doctors first observed that tumors sometimes shrank in response to an infection—the very act of shrinking was evidence of a reaction by the immune system—and it has been widely used as a therapeutic technique for treating allergies for over a century. It is only within the last decade, however, that oncologists have begun to consider it a legitimate option for patients with cancer. Among other things, unlike chemotherapy and radiation, immunotherapy frees the immune system to attack tumor cells and does less harm to normal, healthy tissues. It also has fewer and less dire side effects. And treatments are brief: most patients take four intravenous doses of immune-boosting medication at three-week intervals, and it is that simple. In addition, and perhaps most significantly, because the immune system’s cells have a memory response that stays active for life once it is triggered, a patient would be forever protected against a recurrence of whatever particular tumor had stimulated the response. That is one huge advantage over the standard types of cancer-treatment therapies.
Immunotherapy is a rapidly evolving field that in many ways still offers more questions than answers, but the amount of focus it is receiving in multiple ongoing clinical trials and the development of new immune-based drugs may mean its implementation as the standard of care for many forms of cancer is not far off.
At its most basic, immunotherapy works by activating the immune system to attack whatever foreign invader—virus, bacterium, tumor cell—has assailed the body. The tools that do the work are the T cells or lymphocytes, the white blood cells that respond to infection, which react by proliferating and attacking whatever pathogen has wormed its way in. Because the T cells are armed with specific receptors—each human being has somewhere between one and five billion unique receptors—they can easily locate antigens, which are molecules that bind to the bacteria, viruses, and other unwelcome molecules, giving away their arrival like Henry Hill in Goodfellas. Once the T cells have found their targets, they kill the toxins to which the antigens are bound. That is how the human body recovers from the common cold, for example. In the case of cancer, the T cells would theoretically react to a tumor cell in the same way, recognizing its antigen and then releasing substances that would kill the cell or punch holes in its membrane, rendering it inactive. For decades, researchers took a number of approaches to coerce antigens to function as therapeutic vaccinations, to no avail.
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