Fighting Cancer In Older Patients
(Ivanhoe Newswire)– Battling cancer is difficult at any age, but it is especially difficult for elderly patients because their bodies can not fight the disease as well as younger patients.
However, a new study from the Cancer Therapy & Research Center at The University of Texas Health Science Center at San Antonio shows that some types of immunotherapy previously thought to work only in younger patients can be used to help the elderly, with less toxic effects than many common therapies, if they are combined in ways that account for age-related changes in the immune system.
“We’ve shown that immunotherapy for cancer not only works in aged mice, but actually can work better in aged hosts than in young counterparts by capitalizing on the immune changes that happen with age,” Tyler Curiel, M.D., MPH, a professor in the School of Medicine at the Health Science Center, was quoted as saying.
“As you age, most parts of your body begin to wear out. They keep doing what they’re made to do”, Dr. Curiel was quoted as saying. But over time, they don’t do it as well. The general perception is that the immune system also simply declines with age. “That’s really too simplistic,” he said. “That’s really not the full picture of what’s happening.”
As we age, the body’s immune system does weaken, but it also changes, and that changes how the disease is fought within the body. Dr. Curiel’s group started by examining an immune therapy that previously been had shown to work in younger hosts, including cancer patients. It’s designed to eliminate regulatory T cells (called Tregs), which are cells that turn off immune responses, allowing cancer to progress. Tregs increase in cancer. In young hosts, the drug turns off Treg activity, allowing the immune system to function better. In older hosts, even though the drug turns off the Tregs, it has no clinical benefit.
Dr. Curiel asked the question why, and his team explained that in older mice, when the drug turned off the Tregs, the researchers found that another type of immune suppressor cell (a myeloid-derived suppressor cell or MDSC) exploded in number to take the Tregs’ place, hampering clinical efficacy. That did not occur in young mice.
Additionally the team added a second drug that targets the MDSC, and found that with those tools to help immunity, the older hosts can combat cancer just as well as the younger hosts. Adding the second drug afforded no clinical benefit to young hosts, as their MDSC numbers had not increased.
“We’ve shown that an aged immune system can combat cancer just as well as a young one if you remove the impediments to successful immunity, which are different that those in younger hosts,” Dr. Curiel was quoted as saying. “We’ve shown that if you test all your immune therapy just in young mice and young people, you’ll never learn how it works in older patients – the ones most at risk for cancer. You might conclude that drugs don’t work in aged hosts, when they do. But they have to be combined with some help.”
After discovering this in melanoma, the researchers also examined at whether the same action was the same in colon cancer, a major cancer killer in the elderly.
“The details were different in colon cancer. The bad immune cells that increased in the aged mice and how they were knocked down by the drugs were different than in melanoma,” Dr. Curiel said. “But the result was the same – we identified a drug combination that was highly effective in the aged mice.”
Ultimately this strategy must be developed not only with regard to the age of the patient, but also to the specific kind of cancer.
“It’s a bit complicated, but it’s possible to put into practice, and because these approaches could be so much more specific and so much better tolerated than conventional chemotherapy, it is well worth pursuing. We are grateful to the Voelcker Foundation and the Holly Beach Public Library Association for funding this work.” Dr. Curiel was quoted as saying
Next the team plans to test these concepts in an immune therapy clinical trial for elderly patients.
SOURCE: Cancer Research, April 16, 2012