Research on cancer vaccine starts to show results
The vaccine that Larry Mathews is getting won't protect him from the flu. That's OK - the stakes are far higher than that.
He's hoping the shots will prime his immune system to fight the aggressive cancer that has invaded his brain. If it works as he wants it to, his body's own killer cells will mop up malignant cells that surgery, radiation and chemotherapy couldn't eliminate.
For decades, scientists have been trying to create vaccines like this to recruit the body's immune system to destroy cancer cells the way it wipes out foreign viruses and bacteria.
After many false starts and premature promises, it appears that their research is beginning to pay off.
In late April, the US Food and Drug Administration approved the first cancer vaccine, Provenge, that can modestly extend the lives of men with advanced prostate cancer. Several major insurance plans and Medicare claims processors in some parts of the US, including Kansas and Missouri, have already agreed to pay for the costly treatment.
Mathews is taking part in an initial clinical study at St Luke's Hospital on a brain cancer vaccine developed at University of Kansas Medical Centre. A two-year study aimed at gaining FDA approval is planned to start this autumn.
Worldwide, scientists are working on dozens of vaccines against melanoma and cancers of the breast, lung, colon and pancreas.
Researchers can cite anecdotes of cancer patients given months to live who have survived 15 years or longer after receiving vaccines. But so far, conclusive evidence from large clinical trials is scant.
Even so, experts say several cancer vaccines could gain FDA approval in four or five years.
These therapeutic vaccines are designed for patients who already have cancer. It makes them radically different from conventional preventive vaccines, which immunise against viruses that cause cancer.
The surge in development of therapeutic vaccines doesn't come from any single breakthrough, says Dr William Chambers, director of clinical research and immunology at the American Cancer Society. Rather, it's the result of years of slow, incremental progress.
"Immunotherapy has been a tough nut to crack," Chambers says. "What you're seeing now is the product of a lot of hard work. Some of the successes are showing up."
The immune system identifies alien organisms in the body and then seeks out and destroys them.
But cancer cells get a free pass. For one, they're very similar to normal lung or prostate or colon cells. As they grow, they evolve ways to turn off an immune response or cloak themselves from detection. The goal for vaccines is to train the immune system to recognise ways that cancer cells differ from others and motivate it to attack.
Vaccines represent a major shift in thinking about how to treat cancer, says Dr James Gulley, a researcher at the National Cancer Institute. Conventional cancer therapies aim toxic drugs and radiation at tumours, but can harm other tissues and cause side effects.
Vaccines narrowly target the immune system. Side effects - fever, chills, soreness at the injection site - typically aren't much greater than what you may get from a flu shot.
McClatchy-Tribune
Source:www.scmp.com
