Growing arsenal of therapies may serve Kennedy
______________________________________________________________
By Stephen Smith and Carey Goldberg
Boston Globe Staff
May 22, 2008
Until a few years ago, patients stricken with cancerous brain tumors had precious few treatment options. There was surgery and radiation and not much else.
But today, as Senator Edward M. Kennedy and his doctors plot his course of care for a malignant glioma, they confront a richer palette of possibilities - due in no small part to Kennedy's championing of the war on cancer since its dawn in 1971.
Friends are certain that, secluded in Hyannis Port, Kennedy and his family are working the phones and taking a crash course in cancer care, from standard treatments to novel approaches being tested around the country.
"It's really hard to think of anyone who's helped biomedical research in this country or the National Institutes of Health more than he has, and hopefully he'll get some benefit from how he's helped others," said Dr. Patrick Wen, clinical director of the Center for Neuro-oncology at the Dana-Farber Cancer Institute.
Among the progress that the Kennedys will undoubtedly learn about is a powerful form of chemotherapy that comes in a pill and stands as the drug of choice. And study results being released next week at a major cancer research conference show that a drug now used to treat other types of tumors can extend the period that a brain growth remains in check, although in only about half the patients who received it.
At the same time, researchers around the world are exploring a constellation of experimental treatments, everything from specially engineered cold viruses that explode brain tumors while leaving healthy cells intact to a substance found in scorpion venom that targets cancer cells for destruction. Scientists also said they believe they are edging closer to being able to tailor treatments to the genetic quirks of individual patients' tumors.
Currently, the cancer branch of the NIH is sponsoring 269 experimental trials for adults suffering from gliomas, an agency spokesman said.
None of these therapies come close to being a cure, however, and with brain cancers, advances are typically measured in months of additional life, not years.
"To cure this problem is harder than getting to the moon, apparently, because we got to the moon a long time ago," said Dr. Eric Holland, director of the Brain Tumor Center at Memorial Sloan-Kettering Cancer Center in New York. "All along the way we've been encouraged by things that looked good that at the end of the day didn't change the survival of patients."
Still, there is no denying that advances have been made, both in improving existing treatments and exploring new strategies to combat brain tumors.
In years past, for example, radiation would be trained on a patient's entire brain. Now, radiation, a mainstay of treatment, has become both more precise and more powerful, allowing doctors to target the tumor with more killing rays while not inflicting collateral damage on healthy brain tissue.
"It really has changed dramatically in terms of what we can offer patients today versus what we could even five years ago," said Dr. Howard A. Fine, chief of the Neuro-oncology Branch at the National Cancer Institute.
Fine said he is treating patients who have survived three, five, or even 10 years after being diagnosed with a malignant glioma "who were told they were going to die in six months, see you later. And now they're going about having normal lives."
"But do I also have patients who die in three or four or five months? Absolutely, I do," Fine said. "My point is, it doesn't have to be that way."
For so long, brain cancer had been considered such a formidable foe that researchers shied away from it, preferring to concentrate their efforts on other cancers. Brain tumors are dauntingly complex growths, and the slightest errors in treatment can result in devastating complications. Moreover, a protective barrier between the brain and blood flowing through the rest of the body greatly complicates the delivery of drugs.
Economics comes into play, as well. Simply put, the market for brain cancer drugs pales compared with that for other malignancies, with only 9,000 people a year in the United States diagnosed with the kind of cancer that has beset Kennedy.
"Because the numbers are relatively small," Wen said, "the incentive to develop drugs for brain tumors is less than for breast cancer or prostate cancer."
After so many years of having few options for their patients, cancer doctors in 2005 added an important new weapon. A landmark study showed that the drug temozolomide increased survival by a few months in newly diagnosed brain cancer patients when used in tandem with radiation.
Next week, researchers will present data showing that some brain cancer patients with especially aggressive tumors lived longer when they took a drug already approved to treat colon, lung, and breast cancer in combination with another medication. The study found that in half of the patients taking Avastin and another drug, the tumors had stopped growing after six months.
Other treatments are in various stages of development, including vaccines that would rev up the immune systems of patients to attack tumors, which otherwise are so stealthy that they can hide from disease-fighting cells.
Three radically new methods for attacking brain tumors are close to entering clinical trials locally, said Xandra O. Breakefield, a researcher at Massachusetts General Hospital. The methods aim to use genetically modified cells or viruses to home in on invasive tumor cells and destroy them.
Local biotech companies, too, are adding possible new weapons to the arsenal against brain tumors, including one originally isolated from scorpion venom. TransMolecular Inc. of Cambridge found that a substance called chlorotoxin binds to tumor cells but not to normal cells. Used with radioactive iodine, it delivers lethal radiation only to tumor cells, said Michael Egan, the company's president. It is now being tested in patients with malignant gliomas that have grown back, he said.
Throughout his 45 years in the Senate, Kennedy has been a stalwart defender of biomedical research, arguing for increases in the NIH budget, as well as sponsoring legislation to improve mammograms, securing money for cancer care in Boston, and backing aid for childhood cancers.
"In the cancer research and medical research community, we certainly owe Senator Kennedy a lot of gratitude for his support," said Dr. W.K. Alfred Yung, chairman of neuro-oncology at M.D. Anderson Cancer Center in Houston. "This is also a time that the brain tumor community really needs to galvanize for the senator and his family to give the best advice in terms of the best way to move forward in his treatment." |
