by Dan Stimson

Robert Miller

Larry Alary figures he has no time to waste. Four years ago, he was told he has amyotrophic lateral sclerosis (ALS), a disease that attacks the bodys muscle-controlling nerve cells, or motor neurons. It has no cure, and typically causes paralysis and death within three to five years of diagnosis.

Within two months of his diagnosis, Alary drove 70 miles from his home in Sonoma County, California, to the Forbes Norris MDA/ALS Center at California Pacific Medical Center in San Francisco, seeking expert care and offering to be a "guinea pig" for clinical trials.

About a year and half ago, he was selected to participate in a pilot trial of minocycline, led by the centers director, Robert Miller. Minocycline is an anti-inflammatory drug, primarily used for treating severe acne and arthritis, but research on mice had suggested it might stave off a process akin to cell suicide, a phenomenon believed responsible for the death of motor neurons in ALS.

The pilot trial is now complete, and the results have encouraged researchers to launch a larger, follow-up trial. Meanwhile, Alary, now 62, is still on minocycline, hoping that its keeping his motor neurons alive.

Programmed Cell Death

Until about 10 years ago, cell suicide was considered an important process during embryonic development, but not in disease.

Our developing bodies produce cells that are destined to die. The hands of a human embryo are initially shaped like paddles; the fingers form when cells in the tissue between them are eliminated. In the embryonic nervous system, millions of neurons compete to connect to each other and to muscles; the losers die.

These are considered examples of cell suicide or programmed cell death (PCD) because the dying cells themselves activate proteins that disassemble their working parts. A particularly gruesome type of PCD, called apoptosis, is triggered by the activity of caspases, enzymes that chop apart vital proteins in the cell. Cells that die from injury or other forms of stress tend to swell and rupture, but cells undergoing apoptosis (Greek for "falling off") break apart slowly and eventually become engulfed by immune cells.

In the early 1990s, scientists discovered a link between PCD and cancer. Some cancer cells, it turns out, become resistant to normal PCD, allowing them to multiply uncontrollably and form tumors. More recent studies have shown that in some degenerative diseases, including ALS, the affected cells appear to do just the opposite — inappropriately triggering PCD and causing their own destruction.

Indeed, PCD now has such a prominent place in biomedical research that the scientists who uncovered its essentials in the 1980s (by studying the development of a microscopic worm) were honored with the 2002 Nobel Prize in Physiology or Medicine.

This research opened up the possibility of treating ALS with minocycline, and has encouraged scientists to investigate the role of PCD in other neuromuscular diseases.

When a cell dies by apoptosis, all of its components — including the nucleus (blue), where DNA is stored — break up into bits. An immune cell (green) cleans up the carnage.

ALS

Robert Friedlander, a neurobiologist at Brigham and Womens Hospital and at Harvard Medical School in Boston, was the first to test so-called anti-apoptotic drugs against ALS

	Robert Friedlander

In a 2000 study supported by MDA, he showed that zVAD-fmk, a drug that blocks the activity of most caspases (there are at least 14), extended survival of mice with the disease by about 25 percent. Since zVAD-fmk doesnt penetrate the blood-brain barrier (the blood vessels that surround the brain), it had to be pumped directly into the brains of the mice. After reading a study that showed oral minocycline could cross the barrier and inhibit caspase-1 and caspase-3, Friedlander tested it in the mice and found it improved survival by about 10 percent.

By that time, Miller had already begun testing minocycline in human ALS patients, as had Paul Gordon, then director of the MDA/ALS Center at the University of New Mexico in Albuquerque.

"The [New Mexico] trial showed that standard doses of minocycline were safe and well tolerated," says Gordon, who is now co-director of the Eleanor and Lou Gehrig MDA/ALS Research Center at Columbia Presbyterian Medical Center in New York. " There were no significant differences in adverse events or lab abnormalities between minocycline and placebo." The California trial, he said, showed that high doses of the drug might cause gastrointestinal, liver and kidney problems.

A large trial of the drug, designed to assess its effectiveness, has begun at some 24 sites across the country.

SBMA

Paul Gordon

Spinal-bulbar muscular atrophy (SBMA), also called Kennedys disease, is a motor neuron disease with symptoms similar to those of ALS, but the similarities run deeper than that. In SBMA, theres evidence that motor neurons die by apoptosis.

SBMA is caused by an expanded tract of DNA in the gene for the androgen receptor, a protein that enables cells to respond to testosterone and other masculinizing hormones. The "expanded" androgen receptor doesnt just lose its normal functions — it somehow activates caspases, and is itself a target of caspases.

Federica Piccioni and Kenneth Fischbeck of the National Institute of Neurological Disorders and Stroke (NINDS) recently identified a set of chemicals that inhibit this caspase activity. As part of a project organized by NINDS to discover new drug treatments for SBMA, ALS and other neurological diseases, they tested more than 1,000 chemicals on cells harboring an expanded androgen receptor. They found 21 chemicals that reduced the activity of caspase-3 by 70 percent or more.

"A therapy that inhibits caspase-3 might be helpful in treating SBMA," Piccioni says. Shes planning more laboratory tests on the 21 chemicals to determine which ones appear safe enough and effective enough to be developed into drug treatments for SBMA.

Other Neuromuscular Diseases — DMD and SMA

Melissa Spencer, a molecular biologist at the University of California in Los Angeles, says that anti-apoptotic drugs might be useful against Duchenne muscular dystrophy (DMD), a muscle-wasting disease that almost exclusively affects boys.

In a 1995 study, Spencer found evidence for apoptosis in the muscles of mice with DMD. Later studies revealed that some muscle cells — but not many — appear to die by apoptosis in boys with the disease.

"A lot of people believe that theres apoptosis [in DMD], but that its not really important," Spencer says. "My philosophy is that we should design a large armamentarium of drugs that attack the disease at many different levels." Anti-apoptotic drugs, if they prove effective in mice with the disease, could be part of that armamentarium, she says.

Researchers disagree on whether apoptosis contributes to spinal muscular atrophy (SMA), a motor neuron disease that, in its most severe form, can cause respiratory failure within the first two years of life.

But Marie Hardwick, a molecular biologist at Johns Hopkins University in Baltimore, believes the disease causes neurons to die by some type of PCD, perhaps involving a set of protein-cutting enzymes (proteases) distinct from caspases.

"Im very excited about the possibility that protease inhibitors can be used [against SMA]," she says.

Great Expectations

In a few other diseases (besides ALS), anti-apoptotic drugs have entered clinical trials. Minocycline is being tested against Huntingtons disease. And memantine, a drug that interrupts events "upstream" of apoptosis, recently was found to slow the rate of mental decline in people with moderate to severe Alzheimers disease.

Meanwhile, drugs that promote apoptosis have taken center stage in clinical trials against cancer. This has some people wondering: Could taking anti-apoptotic drugs create a risk of cancer?

"In theory, this is a concern," Friedlander says. "But weve never seen it in any of the experimental models." Also, he says, theres no evidence of increased tumors in people whove taken minocycline for acne or arthritis.

Critics also question how effective anti-apoptotic drugs will be in the long run, arguing that the drugs might just help a dying cell limp along, without restoring its normal functions.

But Friedlander says that apoptosis itself destroys many cellular functions, so preventing it could help a cell remain functional. Theres also good evidence that apoptosis is contagious, he says, meaning that apoptotic cells may transmit "death" signals to other cells. So, stopping apoptosis in one cell might prevent its neighbors from starting the process.

Alary isnt sure whether this treatment strategy has worked for him.

"I didnt notice a lot of change [from taking minocycline]," he says. "But doctors gave me about three years, and Im starting into my fifth year [with ALS] now, so Im a little ahead of the curve."