BUFFALO, N.Y. (Ivanhoe Newswire) - It mainly targets boys, putting most in wheelchairs by the time they're twelve and it will most likely kill them in their twenties. Duchenne Muscular Dystrophy leaves families with few treatment options and little hope, but now an eight-legged creature could change that.
Most boys could climb these stairs in mere seconds, but for JB Harvey it takes a lot longer. JB has Duchenne Muscular Dystrophy, a disease that slowly destroys muscles people with it rarely make it to 30.
"If you don't stop and think about what we've been told his future is, he's a typical 5-year-old kid," Beth Harvey, JB's mom, told Ivanhoe.
JB's grandpa, Jeff Harvey, wants to change that future. An internet search led him to work being done by University at Buffalo researcher, Fred Sachs. He's exploring the effects of spider venom on muscles.
"One spider showed up with a compound that worked," Dr. Frederick Sachs, SUNY distinguished professor at the University at Buffalo, told Ivanhoe.
The Chilean Rose Tarantula's venom contains a protein that could slow muscle deterioration.
"I've talked to big pharma and the minute I said cell mechanics, their eyes closed, and they nodded out and that was the end of that," Dr. Sachs said.
So, the two formed their own company. Now they're developing a drug for DMD. So far, experiments show dystrophic mice given the drug had no toxic reactions, promising results that could make JB's future much brighter.
"I want to do anything I possibly can to try to make my grandson live as long as possible," Jeff Harvey told Ivanhoe.
"Before I retire, I'd like to see a boy get out of a wheelchair and walk away because of this," Dr. Frederick Sachs said.
Human trials for the drug could start within a year and a half. The therapy won't cure DMD, but if it works it could add years, maybe even decades to patients' lives.
BACKGROUND: Duchenne muscular dystrophy (DMD) is a vicious form of muscular dystrophy that occurs mostly in boys. It is caused by an alteration in a gene, called the DMD gene that can be inherited, but it also can occur in people who do not have a known family history of the condition. The condition causes progressive loss of muscles function and weakness that begins in the lower limbs. Boys with DMD do not make the dystrophin protein in their muscles. It affects approximately one in 3500 boys worldwide. (Source: www.genome.gov)
SYMPTOMS: When a child has DMD, symptoms normally appear before six years old and may appear as early as infancy. The first noticeable symptom is in motor milestones. For example, sitting and standing independently will be more of a challenge. The average age of walking in boys with DMD is 18 months. DMD attacks the leg and pelvic muscles, resulting in a waddle and difficulty climbing stairs. Calf muscles usually enlarge and the muscle tissue eventually is replaced with connective tissue and fat. When the leg muscles contract, the muscles become unusable because the muscle fibers are shortened and fibrosis occurs in connective tissue. Symptoms are usually prevalent in boys ages one to six. There is a steady decline in muscle strength from age's six to eleven. By age ten, patients may need braces to walk and in a wheelchair by 12. Few individuals with DMD live beyond 30. Cardiomyopathy and breathing complications are common causes of death for DMD patients. (Source:www.genome.gov)
TREATMENTS: Treatment is aimed at the symptoms of DMD. Assistive devices for respiratory complications can be needed at night. Aggressive management of dilated cardiomyopathy with anti-congestive medications are used with cardiac transplantation in more severe cases. Prednisone (a steroid shown to prolong the ability to walk by two to five years) is used to improve the function and strength of patients with DMD, but it can cause high blood pressure, weight gain, delayed growth, and behavior changes. Deflazacort is a synthetic version of prednisone used in Europe and is believed to have fewer side effects. Cyclosporine is another medication used in children, but is controversial because of cyclosporine-induced myopathy. Several therapies are under investigation, including PTC124, pentoxifylline, coenzyme Q10, glutamine, and oxandrolone. (Source: www.genome.gov)
NEW TECHNOLOGY: Another new therapy for DMD that's under clinical trials was discovered in the venom of a spider, the Chilean rose tarantula found in South America. The spider's venom was originally used to study the effect it had on important cellular structures (called mechanosensitive ion channels). These channels are small tunnels connecting the inside of a cell to the outside world. Normally the tunnels are closed, but when a cell is contorted or stretched the tunnels open and let calcium and other substances into the cell. This is similar to what happens in DMD. The defective genes are missing proteins that help muscles keep their shape. The cells then buckle, making the ion channels to open and calcium floods in, resulting in the body digesting muscles from the inside out. Researchers believe that if the channels could be closed then symptoms could be suppressed. This is where the spider comes in. A protein in the venom of the Chilean rose tarantula was discovered to keep the ion channels closed. Now researchers are testing the protein therapy in dystrophic mice. Earlier experiments show no toxic reactions while on the drug for 40 days. (Source: www.buffalo.edu)
Frederick Sachs, PhD, SUNY Distinguished Professor at the University at Buffalo, talks about a new possible therapy for Duchene Muscular Dystrophy.
What happens to people who have Duchene Muscular Dystrophy?
Dr. Sachs: Duchene dystrophy is a sex-linked genetic disorder that occurs mostly in boys. It is a disease of cell mechanics. The membrane of cells is rather fragile by itself, and to allow cells and their owners to play Monday night football, cells developed a protein fabric that lines the membrane and makes it tough. That protein is called dystrophin and the code for this protein is the largest gene in the human genome. It is the host to many mistakes in copying DNA. In other words, creating a break in the strand of the protein dystrophin means it can no longer hold tension and can't reinforce the membrane. In dystrophy, as you begin to rip the fabric the hammock lie lattice gets weaker and the membrane loses its reinforcement. That's what dystrophy is about. You lose the reinforcement and the stress that used to belong to the lattice. It is transferred to the cell membrane and that stress opens ion channels that leak calcium into the cell and causes degeneration.
What's the prognosis?
Dr. Sachs: Patients tend to be in a wheelchair by the time they're 12. I don't like having to say it, but Duchenne dystrophy boys tend to die around 25; usually due to heart problems and paralysis of the diaphragm.
How are the current treatments helping?
Dr. Sachs: The only treatment currently is to administer cortisone to suppress inflammation, but cortisone has many serious side effects. It reduces some of the inflammation due to the decaying muscle. The boys swell up. They get moon faces and exhibit other side effects. There is really is no current therapy for dystrophy.
Did you start researching the venom of a spider first?
Dr. Sachs: We didn't start looking for a cure for dystrophy. Back in the early 80s, we discovered that cells are mechanically sensitive. If you stress the cell membrane, there are protein pores in the membrane that open up and let calcium leak into the cell. These pores, known as ion channels, are like biological transistors. The bodies use them for many purposes and are responsible for nerve impulses and synapse function. Channels are enzymes with little pores found in the cell membrane. They can open and close their pores and let ions cross the membrane. The channels that create nerve impulses are voltage sensitive and they create waves of activity that can rapidly send data to and from your brain. Your nerves are biological prototypes from of our own hardware communication technology that uses distributed amplifiers to send the signal long distances. In the nerves, the channels keep amplifying the signal all the way from your toe to your brain. Mother Nature knows what she's doing.
Anyway, by accident we discovered mechanically sensitive ion channels. They let positive ions leak though the cell membrane. They are made of protein and contain pores, or channels the size of atoms, to carry the current. We discovered the mechanical channels in muscle, an organ you don't think of as sensory. In fact it's the prototype motor organ. So why does the muscle have a mechanical sense? We didn't know. The NIH (National Institutes of Health), was not too happy to give us money for discovering them in muscle because they too didn't know they were there (although the NIH has changed their mind and provide funding for this work). We spent a lot of time thinking about how we could explain what the channels do for muscle. Typically, if you find something in the lab whose biological function is unknown, you either try to turn it on or turn it off and see what happens to an animal. Well, we couldn't do that. There was no drug to turn them on or off and there was not a known drug that affects anything in this class of ion channels. There are many for other types of channels. For example, the drugs prescribed for cardiac arrhythmias act mostly on ion channels of the heart.
So what do you do if you don't have a drug? You can't go to a drug store and say, "I want a drug to work on this thing." While the big drug companies have libraries of chemical compounds that their chemists have made, you can't get them as an independent investigator. We didn't have a lot of money to have someone else make us a library. So we turned to nature's library, the venoms of animals. At that time I had thought of venoms as something possessed mostly by snakes and scorpions, but it turns out that lots of animals have venoms. For technical reasons we chose to look at the arachnids including centipedes, spiders, and scorpions. Our operational fantasy was that maybe one of these animals had a poison that would make their prey mechanically uncoordinated by interfering with the mechanical channels, and perhaps we could find such a compound. That idea turned out to be wrong, but we did succeed in a way. "In the fields of observation, chance favors only the prepared mind," Louis Pasteur. So we screened lots of venoms, from spiders to scorpions to centipedes. The venom from a spider, a tarantula often kept as a pet, contained a compound that worked.
To do the assay, you take a drop of venom, dilute it in salt water and put it on some cells and see what happens. We inhibited the mechanical sensitivity of cells with venom from the species of our pet tarantula, Rosie (I need to give credit to Dr. Thomas Suchyna, a cofounder of our company, who did all the screening). Along the way we learned that venoms consist of hundreds of different compounds, not one poisonous compound. So even though we had found good venom, we had to find out which of these hundreds of compounds was the active one. With a lot of work we isolated the active compound using chromatography.
Now we had a compound, but we didn't know what it was. It could have been an alkaloid, a protein, a fat, or a neurotransmitter; who knew? It turned out that it was a protein, a small protein, a peptide, about half as big as insulin. We started thinking, "Well, if it's a mechanical sensor, let's look at some mechanical activity that it could affect in muscle." So we started looking at dystrophic muscle. Boys with dystrophy obviously have a disease and that is connected to mechanics because the postural muscles start atrophying. Maybe our mechanical channel is activated as a consequence of dystrophin breakup and that is what is messing up the boys. We started looking in the microscope at muscle cells from mice that had dystrophy and the peptide worked to suppress calcium leakage! We now had a possible drug. When we put our peptide, called GsMTx4, on a stretched cell, the calcium uptake was blocked! We might have a real drug. In order to get it to the clinic, we would have to test it on animals. I went to talk to big pharma, but biomechanics doesn't sell well with big pharma. The minute I said cell mechanics, their eyes closed and they nodded out, and that was the end of that. After a while, I gave up. It just wasn't worth trying, but when Jeff came along things changed.
One of the things that happens in normal muscle, but is particularly pronounced in dystrophic muscle, is that if you stretch them, calcium goes in. That calcium ends up turning on enzymes in the muscle that dissolve it and this atrophy is what you see in human dystrophy. Your intuition might say, well, if the muscles are getting weak then you should do some exercise. That, however, is a bad idea for boys with dystrophy. It makes the disease worse. Stretching contracted muscle, as what happens when you go down stairs, the calcium uptake is greatly increased. Parents of dystrophic boys are often advised to move into ranch houses that doesn't have stairs. You don't want the boys going up and down stairs; you want to minimize the stress on their muscles. Dystrophy in mice is interesting because you can't tell by looking at the mice behavior that they have dystrophy. They are almost normal in their behavior. This is a reminder that mice are not human. I don't understand how people found this mutant mouse in the first place. The mice are weaker than normal mice and they have less endurance but you won't see that unless you exercise the animals. Nonetheless, the dystrophic mice are the standard that's used as an assay for drugs for dystrophy. We did the experiments of injecting GsMTx4 into mice and seeing what happened. The good news is that not much happened. Despite coming from venom it was completely non- toxic. The bad news is that it didn't have a clear effect on making dystrophic animals less dystrophic in behavior. However, that result is a consequence of the fact that dystrophic mice behave almost the same as non-dystrophic mice so there is not much to measure. If you exercise the mice, , you begin to see the differences and that is what we are doing now.
When did you start the clinical applications?
Dr. Sachs: It must have been 8 or 10 years ago. Our molecule, GsMTx4, is a small protein. At the time Big Pharma was not interested in biologics. They have softened a lot since then. As with all basic science, when you try to apply it, you have a lot to learn. Along the way, we're had to figure out how does this protein work to protect muscle? Most drugs work via a lock and key arrangement. You have a drug receptor and a drug comes floating along and slips into the receptor and does something useful. For this to work, the drug has to have a good fit to the lock (the receptor). You can think of putting on a glove. The right glove fits snugly onto the right hand. So it's likely to behave like a specific drug. If you tried to put you left hand in, it wouldn't work. So your right glove is a right hand receptor. This kind of drug interaction is true of most drugs. If you make the drug in its mirror image, it doesn't work the same. We tested the micro image of our drug on the mechanical channels.
All the proteins in your body are known as L-type (left type) amino acids. So Phil Gottlieb in the lab synthesized the right handed version and we tested it. We had a lottery in the lab on the outcome. Surprisingly, both the right and left handed versions worked equally well! How could that be? That will happen if the receptor is pretty loose, like a mitten that can fit on the right or left hand. The right and left handed drugs equally blocked the calcium uptake. Thus, GsMTx4 acts via long range interactions. In a strange sense, GsMTx4 is a bit like a patent medicine that works on everything; it doesn't matter exactly what kind of dystrophy you have. GsMTx4 treats the symptoms not the origin of the disease; it is a therapy not a cure. It doesn't matter where the genetic defect is in the gene that codes for dystrophin, just that the mutation made the dystrophin lattice weak. There are many mutations that produce muscular dystrophy. Dystrophin is coded by the biggest gene in our body. It's the easiest place to make a genetic mistake. Any mutation that breaks the dystrophin chain will destroy its function. The drug that acts on the expression of the disease should work regardless of where the genetic defect occurred. We're treating what we call the phenotype, the expression of the disease, not the cause of the disease.
What did your results show with the mice?
Dr. Sachs: The laboratory experiments show that it really has potential to be a useful therapy for muscular dystrophy. As a therapy, we anticipate that boys would end up taking it for the rest of their life. However, you know that dystrophic boys' muscles can grow; the muscles of a six year old are bigger than a baby's. Since the muscles can grow, all we have to do is slow the atrophy and they can keep up with the growing boys. If GsMTx4 can slow muscle loss, the muscle may actually grow! We anticipate that GsMTx4 (Gs is the Latin abbreviation for the spider: Grammostola Spatulata) that it could be combined with other drugs that are treating other symptoms of the disease without interfering with each other. Our drug doesn't work on any of the other targets that other labs are developing so it shouldn't interfere with their action. None of these other drugs are yet approved. With the mice we learned that GsMTx4 is not toxic, and it doesn't affect the heart, human or ferret. This points out how little we know about many of nature's compounds; although it was originally found in venom, GsMTx4 is not toxic. We are in the middle of a big efficacy test on exercised mice and will know soon how well it serves to alleviate the symptoms of dystrophy.
You got the venom from this tarantula, but you now manufacture it on your own?
Dr. Sachs: Yes. Almost 10 years ago we learned how to synthesize it chemically so we can get kg quantities. The spider provided the library that allowed us to go screening for the active component but the venoms contain hundreds of compounds, the function of nearly all of which are unknown. When we identified the active compound and solved the structure, we realized that we could make it chemically and that's what we do now. The right handed D form of GsMTx4 could not be made naturally in any case! Creating this drug is a perfect example of the way basic science leads to clinical breakthroughs. No one in their right mind would have proposed to look at spider spit as a cure for muscular dystrophy. We didn't do it with that in mind, but our success in finding it is serendipity. Trying to understand the basic biology is what led us there. That is why the best drugs, like penicillin, come out of basic research and not out of the current trendy name of "translational medicine." Drug companies are good at applying research to clinical applications, but they do not do basic research. That is best left to the government and philanthropies. Translational medicine of the best sort comes from basic research. To quote Pasteur, "I beseech you to take interest in these sacred domains so expressively called laboratories. Ask that there be more and that they be adorned for these are the temples of the future, wealth and well-being. It is here that humanity will grow, strengthen and improve. Here, humanity will learn to read progress and individual harmony in the works of nature, while humanity's own works are all too often those of barbarism, fanaticism and destruction."
What do you hope from this drug?
Dr. Sachs: We know GsMTx4 is non-toxic. We tried to kill animals, mice, and rats with an overdose and failed. It's really non-toxic. We've administered it to animals for a month and nothing bad happened. From our current toxicity data I would feel no qualms about trying it on humans. We are now engaged in a project to detail the therapeutic effect on dystrophy. Dystrophic mice and normal mice are not much different unless they are under physical stress. If you want to look for drug effects on dystrophy, you need to look at exercised animals. We're now engaged in collaboration with friends at the University of Maryland to test the drug on exercised animals. Once we have demonstrated convincing efficacy, it should only take about a year and a half to get it approved by the FDA for clinical use. The FDA has already approved GsMTx4 as an orphan drug, and that reduces the preclinical requirements for drug testing.
What do you hope happens?
Dr. Sachs: I'm hoping that before I retire, I will see a boy rise from wheelchair and walk away. That would make me feel good about retiring.
What kind of role has Jeff Harvey played in getting you to where you are now with this research?
Dr. Sachs: Jeff is the energy source for the clinical application of GsMTx4. I had tried to get Big Pharma interested but they only got me discouraged and I gave up and returned to basic research. I figured that someday, somebody will call us and say, "How about applying your work to disease?" Then Jeff showed up and asked that question. Jeff had experience working with biotech start-ups and was not afraid of trying. We got to talking and decided that we'll make a little company that would be a focus for people who wanted to contribute or invest money, the philanthropies, venture capitalists, and so on, or selling out to Big Pharma if they like our approach. So we formed Tonus Therapeutics, a biotech start-up (tonus means force in Greek). Jeff provided the drive and they came from his general and personal interests in the problem. Without Jeff, this approach would never have happened.
It really is the perfect storm?
Dr. Sachs: It is the perfect storm. What are the odds of the two groups meeting up in the same town, not far from each other, with a common goal in mind? Jeff was poking about the Web looking for things about dystrophy that might help his grandson JB. By chance he stumbled on our web site and as it turned out we were both in Buffalo and had a common interest in muscular dystrophy. We got together and that's where we are now. Buffalo is at the core of the work on mechanosensitive channels since we discovered them here, discovered the only known inhibitor, and applied the inhibitor to disease here in Buffalo.
How far away is a clinical trial?
Dr. Sachs: This is not a drug development project because the drug is in hand. We're not hunting for a drug, but merely testing what we have to meet for FDA standards. GsMTx4 is the only drug of its kind in the world and we should be able to apply it! Since all cells are mechanically sensitive, we hope to apply what we have learned in treating dystrophy to treating other diseases. For example, we showed that it is 100% effective in inhibiting atrial fibrillation (that affects over 2 million Americans). It can work on sickle cell anemia and possibly xenocytosis (genetic diseases of red blood cells). It might also work on incontinence and kidney failure, which occurs in most diabetic patients.
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