‘Painting' Keaton's Tumor
SEATTLE, Wash. (Ivanhoe Newswire) - They don't call it "brain surgery" for nothing. Removing a tumor from the brain is one of the most challenging operations a surgeon can perform. Typically, they rely on MRI images to guide them to the right spot, but now there's a new way to light up cancer.
Keaton Wrenn reads at a fifth grade level, but his mom Lisa says this third grader's movements aren't as developed as most kids his age.
"His walking was always pretty really wobbly," Lisa Owen Wrenn, Keaton's mom, told Ivanhoe.
When Keaton was just 16 months, doctors found a golf ball sized tumor in his brain. Oncologist Jim Olson says removing a tumor like Keaton's is tricky because normal tissue looks just like cancerous tissue.
"You can end up leaving big chunks of cancer behind," Jim Olson, MD, PhD, Oncologist, Fred Hutchinson Cancer Research Center, told Ivanhoe.
Olson developed a tumor paint to help surgeons see cancer while they operate. The paint is made from reengineered scorpion venom. It's injected into the bloodstream a day before surgery. Surgeons use a special instrument to see the paint in real-time.
"It brings a light molecule to the cancer, so the cancer cells light up," Dr. Olson explained.
The tumor paint has been used in mice and dogs and is a thousand times more sensitive than MRI scans.
Lisa said the research is exciting. Keaton had the traditional surgery, and today is cancer free.
"He's been through so much, and he just takes it all in stride," Lisa said.
In the preclinical trials, the tumor paint also lit up prostate, colon, and breast cancers. Doctors say it may also be used to detect various forms of skin cancer. Olson says he expects human trials to begin in early 2014.
BACKGROUND: Brain tumors are defined as masses of cells that grow in the brain tissue or in systems around the brain. Some brain tumors are malignant, meaning they are cancerous and contain cancer cells, while others are benign, meaning they are noncancerous. Procedures for removing brain tumors are some of the most complicated forms of surgery. This is because cancer cells may be left behind and can go unnoticed. Treatment options vary depending on the size and location of the tumor. (Source: http://www.mayoclinic.com/health/brain-tumor/DS00281)
SYMPTOMS: Each patient is different, but symptoms can include:
- Speech difficulties
- Behavior changes
- Pattern of headaches
- Issues hearing
- Severe headaches
- Problems with balance
- Nausea or vomiting
- Vision problems
- Loss of sensation in an arm or leg. (Source: http://www.mayoclinic.com/health/brain-tumor/DS00281/DSECTION=symptoms)
TYPES OF BRAIN TUMORS: Primary brain tumors are tumors that derive in the brain or tissue surrounding it. Other places where tumors may form are in cranial nerves, brain-covering membranes, the pineal gland, or pituitary gland. These tumors develop when abnormal cells build up in the brain, creating a large mass. Secondary tumors are ones that are formed elsewhere in the body, and then spread to the brain. Secondary (metastatic) brain tumors are much more common than primary tumors. Common cancer types that may eventually spread to the brain are colon cancer, melanoma, kidney cancer, breast cancer, and lung cancer. (Source:http://www.mayoclinic.com/health/brain-tumor/DS00281/DSECTION=causes)
TUMOR PAINT: A new method for removing brain tumors has emerged. Dr. Olson is using scorpion venom to highlight cancer cells in the brain. To remove the brain tumors, doctors will first scan the brain in an MRI to find the exact location and size of the tumor. Once a patient has decided on surgery, they are then injected with the scorpion venom a day before the procedure. The paint consists of chlorotoxin, which is a protein that attaches to chloride channels on cell surfaces. The second component of the tumor paint is a dye that lights up once a light is projected upon it. (Source: http://www.npr.org/blogs/health/2013/09/12/221060071/why-painting-tumors-could-make-brain-surgeons-better)
Jim Olson, MD, PhD, Oncologist at Fred Hutchinson Cancer Research Center, talks about a new way to treat tumors.
Brain tumors are very hard to treat. Why is that?
Dr. Olsen: That's true for a number of reasons. One is because you can't take out a big chunk of normal tissue around the brain. There's important tissue around the tumor, so surgery is limited because you can't get all that microscopic disease.
What happens if you don't get it all?
Dr. Olsen: If you don't get it all, then you depend on radiation or chemotherapy. Radiation is difficult because the level it would take to kill the cancer cells is often a level that would also kill normal brain cells. So, damaging the normal brain with radiation is no better than with surgery. Finally, chemotherapy in some cases can be effective; however, the fact is that most chemotherapy agents don't get across the blood brain barrier. The brain has a protection that keeps drugs from getting in that protects us from toxins in our environment, but it also keeps our therapies from being as effective as we would like them to be.
I heard that you can hardly tell the difference you're just eyeballing it, is that correct?
Dr. Olsen: Absolutely. When you're in surgery sometimes it's very clear where the cancer is and where the normal brain tissue is, but other times you really can't tell the difference.
So, how are you right now trying to figure that out without the new paint?
Dr. Olsen: Well, the current way that surgeons do it is with their eyes and with their hands. They have intra-operative recording devices that tell them if something has brain waves. So, if they see brain waves, they can be concerned that they might be getting in to normal brain tissue. However, the problem is that sometimes you can get those brain waves even out of tumor tissue or its mixed and so you can end up leaving big chunks of cancer behind. It's really a problem that there are many patients who have surgery that have big amounts of cancer left behind because the surgeons can't tell whether it's normal brain or cancer and they don't want to hurt the patient.
Does brain cancer come back very quickly if you don't get it all out?
Dr. Olsen: There are many kinds of brain cancer, but for some of them that is absolutely true.
So, you've created something that helps doctors see in the operating room, correct?
Dr. Olsen: Our team has developed a molecule called tumor paint. This is a scorpion drive peptide, a little mini protein that acts by targeting a light molecule and it brings it to the cancer so that the cancers light up and we can distinguish the tumor from normal brain.
You are using scorpions to help treat brain cancer?
Dr. Olsen: That's right. We actually don't use scorpions. I've never touched a scorpion or have one in the lab. We use the DNA sequence from a scorpion to make a little mini protein that finds cancer cells, but not normal cells in the body.
Why does that work from scorpions and not from tarantulas?
Dr. Olsen: It might work from tarantulas. Good question, we'll probably get to that one fairly soon here. In this case it was a tail of misadventures where we started looking at this for reasons that were later proven to be scientifically false. Even so, we got on this pathway and we learned that it found the cancer cells, but not normal brain cells and it works. At that point you have to say how important it is to know exactly the reason why. I actually think it's fairly important so we're going back and understanding that now, but all the reasons we started doing this research now have been disproven.
And how does it work? How do you put it in to the brain; do you do it beforehand?
Dr. Olsen: We inject it in to the bloodstream just through an IV.
Is that before surgery?
Dr. Olsen: Usually a day before surgery. It's important to note that at the time of this interview we're not yet in human clinical trials. We're just finished a study in dogs that have cancer whose families brought them in for care. In that case we inject the drug the day before surgery and then the following day while the surgeons are operating use an instrument that can distinguish and see this light and put it up on the computer screen that the surgeon uses as a guide for operating.
When do you have to take this to human trial?
Dr. Olsen: The goal of starting human clinical trials would be at the end of 2013 and so far we're on track for doing that.
What does the color look like?
Dr. Olsen: It is a beautiful bright green in most cases, depending on the instrument.
How small can it go?
Dr. Olsen: In some of our mouse studies we've found as few as two hundred cancer cells traveling from one lymph node to the other.
Which is very small, right?
Dr. Olsen: That's very tiny. It is a hundred thousand times more sensitive than MRI scans and surgeons get to see it in real time.
Is there any danger to it?
Dr. Olsen: We will find that out in the first human clinical trials. We think that the risk of danger is low because this peptide, this mini protein, has already been used in humans without side effects. And also the other part of the molecule, the molecular flashlight has been used in humans very safely for over fifty years. So, we're hoping that it's very safe and very effective.
So it could give surgeons a better roadmap when they have to go in?
Dr. Olsen: Yes, that's the goal.
I would think that children are even harder?
Dr. Olsen: I think that the problem is equally difficult in kids as in adults. I think that there are some pediatric brain cancers where it's very clearly shown that if you get a good resection surgically that you can increase a child's likelihood of survival by as much as 50 percent. If we ever get to the point where we can reduce radiation or chemotherapy because we've gotten better resections that would be terrific.
Could this replace a biopsy?
Dr. Olsen: So, whether or not we would ever use tumor paint for screening would really depend on how safe it is for our cancer patients. If we find that its super safe and we're able to use it in hundreds of thousands of patients without side effects, then we could potentially use it for detecting skin cancer or colon cancer in the future.
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Fred Hutchinson Cancer Research Center