“’Painting’ Keaton’s Tumor”
Jim Olson, MD, PhD
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.
This information is intended for additional research purposes only. It is not to be used as
a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional
interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or
accuracy of physician statements. Procedures or medicines apply to different people
and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Kristen Lidke Woodward
Communications & Marketing
Fred Hutchinson Cancer Research Center
(206) 667-5095
kwoodwar@fredhutch.org
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