Can Viruses Be Used To Fight Cancer?
IRA FLATOW, host:
This is SCIENCE FRIDAY. Im Ira Flatow.
Intriguing news this week about potential new treatments for cancer. Surgery, radiation, chemotherapy - you know, these are the three main weapons in our small arsenal for our war on cancer.
Well, this week comes word that viruses, agents that normally make us sick, might even cause cancer, they might be enlisted to fight pancreatic cancer. And also news that heat treatments might be helpful in combating breast cancer tumors.
Of course, these are things that are all in the research phase or early testing phases. And here to talk about them is Dr. Otis Brawley, chief medical officer for the American Cancer Society. Welcome to SCIENCE FRIDAY, Dr. Brawley.
Dr. OTIS BRAWLEY (American Cancer Society): Thank you, thank you, good afternoon.
FLATOW: Good afternoon. This thing about viruses, this is a really interesting idea, the oncolytic viruses. Tell us about that in cancer.
Dr. BRAWLEY: Yeah, these are naturally occurring viruses, and what some scientists have done is they've isolated these viruses. They have changed them a little bit genetically, and then they took the viruses and mixed them with pancreas cancer cells in a Petri dish and found that the viruses infected the pancreas cancer cells and ultimately killed the pancreas cancer cells.
So this is very early, but this is exciting. This is a different way of killing cancer than radiation or chemotherapy.
FLATOW: As you say, this was done in a Petri dish and not in people at this point.
Dr. BRAWLEY: That's right. If this sort of thing works out, it's going to take perhaps five or 10 good years of solid work before we're going to see this translate into a treatment in humans.
FLATOW: Is it potentially useful in other kinds of tumors?
Dr. BRAWLEY: You know, it could be. And we are already manipulating the immune system in other cancers. For example, there's a drug, the trade name is Provenge, that's used to treat prostate cancer, metastatic prostate cancer. And it is a way of manipulating the immune system such that the person's own immune system attacks the cancer.
FLATOW: And this virus that we were talking about in this case, this went after the cancer stem cells. These are not your normal cells. These are stem cells.
Dr. BRAWLEY: That's right. That's right. Now, cancer stem cells are the things that actually cause, in pancreas cancer, actually cause the actual cancer cells to be grown. And you know, stem cells exist in a number of different cancers. And this was attacking the actual root cause of the pancreas cancer.
FLATOW: And would only cancers that are forms of lumps - I mean those kinds of cancers - would they be the only ones, candidates for use in these kind of stem cells?
Dr. BRAWLEY: Well, perhaps not. You know, it's conceivable that we may have a virus for pancreas cancer. We might have a virus to treat lymphoma or a virus to treat certain types of leukemias or myelomas. You know, the sky is the limit here.
The most important thing is this is good science, it's been well-designed, and we need to support it so that we can develop it in the further treatments.
FLATOW: It's interesting because it does seem to me, as you say, to be a whole different method of attacking cancer. We've tried so many different things.
Dr. BRAWLEY: Oh, it's totally different. It is totally different. In the past we've used chemotherapies that would hopefully get into the cancer and kill it. In some cancers that's actually very successful. In other cancers it helps, or it delays death.
And then we've used radiation to try to kill cancers, and it works very well in certain cancers, and when you have metastatic disease, unfortunately it does not. This is a totally different way of treating cancer.
FLATOW: I just wanted to say that this was presented at a meeting, Digestive Disease Week. So this has...
Dr. BRAWLEY: That's right, that's right. It was presented as an abstract at a meeting in Chicago.
FLATOW: And now the other study that caught our eye this week looked at using heat as a way to kill tumors, sort of hyperthermia.
Dr. BRAWLEY: Yeah. Now, hyperthermia is something that we've used in the past, but this is a very new use of it. Again, this is done in the laboratory, in Petri dishes and then ultimately in laboratory animals.
We have a drug called the PARP inhibitor. Actually, there are several PARP inhibitors now that are very effective, it seems, in treating breast cancers that are caused by what's called a BRCA mutation, a BRACA1 or BRACA2 mutation.
What they've done with heat is, in people who don't have that BRACA mutation, they have stopped BRACA from working and made the drugs, made the tumor, rather, sensitive to the PARP inhibitor. So again, this is good early science.
We may some day, in the next several years, find that we're going to putting something on a woman's breast to heat it up several times a day while we give her these drugs.
FLATOW: How hot are we talking about here?
Dr. BRAWLEY: It was actually up to 42 degrees Celsius, which is only about eight - or eight to 10 Fahrenheit degrees higher than one's normal body temperature.
FLATOW: Wow, so just to repeat what you said, just adding a little bit of heat sort of worked, did the trick?
Dr. BRAWLEY: Adding a little bit of heat in the laboratory seemed to make these drugs work much better.
FLATOW: And of course once again we stress this is only a laboratory, and we're talking about testing it out, which could take years for this to happen.
Dr. BRAWLEY: Yeah, something like this may actually come to the clinic in just a couple of years. This will be a little faster than giving viruses to people.
FLATOW: Isn't there a form of heat used to treat tumors already that uses radio frequencies, radio...
Dr. BRAWLEY: Yes, yes. Radio frequency ablation is commonly used. That's an instrument that sometimes looks very much like an ultrasound unit that someone might hold in their hand. Or it can look more like an X-ray machine and give off radio frequency waves very similar to a microwave.
And we aim those at people's tumors that might be in their liver, at a place where the surgeon's unable to remove it, or a tumor that's metastasized or spread to bone, and it would be very difficult to remove it, but the tumor is causing a lot of pain. We can aim the radio frequency apparatus at that tumor and actually ablate the tumor.
FLATOW: 1-800-989-8255, talking with Dr. Otis Brawley. One of the challenges is - in cancer treatment, is trying to decide which kinds of tumors are most likely to spread so that some people could be spared from chemotherapy. Are we moving any further ahead in that?
Dr. BRAWLEY: Absolutely. The best progress we've made is in breast cancer. We absolutely need a test in prostate cancer, where we think more than half of all men with localized prostate cancer don't need to be treated, but we don't know who those men are.
But in breast cancer we've got a wonderful test that allows us to look at 21 different genes, look at are the genes turned on, turned off, are they over-expressed. And then we get a mathematical formula for those answers.
And it tells us: This woman has a localized breast cancer that's unlikely to have spread to the rest of her body. Therefore we can treat her conservatively. Or this woman has a breast cancer that appears localized but very likely has small metastases spread elsewhere in her body and needs to be treated much more aggressively.
FLATOW: Let's see if we can get a quick phone call in before our time runs out. Alan(ph) in Fairfield, Iowa. Hi, Alan.
ALAN (Caller): Yes, hello. I am a cancer survivor, and my question to you relates to the relationship between toxicity and cancer. Many chemicals are known carcinogens. So obviously cancer is, to some extent, a response to toxicity.
And I'm wondering if it doesn't make sense to reduce the toxic load in the body with something like (unintelligible) or other ways of pulling toxins out of the body in order to make it possible to treat cancers less aggressively, as you were just talking about with breast cancer.
FLATOW: Okay, thanks for that call.
Dr. BRAWLEY: Well, I wouldn't say with treatment, but I will tell you that there's a lot of people who look at things that might reduce toxins as a possible preventative for cancer.
When we look at things like - there's been studies looking at selenium and Vitamin E, Vitamin D and other things, these things actually decrease some toxins and decrease some things that we know cause cancer and may be - may be is the key word here - effective at preventing cancer.
FLATOW: So you seem optimistic then, that progress is being made?
Dr. BRAWLEY: Well, you know, when you look at - progress is definitely being made. As a matter of fact, mortality has decreased by 17 percent, from 1991 to 2007, which is the last year that we have data.
That means that an American is 17 percent less likely to die from cancer in 2007 than an American would be likely to die of cancer in 1991. So there has been some improvement and decrease in mortality.
The improvements are especially true in some of the smoking-related cancers in terms of prevention. But we're also getting much better at treating things like breast cancer, colon cancer, a few others.
FLATOW: Well, one quick question from Michelle(ph) in Buffalo, New York. Hi, Michelle.
MICHELLE (Caller): Hi.
FLATOW: Hi there.
MICHELLE: My question has to do with when - if you use a virus, and it's going to be attacking this tumor, how do you prevent it from attacking any other parts of the body? And is there - you know, once it's done with the tumor, is the lifespan of the virus over?
FLATOW: Good question.
Dr. BRAWLEY: Well, that's the stuff that's got to be worked out over the next five to 10 years. That's one of the reasons why I said this is not ready to be put into humans.
This was very effective in killing pancreas cancer in a Petri dish in a laboratory, and those questions need to be addressed before we can even say it's safe to try it in humans.
FLATOW: Would the virus still be effective, in case you want to scavenge other pancreatic cells and stay in the body?
Dr. BRAWLEY: Possibly. You know, there are - we already know that there are certain viruses that like to attack only certain organs. For example, Hepatitis B attacks the liver. What we need is a virus that's only interested in attacking the target that we want to destroy and not interested in attacking other things.
FLATOW: And of course if it's a stem cell, then that - you want to get all the stem cells because they could then become other pancreatic...
Dr. BRAWLEY: That's right.
Dr. BRAWLEY: That's right. And remember, this virus is actually specific to stem cells and not even to all pancreas cells.
FLATOW: And so you want to wipe out all those pancreatic stem cells.
Dr. BRAWLEY: Yeah, the only way I'm going to be able to cure a patient is to get rid of all the cancer.
FLATOW: And that's why it takes so long to test it out.
Dr. BRAWLEY: Yeah, got to be safe on this one. She's absolutely correct.
FLATOW: All right, and we thank you for taking time to be with us today, Dr. Brawley.
Dr. BRAWLEY: Oh, it's my pleasure.
FLATOW: Have a good weekend.
Dr. BRAWLEY: You too.
FLATOW: Otis Brawley is the chief medical officer for the American Cancer Society.
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