IRA FLATOW, host:
For the rest of the hour, new work on cancer vaccines. This week at the meeting of the American Society of Clinical Oncology, researchers presented work on many cancer-related topics, but one of the hot fields this year was cancer vaccines and ways to stimulate the body's immune system to help battle cancer cells.
And joining me now is Douglas Schwartzentruber. He's the medical director at the Center for Cancer Care at Goshen Health System in Goshen, Indiana. And he presented the results of a study looking at a vaccine and a treatment of metastatic melanoma. He joins us by phone.
Welcome to SCIENCE FRIDAY.
Dr. DOUGLAS SCHWARTZENTRUBER (Medical Director, Center for Cancer Care at Goshen Health System): Thank you. I'm glad to be part of the show.
FLATOW: Tell us what is this vaccine like. Can you describe it for us?
Dr. SCHWARTZENTRUBER: Yes. This is a vaccine that is a portion of actual - an actual protein that is present on the surface of the melanoma cancer cells. And so, this fragment of a protein is injected into the thigh or into the body and it stimulates the immune system to develop a very specific response to the cancer.
FLATOW: Hmm. So you mean white blood cells start to attack the cancer?
Dr. SCHWARTZENTRUBER: That is the principle behind it is that white blood cells would be educated to recognize a cancer and it needs to be given along with another biologic agent called interleukin-2, which is a growth factor for these T lymphocytes, these white blood cells.
Dr. SCHWARTZENTRUBER: And so that they are grown in large quantities in the body now and then they can hopefully go in and find the cancers and attack them.
FLATOW: So you stimulate the body with one drug to make a lot of white cells and then you stimulate them to go attack.
Dr. SCHWARTZENTRUBER: Exactly.
FLATOW: And to find the cancer cells. And how efficient are they at this?
Dr. SCHWARTZENTRUBER: Well, at this point, they could be more efficient. The response rates, in other words the numbers of patients that have shrinkage of their cancers as a result of this treatment, is about 22 percent. You might say, wow, that's not a high number. However, that is double, with the vaccine, than if you just gave the one biologic agent alone, the interleukin-2 alone.
FLATOW: Mm-hmm. And so, you're - so this has passed the laboratory rat studies. And you're testing this on in people.
Dr. SCHWARTZENTRUBER: Exactly. This was a clinical trial with 185 patients. Half the patients received the one FDA-approved drug, called Interleukin-2. The other half received that same Interleukin-2 in conjunction with the vaccine, sort of testing that question, is there a role for a vaccine in melanoma?
FLATOW: Right. And melanoma is very deadly.
Dr. SCHWARTZENTRUBER: It can be. Once it has spread, even though it starts in the skin, it can spread to other parts of the body. And only about 10 percent of people live five years with metastatic or this widely disseminated melanoma.
FLATOW: Mm-hmm. How can you theoretically make it become more efficient instead of just getting a 22 percent? And you say that is double the normal rate. How can you make it more efficient at what it does?
Dr. SCHWARTZENTRUBER: That is the challenge for the next clinical trial. We are just beginning to understand the immune system. And in many ways, this particular study is a proof of principle. It's the first time now that we've seen a vaccine work for melanoma, and it's one of the first times in cancer in general where we've seen a benefit of a vaccine to treat an established cancer.
FLATOW: Mm-hmm. We normally think of vaccines as preventing a disease. You know, you get it in advance to protect you from a disease.
Dr. SCHWARTZENTRUBER: And that is what most of our infectious disease vaccines do. We give it in advance. We try to prevent an infection from developing. In cancer, we're treating established cancer, so it's a much taller order to ask of this vaccine. We're trying to get cancers that are already existing to go away, and we do this with an immune approach, similar to the immune approach that is utilized in some infectious a foreign agents.
FLATOW: Yeah. 1-800-989-8255. Talking about some recent work in developing a cancer vaccine against melanoma.
And this is different than, let's say, standard chemotherapy or cancer treatments where you try to use an external drug to kill the cancer cells themselves. Here, you're tweaking the immune system to do that for you.
Dr. SCHWARTZENTRUBER: You are correct. And so, a standard chemotherapy is a poison. Immune therapy, on the other hand, builds up the body's own immune defenses. The challenge is to get the body's immune system to recognize the cancer as being foreign, as not being part of the body. And once you can get the body to recognize a foreign invader, so to speak, then you can develop successful immunotherapies.
FLATOW: Well, is it simply a - now an engineering process of finding different - these protein markers on the cells with different cancers and then having those white blood cells attack them, too.
Dr. SCHWARTZENTRUBER: It's more complex than that. We've been…
Dr. SCHWARTZENTRUBER: …pretty good…
(Soundbite of laughter)
Dr. SCHWARTZENTRUBER: …at finding these…
Dr. SCHWARTZENTRUBER: …surface proteins on cancer cells. The challenge is how do we direct the immune system to actually recognize these cancer cells and then destroy them.
FLATOW: Mm-hmm. And did you find something different about the melanoma cells at work there?
Dr. SCHWARTZENTRUBER: We have found these proteins. Actually, these were found at least a decade ago. And it's taken that long to make this work in an actually clinical situation where it would produce a benefit to patients.
FLATOW: So you can't - you don't have something that can be readily applied to other kinds of cancer right now?
Dr. SCHWARTZENTRUBER: Not with this very specific.
Dr. SCHWARTZENTRUBER: This is specifically for melanoma. But the hope is that we can apply the scientific principles learned here to other cancers. And at this meeting that you described in Orlando, the ASCO meeting, there was evidence presented also about a lymphoma vaccine.
And so we're beginning to see that there may be other cancers that can be treated with vaccines that are very different within themselves.
FLATOW: Talking about cancer vaccines this hour on SCIENCE FRIDAY from NPR News. I'm Ira Flatow, talking with Dr. Douglas Schwartzentruber.
Of course, everybody is going to want to know now that they've heard about this: How soon can I get this treatment?
Dr. SCHWARTZENTRUBER: That is a good question. We - I don't have a good answer for you. What we do know is that we will try to make it available as soon as possible. We do need to do additional studies to prove indeed that patients live longer as a result of this vaccine.
We know it has a benefit. It shrinks cancers. We still don't know that patients actually live longer because of that.
FLATOW: Ray(ph) in Iowa, hi. Welcome to SCIENCE FRIDAY.
RAY (Caller): Thank you, Ira.
FLATOW: You're welcome.
RAY: See, my question is simply, do people get sick like this or - as compared to chemotherapy? Do they develop flu symptoms?
FLATOW: Side effects.
RAY: Do they get deathly sickly or…
RAY: …how does that work?
Dr. SCHWARTZENTRUBER: The vaccine itself has very, very few side effects. The interleukin-2, which is given in combination with this vaccine, that's have more side effects and - that can be easily managed - but it does cause, like you said, flu symptoms plus some additional ones.
FLATOW: Allan(ph) in Davenport, Iowa. Hi, Allan.
ALLAN (Caller): Yes. Hello. I am on the air, right?
FLATOW: Yes. Go ahead.
ALLAN: Okay. I was wondering, since I heard that the T cells are kind of encouraged to populate, or whatever the term was, does it have an effect, like, on rheumatoid arthritis or other such disease which the T cells go crazy and get to the joints? And I'll take my answer off the air. Thank you.
FLATOW: Okay. Good question.
Dr. SCHWARTZENTRUBER: Okay. The answer, at the present, is no, because these T cells, these lymphocytes, are educated very specifically to recognize the cancer cell only.
And at present, we only know that these proteins are present on the melanoma cells. They can be present on some normal skin pigment cells, but the side effects there are minimal.
FLATOW: Are we going to - just waiting to hear, because I - it's fascinating, how do you educate a T cell?
Dr. SCHWARTZENTRUBER: The process of the vaccination creates a very specific interaction, now, between a T lymphocyte as it recognizes a protein. So it's a very specific mechanism of the immune system to sort of supercharge this cell into becoming a killer cell, you might say.
The interleukin-2 then makes it grow into larger numbers so that you have a large population that can go throughout the body.
FLATOW: Mm-hmm. And I guess the question that we asked before is why -and the one that you said has taken you 10 years to figure out and for other cancers - is how to educate T cells to recognize the other ones, the other kinds of cancers.
Dr. SCHWARTZENTRUBER: Yeah. And again, those are some basic immuno-principles that we can make happen in the laboratory, and this is a first time now that we've been able to demonstrate…
Dr. SCHWARTZENTRUBER: …that we can actually do it on people.
FLATOW: Wow. And so where do you go from here?
Dr. SCHWARTZENTRUBER: The next studies will need to be designed. As we combined two treatments in this particular trial, we envision combining other pathways of the immune system. There are other mechanisms that can further activate a T cell. Hopefully, other mechanisms that can further weaken the cancer cell so that we can create a whole number of pathways that work together to achieve that common goal.
FLATOW: Mm-hmm. Is there a different level? Do you tweak yourself to another level of testing?
Dr. SCHWARTZENTRUBER: Certainly, we'd like to. You know, we've doubled responses with this trial. I think we need to double them again in the next one.
FLATOW: Mm-hmm. And include more people in the testing process?
Dr. SCHWARTZENTRUBER: Yes, more people would be included in the process.
FLATOW: Yeah. And so you'll try this out on another group of people. I'm sure people are going to be asking us, where do I go to get in on the study? Is there something that we can tell them?
Dr. SCHWARTZENTRUBER: At present, we're going to need to be patient, I think. I am in discussion with various agencies and sponsors so that we can bring another clinical study soon, and hopefully even have this vaccine available within a short period of time, even in a different kind of a study so that it could be processed very quickly.
FLATOW: Wow. Thank you very much, Doctor, for taking time to be with us.
Dr. SCHWARTZENTRUBER: Thank you.
FLATOW: Douglas Schwartzentruber is medical director of the Center for Cancer Care at Goshen Health Systems in Goshen, Indiana. And some very interesting and exciting news there.
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