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(CNN) -- Researchers from the National Institutes of Health are fighting cancer by using the immune system to attack tumors. This new approach has had limited success so far, but experts say there is much promise for the future.
CNN anchor John King and medical correspondent Dr. Sanjay Gupta discussed the new method Thursday with researcher Dr. Steven Rosenberg from the National Cancer Institute in Bethesda, Maryland.
KING: According to the report, it worked on two patients, didn't work on 15 others. Is there something different about the 15 that it didn't work on? Or maybe better put, is there something in the two it did work on that leads you to the next development?
ROSENBERG: It's important to emphasize this is a highly experimental treatment that's still in the course of development. Of course, all of the patients that we treated in this report in [the journal] Science were treated two years ago. We waited to publish it to see if, in fact, the tumors that disappeared would stay away, and they have.
We've used viruses to introduce new genes into cells to make them into cancer-fighting cells, and we can do it much better two years later. So, my hope is, as we continue to improve this technology, the response rates are going to go up. ...
GUPTA: Do you think this is something that can be used for other cancers ultimately, as well?
ROSENBERG: The critical finding here was the ability to take a normal lymphocyte out of the blood of a patient -- these are the immune fighting cells, they're white blood cells -- and convert a normal cell that could not recognize the cancer, and by genetic engineering techniques convert it into a cell that could recognize the cancer.
Now in this paper we published in Science, we showed that we could insert genes that could make these normal lymphocytes recognize melanoma, and when we gave them to patients, they could in some patients cause those tumors to regress.
We have now found viruses that can introduce molecules into normal lymphocytes that can convert those cells into cells that can recognize breast cancer, colon cancer, other kinds of common cancers. But we haven't yet begun to treat those patients. Those are clinical trials that we hope to start in the next several months. ...
KING: If there's somebody watching right now who has cancer, or a family member who has cancer, and they want to take part in those trials or they want to see if there's any experimental treatment available for them, what's the answer?
ROSENBERG: I would emphasize that these are very early studies. This is a highly experimental treatment only available now here at the clinical center for the National Cancer Institute.
When we do begin treating patients with other kinds of cancers it will be in small numbers of patients that will be studied very intensively so we can learn how to improve it. But we'll only be treating a small number of patients, and those trials won't begin for many months.
KING: You're in a difficult position, I assume. You're optimistic. You think you're on to something, but you don't want to raise hopes up too much. How difficult is that as a challenge? And what would you say to someone out there who's saying right now am I a year away, maybe, from there being a cure?
ROSENBERG: Cancer patients deserve optimistic doctors. And I'm optimistic. This is an example of how basic scientific research is being translated into findings that can help cancer patients. And it emphasizes how important modern research is in molecular biology.
I think as we continue to learn about the processes that are involved in gene insertion into cells and how they function, we're going to improve this whole area of gene therapy quite dramatically. I believe this is just a start.
It's a treatment very much in the infancy of its development. And I'm quite optimistic we're going to be able to improve upon it in our studies here at the NCI, but by other investigators around the world, as well.
GUPTA: And this Mark Origer [one of the patients in whom the treatment succeeded], is he cured now, Dr. Rosenberg?
ROSENBERG: We treated Mark in December of 2004. So he's been a little over a year-and-a-half disease-free. We're going to continue to follow him. It's very hard to talk about cure, since we've only begun these treatments almost two years ago. And so we're going to have to follow Mark very carefully. We see him every three months, and we'll continue to do that for the next five years.
GUPTA: This has been 30 years of Dr. Rosenberg's work. He told me that 30 years ago he met a patient that sort of gave him this idea, and a lot of that's culminated today. So congratulations, as well, Dr. Rosenberg.
ROSENBERG: Thank you.
KING: Do you need more money, more support, more help? Or do you have everything you need right now to see how far you can take this?
ROSENBERG: We're working around the clock to try to improve this. I'm just one member of a big team that's involved in performing these studies here at the National Cancer Institute. We're working as hard as we can. We have the resources we need here at the NCI to perform the work we need to do.
Dr. Steven Rosenberg says "Cancer patients deserve optimistic doctors."