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….

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.

The original press release about this study is here. A brief bio of Dr. Rosenberg is here. He’s been working on this for 30 years.

The diligence and strength of character required for a lifetime of medical research is often confounding. Credit where credit is due — to the good doctor.