New study looks at immunotherapy to treat common cancers
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HARI SREENIVASAN: There is important news in the fight against cancer. A study this week says scientists have devised a new approach that represents the blueprint for making immunotherapy available to treat common cancers and to target what is unique about each person’s cancer.
For more, we are joined from Washington by Dr. Steven Rosenberg. He is the chief of the surgery branch at the National Cancer Institute’s Center for Cancer Research and the senior author of the study.
Thanks so much for joining us. So, in this experiment, the interesting thing is that there’s not any sort of miracle drug, you’ve found a way to supercharge a patient’s own immune systems to fight a cancer. How did you do that?
STEVEN ROSENBERG: This is a way to take advantage of the patient’s own natural immune defense against the cancer. One of the major issues in all of cancer treatments is finding ways to attack the cancer without also attacking normal cells. Cancer becomes a cancer because a normal cell accumulates in its DNA a large number of mutations. That is, changes in the DNA sequence that results in new proteins.
In this paper, we’ve worked out a way to target the exact mutations that result from making a normal cell into a cancer cell. And so in that sense it’s a very highly specific and highly unique treatment that has to be developed for each individual patient.
HARI SREENIVASAN: So, you really did the DNA sequencing of this specific tumor?
STEVEN ROSENBERG: That’s right. So what one has to do in performing this new treatment is to sequence a patient’s cancer, identify all of the mutations, that is the differences from normal that exist in that patient’s DNA sequence, and then specifically target the individual mutations that have occurred among the three billions bases of DNA.
We could target the single base change that results in making that normal cell a cancer cell. And in doing that, we can actually affect the cancer without affecting normal tissues. Now it’s a very experimental technique. It has to be developed individually for each patient.
HARI SREENIVASAN: Right, so how long does that take if it’s something so specific to each patient?
STEVEN ROSENBERG: Well, from the time that we actually resect the cancer and can begin to do the sequencing, one can have a treatment ready in about five to six weeks. But it’s a very complex kind of treatment. And in this first patient in which we demonstrated that this kind of approach can work, it took about two months to develop the treatment for that individual patient. But it represents a blueprint for how to do this for other individuals as well.
HARI SREENIVASAN: All right, so you’ve only had one patient as you mentioned. So why is this so groundbreaking?
STEVEN ROSENBERG: Well, one of the major problems we have in cancer is the fact that although we can cure about half of all patients that develop cancer in 2014, half of the patients that develop cancer will ultimately die of that disease. We don’t have cures for most solid cancers once they’ve spread throughout the body. And when we apply treatments like surgery or radiation or chemotherapy, we often attack the cancer but can non-discriminitely affect normal tissues as well.
The unique aspect of this particular treatment that takes advantage of the exquisite specificity and sensitivity of the body’s own immune system is that we can target something that’s absolutely unique to the cancer, so that it has no impact at all on the patient’s normal tissues. Now this has been done in one patient, the patient that had 26 mutations inside their cancer. We were able to find the single one that we could target but since almost all cancers contain mutations as we continue to develop this, hopefully this kind of approach can be used to target the cancers that start in many different organs in the body.
HARI SREENIVASAN: So people are going to wonder that exact question. This is one specific cancer, one specific patient. How long til your research completes and this can be applied to other cancers and in a wider audience?
STEVEN ROSENBERG: Well, we have some immunotherapies today, like Interleuken-2 that can stimulate the body’s immune system against melanoma. We have other drugs that can stimulate the immune system against kidney cancer, but we have not had immune based treatments that can join surgery, radiation, and chemotherapy to attack the common cancers. Cancers that start in the colon and in the rectum and in the pancreas, the esophagus, the ovary, the prostate.
This particular approach can work indiscriminately regardless of where the cancer arose. And in this particular patient, the cancer arose in the bile ducts in the liver and it spread throughout the liver and into the lung. And so again, I want to emphasize it’s a highly experimental treatment. The paper and science that was just published a few days ago shows that you can successfully attack an individual mutation inside a cancer. And we’re now working around the clock to try to simplify this procedure, so that we can bring it to additional people.
HARI SREENIVASAN: All right, Dr. Steven Rosenberg, joining us from Washington. Thanks so much.
STEVEN ROSENBERG: You’re welcome.