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    What's Next for Gene Therapy to Treat Cancer

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    By Matt Smith
    WebMD Health News

    The FDA’s approval of a treatment that uses genetically modified immune cells to fight a type of childhood leukemia has opened the door to a new way of fighting cancer. The treatment, known as CAR T-cell therapy, is approved for children with acute lymphoblastic leukemia, the most common type of childhood leukemia.

    To find out more about the significance of this decision and its implications for future treatments, WebMD talked to two doctors involved in immunotherapy research: Yi Lin, MD, who treats blood cancers at the Mayo Clinic and has led several trials of a similar process; and Stephan Grupp, MD, a pediatric oncologist at the Children’s Hospital of Philadelphia. Grupp developed the first pediatric trial of the newly approved therapy and treated the first patient to receive it, Emily Whitehead.

    WebMD: What does this decision mean for cancer research?

    Lin: It’s a new way to treat cancer. As opposed to looking at drugs that stimulate the immune system, this is a way of genetically manipulating someone’s own immune cells and giving that whole product back as a way to fight blood cancer.

    WebMD: How does this treatment differ from previous attempts to harness the immune system to fight cancer?

    Grupp: It absolutely is a kind of immunotherapy, because we’re harnessing the immune system to fight cancer. But it’s a new way to do it because we’re using these genetically reprogrammed cells. This particular treatment is really the first engineered cell therapy that’s been successful against cancer.

    WebMD: What kind of follow-up care is required after this treatment?

    Grupp: In the immediate two weeks post-therapy, they need intensive follow-up. We need them in the area of the hospital that gave them the cells. There’s a pretty good chance they’ll be admitted to hospital for a fever, because any cancer patient with a low white-cell count and a fever gets admitted. That’s a period where if you’re going to get sicker because you have a high disease burden, you will. That period requires intensive monitoring, and it ends two or three weeks after the cells go in.

    After that, there is very little we have to do — with one exception. The patients return to their pre-cancer level of functioning quite quickly. That’s been quite striking in the quality-of-life data to see that. These kids get better so fast. But one thing we do need to follow up on is these cells are killing B-cell cancers, leukemia and lymphoma. On the way to killing those cancers, they also kill normal B-cells in the patient’s body. Normal B cells make antibodies which are a part of your protection against infection. Fortunately those antibodies are replaceable with an infusion … As long as you keep up on that medication to replace the antibodies, that’s really the main area of follow-up that we see in these patients.

    WebMD: What do you think this decision means for research? Do you expect it will change where efforts are being expended?

    Lin: This will certainly be a very important positive reinforcement, if you will, to encourage people to do more research with this modality. By no means is this product the answer to everything. This is really just the beginning. And to have FDA approval means this is something we can get into clinical practice, which is very important to encourage more research.

    Even in blood cancer, I don’t think we have all the answers yet. We can see a lot of toxicities. Can we improve the way we make CAR T cells or manage CAR T care to reduce some of these toxicities, and still maintain efficacy? There’s still more research that can be done.

    WebMD: What do you think will come next?

    Grupp: There’s the soon, and then there’s the later. From the soon point of view, I have every expectation that a similar cell-engineered therapy for lymphoma instead of leukemia will probably be approved this year as well. So that’s going to be one approval for leukemia, one approval for lymphoma. Beyond that, I think there’s a lot of interest in whether there’s other blood cancers we can treat with this kind of engineered cell therapy. I am certain the answer is going to be yes.

    I think much more importantly to the general field of cancer, this treatment has been so transformative to patients with leukemia and lymphoma — but what about other common adult cancers that aren’t blood cancer? For breast cancer, lung cancer, pancreatic cancer, we’re not at the point now where we can say these engineered cells are going to successfully treat those cancers. That’s the work of the next five years. If this is going to be applicable to those kinds of cancer, that changes the whole ballgame … the pace of drug development for these engineered cells has been incredibly fast, and I hope it keeps up being incredibly fast, because this is a very exciting new way to treat cancer.

    WebMD: Why does CAR T show more promise with blood cancers than other types of tumors?

    Lin: In solid tumors, one of the issues is trying to find some cancer markers that are very restricted to cancer and not healthy organs, and therefore not causing those CAR T cells to cause excessive damage to organs or healthy tissues. That’s been a challenge. The other challenge is that the immune effects of the solid tumors are different in some ways than blood cancers. I don’t think we understand all the aspects of that. But what we have seen in pre-clinical studies and early clinical trials is that the CAR T cells in solid tumors can have more of a problem getting into the tumor sites. And when they get into the tumor sites, they can be suppressed by the immune system. We seem to see more of that in solid tumors than we do in blood cancers.

    WebMD: Are there any concerns about the speed of the process?

    Grupp: I think we’re trying to move with all deliberate speed. We are being held accountable by the patients — and in my case the parents — and the regulatory agencies and the hospitals. Everybody is watching this stuff like a hawk. There have been significant toxicity concerns that have been well controlled, and there also have been toxicity concerns with other cell therapy products that have not been well controlled, and that has appropriately slowed down those development programs. Although it’s a very fair question to ask – are we moving too fast? – I honestly don’t think so. The level of scrutiny that’s being applied to these trials, and the data that comes from these trials, and the results that come from these patients, is extraordinary.

    Yi Lin, MD, treats blood cancers at the Mayo Clinic.

    Stephan Grupp, MD, is a pediatric oncologist at the Children’s Hospital of Philadelphia.

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