On August 30, 2017, the U.S. Food and Drug Administration approved an immune-system based therapy, called CTL019, for children and young adults who have relapsed two or more times in treatments for B-cell acute lymphoblastic leukemia (ALL). This new treatment arose from the work by Carl June (C.J.) — Richard W. Vague Professor in Immunotherapy at the Perelman School of Medicine, University of Pennsylvania. He developed methods to engineer a patient’s T cells into so-called chimeric antigen receptor T (CAR-T) cells, which recognize and kill a person’s unique cancer. This is called immunotherapy — training a person’s body to kill disease. One treatment can establish a lifelong cure, June tells Scientific American Custom Media (SACM).
SACM: What are the key features of immunotherapy?
C.J.: The immune system has been amenable to changes with vaccines that have cured many infections that used to kill people. The second thing is the importance to the immune system of the T-cells, which are critical in fighting off viruses. A single treatment of cellular immunotherapy gives a person cancer-fighting CAR-T cells that can last a lifetime. That is very different than most of the other cancer therapies, which are often given over and over.
SACM: Can immunotherapy only fight ALL?
C.J.: I think immunotherapy is eventually going to treat all cancers as we learn more. Rather than directly targeting the cancer, immunotherapy targets the immune system, and then the immune system deals with the cancer. So, in a way it’s more like a device-independent thing, like a software system. In the past, all cancer therapies were specific for each kind of cancer. But, using the immune system, we can redirect the target of the T cells, and then the CAR-T cell approaches can be very similar for different kinds of cancer.
SACM: With the immune system doing the heavy lifting, does that reduce side effects for patients?
C.J.: With chemotherapy, the primary effects have been off-target—loss of appetite, nausea, vomiting, all those things. Those don’t help you get better. Now, immunotherapy does have side effects, but in general, they’re on-target: It’s an over-active immune system, which can lead to different kinds of auto-immunity, and that can affect the joints or colon or other areas. But it also means the treatment is working. What we have found is that patients are more willing to have those kinds of side effects because they accept that it’s a sign the therapy is helping them get better.
SACM: You’ve had great success in treating pediatric leukemia with immunotherapy. What is your latest advance with that?
C.J.: When we used CAR-T therapy with children and young adults with ALL, more than 90% of them went into remission. Whenever you start something at a single center like we did in Philadelphia, you don’t know initially if you just got lucky and happened to pick people who are going to do well. But a global clinical trial carried out by Novartis — using our immunotherapy method for pediatric leukemia — got the same results in an international trial, remission in approximately 90% of the children treated. So, now we know that our initial results weren’t a fluke, and that’s very gratifying. We also now know, because the first patients we treated are still in remission, that it’s durable for at least five years. So, we now believe that some patients are cured.
SACM: Although you’ve focused on pediatric leukemia, what other cancers could be treated with immunotherapy?
C.J.: Today, the number one cause of cancer death in kids is brain cancer. So, the next big medical need is learning how to treat brain cancer, and other solid tumors. That’s what we’re working on now.
SACM: With patients cancer-free for five years, are you starting to feel confident that it’s a permanent repair?
C.J.: Leukemia starts in the bone marrow, and with next generation sequencing we can find a single leukemic cell in a million cells. Most of our patients start with 90% of their bone marrow being cancer cells, and after treatment they have less than one cancerous cell in a million bone-marrow cells. It’s a huge reduction. We don’t know that there’s not some sanctuary where there’s some cancer cell hiding out in a patient, but they are clinically well. Only time will tell, if it is completely eradicated or not.
SACM: And there’s no tune-up or anything after the first treatment?
C.J.: Nothing. That’s what’s so nice about it. It’s just a complete change in medical-care delivery.