Stephan Grupp, MD, PhD
Data from the phase II ELIANA study presented at the 2016 ASH Annual Meeting showed that the CAR T-cell therapy CTL019 induced an 83% complete remission (CR) or CR with incomplete blood count recovery (CRi) rate in pediatric and young adult patients with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL).
Patients were enrolled in the study at 25 centers in the United States, Europe, Asia, and Australia. Among the first 50 patients enrolled, the 6-month overall survival rate was 89% (95% CI, 76-95) and the disease-free survival rate was 60%.
In an interview with OncLive
, lead study investigator Stephan Grupp, MD, PhD, the Yetta Deitch Novotny Professor of Pediatrics at the Perelman School of Medicine at the University of Pennsylvania, discussed the study results and the next steps with CAR T-cell therapy in ALL.
OncLive: Can you discuss the breakthroughs with CAR T cells?
The whole idea of CAR T cells is engineering T cells to be able to attack cancer. This has been the most successful in patients with a specific type of leukemia. ALL is the most common childhood cancer. We're using CD19-targeted cells and there are several other groups that are doing this as well. Several groups have come out with beneficial short-term clinical results and now we’re getting longer term clinical results.
The big question is whether this can be FDA approved. There is data from a global registration trial for a specific CD19-targeted CAR product, called CTL019, which has been licensed to the drug company, Novartis. Novartis has completed a global registration trial for this drug, which has been tested in 25 centers across 11 countries.
Two important questions to consider are can you do this safely in multiple institutions and can you still have the same outcome as a single dedicated institution that’s done a lot of CAR T cell work. Fortunately, the answer to both of those questions is, “Yes.” The registration trial reported that for the first 50 patients that received CTL019 showed an 83% complete response rate in these patients with relapsed/refractory ALL. That compares very favorably to the broad data and to our specific data previously.
CAR T cells are a little bit different than other cancer treatment modalities, and certainly have unique toxicities that are familiar to a bone marrow transplant. A principal toxicity is cytokine release syndrome (CRS). In the process of doing this global trial, we were able to create an algorithm for treating cytokine release syndrome to hopefully get all the physicians aligned on this, do the appropriate training, and be able to treat these patients with exactly the same safety that we saw in the single institution trial, which included no deaths from CRS.
A logistical issue is if you can take these cells and ship them all over the world because you must make that an individual product for each patient. You have to collect cells from the patient, send them to a factory in the United States, and then send it back to the center. We found that it is possible from a logistical standpoint.
Please expand on the long-term data that you are seeing.
We have some long-term results. At 1 year, the event-free survival rates were in the 50% to 60% range, depending on the study. Also at 1 year, we have overall survival rates around 79% to 80%, and this is across several studies of CTL019. That shows that there is a substantial number of patients who do have long-term disease control.
We’ve also been following these patients for a longer period of time on the single institution trial, but we don’t yet have this follow-up on the registration trial. We’re not seeing a lot of events after a year, and so we’re hoping that patients who reach their year have a much higher likelihood of staying in remission at that point.