In the abstract that we submitted for ASH we reviewed subjects that were paediatric subjects treated on our PLAT-02 trial at Seattle Children’s Hospital, which is a CD19 CAR T-cell immunotherapy trial for CD19 positive leukaemia.
How many patients were involved?
For this abstract we analysed fifty subjects treated on our phase I dose finding portion as well as the first cohort treated on our phase II portion of the PLAT-02 trial. We evaluated the leukaemia free survival potential benefit of transplant within these subject populations.
What did you find?
When looking at these patients treated on our PLAT-02 trial we continue to see late relapse recurrences so we wanted to evaluate the role that transplant plays within this population. We noted that subjects without a history of transplant following attainment of remission following their CD19 CAR T-cell therapy seemed to benefit with pursuing a first transplant following their immunotherapy. However, subjects with a history of transplant, there didn’t seem to be a benefit of pursuing a second transplant following the CD19 CAR immunotherapy, though longer term follow-up is needed. Then, further, we evaluated subjects that had early loss of their functional CD19 CAR T-cells demonstrated by loss of B-cell aplasia. Within that patient population it did seem to benefit subjects to pursue a transplant, whether it was their first or their second, because early loss of T-cell persistence does increase a patient’s risk of relapse. So there does seem to be another benefit to transplant.
What is your take-home message?
The take-home message for doctors is that subjects following CD19 CAR T-cell therapy within a paediatric population treated on our trial did seem to benefit with first transplant following attainment of remission. The role of second transplant is unclear, however, there does also seem to benefit patients first or second transplant if they have early loss of their CAR T-cells to help abrogate that increased risk of relapse. More follow-up is needed and which we will continue to do so on the phase II portion of our trial but that’s what our data suggests thus far.