Two pediatric patients with leukemia have been in remission for over a year after receiving experimental CAR-T cell therapy. While Cellectis’ immunotherapy agent is now being tested in clinical trials involving both children and adult patients, the two infant girls were the first to receive the treatment back in 2015.
The two girls – 11-months-old and 16-months-old at the time of treatment – are both doing well over a year after receiving the modified CAR-T cells. The doctors at Great Ormond Street Institute of Child Health, University College London, who administered the experimental treatment have now presented the case studies in an article published in the journal, Science Translational Medicine.
The cases involved the use of so-called “off-the-shelf” CAR-T cells to target cancer cells. CAR-T cell therapy normally involves gene editing a patient’s own immune cells to allow them to destroy tumor tissue.
While this approach has been shown to be relatively safe and effective, it requires an expensive and laborious procedure of collecting enough immune cells from the patient to be edited. If a patient is very young or very sick, the number of viable immune cells may be limited.
If a patient were to be infused with off-the-shelf cells which are not their own, it’s likely that the foreign cells would attack their body in a phenomenon known as graft-versus-host disease. To combat this response, pharmaceutical company Cellectis developed a gene editing tool to turn off the gene, called TCRαβ, responsible for allowing the donor cells to attack the host.
Cellectis’ gene editing tool allowed for the creation of UCART19 cells which could be universally accepted by patients with B-cell acute lymphoblastic leukemia. However, because the gene editing tool is not 100 percent accurate, both pediatric patients treated with the UCART19 cells developed some signs of graft-versus-host disease.
A gene editing technique known as TALEN was used by Cellectis to silence TCRαβ, however researchers are now looking to CRISPR for an easier and less-expensive gene editing tool. CRISPR-edited cells are now being assessed in two cancer clinical trials taking place in the US and China.