The researchers who gave Cellectis’ off-the-shelf CAR-T therapy to babies with previously incurable leukemia have written up their findings. Both children remain disease-free 12 to 18 months after treatment with UCART19.
Cellectis reported on the progress of the patients at a meeting of the Recombinant DNA Advisory Committee last month, and the key data in the researchers’ Science Translational Medicine paper are the same as the French biotech presented then. The two patients have been disease-free for 18 and 12 months, respectively. One experienced grade 2 skin graft versus host disease (GvHD)—a big worry with off-the-shelf approaches—but doctors controlled it with systemic steroids and a bone marrow transplant.
The lack of serious, uncontrollable GVHD is a boost for the patients and Cellectis, which is betting its editing of T cell receptor genes can enable the creation of off-the-shelf CAR-T therapies that are not rejected by recipients. Cellectis has seen one suspected case of grade 1 skin GvHD in the four patients treated in its phase 1 program. However, given the limited safety data generated on UCART19 to date, the researchers remain cautious.
“Important caveats include concerns relating to residual risks of GvHD, carriage of translocations and other genetic changes by the edited cells, and the use of lymphodepleting agents and their attendant risks of viral reactivation and other complications,” researchers from Great Ormond Street Hospital and other organizations involved in the cases wrote.
If Cellectis can show these issues don’t outweigh the benefits of UCART19, it and its partners Pfizer and Servier could upend the CAR-T field. The first wave of therapies from Kite Pharma and Novartis modify patients’ own T cells to create personalized, autologous therapies. The logistics and cost of this process could limit its commercial viability. Off-the-shelf CAR-T is free from these issues, but Cellectis has yet to generate data to show its approach can match the safety and efficacy of its rivals.