Sangamo has significant experience in process development and manufacturing of modified cell therapy products gained through its T-cell and hematopoietic stem cell (HSC) programs in HIV, which were the first genome editing products to enter human clinical trials. In collaboration with Bioverativ we are also developing modified HSC treatments for beta-thalassemia and sickle cell disease. Cells are removed from the body and undergo ZFN-mediated genome editing. In these autologous therapies, the modified cells are grown and tested before being infused back into the patient.
Modified T-cells have demonstrated spectacular success in treating some cancers. With the exception of two cases these have been autologous therapies. A more useful product would be an off-the-shelf or allogeneic product that could be administered to any patient on diagnosis rather than after precious weeks of manufacturing their own cells. Using our ZFN-mediated genome editing technology to knock out genes that identify these cells as foreign to a patient, we are working to make this possibility a reality.
We are developing ZFN-mediated genome editing-based therapies for serious blood disorders and cancer.
In hematopoietic stem cells, our ZFN genome editing technology can be used to precisely disrupt regulatory sequences that control the expression of key transcriptional regulators, such as BCL11A, to reverse the switch from expression of the mutant adult beta-globin back to the production of functional fetal gamma globin. Naturally occurring high levels of fetal hemoglobin have been shown to ameliorate symptoms of both beta-thalassemia and sickle cell disease. These programs are being developed with our collaborators, Bioverativ, the planned spin-off of Biogen’s hemophilia business.
We have demonstrated highly efficient (>90%) knock out the expression of both the T-cell receptor (TCR) and of HLA Class I protein on the cellular surface and > 80% of both genes simultaneously in primary T-cells. In addition, we can simultaneous achieve highly efficient (60-70%) targeted gene integration into these sites. These methods have potential use in the development of allogeneic T-cell therapies.
Because ZFN-mediated genome editing requires only transient expression of the ZFNs to effect a permanent change in the genome, we can use electroporation of messenger RNA (mRNA) to deliver the ZFNs.
To insert a gene, ZFNs are delivered by electroporation of mRNA and a non-integrating vector, an adeno-associated virus (AAV) is used to provide a therapeutic DNA sequence, the "donor template". The “donor template” can encode an entire gene that integrates at the targeted site of ZFN action.