Blood disease trial participants given Vertex’s and CRISPR Therapeutics’ CRISPR/Cas9-based gene-editing therapy CTX001 demonstrated a “consistent and sustained response” to the treatment, according to new phase 1/2 trial data the companies have announced.

New findings from the companies’ two phase 1/2 clinical trials showed that all seven transfusion-dependent beta thalassemia patients given the drug were transfusion-independent with three to 18 months of follow-up after infusion. Additionally, all three sickle cell patients were free of vaso-occlusive crises with three to 15 months of follow-up after infusion. To date, a total of 19 trial participants have been dosed with the gene therapy.

“Our vision with this approach is to use the patients’ own stem cells to provide a transformative treatment for these diseases, something almost unimaginable a few years ago,” said Haydar Frangoul, the trial’s chief investigator. “With these data in 10 patients, we can see the potential to fulfill this vision. With more data and longer duration of follow-up, we will hopefully confirm that we have a durable therapy that may transform the lives of many patients.”