SAN DIEGO — As its competitors celebrate the landmark approval of two sickle cell gene therapies, Editas Medicine detailed promising early results in a small group of patients for its own gene-edited sickle cell treatment.

Across two studies in sickle cell disease and transfusion-dependent β-thalassemia, Editas reported that 11 patients have not had pain crises known as vaso-occlusive events since receiving its gene-edited therapy, known as EDIT-301. But, on average, the patients have not been followed for very long in the study — between a few weeks and one and a half years. The data were presented at the American Society of Hematology annual meeting on Monday.

On Friday, Vertex/CRISPR Therapeutics and bluebird bio won approval for their sickle cell disease gene therapies. Vertex and CRISPR Therapeutics’ treatment, Casgevy, became the first therapy that uses gene editing to receive FDA approval.

Hoping to follow, Editas expects to file an application with the FDA based on its ongoing studies in sickle cell disease and thalassemia in 2025.

The administration of EDIT-301 is similar to the other sickle cell gene therapies. A patient’s cells are apheresed, meaning they are removed from their blood and then shipped to be engineered. The patient receives chemotherapy to clear space for the new blood cells, and afterward, the newly-engineered cells are reinfused.

Unlike Casgevy, which edits a gene called BCL11A to turn on fetal hemoglobin, Editas’ therapy edits the HBG1 and HBG2 promoters, which the company argues can lead to higher levels of fetal hemoglobin expression. Editas said that the six patients who received their infusions more than five months ago have maintained normal hemoglobin levels so far.

“If we can make patients [reach] normal hemoglobin — that we feel is actually a step up from the standard of care for these patients,” Editas chief medical officer Baisong Mei told Endpoints. However, Editas’ hemoglobin data are still early and in a handful of patients.

To edit the gene, Editas’ therapy also uses a different nuclease — AsCas12a as opposed to Cas9. All in all, Editas reported that it treated 17 patients across two conditions — 11 with sickle cell disease and six with beta thalassemia.

Editas was the first company to test CRISPR/Cas9 in a human trial. But it stopped work on that program for a rare eye disease last year and pivoted to a focus on sickle cell disease at the beginning of this year. After the shift, Editas laid off 20% of its staff.

In August, Editas said it may partner with another company to commercialize its sickle cell program.


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