ABOVE: Red blood cells, 50x magnification

US AIR FORCE, CHRISTOPHER HUMMEL

Two companies have jointly launched a trial of an experimental CRISPR-Cas9 therapy for the blood disorder β-thalassemia, according to announcement posted Friday (August 31) on clinicaltrials.gov. Although the study itself is to be carried out in a hospital in Germany, it marks the first clinical trial of CRISPR genome-editing technology to be sponsored by US companies, Boston-based Vertex Pharmaceuticals and CRISPR Therapeutics, a Swiss biopharmaceutical with labs in Cambridge, Massachusetts.

“This is one important step of many toward bringing the promise of this new technology to patients with serious diseases like sickle cell [disease] and beta thalassemia, and we are thrilled to be at the forefront of what we believe may be a fundamental change in the treatment of disease,” Vertex spokesperson Heather Nichols says in a statement, according to STAT News.

See “CRISPR Inches Toward the Clinic”

The therapy, known as CTX001, is designed to treat diseases characterized by a deficiency in the production of hemoglobin in adults. Rather than target the genetic mutations responsible for this deficiency, CTX001 works by cleaving a gene called BCL11A that represses the production of fetal hemoglobin, normally only produced in infancy. The therapy will be tested ex vivo—blood cells will be removed from the patient, edited, and then replaced. Preclinical data suggest that, when this repression is lifted, patients with β-thalassemia or sickle cell disease should be able to produce enough hemoglobin to mitigate the effects of their disorder.

Plans for the new study were first reported last winter, when CRISPR Therapeutics began submitting applications to regulatory authorities for permission to start clinical trials—first in Europe for the study that’s now been launched, and later in the US, where their clinical work has yet to receive the green light. “Just three years ago we were talking about CRISPR-based treatments as a sci-fi fantasy,” CRISPR Therapeutics CEO Samarth Kulkarni told Wired at the time. “But here we are.”

See “CRISPR to Debut in Clinical Trials”

Enrollment for the study has already opened, although no patients had been enrolled or had received treatment as of Friday, reports Boston Business Journal.