Vertex now looks likely to gain US approval for the first ever CRISPR gene edited therapy by the end of the year, but could face immediate competition from Bluebird Bio.

The company is seeking a priority review from the US Food and Drug Administration.

The drug pricing watchdog said improvement to patients’ quality and length of life from lovo-cel and exa-cel were likely, but noted ongoing uncertainty around durability and toxicity concerns.

The companies completed a rolling BLA filing for exagamglogene autotemcel (exa-cel) for sickle cell disease and beta thalassemia, a decade after the discovery of CRISPR.