Gilead Sciences Inc. has filed for approval with the U.S. Food and Drug Administration for an investigational cancer therapy that treats a rare cancer of the white blood cells.

The Foster City, Calif.-based company's biologics license application is for the chimeric antigen receptor T cell therapy KTE-X19. The drug treats adult patients with mantle cell lymphoma whose disease has returned or is resistant to prior therapies. CAR-T cell therapies involve infusing patients with lab-enhanced versions of their own cells to help fight cancer cells.

Mantle cell lymphoma is a rare form of non-Hodgkin lymphoma typically affecting men over the age of 60.

KTE-X19 is not yet been approved anywhere in the world but has previously received a breakthrough therapy tag from the FDA and a priority medicine designation from the European Medicines Agency.

Gilead inherited the drug after the acquisition of Kite Pharma Inc. in 2017.

The application is based on data from a mid-stage study called Zuma-2, which showed 93% of the 60 patients responded to the therapy, including 67% of patients who had no signs of cancer remaining after a single infusion.

Gilead plans to file for marketing authorization for KTE-X19 in Europe in early 2020.