The U.S. Food and Drug Administration granted breakthrough therapy designation to Astellas Pharma Inc. and Seattle Genetics Inc.'s urothelial cancer drug enfortumab vedotin.

Urothelial cancer, or transitional cell cancer, is the most common type of cancer affecting the bladder.

The drug is intended to treat patients with urothelial cancer that progressed locally or has spread to other parts of the body and have been previously treated with checkpoint inhibitors. Checkpoint inhibitors work by blocking certain proteins produced by some types of immune system cells and cancer cells.

The designation was based on the early results of a phase 1 study evaluating enfortumab vedotin as a monotherapy.

Japanese Astellas and Seattle Genetics are evaluating enfortumab vedotin in another trial, EV-103, in combination with checkpoint inhibitor therapy. The two companies are also investigating the drug to treat solid tumors, such as ovarian and non-small cell lung carcinoma.