The European Patent Office upheld BioTime Inc.'s key patents to develop a treatment for retinal degenerative diseases.

"The EPO's decision to uphold these patents protecting OpRegen reinforces BioTime's ability to defend its intellectual property and patent portfolios, which is one of the largest in the pluripotent cell therapy industry," BioTime's general counsel Stephana Patton said in a statement.

The patents were challenged by a "large pharmaceutical company and an anonymous filer," the company said. OpRegen is undergoing a phase 1/2a dose-escalation study.