U.S. regulators have approved the first drug for bladder cancer that harnesses the body’s immune system. It is the first advance in decades against the most common type of bladder cancer, one which almost always kills patients within months.

Tecentriq won approval for treating patients with advanced urothelial cancer after chemotherapy stops helping them.

The drug, developed by the Roche Group’s Genentech unit, blocks a protein found on many tumor cells that deactivates key immune-system cells that kill cancer cells.

While most patients with bladder cancer die after about six months on chemotherapy, Genentech says some of those given Tecentriq in trials are alive three years after starting treatment. It has a list price of $12,500 per month.

A similar drug, from Bristol-Myers Squibb, was approved for Hodgkin lymphoma.