There are expected to be about 77,000 new cases of bladder cancer this year in the United States and 16,000 deaths, according to the American Cancer Society. About three-quarters of the cases are in men, making bladder cancer the fourth most common cancer in men. It is treated with surgery, chemotherapy and radiation, though those are not very effective once the cancer is in advanced stages.

Tecentriq was approved for urothelial carcinoma, which accounts for 90 percent of all bladder cancers, in cases in which the disease is locally advanced or metastatic and not controlled by platinum chemotherapy. The F.D.A. granted accelerated approval, meaning Roche will have to perform additional studies to confirm the drug works.

Tecentriq will cost about $12,500 a month. That is roughly in line with the price of the competing checkpoint drugs. The high price of drugs, including cancer drugs, has become a public concern and political issue lately.

In the study that formed the basis of the approval, Tecentriq shrank tumors significantly in 14.8 percent of the patients, and the cancer completely disappeared in 5.5 percent. There was no control group with which to compare those results.

It is not yet clear whether the drug will allow people to live longer. But the other checkpoint inhibitors do allow a certain percentage of the population to live a long time, and Roche executives say this appears to be the case with its drug as well.

Roche, based in Switzerland, is the leading supplier of cancer drugs because of its acquisition of the American biotechnology company Genentech, which developed the blockbusters Rituxan, Herceptin and Avastin.

Now it is trying to catch up in immunotherapy, which is one reason it sought its first approval for bladder cancer, a territory not yet claimed by Merck or Bristol-Myers, though they are testing their drugs for that disease as well.