WEDNESDAY, Sept. 18, 2024 (HealthDay News) -- When given after organ-removal surgery, Keytruda brings patients battling advanced bladder cancers more time cancer-free, a new trial finds.

Folks with "high-risk" bladder cancers -- tumors that had already invaded nearby muscle -- doubled the time they were cancer-free after surgery if they got post-op Keytruda (pembrolizumab), compared to those who didn't get the drug.

“This study shows that pembrolizumab can offer patients another treatment option to help keep their disease from coming back,” said lead investigator Dr. Andrea Apolo.

“Extending the time that these patients are cancer-free makes a big difference in their quality of life," said Apolo. She is senior investigator in the Genitourinary Malignancies Branch of the Center for Cancer Research at the National Cancer Institute (NCI).

The study was funded by the NCI and published Sept. 14 in the New England Journal of Medicine.

As Apolo and colleagues explained, high-risk bladder cancers with muscle invasion are typically treated by surgeries that remove the entire bladder.

To boost the odds that cancer cells in surrounding tissue are destroyed, many patients also get a pre-surgical round of cisplatin chemotherapy.

Not everyone can tolerate the side effects of cisplatin, however. In many cases, these patients are simply monitored closely after their surgeries, to spot any signs of cancer's return.

In recent years, however, doctors have turned to post-op use of immunotherapy drugs. Once such drug, Opdivo (nivolumab) received U.S. Food and Drug Administration approval in 2021 for post-surgical use against high-risk bladder cancers.

The new trial tested the same strategy with Keytruda, a drug in the same class. It involved 702 patients with high-risk bladder cancers, who all underwent bladder removal. Two-thirds had also received pre-op cisplatin.

Half of the patients then went on to receive post-surgical Keytruda, given once every three weeks for a year after their operation. The others were simply monitored.

The result: With a follow-up of four years, patients who got Keytruda remained cancer-free for an average of nearly 30 months, compared to just over 14 months for those who didn't get the drug, the NCI team said.

The specific type of bladder tumor seemed to matter.

The team found that if a bladder cancer was PD-L1-positive (meaning tumor cells produce a large amount of the PD-L1 protein on their surface), the time a patient spent cancer-free rose to almost 37 months, on average. That's compared to the 21-month average of people with this tumor type who were only monitored after their surgeries.

If the tumor was PD-L1-negative, average cancer-free survival time dropped to 17.3 months, but that was still a big improvement on the 9-month average among patients with this tumor type who did not get Keytruda, the researchers said in an NCI news release.

More information

Find out more about bladder cancer at the American Cancer Society.

SOURCE: U.S. National Cancer Institute, news release, Sept. 17, 2024