GSK has high hopes for Jemperli as it transitions to what’s being called the “new GSK,” with a greater focus on experimental drugs for infectious disease, cancer and immune conditions. The U.K.-based company expects the drug to achieve peak sales of as much as 2 billion pounds, or roughly $2.8 billion, fueled by applications for new indications.

Still, Jemperli is the seventh drug of its kind to come to market. By blocking a protein known as PD-1, Jemperli stands in direct competition with other immunotherapies like Keytruda, Bristol Myers Squibb’s Opdivo, and others sold by Roche, Pfizer, AstraZeneca and Regeneron.

GSK used subsets of an ongoing study named GARNET for its latest Jemperli approval application, including patients with endometrial cancer as well as other types like colorectal. Overall, Jemperli shrank tumours in 41.6% of 209 patients, with the median response lasting for almost three years. The response rate among non-endometrial cancer patients in the group was 38.7%.

Like many cancer drugs, Jemperli was given an accelerated approval, meaning the FDA cleared the drug based on its ability to shrink tumours — a marker that researchers expect will translate into health benefits. But to keep the approval, GSK will have to provide more evidence that treatment with its drug offers better overall outcomes for patients, such as helping them live longer.

The FDA has signalled it may be getting tougher about that confirmatory research. In April, the agency convened an unusual three-day meeting, wherein outside experts weighed in on whether the agency should pull accelerated approvals for six cancer immunotherapy indications that lacked evidence of extending life.

In the end, the panel recommended the agency maintain four of the six approvals. The companies behind the other two – Merck, for Keytruda’s use in gastric cancer, and Bristol Myers, for Opdivo’s use in liver cancer – announced in July they would voluntarily withdraw their medicines for those specific indications.