GSK Plc’s Jemperli helped extend the lives of patients with endometrial cancer in a late-stage test, suggesting the medicine could become the top seller the UK drugmaker is predicting.

Jemperli, when combined with chemotherapy, produced a “statistically significant and clinically meaningful benefit in the overall patient population,” the company said without releasing details of the results.

GSK has invested heavily in the drug and is seeking to eventually show it could be used to treat several types of cancer.

The results stem from the first part of the analysis of the late-stage study. The full results will be presented at a medical conference. Endometrial cancer is found in the inner lining of the uterus and is the most common gynecologic cancer in developed countries.