Shares of the Cambridge, U.K., pharmaceutical giant at last check were nearly 1.7% higher at $54.39.
Tagrisso, the company said, "demonstrated a statistically significant and clinically meaningful improvement in disease-free survival."
At two years, 89% of patients in the trial treated with Tagrisso remained alive and disease-free compared with 53% on placebo.
AstraZeneca said the results of the trial will be presented Saturday at the American Society of Clinical Oncology ASCO20 Virtual Scientific Program.
Consistent disease-free survival results were seen across all subgroups, including patients who were treated with surgery followed by chemotherapy and those who received only surgery.
The trial enrolled 682 patients in more than 200 centers across more than 20 countries, including the U.S., in Europe, South America, Asia and the Middle East.
"We are discussing these outstanding data with regulatory authorities and look forward to bringing the benefits of Tagrisso to patients with early-stage disease," said José Baselga, executive vice president for oncology R&D.
Last week, AstraZeneca said it had received more than $1 billion from the U.S. government to boost the manufacturing of an experimental coronavirus vaccine from the University of Oxford.
The company said it received the funding from the U.S. Biomedical Advanced Research and Development Authority to develop, produce and deliver the vaccine, which is being developed by Oxford and the U.K. government.