Eli Lilly and Co said a combination of its experimental breast cancer drug and another widely used treatment slowed disease progression in a key study in patients who had relapsed or did not derive enough benefit from anti-estrogen therapy.
Lilly's drug, abemaciclib, is part of the same new class of breast cancer treatments as Pfizer Inc's recently approved drug, Ibrance, which generated $643 million in 2016.
In August, Lilly elected to continue the late-stage study, even though an interim data evaluation suggested the combination treatment was not delaying disease progression.
The trial compared combined use of Lilly's abemaciclib and anti-estrogen therapy fulvestrant with fulvestrant alone, the drugmaker said on Monday.
Lilly is also evaluating abemaciclib as a single agent in breast cancer patients who have not derived enough benefit from prior treatments, and multiple other studies are testing abemaciclib with other drugs.
Abemaciclib, which was granted US Food and Drug Administration breakthrough therapy status for breast cancer in 2015, is also being tested for use in lung cancer.
Lilly said it planned to submit an application to market abemaciclib as a monotherapy in the second quarter, and as a combination therapy in the third quarter.
After skin cancer, breast cancer is the most common cancer in women in the United States, according to the US Centers for Disease Control and Prevention.
About 40,610 women will die from breast cancer in 2017, the American Cancer Society estimates.
Lilly's shares rose about 1.5 per cent in light pre-market trading on Monday.