The independent data monitoring committee recommended the trial continue without modification through the first half of 2017 despite the fact that its interim look at the data suggested the combination treatment was not delaying progression of the disease.

Lilly shares were down 1.2% in morning trading.

Leerink analyst Seamus Fernandez said continuation of the study, called Monarch 2, would allow Lilly to better understand abemaciclib, which is also being tested in a variety of other trials.

The Monarch 2 study included 669 patients who had previously failed to benefit from anti-estrogen treatment for metastatic breast cancer. It compared combined use of abemaciclib and anti-estrogen therapy fulvestrant with fulvestrant alone.

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Lilly’s drug is from the same new class of breast cancer treatments as Pfizer’s (PFE) recently approved Ibrance, which brought in more than half a billion dollars in second-quarter sales. They work through a new mechanism, by blocking the proteins CDK 4 and CDK 6.

Lilly is evaluating abemaciclib as a single agent in breast cancer patients who have not derived enough benefit from prior treatments. Three other studies are testing abemaciclib with other drugs.

Abemaciclib, which was granted the U.S. Food and Drug Administration’s (FDA) breakthrough therapy status for breast cancer last year, is also being tested for use in lung cancer.

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After skin cancer, breast cancer is the most common cancer among women in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC).

About 40,000 of the 220,000 American women diagnosed with breast cancer die each year, the CDC estimates.