Eli Lilly and Co. said it is halting testing of an experimental drug for rheumatoid arthritis because the studies show the medicine is not effective.

The decision to stop testing the therapy, called tabalumab, in rheumatoid arthritis wasn’t based on safety concerns, the Indianapolis-based drugmaker said Thursday in a prepared statement. Lilly said it will continue to develop it as a treatment for lupus.

In December, Lilly said it was stopping one of three late-stage rheumatoid arthritis studies of tabalumab after it failed to provide a benefit. Lilly then did an analysis of the other two studies and determined the drug was unlikely to help patients. The setback comes as Lilly, counting on sales of new medicines to revive growth, faces generic competition to schizophrenia drug Zyprexa, which generated $5 billion in annual revenue before losing patent protection in October 2011.

“While we are obviously disappointed by these results in rheumatoid arthritis, we continue to believe that tabalumab could have significant potential for patients in other disease areas,” said Eiry Roberts, vice president of autoimmune product development at Lilly, in a statement.

Lilly shares fell about 1 percent Thursday morning, to $53.41 each.