AbbVie Inc (NYSE:ABBV) stock was falling hard today following results from a Phase 2 study of lung cancer drug Rovalpituzumab Tesirine (Rova-T).

Rova-T is a drug that is designed to target cancer-stem cell-associated delta-like protein 3. These cancer cells are found in 80% of patients with small cell lung cancer. The drug combines an antibody with a cytotoxic agent that targets the cancer cells while leaving the healthy cells mostly unharmed.

The recent Phase 2 study of Rova-T was for treating small cell lung cancer patients with relapsed or refactory disease after receiving at least two prior treatments. The primary goal was to determine how well the drug worked as a third-line and later treatment for these types of patients.

The bad news fro AABV stock includes an objective response rate of 16% for Rova-T in the Phase 2 study. The company also only saw a median survival time of 5.6 months for patients on the treatment. The probability of patients surviving cancer after 12 months came in at 17.5%.

The poor results from the Phase 2 study means that AbbVie Inc is changing its plans for Rova-T. The drug maker was previously planning to seek accelerated approval from the U.S. Food and Drug Administration for  Rova-T. However, after consulting with the organization, it won’t be moving forward with these plans.

“Although the results from the study were not what we hoped for, we look forward to receiving data from the ongoing Phase 3 studies in the first- and second-line settings and remain committed to developing Rova-T for the treatment of patients with small cell lung cancer,” Mike Severino, M.D., Executive Vice President of Research and Development and Chief Scientific Officer for AbbVie Inc, said in a statement.

ABBV stock was down 13% as of noon Thursday.

As of this writing, William White did not hold a position in any of the aforementioned securities.