Eli Lilly and Co. suspended a late-stage clinical trial of a medicine for skin-cancer patients after 12 patients in the study died.

The deaths, among the 300 patients in the study, “may be treatment-related,” said Amy Sousa, a Lilly spokeswoman, in a telephone interview Monday. Lilly was testing the drug, tasisulam, as a medication for patients whose skin cancer had spread and who didn’t benefit from earlier treatment, the Indianapolis-based company said in a prepared statement.

Lilly has struggled to get new products approved before patents expire on older medicines, led by the antipsychotic treatment Zyprexa. Two setbacks in October for diabetes products under development spurred analysts to suggest Lilly look for acquisitions to bolster revenue.

“We are thoroughly reviewing the clinical trial data to understand what modifications to the study protocol or dosing would be needed to improve patient safety on this trial,” Richard Gaynor, Lilly’s vice president of oncology product development and medical affairs, said in the statement.

No new or existing patients will be given the drug while the company evaluates safety data for the trial, which is spread across 18 countries. Studies will continue in breast, ovarian, and renal cancers and against soft-tissue sarcoma, the company said. Tasisulam works by killing cancer cells and also by preventing them from replicating, the company has said.

About 68,130 new cases of melanoma, or skin cancer, were diagnosed this year in the United States, and about 8,700 people died from the disease, according to the National Cancer Institute, based in Bethesda, Md.

Lilly shares declined less than 1 percent in extended trading after dropping 1 cent, to $34.97 each at the markets close Monday.