(Reuters) - Zafgen Inc said on Monday the U.S. Food and Drug Administration had placed a clinical hold on U.S. trials of its experimental diabetes drug, citing possible heart safety risks.

Zafgen said it planned to assess the options put forward by the FDA in a letter last week and request a meeting with the agency to discuss the next steps with the clinical trial.

The drug ZGN-1061 is undergoing mid-stage trials outside the United States and no safety signals have been found to date, the company said, adding that it expects to report topline data from the study in early 2019.

Shares of the company, which closed at $9.10 on Friday, were halted.