Hemispherx Biopharma Inc said U.S. regulators had declined to approve its new drug application for Ampligen, its experimental drug for treating chronic fatigue syndrome, five years after the company first filed for the drug's approval.
Hemispherx, based in Philadelphia, said it plans to request an "end-of-review conference" with the Food and Drug Administration and may submit a formal appeal regarding the regulator's decision.
The FDA said Hemispherx should conduct at least one additional clinical trial, complete various nonclinical studies and perform a number of data analyses, according to a statement from the company.
In its Complete Response Letter, the FDA said the submitted data did not provide substantial evidence of efficacy of Ampligen for the treatment of chronic fatigue syndrome.
The FDA also said the data did not provide sufficient information to determine whether the product was safe for use "due to the limited size of the safety database and multiple discrepancies within the submitted data."
Hemispherx first applied for approval of Ampligen in October 2007.
In November 2009, the FDA had called for at least one additional clinical study of Ampligen, including at least 300 patients on dose regimens intended for marketing.