U.S. Food and Drug Administration medical reviewers on Friday said they have several issues with data Allos Therapeutics Inc. (ALTH) submitted to support getting FDA approval for its proposed lymphoma drug Folotyn.

FDA scientists said they can't precisely determine how Folotyn affected some of the patients studied because of inconsistencies in how the patients were evaluated.

Allos is seeking FDA approval to offer Folotyn to patients with an aggressive type of non-Hodgkin's lymphoma, a common blood cancer. Specifically, the company wants to market the product to people with peripheral T-cell lymphoma. About 9,500 people get diagnosed with the disease annually in the U.S.

An FDA-sponsored panel of medical experts will review the product next week.

In briefing documents on its Web site, the FDA asked the panel to advise it on whether Folotyn's benefits outweigh the risks.

Allos enrolled more than 100 patients with lymphoma into a clinical trial. Allos evaluated patients' tumors size and status by doing imaging scans every 14 weeks.

Twenty-nine, or 27%, of the patients enrolled had their tumor growth affected by the drug. However, the FDA noted reviewers on an independent committee that Allos had evaluate the scans didn't agree on how well the patients responded to Folotyn.

The FDA said that because of the long time between scans and the disagreement among the team that reviewed the scans, it wants the panel's advice on the significance of the data Allos submitted.

-By Jared A. Favole, Dow Jones Newswires; 202.862.9207; jared.favole@dowjones.com