March 12 (Reuters) - The U.S. Food and Drug

Administration's staff reviewers said on Tuesday they were

unclear if Geron's ( GERN ) blood disorder drug provided a clear

benefit to patients in a late-stage trial and raised multiple

safety concerns with the treatment.

Geron ( GERN ) is seeking approval of the injectable drug, called

imetelstat, for treating transfusion-dependent anemia in

patients with a group of blood cancers called myelodysplastic

syndromes (MDS).

The drug, if approved, will compete with Bristol Myers

Squibb's ( BMY ) Reblozyl, which has been approved by the FDA

for the same disease indication.

Last year in January, Geron ( GERN ) CEO John Scarlett told Reuters

that the company anticipates a peak market potential of $1.2

billion for imetelstat in the United States and some key EU

countries by 2030.

While Geron's ( GERN ) drug met the main goal of increasing

independence from transfusion at eight weeks in a late-stage

study, the FDA's staff said the "clinical meaningfulness" of the

data was unclear.

"The general consensus among MDS experts has been that only

a 16-week or longer period of transfusion independence is

clinically meaningful," the agency's staff said ahead of a

meeting of FDA's independent advisers scheduled for Thursday.

The agency said that while the drug is believed to work

by treating the underlying cancer, the study did not show a

"disease-modifying effect" in either extending survival or

helping drive disease remission.

It also highlighted a high rate of low red blood cell

count in the late-stage study.

Wedbush analyst Robert Driscoll said it was expected

that the briefing documents would lean negative and added that

Geron ( GERN ) will be able to provide a strong case against the points

made by the FDA.