UPDATE 3-Geron's blood disorder drug gets FDA advisers' backing

(Adds panel member's comment in paragraph 7, analyst comment in paragraph 9)

By Pratik Jain and Christy Santhosh

March 14 (Reuters) - Advisers to the U.S. Food and Drug Administration on Thursday backed benefits of Geron's blood disorder drug, saying it outweighed the risks associated with the treatment, based on data from a late-stage trial.

The panel, by a wide 12-to-2 margin, voted in favor of the benefits of the injectable drug, called imetelstat, stating the associated risks and toxicities of the treatment appear to be manageable.

Geron is seeking approval to use imetelstat for treating transfusion-dependent anemia in patients with a group of blood cancers called myelodysplastic syndromes (MDS).

The FDA's advisory panel meeting followed a review from the agency's staff on Tuesday, who pointed to a lack of clarity in data regarding the benefit to patients and raised multiple safety concerns.

Much of the panel's discussion as well as the agency's concerns centered on the high rate of cytopenias, or low red blood cell count, in patients tested with the drug.

Geron said the adverse effects were not uncommon, which most panel members agreed with, given the current limited treatment options for patients.

"This is not a curable disease and there are very few options. The community of doctors who take care of these patients know how to manage these side effects," said Dr. Ranjana Advani, a panelist who voted in favor of the drug.

Imetelstat, if approved, will be Geron's first commercial treatment in the market and will compete with Bristol Myers Squibb's Reblozyl, which received a label expansion by the FDA last year for the same disease indication.

Baird analyst Joel Beatty projects imetelstat, if approved, will generate $933 million in sales by 2029, and estimates the market opportunity to be four times larger compared to Reblozyl.

The U.S. health regulator also highlighted concerns over lack of other benefits, beyond the drug meeting the main study goal of increasing independence from transfusion at eight weeks.

A company spokesperson presenting at the panel meeting indicated that "transfusion independence has been the regulatory gold standard for approvals in this patient setting".

The regulator, which usually follows the advice of its panel but is not bound to do so, is expected to make a decision on the drug by June 16.

(Reporting by Pratik Jain and Christy Santhosh in Bengaluru; Editing by Krishna Chandra Eluri)