UPDATE 1-Geron says FDA puts cell therapy drug on clinical hold

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May 14 (Reuters) - Geron Corp (GERN.O) said U.S. health regulators placed a clinical hold on its investigational new drug submission for GRNOPC1, a cell therapy for spinal cord injury, sending its shares down 22 percent to their lowest in more than four years.

"We have not yet received a letter from the FDA explaining the decision to place the submission on hold, so we are unable to comment specifically," Chief Executive Thomas Okarma said in a statement.

The biopharmaceutical company said it had received a verbal notice from the U.S. Food and Drug Administration about the clinical hold.

A clinical hold is an order that the FDA issues to delay a proposed trial or to suspend an ongoing investigation.

Shares of the company, which is working to develop therapeutics based on human embryonic stem cells, fell $1.08 to $3.82 in late trade on Nasdaq. (Reporting by Aradhana Aravindan in Bangalore; Editing by Himani Sarkar)