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July 21 (Reuters) - Agios Pharmaceuticals AGIO.O said on Tuesday it will stop development of its sickle cell disease treatment, sending its shares down 14% in premarket trading.

The trial was designed to characterize the dose-response relationship of the drug tebapivat in sickle cell disease and evaluate whether its profile was meaningfully differentiated relative to other drugs from its class.

Over the 12-week treatment period, improvements in hemoglobin levels and hemolysis - premature destruction of red blood cells - were observed across all tebapivat dose levels.

However, the trial did not demonstrate the level of differentiation required to support continued development, said the company.