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ORLANDO, Fla. — Last month, Constellation Pharma (CNST) added $1 billion in market value based on positive responses in a study of its lead drug in just four myelofibrosis patients. The gigantic stock move on such scant data ignited a ferocious debate between believers and skeptics. Both sides were eager to see if that 100% response rate would hold up when more patients were treated.

On Monday at the annual meeting of the American Society of Hematology came the answer: no, but pretty close.


With 15 myelofibrosis patients now treated and evaluable in its mid-stage study, the spleen response rate to the drug, CPI-0610, when used on top of Incyte’s market-leading drug Jakafi, stands at 80%.

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