07:19 AM EST, 11/12/2024 (MT Newswires) -- AstraZeneca ( AZN ) and Merck ( MRK ) said Tuesday their phase 3 study of Koselugo in adults with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas demonstrated a "statistically significant and clinically meaningful" objective response rate against placebo.

Neurofibromatosis type 1 is a genetic condition in which about 30% to 50% of patients develop tumors on the nerve sheaths, the companies said.

The trial enrolled 145 adult participants who received Koselugo or placebo for 12 28-day cycles, the companies said.

Koselugo's safety profile in the trial was "consistent" and no new safety signals were seen, they added.

Shares of AstraZeneca ( AZN ) were down nearly 2% in recent premarket trading, while Merck ( MRK ) was little changed.

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