Prelude Therapeutics Says PRT3789 Shows 'Encouraging Signs' in Phase 1 Trial; Shares Fall

Prelude Therapeutics (PRLD) said Friday that interim data from a phase 1 trial of PRT3789 showed "encouraging signs of anti-tumor activity" in patients with SMARCA4-mutated non-small cell lung cancer and esophageal cancer.

"We are encouraged by the early clinical activity and emerging safety profile observed to date with PRT3789," said Jane Huang, president and chief medical officer. "These data represent initial proof of concept that selective SMARCA2 degradation can yield antitumor activity in certain SMARCA4 mutated cancers."

As of the data cutoff date, 65 patients were safety evaluable, enrolled and treated, the company said, adding that PRT3789 was generally well-tolerated with no dose-limiting toxicities or study drug-related serious adverse events.

Among 26 patients with advanced NSCLC or esophageal cancer who were heavily pre-treated, seven showed tumor shrinkage, the company said. Of the 20 patients with tumor types other than NSCLC and esophageal cancer, none demonstrated tumor shrinkage at dose levels studied to date, it added.

Shares of Prelude Therapeutics fell past 27% in recent trading.

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