ArriVent BioPharma stock declined sharply on Tuesday after the biopharmaceutical company published disappointing results for its lung-cancer drug.

Shares of ArriVent BioPharma plunged 54% to $13, on pace for its largest single-day decline on record, according to Dow Jones Market Data. The stock is down 36% this year and 64% from its all-time closing high of $35.63 set in November 2024.

In a Phase three clinical trial of ArriVent Biopharma's firmonertinib, the company said the treatment didn't meet its primary goal for progression-free survival. In other words: how long patients lived without their cancer getting worse.

Firmonertinib is a once-daily pill designed to block abnormal activity in a protein that can drive the growth of lung-cancer cells. The treatment is already approved for certain patients in China.

At a higher dose, patients went a median 11 months without their cancer worsening, compared with 9.5 months for chemotherapy, ArriVent BioPharma said. A lower dose resulted in median progression-free survival of 8.4 months.

The trial did provide some positive results. About 60% of patients receiving a higher dose of firmonertinib reported their tumors had shrunk, compared with 33% with chemotherapy.

While firmonertinib's latest results were "consistent" with previous clinical studies, they "didn't show a meaningful improvement" over chemotherapy, CEO Bing Yao said in a news release.

Yao noted the company would evaluate the full data set as it determines a development path for firmonertinib.