Pliant Therapeutics (PLRX) shares were down almost 50% Monday after the company said it has ended its Beacon-IPF phase 2b trial of bexotegrast in idiopathic pulmonary fibrosis after an independent review found an imbalance in IPF-related adverse events between treatment and placebo groups.

Despite this safety concern, early data showed efficacy on forced vital capacity, the company said.

The study is the first late-stage IPF trial halted due to safety reasons while also demonstrating "strong" efficacy signals, it added.

The percentage of IPF-related adverse events in the active groups was around 10%, similar to the phase 2a Integris-IPF trial; however, the placebo group in Beacon-IPF showed a lower adverse event rate, driving the observed imbalance, according to the company.

Pliant Therapeutics said it will review the full dataset to better understand the benefit-risk profile and may plan new studies with lower doses for pulmonary fibrosis or other diseases, such as liver conditions.

Price: 1.75, Change: -1.69, Percent Change: -49.13