Pliant Therapeutics Halts Phase 2b/3 Lung Fibrosis Trial on Safety Concerns

In a significant setback for the biotechnology sector, Pliant Therapeutics has announced the suspension of its phase 2b/3 clinical trial for idiopathic pulmonary fibrosis (IPF) treatment. The decision, made on the recommendation of the trial's independent Data Safety Monitoring Board (DSMB), has sent ripples through the pharmaceutical industry, raising questions about the future of integrin inhibitors in fibrosis treatment.

Trial Suspension Details

The BEACON-IPF trial, which was evaluating bexotegrast, a dual selective inhibitor of αvβ6 and αvβ1 integrins, has been voluntarily paused by Pliant Therapeutics. The study was testing two doses of the drug—160 mg and 320 mg—against a placebo in a 52-week, multinational study. Prior to the suspension, the trial had been progressing well, with enrollment of the planned 360 patients expected to complete in the first quarter of 2025.

Pliant's CEO, Bernard Coulie, M.D., Ph.D., had previously expressed optimism about the trial's progress, noting in November that the "continued strong execution" of BEACON-IPF had been "a highlight to this quarter's progress." The company had anticipated sharing data from the trial in mid-2026.

Safety Concerns and Next Steps

The specific safety concerns that led to the trial's suspension have not been disclosed. Pliant stated that the pause in enrollment and dosing followed a prespecified review of the study's data by the DSMB. The company is now reviewing the data "to understand the DSMB's rationale for their recommendation."

In line with regulatory protocols, Pliant has informed BEACON-IPF clinical trial investigators and is in the process of notifying global regulatory authorities about the trial suspension. The lack of specific information regarding the safety issues has left many in the industry speculating about the nature and severity of the concerns.

Implications for Pliant and the Broader Industry

This setback comes at a crucial time for Pliant Therapeutics. The company had previously reported promising phase 2 data for bexotegrast in primary sclerosing cholangitis, a liver condition characterized by inflammation and scarring of bile ducts. The 320 mg dose had shown safety and efficacy in slowing disease progression in that trial.

The suspension of the BEACON-IPF trial raises questions about the broader applicability of bexotegrast and similar integrin inhibitors in fibrosis treatment. It also highlights the unpredictable nature of drug development, particularly in complex diseases like IPF.

As the pharmaceutical industry closely watches for further developments, this event serves as a reminder of the rigorous safety standards upheld in clinical trials and the critical role of independent monitoring boards in safeguarding patient well-being.