Pliant Therapeutics’ idiopathic pulmonary fibrosis (IPF) candidate has impressed investors. With phase 2 data supporting more development, the biotech boasted a 60%-plus stock surge on Monday morning.
Across three dose levels, investigators treated 67 patients with PLN-74809, around 80% of whom were on Boehringer Ingelheim’s Ofev or Roche’s Esbriet. Safety, the primary endpoint, looks clean based on the information available, with no deaths or drug-related serious adverse events or discontinuations because of adverse events. Pliant reported dose-proportional increases in plasma concentrations, its top secondary endpoint.
Evidence of whether PLN-74809 helps patients comes from exploratory endpoints, one of which looked at changes in the respiratory health measure forced vital capacity (FVC). The pooled analysis of the three dose cohorts linked PLN-74809 to an 80% reduction in FVC decline at Week 12, with the treatment arm falling 15.1 mL versus a 74.1-mL drop in the placebo cohort.
The pooled analysis masks variation between the three treatment arms—and an inverse dose response between the two highest doses. FVC fell 46.1 mL at the 40-mg dose and 25.1 mL at the 160-mg dose. Yet, FVC increased by 24.6 mL relative to baseline in the 80-mg arm. Despite the result muddying the claims of a dose response, the principal investigator hailed the signs of efficacy as encouraging.
“IPF studies are challenging, as large samples sizes are usually required to detect a treatment effect,” Lisa Lancaster, M.D., professor at Vanderbilt School of Medicine, said in a statement. “The results from Integris-IPF are impressive, with PLN-74809 demonstrating a favorable safety profile and treatment effect both on and off standard of care therapy.”
Pliant has a chance to clear up the question of whether PLN-74809 causes dose-dependent changes in FVC when it shares data on the 320-mg cohort. Investigators recently completed enrollment in the 320-mg arm, putting the biotech on track to report interim 12-week data early next year. While working to gather the data, Pliant plans to share its existing results with regulators and discuss the next steps.
Shares in Pliant rose more than 60% in premarket trading, climbing to over $14. Investors moved the stock back up to a level last seen early in 2022 as they reassessed the chance of Pliant succeeding in an indication that has thwarted companies including Galapagos in recent years.