Endeavor BioMedicines announces that its Phase 2b WHISTLE-PF trial of taladegib met its primary and key secondary endpoints in 213 patients with idiopathic pulmonary fibrosis. The investigational Hedgehog signaling pathway inhibitor demonstrated statistically significant improvements in lung function and reductions in lung fibrosis compared to placebo. These findings suggest taladegib could become the first treatment to reverse the course of this progressive, fatal disease. Endeavor plans to engage with global regulatory authorities to discuss Phase 3 development.
Efficacy results of the WHISTLE-PF trial
- ▪The Phase 2b WHISTLE-PF trial of taladegib demonstrated statistical significance for multiple secondary endpoints, including reduced lung fibrosis and increased total lung capacity on quantitative high-resolution computed tomography imaging.
- ▪Endeavor BioMedicines stated that the Phase 2b WHISTLE-PF trial results support the potential of taladegib to reverse the course of idiopathic pulmonary fibrosis by reducing lung fibrosis and improving lung function.
- ▪Patients treated with taladegib in the Phase 2b WHISTLE-PF trial experienced a numerical, though not statistically powered, improvement compared with placebo in symptoms measured by the Living with Pulmonary Fibrosis Symptoms questionnaire.
- ▪Endeavor BioMedicines announced on October 8, 2026, that its Phase 2b WHISTLE-PF trial of taladegib met its primary endpoint, showing a statistically significant improvement in percent predicted forced vital capacity compared to placebo.
Design of the WHISTLE-PF trial
- ▪In the Phase 2b WHISTLE-PF trial, 73% of the 213 enrolled idiopathic pulmonary fibrosis patients used background standard-of-care treatment.
- ▪The Phase 2b WHISTLE-PF clinical trial was a 24-week, randomized, double-blind, placebo-controlled, dose-ranging trial that enrolled 213 patients with idiopathic pulmonary fibrosis across 74 sites in 14 countries.
Taladegib mechanism and safety
- ▪Taladegib is designed to block the Hedgehog signaling pathway, a cellular wound-healing pathway, by binding to and inhibiting a key receptor to eliminate aberrant scarring and potentially resolve the excessive wound-healing process in pulmonary fibrosis.
- ▪In the Phase 2b WHISTLE-PF trial, taladegib demonstrated a tolerability profile consistent with previous studies, with serious adverse events balanced between the placebo and taladegib arms.
Future plans for taladegib
- ▪Lisa Lancaster, M.D., Chief Medical Officer of Endeavor BioMedicines, stated that the company looks forward to presenting the WHISTLE-PF trial data at a future medical meeting.
- ▪Following the Phase 2b WHISTLE-PF trial results, Endeavor BioMedicines plans to engage with global regulatory authorities regarding plans for Phase 3 clinical development of taladegib.
Regulatory designations for taladegib
- ▪Taladegib is the first and only investigational idiopathic pulmonary fibrosis therapy to receive PRIority MEdicines designation from the European Medicines Agency.
- ▪Endeavor BioMedicines has received Orphan Drug Designation for taladegib from the U.S. Food and Drug Administration and the European Medicines Agency's Committee for Orphan Medicinal Products.
Idiopathic pulmonary fibrosis background
- ▪Current standard-of-care therapies for idiopathic pulmonary fibrosis only slow the decline of lung function but do not halt or reverse disease progression.
- ▪Idiopathic pulmonary fibrosis is a chronic, progressive lung disease affecting more than 150,000 adults in the United States, with an average life expectancy of only three to five years after diagnosis.
Debatable claims
- ▪Halting lung function decline is a more realistic goal for pulmonary fibrosis treatments than reversing it
- ▪Regulators should grant accelerated approval to taladegib based on Phase 2b results
- ▪Endeavor's Phase 2b data justifies claiming taladegib can reverse pulmonary fibrosis
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