Rentosertib for Pulmonary Fibrosis

What did the rentosertib pulmonary fibrosis trial find?

Rentosertib inhibits TNIK, a protein involved in signaling associated with fibrosis. The randomized phase 2a trial, published in Nature Medicine in 2025, compared three dosing schedules with placebo. At 12 weeks, average forced vital capacity increased by approximately 98 milliliters with 60 milligrams once daily, versus a decline of approximately 20 milliliters with placebo. Lung function was a secondary endpoint. [Original clinical trial](https://www.nature.com/articles/s41591-025-03743-2)

Safety needs equal attention: treatment-related adverse events were more frequent with rentosertib, including liver-test abnormalities and diarrhea. Sixteen participants discontinued treatment across all groups. These findings support further investigation rather than a conclusion that lasting benefit has been established. [Trial results and safety findings](https://www.nature.com/articles/s41591-025-03743-2)

Does the new aging-marker analysis strengthen the treatment evidence?

The September 7 report appeared in Nature Biotechnology and examined stored blood samples from a subset of the original trial. Researchers applied six protein-based aging models and observed treatment-associated shifts toward younger predicted biological age. This was an additional analysis of existing participants, so it should not be counted as a separate trial confirming clinical effectiveness. [September biomarker study](https://www.nature.com/articles/s41587-026-03286-y)

The authors acknowledge that their analysis cannot fully separate changes related to lung disease from changes in aging itself. Several authors disclosed employment at the drug's developer, Insilico Medicine. The practical interpretation is that the findings generate hypotheses for future trials; they do not show that patients gained extra years of healthy life. [Study limitations and disclosures](https://www.nature.com/articles/s41587-026-03286-y)

What would stronger evidence mean for people with pulmonary fibrosis?

Idiopathic pulmonary fibrosis causes progressive scarring around the lungs' air sacs, making breathing increasingly difficult. Its course varies: some people deteriorate gradually, while others experience sudden worsening. That variability helps explain why an encouraging short-term measurement cannot describe the full experience of living with the disease. [NHLBI overview of pulmonary fibrosis](https://www.nhlbi.nih.gov/health/idiopathic-pulmonary-fibrosis)

Clinically, the next questions are whether any improvement persists, whether patients function better in daily life, and whether adverse effects remain manageable during longer treatment. Those are priorities for interpreting future research, not outcomes established by the current reports. Meanwhile, care can include antifibrotic medicines, pulmonary rehabilitation, oxygen when indicated and transplant assessment for selected patients. Patients considering research participation should discuss how a study fits alongside their existing treatment. [NHLBI treatment information](https://www.nhlbi.nih.gov/health/idiopathic-pulmonary-fibrosis/treatment)