What is rentosertib?

Rentosertib is an experimental medicine being tested in people with idiopathic pulmonary fibrosis (IPF), a disease that scars the lungs. In the trial now running it is a tablet taken once a day. It is not licensed anywhere in the world, and it is not available in the UK.

What it is, in plain English

Rentosertib is a small chemical molecule, the kind that can be pressed into a tablet and swallowed. It is designed to block a single protein inside cells called TNIK, short for TRAF2- and NCK-interacting kinase, which is an enzyme that switches other proteins on and off. Insilico Medicine, the company that developed it, says TNIK sits above several of the biological signals that drive scarring in the lung. Whether blocking it slows that scarring in people is the question the current trial is designed to answer.

Names and codes

The medicine has three names you will see used interchangeably.

• Rentosertib is the international non-proprietary name. The USAN Council approved it in March 2025. The ending “-sertib” is the standard suffix given to serine/threonine kinase inhibitors. The first part comes from Feng Ren, Insilico Medicine’s co-chief executive and chief scientific officer, who was first author of the 2024 Nature Biotechnology paper describing the drug.
• ISM001-055 is the internal development code, used in most press coverage.
• INS018_055 is the code used in trial registries and in the Nature Biotechnology paper.

There is no brand name.

Who makes it

Insilico Medicine was founded in 2014 and has offices in Shanghai, Hong Kong, Abu Dhabi, Cambridge Massachusetts, New York and Montreal. It listed on the Hong Kong stock exchange (HKEX: 3696) on 30 December 2025.

Insilico owns rentosertib outright. Unlike several of its other programmes, it has never been licensed or sold to a larger pharmaceutical company, and Insilico is paying for the Phase III trial itself. That matters when you read results: the sponsor designed the trials, employs many of the authors and funds the analysis.

How it is taken in trials

In the Phase III trial, rentosertib is an oral tablet taken once a day, on top of whatever standard treatment a participant is already on. Earlier trials used capsules and tested twice-daily dosing as well.

A second version, a nebulised inhalation solution breathed into the lungs, is at a much earlier stage. Chinese regulators cleared it to begin human testing on 28 April 2026.

Where it is in development

The first patient in the Phase III trial, GENESIS-IPF-3, was dosed on 10 September 2026 at Peking Union Medical College Hospital in Beijing. The trial plans to enrol 320 people at 47 centres, all in China, and to follow them for 52 weeks. Estimated completion is October 2029.

Before that, a 71-person Phase 2a trial ran in China from 2023 to 2024. Its main purpose was safety, not proving benefit. The full results are on the Phase 2a page, including both the lung-function findings and the liver-related side effects that led several participants to stop treatment.

There is no application before the MHRA, and no UK or European trial site has ever existed.

Key facts