What happened

Shares of Pliant Therapeutics (PLRX -4.38%), a clinical-stage biotech company, are on the move following a clinical trial readout for its lead candidate, PLN-74809. Investors impressed with the positive results drove the stock 23% higher shortly after the market opened this morning. The stock was up 11.1% as of 11:23 a.m. EDT on Tuesday.

So what 

Pliant's developing PLN-74809 for people who experience progressive lung scarring that occurs for reasons medicine can't explain yet. Idiopathic pulmonary fibrosis (IPF) is lethal, but there aren't any available treatments to prevent its progression.

Crowd of cheering doctors.

Image source: Getty Images.

Treatment with PLN-74809 should disrupt a specific pair of proteins involved in the formation of scar tissue. The biotech stock is rising today in response to clinical trial data that says it did just this for a handful of IPF patients. 

All four patients evaluated with a PET scan showed more than 50% target engagement after receiving one dose. Two of the patients who received higher doses exhibited more than 90% target engagement. 

Now what

It's important to note that PLN-74809 is a novel drug candidate with an all-new mechanism of action. We still can't say for sure if the target is a valid one. We'll find out once the company reads out the results from an ongoing phase 2 trial called Integris-IPF.

The Integris-IPF study, meant to enroll 84 patients, began in March 2020 and is only treating patients for 12 weeks before measuring PLN-74809's ability to improve their lung capacity. If PLN-74809 had what it takes to quickly improve outcomes for people with this slowly progressing disease, I think we would have heard about it already. It's probably best to watch the next chapter of this risky drugmaker's story play out from a safe distance.