Down 87% since Friday, why is this ASX 300 healthcare stock sliding again today?

S&P/ASX 300 Index (ASX: XKO) healthcare stock Immutep Ltd (ASX: IMM) has been on a decidedly wild ride these past four trading days.

After entering a trading halt on Monday, 9 March, Immutep shares resumed trading last Friday. And by the time the closing bell sounded, the Immutep share price had crashed a very painful 88.6%.

Investors were overheating their sell buttons on the day, after the ASX 300 healthcare stock reported that the Phase III lung cancer study of its eftilagimod alfa (efti) product had been discontinued.

“We are very disappointed and surprised with the outcome of the futility analysis, in light of efti’s performance in every other clinical trial,” Immutep CEO Marc Voigt said at the time.

On Monday, bargain hunters swooped in, sending the Immutep share price up 35.6% by close. But a lot of those gains evaporated again on Tuesday, with shares closing the day down a sharp 16.4%.

See what I mean about a ‘decidedly wild ride’?

Now, here’s what’s happening today.

ASX 300 healthcare stock slides again

The Immutep share price is slumping again today, down 1.9% in morning trade at 5.1 cents. That sees the share price down 87.3% since exiting its trading halt on Friday, as investors appear to have lost confidence in the company’s outlook.

Today’s fall comes despite the company announcing positive results this morning from the first-in-human Phase I study in healthy participants evaluating IMP761.

According to the release, IMP761 is a first-in-class LAG-3 agonist antibody that enhances the physiological inhibitory function of LAG-3 on T-cell receptor signalling, potentially suppressing pathogenic T cell responses in autoimmune diseases.

(Quite a mouthful, I know!)

The ASX 300 healthcare stock reported that the single ascending dose portion of the study has been successfully completed. The drug was well tolerated across all dose levels, with no safety concerns or dose-limiting toxicities observed.

The study is now progressing in the multiple ascending dose portion, which is evaluating pharmacokinetics and safety across two dose levels. Immutep expects to complete this stage of the study in the third quarter of calendar year 2026.

What did management say?

Commenting on the new trial results that have yet to lift the ASX 300 healthcare stock today, Immutep chief scientific officer Frederic Triebel said:

IMP761 continues to show a clear immunosuppressive effect in healthy participants challenged with a foreign antigen in an intra-dermal reaction, with durable inhibition of T-cell–mediated responses after a single administration.

These first-in-human findings support our mechanistic aim of selectively silencing pathogenic, self-antigen–specific memory T cells via LAG–3 agonism and provide the basis for dose levels to be tested in a future phase II trial in patients with autoimmunity.

Immutep said it will present the results of the phase I trial at the European Alliance of Associations for Rheumatology annual congress in London on 4 June.

The post Down 87% since Friday, why is this ASX 300 healthcare stock sliding again today? appeared first on The Motley Fool Australia.

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Motley Fool contributor Bernd Struben has no position in any of the stocks mentioned. The Motley Fool Australia’s parent company Motley Fool Holdings Inc. has no position in any of the stocks mentioned. The Motley Fool Australia has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Scott Phillips.