The (ASX: XJO) is continuing its positive run and pushing higher on Monday. In afternoon trade, the benchmark index is up 0.45% to 8,137.

4 points. Four ASX shares that have failed to follow the market higher today are listed below. Here's why they are falling: ( ) The Cettire share price is down 7% to $1.

47. Investors appear concerned what impact potential changes to duty-free thresholds in the United States could have on the online luxury products retailer's business model. According to the AFR, analysts at Barrenjoey estimate that the proposed legislation could disrupt Cettire's pricing advantage.

This could mean slower growth and lower margins than the market has been pricing in for the company. ( ) The Immutep share price is down 11% to 35.7 cents.

This morning, this clinical-stage biotechnology company announced positive efficacy and safety results from the TACTI-003 Phase IIb trial. It is evaluating eftilagimod alpha (efti) in combination with antiPD-1 therapy KEYTRUDA (pembrolizumab) as a first-line treatment of recurrent or metastatic head and neck squamous cell carcinoma patients. While the results were promising, they don't appear to have been strong enough to get the market excited.

( ) The Paladin Energy share price is down 3% to $9.08. This appears to have been driven by profit taking in the uranium industry after some strong gains last week.

In other news, this morning Paladin Energy revealed that the hearing to approve the acquisition of Fission Energy began on.