The S&P/ASX 200 Index (ASX: XJO) is on course to record a small gain. In afternoon trade, the benchmark index is up 0.2% to 7,698.4 points.

Four ASX shares that are rising more than most today are listed below. Here's why they are racing higher:

The Argosy Minerals share price is up 10% to 14.3 cents. This morning, this lithium developer announced that it has received government approval for the development of its 10,000tpa lithium carbonate expansion operation at the Rincon Lithium Project in Argentina. This means that the company now has the thumbs up to increase its production to 12,000tpa. Management said: "This significant milestone further confirms Argosy's ambitions and near-term growth phase to fully develop the Rincon Lithium Project."

The Immutep share price is up 10% to 42.5 cents. This follows the release of the preliminary top-line results from Cohort B of the TACTI-003 Phase IIb trial evaluating eftilagimod alpha (efti) in combination with Keytruda. The trial is for the first-line treatment of recurrent/metastatic head and neck squamous cell carcinoma patients with negative PD-L1 expression. Management declared the results as "positive".

The Pointsbet share price is up 5% to 83.2 cents. Investors have been buying this sports betting company's shares following the release of its third-quarter update. PointsBet reported a 7% increase in turnover to $676.4 million and a 24% lift in total net win to $70.6 million. In addition, the company announced plans to return $127 million or $0.39 per share to shareholders via a capital return. This follows the sale of its US business, which completed earlier this month. PointsBet's shares will trade ex-capital return on Tuesday 30 April. Eligible shareholders will then be paid this capital return on 16 May.

The Regis Resources share price is up 2.5% to $2.16. This follows the release of the gold miner's quarterly update this morning. Regis Resources reported gold production of 90,600 ounces at an all-in sustaining cost (AISC) of $2,735 per ounce. This includes a $234 per ounce non-cash inventory adjustment. Pleasingly, management has been able to maintain its FY 2024 guidance despite the impact of substantial and protracted regional wet weather. The gold miner expects gold production of 415,000 ounces to 455,000 ounces with an AISC of $1,995 per ounce to $2,315 per ounce. The latter includes a ~$200 per ounce non-cash inventory adjustment.