(Reuters) - Regeneron Pharmaceuticals ( REGN ) beat fourth-quarter sales and profit estimates on Tuesday, on continuing demand for its eczema treatment, Dupixent, and announced a dividend and stock buyback program, sending its shares up 2.2% premarket.

U.S. sales of Eylea, which has been its long-standing cash cow, rose by 2% to $1.5 billion, including $305 million from the higher 8-milligram dose version.

Analysts were expecting $1.77 billion in total Eylea sales, according to LSEG data.

Regeneron, which developed Eylea in collaboration with Bayer AG, seeks to upgrade the eye medication users to a high-dose version as the drug faces threats from biosimilars and rivals, including Swiss drugmaker Roche's Vabysmo.

Roche said last week it expects its adjusted per-share profit to increase at a high single-digit percentage this year, banking on strong demand for Vabysmo.

Regeneron said last month that overall Eylea sales benefitted by about $85 million from higher wholesaler inventory levels. However, the higher dose was negatively impacted by lower inventory levels and a lower net selling price compared to a year ago.

The Tarrytown, New York-based drugmaker's board also approved the initiation of a cash dividend program, which will continue on a quarterly basis, with 88 cents per share payable to shareholders on March 20.

It also announced an additional $3 billion share repurchase program, bringing total current capacity to around $4.5 billion.

Regeneron's total revenue of $3.79 billion beat analysts' expectations of $3.75 billion, as per LSEG-compiled data.

Sales of anti-inflammatory drug Dupixent rose 15% to $3.7 billion. The French partner, Sanofi, records Dupixent's sales and the profits are split equally between the companies.

Its skin cancer drug, Libtayo, brought in sales of $366.9 million, above estimates of $333.5 million. Regeneron bought the global rights to the cancer drug from partner Sanofi in 2022.

The company reported an adjusted profit of $12.07 per share in the quarter, above analysts' average estimate of $11.28.