(Reuters) -U.S. drugmaker Regeneron Pharmaceuticals Inc ( REGN ) missed Wall Street estimates for first-quarter profit on Thursday due to softer sales of its blockbuster eye drug Eylea and its eczema treatment, Dupixent.

Excluding items, the company reported a profit of $9.55 per share for the quarter, compared with analysts' estimates of $10.09 per share, according to LSEG data.

Regeneron has been looking to switch Eylea patients to the high-dose version as the eye drug, which has long been its cash cow, faces the threat of biosimilars and fierce competition from rivals including Roche's Vabysmo.

Sales of Eylea, jointly developed with Bayer AG, was $1.40 billion in the reported quarter, including $200 million from the higher, 8 milligram dose version of the drug.

The high-dose Eylea sales figure was in line with estimates from JPM analysts.

Analysts were expecting $1.86 billion in total Eylea sales, according to LSEG estimates.

Regeneron posted total revenue of $3.15 billion, falling short of estimates of $3.22 billion.