(Reuters) - Fears of the demise of blockbuster eye drug Eylea were "greatly exaggerated," Regeneron Pharmaceuticals Inc's REGN.O chief executive said on Thursday, after the treatment and new eczema drug Dupixent powered the company's fourth-quarter results.

Investors have long fretted over Eylea's grip on the market, as the drug that has driven Regeneron's growth since 2011 faces a potential threat of rival treatments from Novartis AG NOVN.S and Roche Holding AG ROG.S.

But, Eylea would not face competition until late 2019 since rival products have so far been unable to improve on the drug’s effectiveness and safety profile, CEO Leonard Schleifer said on an earnings call.

“I think that right now Eylea may be the drug of choice, based on the safety and efficacy profile, to be treating anybody that I care about,” President George Yancopoulos said.

Eylea’s fourth-quarter U.S. sales increased nearly 14 percent to $975 million. That beat the consensus estimates of $960 million, according to brokerage Guggenheim.

Dupixent, a potential blockbuster that won U.S. approval last March, raked in sales of about $139 million, also topping consensus estimates of $122 million, according to Guggenheim.

Regeneron shares rose about 5 percent to $352.50 in early trading on Thursday, before giving up most of their gains by late morning.

With the uncertainty on Eylea’s future, Dupixent is viewed as Regeneron’s next driver and core to its strategy of investing in medicines with the potential to treat more than one disease.

Regeneron’s total revenue rose nearly 30 percent to $1.58 billion in the quarter ended Dec. 31.

A $381 million charge related to U.S. tax law reform led to a 31 percent drop in Regeneron’s net profit to $173.5 million. Excluding items, it earned $5.23 per share.

Analysts on average were expecting earnings of $4.53 per share on revenue of $1.51 billion, according to Thomson Reuters I/B/E/S.

The company said “unfair paperwork” for patients and doctors was weighing on insurer reimbursements for the eczema drug, Dupixent.

With Eli Lilly & Co LLY.N, Incyte Corp INCY.O, Pfizer Inc PFE.N and AbbVie Inc ABBV.N targeting the market, Regeneron is aiming for Dupixent to be approved to treat asthma this year.

It is also hoping to mark its foray into the field of immuno-oncology this year with the approval of cemiplimab as a skin cancer treatment.

Regeneron and French partner Sanofi SA SASY.PA said they would speed up development of the two drugs and invest about $1 billion more than planned on cemiplimab.