NEW YORK (TheStreet) -- Regeneron Pharmaceuticals' (REGN) - Get Regeneron Pharmaceuticals, Inc. Report shares may have breached $500, but they're headed even higher, said TheStreet's Jim Cramer, portfolio manager of the Action Alerts PLUS portfolio, on CNBC's "Mad Dash" segment Wednesday.

The stock traded above $500 for the first time ever this week, and Cramer said investors are excited about a novel cholesterol formulation that the biotech company is "well ahead on."

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REGN data by YCharts

Cramer noted that analysts at Canaccord Genuity Wednesday raised their price target on Regeneron to $600.

Under CEO Leonard Schleifer, Regeneron has an "unbelievable" pipeline of drugs, he said.

Some observers think the company is a "one-trick pony" with its Eylea drug, Cramer said. "They have often made that mistake," he commented. "Regeneron goes higher."

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Cramer also said that criticisms of Schleifer over his compensation are unjustified, because the executive has taken the stock from $5 to $500.

"All he does is ... he works his butt off," Cramer said. "I mean the guy never stops. He never stops working for you!"

At midmorning Wednesday, shares of Regeneron were up $8.72, or $1.7%, at $512.87.

Elsewhere in the biotech sector, Sarepta's (SRPT) - Get Sarepta Therapeutics, Inc. Report shares were surging higher, Cramer noted. The stock closed at $16.38 Tuesday. By midmorning Wednesday, it roared upward by 51.2% to $24.77 after rallying in premarket trading.

Sarepta announced late Tuesday it was beginning the process of seeking regulatory approval for a treatment for Duchenne muscular dystrophy.

Cramer said he actually prefers BioMarin Pharmaceutical's (BMRN) - Get BioMarin Pharmaceutical Inc. Report entry for treating Duchenne muscular dystrophy.

At the time of publication, Cramer's Action Alerts PLUS had no position in companies mentioned.