Red-hot shares of

ImClone Systems

(IMCL)

cooled off Monday after a downgrade from SunTust Robinson Humphrey.

Despite positive data on Erbitux at the American Society of Clinical Oncology conference two weeks ago, analyst David Witzke downgraded ImClone to neutral from buy, telling investors the company had a lack of near-term catalysts. With ImClone's stock doubling so far this year as Erbitux continues to show promise, the analyst told investors to sell shares.

"There is a lot of good news already built into the stock and we recommend taking profits here following the most recent ImClone rally and the anticipated lull in price movement in the near term," said Witzke, in his note. (SunTrust does and seeks to do business with the companies covered in research reports.)

In reaction, shares of the company dropped 99 cents, or 1.2%, to $79.17.

Billionaire financier Carl Icahn recently disclosed that his stake in the biotech company had fallen below 5%. In a June 10 filing with the

Securities and Exchange Commission

Icahn said he held a 4.8% stake, or 3,656,399 shares. Icahn had previously reported that he held a stake of 6.9%. Shares were trading in the mid-forty range at that time in March.

While Witke recommends investors take some money off the table, he agreed that ImClone's prospects look better and said that Wall Street sales and earnings estimates will likely have to come up because of a strong Erbitux launch. But in order to show sustained growth down the road, the analyst warns that ImClone will have to beef up its pipeline, which could come at the expense of current shareholders.

"ImClone is looking to in-license late stage clinical candidates to fill in the hole in its pipeline between Erbitux and its preclinical candidate," said the analyst, "While this is a long-term positive, we believe it is almost certainly to be dilutive to earnings in the near term."