Shares of the following companies are actively trading in the pre-market hours Thursday on Nasdaq. The companies are Dendreon, Entropic Communications, Cadence Pharma, Zipcar, On Assignment, GT Solar and Randgold Resources.

Losers

Shares of Dendreon Corp. (NASDAQ:DNDN) plunged 63 percent after the biotechnology company withdrew its 2011 sales forecast citing reimbursement issues over its prostate cancer drug Provenge.

"We believe the market potential for Provenge is substantial, and the primary issue affecting the dynamics of our launch is the reimbursement knowledge around PROVENGE. We anticipate the positive National Coverage Determination (NCD) and Q-code will have a significant impact on increased physician adoption," said Mitchell Gold President and CEO.

"However, we believe this will take time, and for the remainder of 2011, the launch trajectory will reflect a more gradual adoption of Provenge as physicians gain confidence in this positive reimbursement landscape," Gold added.

Entropic Communications Inc. (NASDAQ:ENTR) shares fell 25 percent after it reported lower-than-expected quarterly results. San Diego, California-based company earned quarterly profit of $7.80 million or 9 cents per share, up from $3.10 million or 4 cents per share in the prior-year quarter. Net revenues rose 51 percent to $61.50 million. Analysts polled by Thomson Reuters expected the company to earn 18 cents a share on revenue of $65 million.

Shares of Cadence Pharmaceuticals Inc. (NASDAQ:CADX) plunged 15 percent after it reported wider quarterly loss. For the second quarter, the company reported a net loss of $19.2 million, or 30 cents per share, compared to a net loss of $12.2 million, or24 cents per share last year.

Shares of Spectrum Pharmaceuticals, Inc. (NASDAQ:SPPI) lost 9 percent after its second-quarter profit missed Wall Street expectations. The company reported a profit of 12 cents a share, compared to a loss of 20 cents a share last year. Analysts had expected a profit of 15 cents a share.

Gainers

Shares of Zipcar Inc. (NASDAQ:ZIP) rose about 12 percent after it reported a narrower loss for the second quarter. The company reported a second quarter GAAP loss of 17 cents per, compared to the loss of 95 cents per share in the prior year.

On Assignment, Inc. (NASDASQ: ASGN) shares surged 10 percent on strong second-quarter performance. Net Income was $5.9 million, or 16 cents per share compared with $0.9 million, or 3 cents per share, in the second quarter of 2010. Revenues rose 38 percent to $143.7 million.

Shares of GT Solar International, Inc. (NASDAQ:SOLR) gained 6 percent after its first-quarter profit topped Street view on strong revenue growth. The maker of solar and LED equipment reported net income of $52.07 million or 41 cents per share, up from $16.50 million or 11 cents per share for the year-ago quarter. Revenue for the quarter surged 71 percent to $231.10 million. Analysts expected earnings of 31 cents per share on revenue of $225.98 million for the quarter.

Shares of Randgold Resources Ltd (NASDAQ:GOLD) were up 5 percent on higher quarterly profit. Quarterly earnings per share were $1.22, higher than 38 cents in the prior-year quarter. Total revenues rose to $321.16 million from $102.57 million in the previous year.