NEW YORK ( TheStreet) -- Biotech stocks were in play in the small-cap space on Monday, with shares of Orexigen Therapeutics ( OREX) among the biggest gainers after it released data that showed that its diet drug Contrave did not increase blood pressure in obese and overweight patients. In February, regulators denied approval of the drug, saying they needed more clinical evidence that it did not pose cardiovascular risks to patients.

Shares were soaring 16% to $3.33. Vivus ( VVUS) also saw its stock surge after it said a study showed that its experimental weight-loss drug, Qnexa, helped patients sustain weight loss of greater than 10% over two years. The drug also helped cut down blood pressure while improving lipid levels. Shares were soaring 9% to $6.88 on volumes of over 10 million shares in noon trading.

Adeona Pharmaceuticals ( AEN), Pluristem Therapeutics ( PSTI) and Aastrom Biosciencies ( ASTM) were other stocks that were posting big gains Monday.

Shares of Epicor Software ( EPIC) jumped 11% to $12.50 after the company said it would sell itself to private-equity shop Apax Partners for $12.50 in cash.

Capstone Turbine ( CPST) saw its stock rise 5.6% to $2.05 after it received additional orders in the Russian and U.S. markets.

Shares of Westport Innovations ( WPRT) climbed more than 10% to $26.50. President Obama on Friday said that natural gas has an important role to play in the transportation sector and called upon members of Congress to pass a bill that will help achieve the goal of extracting natural gas in a safe, environmentally sound way and provide incentives to use clean-burning natural gas in vehicles instead of oil-based fuels.

Clean Energy Fuels ( CLNE) shares were also up 7% at $17.47.

Rare earth players Avalon Rare Metals ( AVL) and Rare Element Resources ( REE) were gaining 4% and 5.6%, respectively.

--Written by Shanthi Bharatwaj in New York

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