Shares of Dimension Therapeutics Inc. (DMTX rose 9.5% to $4.60 in premarket trading on Monday, Sept. 18, after Ultragenyx Pharmaceutical Inc. (RARE - Get Report) made a bid to buy Cambridge, Mass.-based Dimension for $5.50 per share, or about $138 million, in cash. Dimension on Aug. 25 said it had agreed to sell to Regenxbio Inc. (RGNX - Get Report) in an all-stock deal for an implied value of about $3.41 per share.

"Our all-cash offer provides meaningfully greater value and certainty to Dimension shareholders compared to the proposed all-stock acquisition by REGENXBIO," said Ultragenyx president and CEO Emil D. Kakkis in a statement. "We believe Ultragenyx and its product candidates are highly complementary to Dimension's and present no competitive overlap, giving us confidence that we could combine our two companies quickly and seamlessly."

Novato, Calif.-based Ultragenyx said it would fund the purchase from cash resources on its balance sheet. The proposal is not legally binding upon Ultragenyx.

Meanwhile, shares of Nabriva Therapeutics plc (NBRV - Get Report) rose 89.5% to $13 after the firm unveiled positive topline results from a Phase 3 study of intravenous and oral lefamulin for the treatment of community-acquired bacterial pneumonia.

Other biotech stock movers include Pain Therapeutics Inc. (PTIE , up 10.3% to $4.29. The National Institute on Drug Abuse has awarded the Austin, Texas-based firm a $2.2 million research and development grant to develop Fenrock, a transdermal patch that containing prescription drug fentanyl to manage pain. Also on Monday, Pain Therapeutics said it was awarded a $1.8 million grant by the National Institutes of Health for a technology the company is developing to diagnose Alzheimer's disease with a blood test.

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