BOSTON ( TheStreet) -- Adam Feuerstein's take on the biotech week that was Oct. 18, 2010:

The weekly shocker: U.S. regulators reject Amylin Pharmaceuticals' ( AMLN) diabetes drug Bydureon.

Not everyone was surprised by the Bydureon decision. Meet the short-seller who got Amylin right.

Amylin's Really Bad Day: Reader Mailbag.

The week's best-performing stocks in the sector: Clarient ( CLRT) (39%), Verenium ( VRNM) (21%), Pharmathene ( PIP) (21%), Aryx Therapeutics ( ARYX) (20%), Labopharm ( DDS) (15%).

Alexza Pharmaceuticals ( ALXA) and Valeant Pharmaceuticals ( VRX) part ways over the delayed AZ-004.

Generex Biotechnology ( GNBT.PK) exiled to the pink sheets.

Gilead Sciences ( GILD) earns 90 cents a share (adjusted) in the third quarter on total revenue of $1.94 billion, topping Street consensus.

Genzyme ( GENZ) forecasts 2011 earnings (adjusted) of $4.30-$4.60 a share, well above Street consensus of $3.85, and says Sanofi-Aventis ( SNY) is significantly undervaluing the company with its $69-a-share takeover offer. Based on the valuation multiple Sanofi is using today, Genzyme is worth $89 a share, Genzyme said.

Cell Therapeutics ( CTIC) issues press release about European regulatory sign-off on a plan to study pixantrone in children, then the company sells preferred shares convertible into 56.8 million common shares and warrants to raise $21 million.

This week's Biotech Stock Mailbag: Titan Pharma ( TTNP.OB), Mela Sciences ( MELA), AVI Biopharma ( AVII), Vanda Pharmaeuticals ( VNDA) and Savient Pharmaceuticals ( SVNT).

Transcept Pharmaceuticals ( TSPT) releases results from a highway driving study of its Intermezzo sleeping pill, plans to resubmit the drug to the FDA in the first quarter 2011.

The week's worst-performing stocks: Amylin Pharmaceuticals ( AMLN) (-46%), Alkermes ( ALKS) (-25%), Molecular Insight Pharmaceuticals ( MIPI) (-22%), Somaxon Pharmaceuticals ( SOMX) (-14%), Senesco Technologies ( SNT) (-13%).

Cubist Pharmaceuticals ( TSPT) sells $400 million in convertible debt.

A paragraph IV generic challenge was filed against Silenor, the sleeping pill recently launched by Somaxon Pharmaceuticals ( SOMX).

Alexion Pharmaceutials ( ALXN) announces positive, interim results from a pivotal study of Soliris in patients with atypical Hemolytic Uremic Syndrome. The company also reports third-quarter earnings of 50 cents a share on revenue of $141.6 million, topping Street consensus.

--Written by Adam Feuerstein in Boston.

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