Biotech stocks improved over last week's dubious results on a better-looking Monday for the sector as the JPMorgan Healthcare Conference kicked off in San Francisco with opening presentations and announcements.

InterMune ( ITMN) rose after announcing that in early stage testing, its candidate ITMN 191, a monotherapy for patients with chronic Hepatitis C virus, met its goal. The company will progress to early stage testing of the drug in combination with standard of care.

The company, which is developing the drug with Roche, said that it's on track to announce top-line data and safety results from at least three doses in previously untreated patients as part of the ongoing MAD clinical study in the first quarter. Shares added $4.27, or 31.9%, to $17.64, helping to propel the Nasdaq biotechnology index, which was up 8.39, or 1%, at 831.17.

In other Hepatitis C treatment news, Pharmasset ( VRUS) was rising on Monday with postitive data for a short-term, early stage study on its hepatitis C candidate, R7128, for which it's also developing with Roche.

The company said that in a four-week, 50 patient trial of R7128 in combination with standard of care, 85% of patients given a 1,500 milligram dose and 30% given a 500 milligram dose had undetectable levels of the virus after four weeks. Safety and tolerability of the Pharmasset drug combination were comparable to placebo.

Shares rose $3.77, or 27%, to $17.76.

Elsewhere, updated guidance sent stocks both up and down. First up: Biogen Idec ( BIIB) said it now predicts 2007 earnings at the top end of the previously announced guidance range of $2.60 to $2.70 a share, or 16% to 20% annual growth. Analysts surveyed by Thomson Financial are looking for $2.62 a share.

Also upbeat about 2008, Biogen expects adjusted earnings in the range of $3.20 to $3.35, compared to the consensus target of $3.20 a share.

The company, which also announced positive patient and safety data on its multiple sclerosis drug Tysabri, gained $2.65, or 4.8%, to $57.87.

Emergent Biosolutions ( EBS) tacked on $1.70, or 33%, to $6.64, after issuing revenue guidance above the consensus. The Rockville, Maryland-based company is looking for 2007 revenue of $183 million, versus the consensus target of $180.82 million. Emergent is now looking for 2008 revenue above analysts' expectations--$180 to $195 million, in comparison to the $160.19 million consensus target.

The biopharmaceutical company said revenues will be driven by delivery of doses of anthrax vaccine BioThrax under its $448 million contract with the U.S. Department of Health and Human Services.

Meanwhile, Allos Therapeutics ( ALTH) gained $1.05, or 17.5%, to $7.20 after announcing that it began patient enrollment in a midstage trial comparing its PDX (pralatrexate) and Genentech ( DNA) and OSI Pharmaceuticals' ( OSIP) Tarceva in patients with stage IIIb/IV non-small cell lung cancer who smoke or have smoked cigarettes and who have tried at least one chemotherapy regimen unsuccessfully.

On the falling side, medical device company EV3 ( EVVV) was battered after giving guidance below expectations. The company said the results of its first quarter of combined operations with FoxHollow were below its expectations, due to problems merging the sales forces of the two companies, among other things. The company also said higher-than-anticipated inventory levels also badgered fourth quarter results, which is expected to affect the first quarter of 2008 as well.

As a result, the company now expects $92.2 million in the fourth quarter compared to analyst expectations of $107.61 million, and revenue of $107 million in the first quarter of 2008, compared to the Street expectations of $129.3 million. Additionally, the company is looking for revenue of $500 million in 2008, compared to the consensus target of $561.27 million.

EV3 gave up $1.91, or 15.7%, to $10.26.

LifeCell ( LIFC) also gave a financial forecast. The company reported fourth-quarter sales of $52.6 million, compared with $39.3 million in the comparable 2006 period. Analysts surveyed by Thomson Financial were looking for revenue of $50.1 million. Full year 2007 sales totaled $190.5 million, compared to $140.6 million in 2006 and the consensus target of $188.5 million.

The company said it expects full year net income of 98 cents a share to $1.06 a share on revenue of $233 million to $243 million, compared to the Thomson Financial consensus target of $1.06 a share on revenue of $232.4 million.

Shares were trading down $2.71, or 6.3%, at $40.52.