BOSTON ( TheStreet) --Biotech earnings season kicks off in earnest this week with all four of the largest stocks in the sector -- Biogen Idec ( BIIB - Get Report), Gilead Sciences ( GILD - Get Report), Celgene ( CELG - Get Report) and Amgen ( AMGN - Get Report) --reporting third-quarter results this week.

Perhaps the most closely watched earnings report this week will come from Vertex Pharmaceuticals ( VRTX - Get Report), which will announce the first full quarter's worth of sales from its hepatitis C drug Incivek.

The Nasdaq Biotechnology Index (NBI) is up over 4% this year compared to a 1.5% loss for the S&P 500.

Click through the following pages for a summary of third-quarter earnings expectations and issues for each of the "Big Four" biotech stocks plus others reporting financial results this week.

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Amgen
Reporting date: Monday Aug. 24, after market close.
Current consensus: Adjusted earnings of $1.29 per share on total revenue of $3.87 billion.
The year-ago quarter: Amgen reported adjusted earnings of $1.36 per share on total revenue of $3.82 billion.
Key product details: If prescription data hold true, strong U.S. sales from Neulasta (consensus $735 million), Enbrel (consensus $880 million) and Xgeva (consensus $96 million) may help Amgen exceed financial expectations for the quarter.
On the conference call: More details, including cost savings guidance, resulting from Amgen's announcement last week that it was cutting 380 research jobs. The effect on sales of the anemia drugs Epogen and Aranesp following the FDA's decision to recommend lower doses when treating chronic kidney disease patients. Pipeline update on the phase III study of the melanoma drug Oncovex.
Current 2011 guidance: The upper end of the range of $15.1 billion to $15.5 billon, compared to the current consensus of $15.42 billion. Adjusted earnings in the upper end of the range of $5 per share to $5.20 per share. Current consensus is $5.21 per share.
Stock performance: Amgen's stock price has declined between 1-3% in each of the past four quarters despite earnings that have exceeded expectations.

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Cell Therapeutics ( CTIC - Get Report)
Reporting date: Tuesday Oct. 25, before market open.
Current consensus: A net loss of 9 cents a share on negligible revenue.
The year-ago quarter: A net loss of 12 cents per share on negligible revenue.
Key product details: Cell Therapeutics has no approved drugs to market.
On the conference call: Cell Therapeutics needs additional cash to fund drug development efforts and to pay for drug marketing expenses, if the company is ever able to get a drug approved. An update on efforts to get the long-delayed lymphoma drug pixantrone approved in Europe, where a regulatory opinion could be issued in the first quarter of next year. Cell Therapeutics is also expected to resubmit pixantrone for U.S. approval by the end of October.
Current 2011 guidance: None given.

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Celgene
Reporting date: Thursday Oct. 27, before market open.
Current consensus: Adjusted earnings of 94 cents per share on total revenue of $1.19 billion.
The year-ago quarter: Adjusted earnings of 75 cents per share on total revenue of $910.11 million.
Key product details: Revlimid sales consensus is $818 million. Abraxane sales consensus is $91 million.
On the conference call: Discussion of Revlimid prescription trends and an update on European approval for use in the front-line setting.
Current 2011 guidance: Adjusted earnings in the range of $3.45 to $3.55 per share on total revenue of $4.6 billion to $4.7 billion, which includes Revlimid sales of $3.15 billion to $3.25 billion.
Stock performance: Celgene beat and raised guidance in the second quarter but the stock fell 1%.

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Gilead Sciences
Reporting date: Thursday Oct. 27 after market close.
Current consensus: Adjusted earnings of $1.01 per share on total revenue of $2.12 billion. Total product sales of $2.03 billion.
The year-ago quarter: Adjusted earnings of 90 cents per share on total revenue of $1.94 billion.
Key product details: Worldwide HIV drug sales are expected to reach $1.73 billion for the quarter, including worldwide Truvada sales of $698 million and worldwide Atripla sales of $842 million.
On the conference call: Color on the new launch of the new HIV drug Complera plus updates on the company's HIV and hepatitis C drug pipeline. Further discussion of how budget cutbacks and the poor economy are affecting state government purchases of Gilead's HIV drugs.
Current 2011 guidance: Total product sales in the range of $7.9 billion to $8.1 billion. The current 2011 analyst consensus calls for Gilead to earn $3.94 a share (adjusted) on total revenue of $8.37 billion.
Stock performance: Better-than-expected results in the second quarter led to a small, 1% gain in the company's stock price, while a top- and bottom-line miss in the first quarter sent Gilead shares down 5%.

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Vertex Pharmaceuticals
Reporting date: Thursday Oct. 27, after market close.
Current consensus: Earnings of 17 cents per share on total revenue of $343.42 million. (Consensus earnings estimates do vary widely depending on which research service you use.)
The year-ago quarter: A net loss of $1.04 per share on total revenue of $23.8 million.
Key product details: Sales of the hepatitis C drug Incivek are what investors will focus their attention on the most. Current consensus is at $321 million although that number has changed almost daily and the "whisper number" is closer to $400 million.
On the conference call: Management's outlook on the Incivek launch with important discussion of recent prescription trends which have shown flattening growth for the hepatitis C drug. Updates on the commercial plans for the cystic fibrosis drug VX-770.
Current 2011 guidance: Total operating expenses (adjusted for cost of revenue and stock-based compensation) of $960 million to $980 million.

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Biogen Idec
Reporting date: Friday Oct. 28, before market opens.
Current consensus: Adjusted earnings of $1.52 per share on total revenue of $1.27 billion.
The year-ago quarter: Adjusted earnings of $1.35 per share on total revenue of $1.18 billion.
Key product details : Worldwide Tysabri end-user sales consensus of $396 million, broken down to U.S. sales of $188 million and ex-U.S. sales of $208 million. Worlwide Avonex sales consensus is $669 million.
On the conference call: Listen for discussion of Tysabri new patient adds, particularly outside the U.S. where a new test is being used to identify MS patients at the lowest risk for a serious Tysabri-related side effect. Also, update on regulatory plans for the experimental MS pill BG-12.
Current 2011 guidance: Revenue growth in the low to mid-single digits versus 2010. Adjusted earnings above $5.70 per share. Current consensus calls for Biogen to earn 5.88 per share on total revenue of $4.96 billion.

--Written by Adam Feuerstein in Boston.

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