While quite a few pharma companies have reported earnings so far, Biogen Inc. BIIB is the only major biotech company to have released first quarter results. But this week, we will see a flurry of biotech companies announcing results with biggies like Amgen Inc. AMGN, Celgene Corporation CELG, Gilead Sciences Inc. GILD and Alexion Pharmaceuticals, Inc. ALXN reporting on Apr 28.Let’s see how these biotech stocks are poised ahead of the scheduled announcements.Gilead, known for its blockbuster hepatitis C virus treatments - Harvoni and Sovaldi - has an impressive earnings record having surpassed expectations all throughout 2015. This Zacks Rank #1 (Strong Buy) stock, which has a positive Earnings ESP of 1.65%, looks poised to beat expectations in the first quarter as well. The company’s HCV and HIV treatments will continue to drive the top line though investors will be keeping an eye on HCV market dynamics given the entry of a new competitor – Merck’s MRK Zepatier. Gilead also has a share buyback program in place that should boost the bottom line (Read more: Biotech Stock Gilead Likely to Beat in Q1 Earnings). Amgen is also likely to beat earnings in the first quarter because it has the right combination of two key ingredients -- Zacks Rank #3 (Hold) and a positive ESP. The company, which will be reporting results after the market closes on Apr 28, has a strong track record as well. Products like Enbrel, Xgeva, Vectibix, Sensipar, Prolia and Kyprolis should continue performing well and cost control and share buybacks should drive the bottom line (Read more: Amgen May Beat Q1 Earnings: Will the Stock Gain?). Alexion, scheduled to report first quarter results before the market opens on Apr 28, has a disappointing track record with the company missing expectations in three of the last four quarters. The Zacks Rank #3 (Hold) stock has an ESP of 0.00% for the first quarter thereby making it difficult to predict an earnings beat.The company had provided first quarter guidance at the time of releasing fourth quarter 2015 results. Focus will be on the performance of newly launched products – Strensiq and Kanuma (Read more: Alexion Q1 Earnings: What's in Store for the Stock?). Celgene, a Zacks Rank #2 (Buy) stock, will also be reporting first quarter results before the market opens on Apr 28. Celgene’s surprise history is generally good with the company surpassing expectations in two of the last four quarters. However, our proven model does not conclusively show that Celgene is likely to beat estimates in the first quarter (Read more: Celgene Q1 Earnings: What's in Store for the Stock?). Myriad issues have been plaguing the biotech sector which has been under immense pressure over the last few months thanks to the increasing political and media focus on high price tags for new drugs as well as the changing competitive scenario.Biosimilar competition in the U.S. is now a reality given the launch of Sandoz’s Zarxio (a Neupogen biosimilar) last year. Several companies are working on bringing biosimilar versions of multi-billion dollar revenue-generating products like Enbrel and Humira among others to market.But according to our Earnings Trend report, Medical is one of the sectors expected to perform well in the first quarter with earnings slated to grow 2% on revenue growth of 9%. So stay tuned and check later on our full write-up on earnings releases of these stocks!Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >> Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report MERCK & CO INC (MRK): Free Stock Analysis Report ALEXION PHARMA (ALXN): Free Stock Analysis Report GILEAD SCIENCES (GILD): Free Stock Analysis Report CELGENE CORP (CELG): Free Stock Analysis Report AMGEN INC (AMGN): Free Stock Analysis Report BIOGEN INC (BIIB): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research